What do you think of this?
I think the debate about climate change should be dispassionate. That is not easy when we are talking about issues such as climate change, Emission Trading Schemes, clean coal, global targets, and the future of Earth’s climate.
Here is an attempt to explain why I think the science of anthopogenic climate change is compelling. I have used several graphs which demonstrate clear trends in atmospheric CO2, global temperatures, sea level rise, melting ice, ocean acidity and ocean temperatures. All graphs reflect direct measurements.
(Note: Click on any graph to enlarge it]
What can we all agree on?
There are 5 crucial points in the climate change debate that I think we can all agree on.
Natural process has driven Earth’s climate since the birth of the planet, and there have been massive natural climate shifts shifts over geological time periods. Natural forces will continue to shape Earth’s climate until the end of time.
Atmospheric CO2 is rising, and is higher now than it has been for at least the last 800 000 years. CO2 is a greenhouse gas.
The planet is warming. The Earth is warmer now than it was 100 years ago.
A doubling of atmospheric CO2 will cause at least some global warming.
Atmospheric CO2 concentrations may double by the end of the century.
I don’t think the argument is about climate change. I think the debate is about the extent of the problem, and its cause. I can’t prove that humans are causing climate change, or that climate change will be a threat. I don’t think you can prove anything in science. However, I can provide convincing and compelling evidence.
Atmospheric CO2 is going up
The Mauna Loa station on Hawaii has been monitoring atmospheric CO2 since the 50’s. They have noted a steady rise in atmospheric CO at a rate of about 2 parts per million per year. The graph is getting steeper. Atmospheric CO2 is currently 30% higher than it has been for at least the last 600 000 years.
CO2 has been removed from the atmosphere over the course of hundreds of millions of years by the formation of fossil fuels (oil, coal and natural gas). If we keep going at the current rate, all of that fossil fuel will be burnt, and CO2 released back into the atmosphere, over a three hundred year period. Surely, that will upset the finely tuned balance of the carbon cycle, and it makes intuitive sense to think that 7 billion tonnes of human CO2 emissions each year will have an effect of atmospheric levels of CO2.
I think that most would agree that rising atmospheric CO2 is due to human dependance on fossil fuel. The critical is what will be the effect of that rising CO2 on global temperature, noting that CO2 is about to get a lot higher.
How significant is CO2 as a greenhouse gas?
Atmospheric CO2 has not been above about 280 ppm for the last 400 000 years
Atmospheric CO2 is currently 30% higher than it has been for the last 400 000 years. Below is a graph of atmospheric CO2 over the last 1000 years, demonstrating the accelerating rise in atmospheric CO2, taken from the CSIRO web site The Vostok ice core is a cylinder of ice collected by drilling from the surface to near the bottom of the Antarctic ice sheet. Total length was 2083 meters, brought back in 4-6 meter sections. The core shows annual layers, which can be used to date the air bubbles trapped in the ice. Analysis of the gas content of the bubbles gives the concentration of carbon dioxide in the atmosphere when the ice formed. Ratios of oxygen isotopes and deuterium gives air temperature at the station at the time ice was formed.
We can now look back in time further than 800 000 years. Dr Tripati, from UCLA is part of a research team that developed a new technique to assess carbon dioxide levels in the much more distant past — by studying the ratio of the chemical element boron to calcium in the shells of ancient single-celled marine algae. Tripati has now used this method to determine the amount of carbon dioxide in Earth’s atmosphere as far back as 20 million years ago. “A slightly shocking finding,” Tripati said, “is that the only time in the last 20 million years that we find evidence for carbon dioxide levels similar to the modern level of 387 parts per million was 15 to 20 million years ago, when the planet was dramatically different.”
It has been known that modern-day levels of carbon dioxide are unprecedented over the last 800,000 years, but the finding that modern levels have not been reached in the last 15 million years is new.
In the last 20 million years, key features of the climate record include the sudden appearance of ice on Antarctica about 14 million years ago and a rise in sea level of approximately 75 to 120 feet.
“We have shown that this dramatic rise in sea level is associated with an increase in carbon dioxide levels of about 100 parts per million, a huge change,” Tripati said. “This record is the first evidence that carbon dioxide may be linked with environmental changes, such as changes in the terrestrial ecosystem, distribution of ice, sea level and monsoon intensity.”
Global temperatures are going up
This graph demonstrates annual global temperatures from 1850 to 2008, as provided by the Hadley Met Office in Britain. For those concerned about climate change, this graph demonstrates a clear warming trend. For those who are sceptical, this very same graph is used to demonstrate a definite cooling trend since 1998. How can that one be sorted out?
1998 was the hottest year on this graph. The years since have been less hot. Does that represent a cooling trend?
1998 was a strong El Nino year, whilst 2008 was a strong La Nina year. Despite the cooling effect of the La Nina, 2008 was still the 10th hottest year ever recorded. In fact, the 10 hottest years ever recorded have been the last 10 years. The Hadley Met Office state that their records show an unequivocal warming rate of 0.2 degrees per decade.
The climate system is inherently chaotic and non linear. If rising CO2 is causing warming, you would not possibly expect there to be a straight line correlation when you consider the complexity of the climate system.
What has caused the last 10 years to be the hottest 10 years since records began? It doesn’t seem to be the sun.
Hadley Met Office again
The time series shows the combined global land and marine surface temperature record from 1850 to 2008. The year 2008 was tenth warmest on record, exceeded by 1998, 2005, 2003, 2002, 2004, 2006, 2001, 2007 and 1997.
The 1990s were the warmest complete decade in the series. The warmest year of the entire series has been 1998, with a temperature of 0.546°C above the 1961-90 mean. Thirteen of the fourteen warmest years in the series have now occurred in the past fourteen years (1995-2008). The only year in the last fourteen not among the warmest fourteen is 1996 (replaced in the warm list by 1990). The period 2001-2008 (0.43°C above 1961-90 mean) is 0.19°C warmer than the 1991-2000 decade (0.24°C above 1961-90 mean).
If you look at the data and sort of cherry-pick a micro-trend within a bigger trend, that technique is particularly suspect,” said John Grego, a professor of statistics at the University of South Carolina.
The ups and downs during the last decade repeat random variability in data as far back as 1880.
“The last 10 years are the warmest 10-year period of the modern record,” said NOAA climate monitoring chief Deke Arndt. “Even if you analyze the trend during that 10 years, the trend is actually positive, which means warming.”
The cooling trend disappears if the analysis starts in 1997. And it trends upward if you begin in 1999, he said.
“To talk about global cooling at the end of the hottest decade the planet has experienced in many thousands of years is ridiculous,” said Ken Caldeira, a climate scientist at the Carnegie Institution at Stanford.
Satellite Measurement of Global Temperature
Satellite data have been collected for the upper air since 1979 with almost complete global coverage.
Previously reported discrepancies between the amount of warming near the surface and higher in the atmosphere have been used to challenge the reliability of climate models and the reality of human- induced global warming. Speciﬁcally, surface data showed substantial global-average warming, while early versions of satellite and radiosonde data showed little or no warming above the surface. This signiﬁcant
discrepancy no longer exists because errors in the satellite and radiosonde data have been identiﬁed and corrected. New data sets have also been developed that do not show such discrepancies.
• For observations since the late 1950s the most recent versions of all available data sets show that both the surface and troposphere have warmed, while the stratosphere has cooled. These changes are in accord with our understanding of the effects of radiative forcing agents and with the results from model simulations.
• Since the late 1950s, all radiosonde data sets show that the low and mid troposphere have warmed at a rate slightly faster than the rate of warming at the surface. These changes are in accord with our understanding of the effects of radiative forcing agents on the climate system and with the results from model simulations.
• For observations during the satellite era (1979 onwards), the most recent versions of all available data sets show that both the low and mid troposphere have warmed. The majority of these data sets show warming at the surface that is greater than in the troposphere. Some of these data sets, however, show the opposite – tropospheric warming that is greater than that at the surface. Thus, due to the considerable disagreements between tropospheric data sets, it is not clear whether the troposphere has warmed more than or less than the surface.
