9. The trail of intentional obfuscation and ignorance is rich with many turns.  The more carefully one tries to follow this critical science the more clear the pattern is, and the more alarming.  The following are a number of articles and references I have run onto and managed to preserve.

There is an Excellent Washington Post review online.  Includes the full IPCC report in downloadable format. 

Intergovernmental Panel on Climate Change Report
"Most of the observed increase in globally averaged temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations."
-- Climate Change 2007: The Physical Science Basis

• Humans Faulted for Global Warming (Post, Feb. 3, 2007)

• Q&A Transcript, Post's Eilperin (Feb. 5, 2007)

• Q&A Transcript: IPCC Coordinating Lead Author (Feb. 13, 2007)

• Working Group I Report | Group II Report | Group III Report

More  AAAS Articles
Science 13 April 2007:
Vol. 316. no. 5822, pp. 188 - 190

Global Warming Is Changing the World

Richard A. Kerr

An international climate assessment finds for the first time that humans are altering their world and the life in it by altering climate; looking ahead, global warming's impacts will only worsen

In early February, the United Nations--sponsored Intergovernmental Panel on Climate Change (IPCC) declared in no uncertain terms that the world is warming and that humans are mostly to blame. Last week, another IPCC working group reported for the first time that humans--through the greenhouse gases we spew into the atmosphere and the resulting climate change--are behind many of the physical and biological changes that media accounts have already associated with global warming. Receding glaciers, early-blooming trees, bleached corals, acidifying oceans, killer heat waves, and butterflies retreating up mountainsides are likely all ultimately responses to the atmosphere's growing burden of greenhouse gases. "Climate change is being felt where people live and by many species," says geoscientist Michael Oppenheimer of Princeton University, a lead author of the report. "Some changes are making life harder to cope with for people and other species."

The latest IPCC report (www.ipcc.ch/SPM6avr07.pdf) sees a bleak future if we humans persist in our ways. The climate impacts, mostly negative, would fall hardest on the poor, developing countries, and flora and fauna--that is, on those least capable of adapting to change. Even the modest climate changes expected in the next few decades will begin to decrease crop productivity at low latitudes, where drying will be concentrated. At the same time, disease and death from heat waves, floods, and drought would increase. Toward midcentury, up to 30% of species would be at increasing risk of extinction.

Wetter's better? Warmer and wetter high latitudes will yield more crops but also more flooding

"This stark and succinct assessment of the future … is certainly troubling," wrote economist and coordinating lead author Gary Yohe of Wesleyan University in Middletown, Connecticut, in an e-mail message from the final meeting of the IPCC working group in Brussels, Belgium. It is now obvious, he says, that even if greenhouse gas emissions are immediately reduced, changes are inevitable. Humans will have to adapt, if we can.

Toning down the message.

The working group's report had a difficult coming-out party on 6 April. Like the reports from the two other IPCC working groups (WGI--see Science, 9 February, p. 754--and WGIII, due out on 4 May), Working Group II's involved a couple of hundred scientist authors from all six continents analyzing and synthesizing the literature over several years. Reviews by hundreds of experts and governments generated thousands of comments. Twenty chapters totaling 700 printed pages led to a Technical Summary of 80 to 100 pages and a Summary for Policymakers (SPM) of 23 pages. Then came the hard part: the 4-day plenary session in Brussels, which brought together scientists and representatives of 120 governments. There, unanimity among governments is required on every word in the SPM, ostensibly to ensure that the phrasing clearly and faithfully reflects the reviewed science of the chapters.

This time, there were "bigger bumps than normal," says climate scientist Stephen Schneider of Stanford University in Palo Alto, California, a coordinating lead author. "It was longer and more painful than usual," Oppenheimer agrees. Especially as the deadline approached early Friday morning, a few countries--attendees mention coal-rich China and oil-rich Saudi Arabia most often--insisted on substantial changes. Sometimes, the softening of the summary could be taken