• The most recent climate model simulations give a range of results for changes in global-average temperature. Some models show more warming in the troposphere than at the surface, while a slightly smaller number of simulations show the opposite behavior. There is no fundamental inconsistency among these model results and observations at the global scale.
• Studies to detect climate change and attribute its causes using patterns of observed temperature change in space and time show clear evidence of human influences on the climate system (due to changes in greenhouse gases, aerosols, and stratospheric ozone).
• The observed patterns of change over the past 50 years cannot be explained by natural processes alone, nor by the effects of short-lived atmospheric constituents (such as aerosols and tropospheric ozone) alone.
Information taken from the US Climate Change Science Program (CCSP)
The sun is not getting brighter
No one denies that the single most important determinant of global temperature is the brightness of the sun and the Earth’s proximity to it. The Sun is a massive nuclear fusion reactor a million times larger than Earth. The sun is responsible for almost all the energy reaching our planet, and in the past few decades scientists have learned that solar activity varies over time. Surely it must have a large impact on our changing climate.
What does the science say? The brightness of the sun certainly varies with time. On timescales that vary from millions of years through to the more familiar 11-year sunspot cycles, variations in the amount of solar energy reaching Earth have a huge influence on our atmosphere and climate. Sun spots are important. In simple terms, sun spots correlate with solar brightness, and there is an 11-year sunspot cycle. Comparing solar brightness (total solar irradiance or TSI) to global temperatures reveals that although TSI and temperatures both followed similar trajectories prior to the early 1970s, they have diverged significantly since then, with trends in TSI remaining relatively flat while temperature increases have accelerated. Something other than the sun must be influencing a warming planet. Several review articles in Nature and New Scientist indicate that brightening of the Sun is unlikely to have had a significant influence on global warming since the 1970’s.
A recent study and review of existing literature (“Variations in solar luminosity and their effect on the Earth’s climate”. Nature 443 (7108): 161–166) suggests that the evidence is solidly on the side of solar brightness having relatively little effect on global climate over recent decades. The consensus amongst climate scientists is that solar variability could have been an important driver of climate warming until the mid 20th century, but since then the warming has been far too rapid to be significantly accounted for by this.
The bottom line is that any study on solar brightness that I can find shows that there has been no net increase in solar brightness since the mid 1970s.
Trend or fluctuation?
One man’s trend is another man’s fluctuation. If rising levels of atmospheric CO2 are driving global warming, would you expect a straight line correlation between atmospheric CO2 and global temperature? You would if CO2 was the only factor influencing global temperatures. However, it is not. Of course all the natural forces that determine global temperature are still working.
If 1998 was the hottest year ever recorded, and if the years since then have been less hot, could that be due to natural process, or does it mean that CO2 levels in the atmosphere are irrelevant?
It is possible that 1998 was the hottest year because of a combination of anthropogenic climate change and a strong El Nino year. It is possible that 2008 went against the trend because of a strong La Nina event.
Despite 2008 being a La Nina year, it was still the 10th hottest year ever recorded.
This graph is from HadCRUT and R. F. Keeling et al, Carbon Dioxide Research Group, Scripps Institution of Ocenography. It shows a non-linear relationship between atmospheric CO2 and global temperatures. According to this graph, thereis a strong relationship between CO2 and temperature.
Sea level is rising
Sea level has been rising since the end of the last ice age. As ice sheets disintegrated, around 10,000 years ago, sea levels started to rise. Around 2000 years ago sea level rise had almost stopped, and from 1000 years ago to the late 19th century, sea level was relatively stable, varying by less than 0.2m over the whole period. Since the mid-19th century, sea level has started to rise again. It has been rising at a rate that has not been experienced for the past 5000 years. Most of this rise comes from warming of the world’s oceans and melting of mountain glaciers, which have receded dramatically in many places especially during the last few decades.
The Australian National Tidal Centre has been monitoring sea level change from 14 stations around Australia . Using SEAFRAME (Sea-Level Fine Resolution Acoustic Measuring Equipment) and historical tide records, their results are consistent with other observations around the world. From 1961-2003 they identify a 1.8mm per year sea level rise, but from 1993-2003 that had increased to around 3.1mm/year sea level rise. Since 1993, this figure has been backed up by data from the TOPEX/POSEIDON satellite altimeter. That equates to a 30 cm sea level rise by the end of the century, assuming that global warming is kept in check. Given that atmospheric CO2 continues to rise, and that the hottest 10 years ever recorded have been the last 10 years from 1998 to 2008, I think it can safely be assumed that the planet will continue to warm. That suggests we face an average sea level rise of more than 30 centimetres by the end of the century.
To dismiss sea level rise as alarmist is to ignore direct scientific observation. The oceans also appear to be warming.
The oceans are warming
The average water temperature worldwide was 62.6 degrees F, according to the National Climatic Data Center (2/9/09), the branch of the U.S. government that keeps world weather records. June was only slightly cooler, while August could set another record, scientists say. The previous record was set in July 1998 during a powerful El Nino weather pattern.
At a full degree above the 20th century average of 61.5 degrees, “the global ocean surface temperature for July 2009 was the warmest on record,” the center said.
Large portions of many continents had substantially warmer-than-average temperatures, the center stated.
“The greatest departures from the long-term average were evident in Europe, northern Africa, and much of western North America,” according to the National Oceanic and Atmospheric Administration, which oversees the center. “Broadly, across these regions, temperatures were about 4-7 degrees F above average.”
Goddard Institute for Space Studies graph of land and ocean temperatures. There is a significant inertia in the warming of the oceans, and ocean temperature trends have poorer historical records than atmospheric temperature measurements. The ARGOS buoy system will lead to more precise records of global ocean temperature trends. They have only been deployed since 2002, so it is too early to draw long term trend conclusions.
The Southern Oscillation and increasing GHGs continue to be, respectively, the dominant factors affecting interannual and decadal temperature change. Solar irradiance has a non-negligible effect on global temperature. Given our expectation of the next El Nino beginning in 2009 or 2010, it still seems likely that a new global temperature record will be set within the next 1-2 years, despite the moderate negative effect of the reduced solar irradiance. [Goddard Institute for Space Studies]
The oceans are becoming more acidic
The Royal Society of London published a report Ocean acidification in 2005, which summarised the salient points:
-Carbon dioxide from the atmosphere dissolves in the ocean making it more acidic.
-This is inevitable with high carbon dioxide, no fancy models are involved.
-The oceans have already become 30% more acidic than before fossil fuel burning started.
-Acidification will kill corals, and destroy other marine life.
-There has been no period like this in the past 2 million years.
Laboratory experiments have shown that reductions in oceanic pH will profoundly impair the ability of hard-bodied plankton to build their calcite shells. This in turn impairs the ability of the oceans to sequester CO2, as less shells means less limestone being formed on the ocean floor, and so less CO2 being sequestered. This is a positive feedback loop, something that computer modelling struggles with.
The North Pole icecap is melting
Including March 2009, the past six years have all had ice extent substantially lower than normal. The linear trend indicates that for the month of March, ice extent is declining by 2.7% per decade, an average of 43,000 square kilometers (16,000 square miles) of ice per year. (Nat. Ice Centre Data)
The satellite data is part of a longer trend in diminishing Polar Sea Ice. A mixture of anecdotal accounts of ice extent and instrumental measurements suggest that by the mid-twentieth century the Arctic had warmed to its highest temperature since instrumental records began in 1840. That warming trend is continuing. (Overpeck,J.T. et al, ‘Arctic Environmental Change of the Last Four Centuries’, Science)
The melting of the Arctic will not contribute directly to sea level rise. Ground based ice in Greenland and the Antarctic WILL contribute to sea level rise if it melts. The melting of the Arctic Polar Cap will lead to a reduced albedo, and the darker exposed ocean will absorb more radiant energy from the sun. A warming Arctic Oceon may well influence the melting rate of the Greenland ice sheet.
New NOAA Web site tracks Arctic sea ice loss www.arctic.noaa.gov/future/
Greenland is melting
Greenland is the world’s second largest ice sheet. It is about as big as NSW, Queensland, and the NT put together, and the thickness of the ice is generally about 2 km. The coastline of Greenland is 39,330 km long, about the same length as the Earth’s circumference at the Equator. Because Greenland’s ice sheet is on land, any melting will contribute to sea level rise, and if all the ice melted it would lead to a 7m sea level rise.
While Arctic temperatures have generally increased, there is some discussion over the temperatures over Greenland. First of all, Arctic temperatures are highly variable, making it difficult to discern clear trends at a local level. Also, until recently, an area in the North Atlantic including southern Greenland was one of the only areas in the World showing cooling rather than warming in recent decades, but this cooling has now been replaced by strong warming in the period 1979-2005.
The critical question concerning Greenland is how fast is the ice melting? A new study published in the journal Science reveals that global warming is melting Greenland’s ice sheet three times faster than scientists had thought. Research had indicated that global warming was melting the ice sheet at 80 cubic kilometres a year. But new GRACE satellite data shows the ice sheet is now disappearing three times faster than scientists had thought.
The Gravity Recovery and Climate Experiment (GRACE) satellite measures changes in the Earth’s gravity field and found that from February 2003 to January 2008, Greenland lost mass at a rate of 179 Gigatonnes per year. This is equivalent to a global sea level rise of 0.5 mm per year. The rate is also increasing over time, suggesting an acceleration of mass loss.
Time series of the monthly GRACE data between February 2003 and January 2008, for the entire Greenland ice sheet.
The interior of Greenland (>2000 m) shows a statistically insignificant positive trend in ice cover and appears to be in mass balance.
What GRACE shows is that the Greenland interior is in mass balance but losing mass around the coastal regions. This equates to an overall mass loss. On average, Greenland contributed 0.5 ± 0.1 mm/yr to global mean sea level rise between 2003 and 2008. Trends are increasingly negative, partly due to the record mass loss during the summer of 2007, when mass loss occurred also at high elevations.
New study of Greenland under “more realistic forcings” concludes “collapse of the ice-sheet was found to occur between 400 and 560 ppm” of CO2
The Antarctic ice cap is both shrinking and growing
Three things determine the size of an ice sheet. The first is how much precipitation as snow falls on the ice sheet, leading to accumulation. The second is how quicly the ice melts, leading to degredation of the ice sheet. The third is how quickly the ice sheet flows towards the ocean, leading to calving, the formation of icebergs.
In Greenland and the North Pole, conditions are clearly in favor of mass loss of ice. Ice is melting faster than snow is falling. Things are more complicated at the South Pole. East Antarctica is increasing in size, whilst West Antarctica is decreasing.
Antarctica is a unique place, and there is a reason why it behaves differently to the Northern Himisphere ice sheets.
Antarctica (1.3 times the size of Europe) is the coldest, driest and windiest continent on earth. Antarctica is divided into East and West by the Transantarctic Mountains, and the continent contains about 90% of the world’s ice. On average, the Antarctic ice sheet is 1.6 km thick, but in parts of the East Antarctic reaches a staggering thickness of 4 km. The reason why things happen differently in Antarctica is because it is so cold, much colder than the North Pole or Greenland. It is cold because it is high. Antarctica has the highest elevation of all continents. It is TWICE as high as the continent of Europe, and has 27 peaks higher than Mt Koscioscko. The coldness of Antarctica means that there are very few days that get above 0 degrees, and it will have to get a lot warmer before there are a significant number of days above zero.
Scientists have been debating whether the Antarctic ice sheet is expanding or shrinking overall, because the center of the sheet tends to gain mass through snowfall whereas the coastal regions are more vulnerable to melting. Analysis shows that Antarctic surface temperatures increased an average of 0.12°C per decade between 1957 and 2006. That’s a rise of more than 0.5°C in the last half century. West Antarctica warmed at a higher rate, rising 0.17°C per decade. The results, published Jan. 22 in Nature, confirm earlier findings based on limited weather station data and ice cores. While some areas of East Antarctica have been cooling in recent decades, the longer 50-year trend depicts that, on average, temperatures are rising across the continent.The new Antarctic measurements, using data from two NASA satellites called the Gravity Recovery and Climate Experiment (GRACE), found that the amount of water pouring annually from the ice sheet into the ocean is causing global sea level to rise by 0.4 millimeters a year.
West Antarctica is particularly vulnerable to climate changes because its ice sheet is grounded below sea level and surrounded by floating ice shelves. If the West Antarctic ice sheet completely melted, global sea level would rise by 5-6 meters.
British Antarctic Survey
Increased growth in Antarctic sea ice during the past 30 years is a result of changing weather patterns caused by the ozone hole according to new research published this week (Thurs 23 April 2009).
Reporting in the journal Geophysical Research Letters scientists from British Antarctic Survey (BAS) and NASA say that while there has been a dramatic loss of Arctic sea ice, Antarctic sea ice has increased by a small amount as a result of the ozone hole delaying the impact of greenhouse gas increases on the climate of the continent.
“Our results show the complexity of climate change across the Earth. While there is increasing evidence that the loss of sea ice in the Arctic has occurred due to human activity, in the Antarctic human influence through the ozone hole has had the reverse effect and resulted in more ice. Although the ozone hole is in many ways holding back the effects of greenhouse gas increases on the Antarctic, this will not last, as we expect ozone levels to recover by the end of the 21st Century. By then there is likely to be around one third less Antarctic sea ice.”
Using satellite images of sea ice and computer models the scientists discovered that the ozone hole has strengthened surface winds around Antarctica and deepened the storms in the South Pacific area of the Southern Ocean that surrounds the continent. This resulted in greater flow of cold air over the Ross Sea (West Antarctica) leading to more ice production in this region.
The satellite data reveal the variation in sea ice cover around the entire Antarctic continent. Whilst there has been a small increase of sea ice during the autumn around the coast of East Antarctica, the largest changes are observed in West Antarctica. Sea ice has been lost to the west of the Antarctic Peninsula – a region that has warmed by almost 3°C in the past 50 years. Further west sea ice cover over the Ross Sea has increased.
Mountain glaciers are receding
Global glacial mass balance in the last fifty years, reported to the WGMS and NSIDC. The increasing downward trend in the late 1980s is symptomatic of the increased rate and number of retreating glaciers.
A letter David Bellamy published on 16 April 2005 in New Scientist asserted that a large percentage (555 of 625) of the glaciers being observed by the World Glacier Monitoring Service were advancing, not retreating. George Monbiot of The Guardian tracked down Bellamy’s original source for this information and found that it was Fred Singer’s website. Singer’s figure was actually 55%, but Bellamy later admitted a misprint by not hitting the shift key. Singer claimed to have obtained these figures from a 1989 article in the journal Science, but no such article exists. Bellamy has since stated that his figures on glaciers were wrong, and announced in a letter to The Sunday Times that he had “decided to draw back from the debate on global warming”. Bellamy’s 555 is a misprint of an incorrect statement, but has been repeatedly quoted in the sceptics literature. The fact is that nearly all glaciers are retreating.
The World Glacial Monitering Service states that the average mass balance of the glaciers with available long-term observation series around the world continues to decrease, with tentative figures indicating a further thickness reduction of 1.3 and 0.7 metres water equivalent (m w.e.) during the hydrological years 2006 and 2007, respectively. The new data continues the global trend in accelerated ice loss over the past few decades.
Atmospheric CO2 is rising, global temperature is rising, the sun is not getting brighter, sea levels are rising, the ocean is getting warmer, arctic ice is melting, and oceans are becoming more acidic. All these changes are part of consistent trends. The evidence that we face a threat is compelling. What does that mean for us in SE NSW. Certainly seas level rise presents a threat. What about rainfall. If the current drought is due to climate change, then we might expect worsening rainfall patterns.
As seen from the Bureau of Met figures, average rainfall across Australia as a whole has increased from 1900 to 2005. The distribution of that rainfall has changed markedly. The Eastern and South Eastern regions of Australia show a drying trend, whilst the North West of Australia is getting much wetter.
National trends (BOM)
There has been a significant reduction in winter rainfall in south-west Western Australia since the 1970s. Rainfall has decreased substantially since 1950 on the east coast, and in Victoria. This decline is less marked if measured from 1900. The last decade has seen very low rainfall in southern and central Victoria Rainfall in north-west Australia has increased substantially since 1950.
This is interesting given that the area affected by decreased rainfall seems to be greater than the area affected by increased rainfall. The data relating to the Southern Oscillation Index shows that there have been more frequent and severe El Nino events (drier periods) since the mid 1970s.
CO2 and Drought
There has been a lot of talk in the local media about the ongoing drought in SE NSW. Is it possible that the current drought is related to climate change? To get an idea of the scale of the problem, is is worth looking at the nations food bowl, the Murray-Darling basin. The Murray-Darling Basin produces about 40% of Australia’s food, and is about as big as the states of Victoria and NSW put together. It is critically important to know what is happening there.
In the southernmost regions that provide most of the Murray-Darling’s flow, the last “normal” year of rainfall and of runoff into the rivers was 1996. The subsequent “Big Dry”, during its first decade, had rough parallels in the Federation drought of 1895-1902 and the Second World War drought of 1937-1945. But the present drought has continued and intensified. Its hold on Victoria is suggested by the rainfall records for Melbourne. January-June in 2009 was the driest first half-year ever recorded in Melbourne, with just 126 millimetres of rain. Prior to 1997, the city’s average annual rainfall was 660ml; since then, it has dropped by 21% to 520ml.
From 2006, the flow deficit has worsened sharply.Total inflows to the basin’s rivers in June 2008 were less than one-seventh of the average figure. For the three years ending in March 2009, an April 7 Murray-Darling Basin Authority press release says, Murray system inflows were only 46% of the previous three-year minimum, recorded in 1943-46. Murray inflows in the first three months of 2009 were the lowest in 117 years of record-keeping.
As well as reflecting historically low rainfall, the declining streamflows also result from greater evaporation due to higher temperatures. CSIRO climate scientist Wenju Cai has calculated that a 1ºC rise in temperature in the Murray-Darling Basin results in a 15% reduction in river flows. Temperatures in the basin in 2007, were the warmest ever at 1.1ºC above average.
Is the drought in the Murray-Darling Basin semi-permanent, and can it be attributed to global warming? An analysis is provided by Bertrand Timbal of the Bureau of Meteorology in a recent paper called “The continuing decline in South-East Australian rainfall: update to May 2009″.
A three-year collaboration between the Bureau of Meteorology and CSIRO has confirmed that the drought is not just a natural dry stretch but a shift related to climate change. Scientists working on the $7 million South Eastern Australian Climate Initiative said the rain had dropped away because the subtropical ridge – a band of high pressure systems that sits over the country’s south – had strengthened over the past 13 years.
”It’s reasonable to say that a lot of the current drought of the last 12 to 13 years is due to ongoing global warming,” said the bureau’s Bertrand Timbal ”In the minds of a lot of people the rainfall we had in the 1950s, ’60s and ’70s was a benchmark. A lot of our [water and agriculture] planning was done during that time. But we are just not going to have that sort of good rain again as long as the system is warming up.”
Dr Timbal said that 80 per cent of the rain loss in south-east Australia could be attributed to the intensification of the subtropical ridge. The research program covers the Murray-Darling Basin, including parts of NSW, all of Victoria and parts of South Australia.
Monash University’s Neville Nicholls, a lead author on the Intergovernmental Panel on Climate Change who has also published work on the subtropical ridge, said he believed the research program’s results were right. “We did think that the loss of rain was simply due to the [rain-bearing] storms shifting south, off the continent,” Professor Nicholls said. “Now we know the reason they have slipped south is that the subtropical ridge has become more intense. It is getting bigger and stronger and that is pushing the rain storms further south.”
The scientific results have implications for many State Government water programs and drought funding, some of which factor in climate change and some of which do not. Melbourne’s dams get roughly a third less water than they did before the drought began in October 1996.
Australian Sea Level
Tha Australian Baseline Sea Level Monitoring Project involves maintenance of an array of SEAFRAME (SEA-level Fine Resolution Acoustic Measuring Equipment) stations, which measure sea-level accurately.There are 14 stations in Australia supported by the National Tidal Centre (NTC) as well as 2 stations run by the private sector.The National Oceanic and Atmospheric Assoc. is involved with three of the standard stations. The CSIRO’s Division of Marine Research and the TOPEX/POSEIDON satellite altimetry experiment supported the installation of the gauge at Burnie.
Sea level measured by land based gauges can detect sea level change due to changes in the volume of the ocean, or due to vertical movement of the land on which they sit. Volume changes occur due to thermal expansion of sea water, and total mass of the ocean can increase through transfers from glaciers, ice caps and Ice Sheets.
Global average eustatic sea level (changes to the density and mass of the ocean) over the last century was 1.7mmm/yr. The average rate of sea level rise for the decadal period 1993-2003 is 3.1mm/yr.
Here are the results for the 16 SEAFRAME stations in Australia, which were all installed in the early 90’s;
Cocos Island 7.2mm/yr, Groote Eyland 6.6mm/yr, Darwin 7.1mm/yr, Broome 7.9mm/yr, Hillarys 8.0mm/yr, Esperance 4.5mm/yr, Thevenard 3.5mm/yr, Port Stanvac 4.6mm/yr, Portland 2.8mm/yr, Lorne 1.7mm/yr, Stony Point 1.7mm/yr, Burnie 1.7mm/yr, Spring Bay 3.5mm/yr, Port Kembla 1.8mm/yr, Rosslyn Bay 1.3mm/yr, Cape ferguson 2.5mm/yr.
Sea-level in Tuvalu
Tuvalu is a climate change debate flash point. For those worried about rising sea-level, Tuvalu is the cannary in the cage. Sceptics take great delight in pointing out that concern for Tuvalu is alarmist.
Professor Ian Plimer (a sceptic) in his book ‘Heaven and Earth’ paints a rather confused picture of the problem. On Page 310 he says “the ocean floor around Tuvalu is sinking, giving the appearance of sea level rise. For the last 20 years, Tuvalu has been the symbolof sea level inundation. Tuvaluis still there. It has not been inundated. Coral atolls grow upwards in response to relative sea level rise”. In a book containing over 2000 references, Plimer provides no citation to support the statement that the ocean floor around Tuvalu is sinking.
There is a SEAFRAME gauge on Tuvalu that has been monitoring sea level, and vertical land movement since March 1993. I have never seen a sceptic refer to the one sea level gauge on the island.
The AusAID funded South Pacific Sea Level and climate monitoring project was set up in response to concerns raised by Pacific Island countries over the potential impacts of an enhanced greenhouse effect on climate and sea levels in the South Pacific.
SEAFRAME gauges not only measures sea level by two independent means, but also a number of ancillary variables, such as air and water temperatures, wind speed, wind direction, wind gust and atmospheric pressure. There is an associated programme of levelling to determine vertical movement of the sea level sensors due to local land movement. Continuous Global Positioning System (CGPS) measurements are also now being made to determine the vertical movement of the
land with respect to the International Terrestrial Frame.
Based upon the 151⁄2 years of sea level data from the project, the sea level rise rate in Tuvalu as at september 2008 was 5.9 mM year−1. This was about four times higher than the global average of 1-2 mm year−1. Sea level in the Tuvalu area had risen approximately 9.14 cm since the inception of the project 151⁄2 years ago. However, it was to be noted that the land is quite stable and the rate of land sinking is -0.06 mM year−1 only. Accordingly, there was no significant impact on the sea level trends.
This information comes from ‘Sea Level Threat in Tuvalu, American Journal of Applied Sciences 2009’.
Sea level in Bangladesh
Like Tuvalu, Bangladesh is a flash point in the climate science debate, with mainstream science saying that 40 million people will be displaced by a sea level rise of less than 1 metre, and sceptics saying that Bangladesh is sinking, which means that inundation has nothing to do with climate change.
Bangladesh is part of the Bengal Basin fillied by sediments washed down from the highlands on three sides of it. The whole country consists of low and flat landformed mainly by the Ganges and the Brahmaputyra river systems. Bangladesh has a population of about 130 million, squeezed into a country about twice as big as the state of Tasmania, making it the most densely populated country in the world after some island countries like Hong Kong.
Determining a trend in sea level rise in Bangladesh is difficult, as there are many local factors that influence sea level, including Monsoon flooding, large tidal variations, and frequent storm surges.
There are three sea level monitoring stations in Bangladesh, and the trends over the last 22 years are as follows, as reported by the SAARC Meteorological Service;
Hiron Point 4.0mm/yr
Char Changa 6.0mm/yr
Cox’s Bazar 7.8mm/yr
11% of the country will be inundated with a 45 cm sea level rise. I can find no information on the vertical movement of Bangladesh. Due to the high levels of sedimentary deposit in Bangladesh, it would seem likely that the country is actually rising, although due to the fact that relative sea level rise is a little above the global average, it seems plausible the Bangladesh is actually subsiding.
15 of Australia’s top climate experts ( August 1, 2009)
Fifteen of Australia’s top climate experts explain how we know humans are altering the atmosphere and why we must act now.
Around the world, thousands of scientists have devoted their professional lives to studying the climate. Not centrally organised, they sometimes build temporary affiliations but they remain scientists throughout – that is, they are independent, constantly challenge each other and are committed to searching for truth through objective, independently verifiable evidence.
Overwhelmingly, this evidence has led to four conclusions. The first is that the world is warming. The global average temperature has increased by about 0.8 degrees since 1850, with most of the increase occurring since 1950. The warming varies among decades because of natural fluctuations but the overall trend has been inexorably upward.
Warming is evident in other indicators, such as rising sea levels and reduced sea-ice and snow cover. Of these, the most important measure is the extra heat in the oceans, which is steadily rising. Claims that climate change has reversed since 1998 are misrepresentations of the full data.
The second conclusion is that the dominant cause of the warming since about 1950 is the increase in the atmospheric concentrations of greenhouse gases released by human activities, of which carbon dioxide (CO2) is the most important.
This critical conclusion is based on several independent lines of evidence, including basic physics, studies of climate changes in both in the geological past and in the industrial era, and finally – but far from solely – from the predictions of climate models. Together, these provide an overwhelming case that increasing greenhouse gas concentrations cause warming, and that CO2 is the largest contributor to the current warming trend.
Other contributors include changes in the sun’s output associated with sunspots and solar flares, and volcanic dust. However, if these were solely responsible for temperature changes since 1850, the world should have cooled over the past half-century rather than warming at an increasing rate.
The third conclusion is that warming will increase in future, if emissions of CO2 and other greenhouse gases maintain their present paths. “Business as usual” scenarios for future emissions lead to likely global temperature increases of up to six degrees above present temperatures by 2100.
These are dramatic temperature increases, which would be accompanied by major disruptions to food supplies, river flows and water availability, significant and ongoing rises in sea level (of up to about a metre by 2100 and potentially metres over longer times), disease threats, disruptions to ecosystems including the extinction of many species, and social and geopolitical destabilisation.
The fourth conclusion is that climate change cannot be reversed for many centuries, because of the massive heat stores in the world’s oceans. Even if CO2 and other greenhouse gas concentrations were stabilised today at their present levels, a further warming of at least 0.6 degrees would inevitably follow (on top of the 0.8 degrees observed since 1850) and sea-level rise would continue for centuries to millenniums.
These four conclusions have been known and agreed among thousands of independent climate scientists for more than a decade. However, new findings suggest that the situation is, if anything, more serious than the assessment of just a few years ago.
The heightened concern among climate scientists arises from a growing realisation that climate change can be accelerated beyond current predictions by reinforcing “climate feedbacks”, which contribute to climate change and are accelerated as it occurs, thus causing climate change to feed on itself. When these feedbacks are sufficiently strong they become “climate tipping points” which can flip the climate into a new state with essentially no way to recover.
Several feedbacks are of immediate concern. Interactions between climate and the earth’s carbon cycle (the exchange of carbon between the atmosphere, the land and the oceans) will act to accelerate climate change if sinks do not keep pace with emissions (as is already happening) and/or if previously stable carbon stores are released to the atmosphere under climate change, for example by the thawing of carbon-rich frozen soils.
Accelerated polar warming will cause loss of ice and a consequent darkening of the surface, leading to more heat absorption and faster warming. Atmospheric concentrations of aerosols (tiny particulates) are likely to decrease in future as nations improve air quality, leading to accelerated warming as the cooling effect of aerosols is reduced.
Oceans are becoming more acidic as a consequence of increased CO2 in the atmosphere. When CO2 concentrations exceed levels to be reached by 2035 under business-as-usual emissions scenarios, there will be severe disruptions to marine ecosystems (including the Great Barrier Reef and ocean food chains), which will endanger fisheries and weaken the uptake of CO2 by oceans.
Temperature rises of two to three degrees (or higher) carry a high risk of irreversible decay of the Greenland ice sheet from surface warming alone, leading to a sea level rise of up to about seven metres. Destabilisation of the West Antarctic Ice Sheet would cause a further few metres of sea-level rise.
A climate conference in Copenhagen in March concluded that societies were highly vulnerable to even modest levels of climate change, with poor nations and communities particularly at risk. Temperature rises above two degrees will be very difficult for contemporary societies to cope with and will increase the level of climate disruption through the rest of the century.
All of these concerns are firmly grounded in science. They have led the great majority of climate scientists to conclude (paraphrasing the summary of the Copenhagen conference) that rapid, sustained and effective emissions reductions are required to avoid ‘‘dangerous climate change’’, regardless of how it is defined.
Higher future emissions increase the risk of crossing climate tipping points and they increase the likelihood that the long-term social and economic costs of both adaptation and mitigation will be higher.
This article was written by Michael Raupach and John Church, CSIRO; David Griggs, Amanda Lynch and Neville Nicholls, Monash University; Nathan Bindoff, Antarctic Climate and Ecosystems Co-operative Research Centre; Matthew England and Andy Pitman, University of NSW; Ann Henderson-Sellers and Lesley Hughes, Macquarie University; Ove Hoegh-Guldberg, University of Queensland; Roger Jones, Victoria University; David Karoly, University of Melbourne; and Tony McMichael and Will Steffen, Australian National University.
Robyn Williams talks to the editor of Science
I have been listening to Robyn Williams run the science show since I was a kid. I have been privelaged enough to meet him on a number of occasions over the last couple of years, and at last meeting, he directed me towards an interview he did with Bruce Alberts in June 2009, the editor of Science magazine. Here are a few extracts from that interview.
Robyn Williams: Bruce Alberts is a top scientist, a former president of the National Academy of Science in the USA. Now he’s editor of the great journal Science, often mentioned in this program.
Robyn Williams: Talking about editorials, I remember one that your predecessor Don Kennedy had which was headlined Debate Over about climate change. Was he right?
Bruce Alberts: I think among scientists the debate is over, of course not among politicians. The problem is always in science that you can always find scientists who take the contrary view, that’s how science advances, and so you could always find a scientist who will take any position on any issue, and those who don’t want to believe in climate change do that. Often the media feel they have to give a balanced view, so they have one of each kind. My old job with the National Academy of Science, its major role is to really tell the government what the consensus opinion of science is and try to avoid that kind of confusion that happens when you could find testimony…scientists on every side. And almost always the consensus of the scientific community is correct, and certainly what you should bet on when looking forward towards the future.
Robyn Williams: Of course you’ve got a tremendous overview of the published papers, not only in your own journal but in other journals. Out of 1,000 papers on climate change, how many can you remember that go against the trend? Any?
Bruce Alberts: Well, I get lots of complaints from people who want to publish papers saying climate change doesn’t exist, but they have a hard time getting their papers published because they don’t pass peer review. So there are actually very few papers that get published in the peer review literature that seriously challenge in any way the basic hypothesis. As in evolution (we’re at a meeting on evolution right now), there are always things you don’t understand, and the creationists use those things you don’t understand, the ‘missing links’, to challenge the whole idea of evolution. In the same way some people use the few things we don’t understand (we never understand everything) to challenge the whole idea of climate change. It’s not a valid way of talking about science.
WHAT WE CAN’T AGREE ON
1-Logarithmic relationship between CO2 and temperature
The debate is not over. There are many uncertainties in the science of climate change.
Listed below are some of the genuine scientific uncertainties. A frequent argument used by sceptics is that there is a logarithmic relationship between atmosphgeric CO2 and glabal temperature. The theory goes like this;
“The absorption of solar radiation of a particular wavelength by any greenhouse gas is a logarithmic function of its concentration – this means that extra concentration has a rapidly diminishing effect. Therefore it is quite likely that if 50 ppm of CO2 already absorbs half of the radiation at particular wavelenghts then increasing it from 400 to 800 ppm would have very little extra effect. This is probably similar to the effect of doubling the dose of a particular vitamin, the effect is much less than the innitial dose.
So, the effect of doubling CO2 from 400 to 800 ppm would be much smaller than doubling it from 50 to 100 ppm.”
This concept has been widely supported by William Kininmonth, a previous head of The National Climate Research Institutute, and one of Australia’s most well know climate sceptics. Kininmonth states that calculations demostrate the logarithmic relationship between atmospheric CO2 and global temperature. As best as I can tell, these calculations derive from T.J.Nelson, and an excerpt from Nelson’s blog follows.
An excerpt from T.J.Nelson “Cold Facts On Global Warming”.
The following is taken from the Blog of T.J.Nelson. These are the figures that sceptics use to support the theory that the relationship between atmospheric CO2 and global tempwerature is logarithmic.
“Because a linear increase in temperature requires an exponential increase in carbon dioxide (thanks to the physics of radiation absorption described above), we know that the next two-fold increase in CO2 will produce exactly the same temperature increase as the previous two-fold increase. Although we haven’t had a two-fold increase yet, it is easy to calculate from the observed values what to expect.
Between 1900 and 2000, atmospheric CO2 increased from 295 to 365 ppm, while temperatures increased about 0.57 degrees C (using the value cited by Al Gore and others). It is simple to calculate the proportionality constant (call it ‘k’) between the observed increase in CO2 and the observed temperature increase:
Also consider that the temperature increase is only 1-2 degrees C. This is much smaller than the seasonal variation, the variation between different locations on the Earth, or even the variation between day and night temperatures. The laws of physics don’t change when you go from New York to New Jersey. Questioning whether k is a constant is grasping at straws. The question people should be asking is: is k equal to zero?
This shows that doubling CO2 over its current values should increase the earth’s temperature by about 1.85 degrees C. Doubling it again would raise the temperature another 1.85 degrees C. Since these numbers are based on actual measurements, not models, they include the effects of amplification, if we make the reasonable assumption that the same amplification mechanisms that occurred previously will also occur in a world that is two degrees warmer.
These estimates assume that the correlation between global temperature and carbon dioxide is causal in nature. This remains to be proved. Therefore, the 1.02 and 1.85 degree estimates should also be regarded as upper limits.”
As an orthopaedic surgeon, I have no possible chance of deciphering the above article. Here is a reponse from Julia Mayo-Ramsay, a member of CEFE and PhD student at the University of Tasmania.
Nelson appears to base his entire argument on the ‘fact’ that CO2 contributes 4 to 8% of the total greenhouse effect (of 33 deg C), and therefore a doubling of CO2 can only increase the total greenhouse effect proportionately. Apart from being wrong about the effect of CO2 (around 9 to 25% of the long wave absorption depending on how you calculate the overlaps, this is way too linear a calculation to be applicable. In particular, he assumes that water vapour amounts are independent of the temperature (they are not). There are a number of other obvious bloopers
(ie. “In fact, the effect of carbon dioxide is roughly logarithmic. Each time carbon dioxide (or some other greenhouse gas) is doubled, the increase in temperature is less than the previous increase”.
Answer – No. Logarithmic means that the effects of doubling are constant).”
Arrhenius first speculated that changes in the levels of carbon dioxide in the atmosphere could substantially alter the surface temperature through the greenhouse effect. Arrhenius used the infrared observations of the moon by Frank Washington Very at the Allegheny Observatory in Pittsburgh to calculate the absorption of CO2 and water vapour. Using ‘Stefan’s law’, he formulated his greenhouse law. In its original form, Arrhenius’ greenhouse law reads as follows:
if the quantity of carbonic acid increases in geometric progression, the augmentation of the temperature will increase nearly in arithmetic progression.
This simplified expression is still used today:
ΔF = α ln(C/C0)
Arrhenius estimated that halving of CO2 would decrease temperatures by 4 – 5 °C (Celsius) and a doubling of CO2 would cause a temperature rise of 5 – 6 °C. In his 1906 publication, Arrhenius adjusted the value downwards to 1.6 °C (including water vapour feedback: 2.1 °C). Recent (2007) estimates from IPCC say this value (the Climate Sensitivity) is likely to be between 2 and 4.5 °C. Arrhenius expected CO2 levels to rise at a rate given by emissions in his time. Since then, industrial carbon dioxide levels have risen at a much faster rate: Arrhenius expected CO2 doubling to take about 3000 years; it is now estimated in most scenarios to take about a century.
Svante Arrhenius was a Nobel laureate in Chemistry in 1903.
How do you make sense of all of that?
For a non-scientist like myself, it is impossible to interpret complex statements like these. Nelson’s article uses complex mathmatics, and Arrhenius is over 100 years old. Direct scientific observation shows that CO2 and global temperature are both increasing at the moment. There is no doubt that the two are closely related, but the question is whether or not CO2 is DRIVING global temperature. I can find many theories of natural forces that could be driving global temperature at the moment. Changes in solar irradiation, volcanic activity, movement of techtonic plates, cosmic radiation, and complexities in the water cycle all provide plausible explainations of rising global temperature. However, there is no convincing evidence to support ANY of these theories.
T J Nelson’s ‘Cold Facts On Climate Change’ is not published anywhere that I can find. He does not appear in any peer reviewed journal, nor any non-peer reviewed journal. His article appears on a blog, and a google search on the author fails to shed any light on who he actually is. Nevertheless, his calculations have been widely used in the sceptic’s literature to discredit the science of climate change. I would be very interested to hear from anyone who can shed some light on this subject.
2-The ‘Hockey Stick’
The Hockey stick graph as shown in the 2001 IPCC report. This chart shows the data from Mann et al. 1999. The colored lines are the reconstructed temperatures, and the gray shaded region represents estimated error bars.
Reconstructions of Northern Hemisphere temperatures for the last 1,000 years according to various older articles (bluish lines), newer articles (reddish lines), and instrumental record (black line).
The hockey stick controversy has to a large extent been focussed on Michael Mann. The “hockey stick” is a term coined for the chart of temperature variation over the last 1,000 years. The chart is relatively flat from the period A.D. 1000 to 1900, indicating that temperatures were relatively stable for this period of time. The flat part forms the stick’s “shaft.” After 1900, however, temperatures appear to shoot up, forming the hockey stick’s “blade.” The combination of the two in the chart suggests a recent sharp rise in temperature caused by human activities.
In 2003, Stephen McIntyre and Ross McKitrick published “Corrections to the Mann et al. (1998) Proxy Data Base and Northern Hemisphere Average Temperature Series” in the journal Energy and Environment 14(6) 751-772, raising concerns about their ability to reproduce the results of the hockey stick.
After testing the work of Mann et al. (1998), McKitrick commented
“The Mann multiproxy data, when correctly handled, shows the 20th century climate to be unexceptional compared to earlier centuries.
More recently, the National Academy of Sciences considered the matter. On June 22, 2006, the Academy released a pre-publication version of its report Report-Surface Temperature Reconstructions for the Last 2,000 Years, supporting Mann’s more general assertion regarding the last decades of the Twentieth Century, but showing less confidence in his assertions regarding individual decades or years, due to the greater uncertainty at that level of precision.
“The basic conclusion of Mann et al. (1998, 1999) was that the late 20th century warmth in the Northern Hemisphere was unprecedented during at least the last 1,000 years. This conclusion has subsequently been supported by an array of evidence.
Based on the analyses presented in the original papers by Mann et al. and this newer supporting evidence, the committee finds it plausible that the Northern Hemisphere was warmer during the last few decades of the 20th century than during any comparable period over the preceding millennium.
3- Al Gore
On 10/10/07, Mr Justice Burton in the UK ruled on 9 errors in Mr Gore’s “Inconvenient Truth” that he felt were alarmist. These included;
– a claim by Mr Gore that melting ice caps would cause potentially devastating sea level rise in the near future. (Al Gore did not put a time frame on sea level rise. It is interesting that sea level is rising much faster than worst case scenario IPCC predictions).
-there is no evidence that atolls in the Pacific had already been evacuated due to rising sea levels.(Justice Burton made his comments in 2007. There are currently plans in place for Island evacuations right throughout the low lying Pacific Nations, and elsewhere).
-the correlation between atmospheric CO2 and global temperature over the last 650 000 years had been overstated (the only person I have read who casts doubt on the correlation between CO2 and temperature has been Professor Ian Plimer. He references Berner to support his case, but Berner actually says the exact opposite…see ‘Heaven and Earth’ section of the web site in the information tool bar).
-you cannot blame the drying of Lake Chad, or Hurricane Katrina on climate change. (I think it is a fair point to say that you can not blame a particular weather event on climate change. I think it is equally fair to say that climate change will change rainfall distribution, and lead to an increase in intensity of Hurricanes).
-there is no proof to support the notion that polar bears are drowning. (I don’t think polar bears are going to be too happy about the possibility of the summer North Pole ice cap disappearing in the next decade or two).
-decreasing ice on Mt Kilimanjaro may be due to regional deforestation rather than climate change. (Ice caps and glaciers around the world are melting, but Justice Burton is here attacking minutia).
-there is no proof that coral bleaching is due to climate change. (really?).
-Mr Gore’s statement that Gulf Stream could shut down was not supported by the IPCC, who state that a shut down of the gulf stream is “very unlikely”. (there is evidence to suggest that the Gulf Stream has already started to slow).
Mr Justice Burton could agree on most broad issues raised in the film. He agreed that Mr Gore’s film was “broadly accurate” in its presentation of the causes and likely effects of climate change.
Despite finding nine significant errors the judge said many of the claims made by the film were fully backed up by the weight of science. He identified “four main scientific hypotheses, each of which is very well supported by research published in respected, peer-reviewed journals and accords with the latest conclusions of the IPCC”.
In particular, he agreed with the main thrust of Mr Gore’s arguments: “That climate change is mainly attributable to man-made emissions of carbon dioxide, methane and nitrous oxide (‘greenhouse gases’).”
The other three main points accepted by the judge were that global temperatures are rising and are likely to continue to rise, that climate change will cause serious damage if left unchecked, and that it is entirely possible for governments and individuals to reduce its impacts.
Click the image above to open the PDF
Here is my (Matthew Nott) response to the Nova pamphlet. Sorry it’s a bit long, but that is half the problem in the climate debate. Nova can present a very simple looking graph such as the one on page 8 of her pamphlet. She presents it as a convincing statement of scientific fact, and although the graph can easily be shown to be a fraud, it takes a couple of hundred words to do it. She make 4 points in her pamphlet, and here is my response to each of them.
POINT1 The greenhouse signature is missing
This is complex, and I’m not sure why this page delivers a knockout blow.
I thought the greenhouse signature was a warming troposphere and a cooling stratosphere, both of which (despite what Nova says) can be demonstrated by satellite studies.
The so called ‘hot spot’ that Nova talks about is one of the predicted effects of excess CO2 in the atmosphere. The idea is that the tropics, being subjected to more direct sunlight than higher latitudes, will warm faster at the surface, in turn re-radiating more energy into adjacent regions of the atmosphere, forming a so-called ‘hot spot’. Nova claims that because the ‘hot spot’ hasn’t been found, this is a knock-out blow. This doesn’t strike me as a convincing point, rather clutching at straws.
Nova is right in saying that evidence for a hot-spot has proved elusive. Allen and Sherwood, studying the second order effect of warming-thermal winds- believe they’ve detected it.
I would say that a knock-out blow should be a little less complex than this, particularly as Nova’s opening line is “The Bottom Line is Simple, Don’t fall for the “complexity” argument”
POINT 2 Ice cores reveal that CO2 levels rise and fall hundreds of years after temperatures change
From what I’ve read, I don’t think this is a particularly controversial point. The single most important determinant of global climate is the brightness of the sun and the earth’s proximity to it. For a number of well explained reasons, as the earth warms, atmospheric CO2 goes up. Natural warming drives an increase in atmospheric CO2.
The difference at the moment, is that CO2 is being driven upwards, not by rising global temperature, but by burning fossil fuel.
Nova’s argument is that that warming drives CO2 upwards, which means that the converse cannot possibly happen. How can she say that, particularly when there is no geological historical precedence. She implies that rising CO2 cannot increase temperature, because that is not the way it has happened in the natural world in the past.
She concludes this point by saying that something other than CO2 is causing the warming. How does she possibly make that conclusion?
POINT 3 The world is not warming anymore
I think this is the point that has gained the most traction amongst a sceptical public. This was certainly Prof Ian Plimer’s main point in ‘Heaven and Earth’.
Plimer states repeatedly in his book that the Hadley Met Office in Britain demonstrates global cooling since 1998. The Hadley Met Office state that;
-the 10 hottest years ever recorded have been the last 10 years,
-1998 was a particularly hot year due to a strong El Nino, and Plimer cherry-picks by looking at a trend starting from that year
-their results show an unequivocal warming trend of 0.2 degrees per decade, a warming that cannot be explained by natural process
-if you think that global warming has stopped, you have your head in the sand.
These are Hadley Met Office words, not mine, and yet their figures are repeatedly used by sceptics to prove that the warming trend has stopped.
There are many measures of global temperature other than the Hadley Met Office surface temp figures. The troposphere is warming according to satellite figures (with 2005 being the hottest year ever recorded….2007 second in a tie with 1998), the ocean is warming, the North Pole ice cap is melting, Greenland is melting, glaciers are melting and sea level is rising. To simply say that this warming is because we are coming out of an ice age 12000 years ago doesn’t strike me as very convincing.
I agree that the Urban Heat Island effect is cause for error. No matter how you measure global temp, there is error, but every measure is showing a distinct trend.
The conclusion at the end of page 6 is that because there is not a straight line correlation between CO2 and global temperature, CO2 cannot be driving temperature. This is perhaps the weakest point she makes. Surely, complex natural processes continue to work alongside the warming effect of rising greenhouse gases. How could you ever expect a straight line correlation between CO2 and temperature.
CO2 is already absorbing almost all it can
Here, Nova provides us with a graph demonstrating the logarithmic relationship between CO2 and temp. What the graph clearly shows is that a large increase in CO2 will produce a tiny increase in global temp. If true, this graph would be devastating to the concept of anthropogenic global warming.
There are a couple of fishy things about the graph.
She uses lots of graphs in her pamphlet. All the graphs have sources printed at the bottom of each relevant page, except this one. There is a name to it however. “Archibald. Modtram calculations”.
The graph does indeed come from Archibald in an unpublished paper titled Climate Outlook to 2030, in which he predicts global cooling. Amazingly, Archibald references the graph as coming from another unpublished paper written by himself. In that paper, he says the info for the graph comes from MODTRANS at the Uni of Chicago. Here is what Archibald says about the MODTRAM results;
“Anthropogenic warming is real, it is also miniscule. Using the MODTRANS facility
maintained by the University of Chicago, the relationship between atmospheric carbon dioxide content and increase in average global atmospheric temperature is shown in this graph.” He then goes on to show the graph that eventually ends up in the Nova pamphlet.
Dave Archer is part of the MODTRANS facility and here is his response to the comments made by Archibald. It is too complex for an orthopaedic surgeon. However, Archibald’s interpretation of the MODTRAM results differs wildly from the conclusions put forward by the MODTRAM team.
“My model, used for deception (Filed under: Climate Science 4 October 2007)
Well, not my model exactly. I developed and host a web interface to the modtran model of atmospheric infrared radiation, an early example of a line-by-line code which I downloaded and use to teach and as part of a textbook. Now David C. Archibald from Summa Development Limited, Perth, WA, Australia claims that my “University of Chicago modtran facility” proves that global warming won’t happen.
Archibald begins by discovering that the IR light flux at the top of the atmosphere is more sensitive to changes in atmosphere CO2 when the concentration of CO2 is lower. This will come as no surprise to regular readers of realclimate who will know that the energy flux scales with the logarithm of CO2. The log dependence is why the climate sensitivity parameter is often posed as a temperature change for doubled CO2 concentration; to first order, a change from 10 ppm to 20 would have about as much climate impact as a change from 1000 to 2000 ppm. So Archibald is right on this score, clearly climate is more sensitive to CO2 when levels are lower. However, I think most climate models are aware that atmospheric CO2 is 380 ppm rather than 10 ppm, and they predict global warming anyway. If we were starting out from 10 ppm, the warming would be even worse.
Archibald then takes an atmospheric increase of 40 ppm which he thinks will happen by the year 2030. I’d have guessed 60 ppm by then at least, the way things are going, but whatever, we’ll see. He uses my setup of modtran to calculate that the IR flux to space would drop by 0.4 Watts / m2 as a result of this 40 ppm. Try it yourself. Run the model once with 375 ppm CO2 and another time with 415 ppm, and compare the Iout values in Watts / m2. The exact number you get depends on humidity, setting, clouds, etc. Formulas given in IPCC would say 0.5 Watts / m2; zeroing out water vapor in modtran gets the IR response up to 0.6 Watts / m2 for the default tropical atmosphere case. At any rate Archibald isn’t wildly off here either.
But then Archibald multiplies the radiative forcing by an absurdly low value of the climate sensitivity parameter. In this case he is using the parameter in units of degrees C per Watt / m2. The two forms of the climate sensitivity parameter that we have discussed here are related by a factor of about 4 Watts / m2 for a doubling of CO2. The value Archibald uses is 0.1 degree C per Watt / m2 which was “demonstrated” in a paper entitled “CO2-induced global warming: a skeptic’s view of potential climate change” by Idso, 1998. Translated, Idso’s climate sensitivity winds up to be 0.4 degrees for doubling CO2. IPCC finds it essentially impossible (yeah, I know, highly unlikely or whatever) that the climate sensitivity could be less than 1.5 degrees C for doubling CO2, and 3 degrees C is a best-guess value.
In the end, Archibald concludes that the warming from the next 40 ppm of CO2 rise (never mind the rest of it) will only be 0.04 degrees C. Archibald’s low-ball estimate of climate change comes not from the modtran model my server ran for him, but from his own low-ball value of the climate sensitivity.”
Nova presents this Archibald graph not as theory or conjecture, but as a statement of scientific fact. What it actually represents is a gross distortion of the source science, from an author who hasn’t published his work anywhere, and references his source as his own unpublished work. Nova’s graph is smoke and mirrors, that took me about 5 mins to unravel with google. Most people wouldn’t be prepared to give this graph 5 mins which is why a message like this can have a big impact.
On Professor Ian Plimer
If the local village idiot makes a statement, it remains a valid statement until it can be proven to be wrong. It is irrelevant that the statement is made by an idiot. The same applies to Ian Plimer. There is no point in me saying that he is a fool, or that he consistently misleads the reader of ‘Heaven And Earth’ by making false claims about the references he uses.
It is however relevant to point out the examples of how he misrepresents the science to support his claim that CO2 is an inconsequential greenhouse gas. For examle, he states that during the Phanerozoic period, widespread glaciation was associated with extremely hih levels of atmospheric CO2. The reference that he uses to support this claim says exactly the OPPOSITE!
Plimer says that satellite studies show there is no warming. The reference he uses to support this claim once again says EXACTLY the opposite!
Plimer systematically misrepresents the science to support his case, and it is very easy to demonstrate it. This discussion requires a section of its own, which is at ‘Heaven And Earth, what’s missing from the missing science” under the ‘information’ toolbar.
The fact that ‘Heaven And Earth’ has received uncritical support from other well known Australian climate sceptics such as Prof Bob Carter suggest to me that science of scepticism presents a weak argument.
For more critiques of Plimer’s work, click here
On Bjorn Lomborg
Lomborg argues in ‘Cool It’ that it is more cost effective to adapt to climate change than to prevent it. For example, it is cheaper to buy everyone an air conditioner than it is to prevent global warming. Air conditioners are therefore a much more cost effective way to prevent heat related deaths than reducing emissions. He also makes the point that there will be a greater reduction in deaths due to cold than will die from extreme heat as the globe warms, so global warming is not such a bad thing.
It is cheaper to buy mosquito nets than it is to fix global warming. It is cheaper to save polar bears by preventing hunting than it is to prevent global warming. The list goes on and on.
Lomborgs take on sea level rise is conservative. He predicts a sea level rise by the end of the century of 1 foot, so why worry. He claoms that climate change is only a moderately serious problem, that the solutions are expensive, and that there are many other more pressing problems that can be fixed at less cost. “Which do you prefer, climate change mitigation or AIDS prevention?” is a trick question, to which the answer should be that you don’t have to choose.
In the case of climate change, it is possible, at least in principle, to calculate the cost of emission reductions. On the other side of the balance, the benefits of reducing carbon emissions include decreases in all manner of harms to people and nature, and a lowered probability of truly catastrophic, irreversible changes. How do you put a dollar value on that? What is the dollar value of a slowdown in the rate of melting of the Greenland ice sheet?
From my point of view, I am not too worried about malaria, or polar bears, or the cost of an air-conditioner. I am concerned about changing patterns of rainfall and its impact on farming and ski seasons in SE NSW. I am more concerned about rising sea-level and its impact on coastal communities. Bjorn Lomborg would say it is cheaper to relocate Tathra than it is to fix climate change. I would tell Lomborg to get stuffed.
Professor Bob Carter is a well know Australian sceptic who says that there has been no warming in the last 50 years. I think that statement excludes him from the debate. William Kinninmonth is the other prominent Australian sceptic who has presented no research in peer reviewed literature about the science of climate change.
I am prepared to read anything I can find that casts doubt on the theory of anthropogenic climate change. I am unable to find anything that convinces me that CO2 is an inconsequential greenhouse gas.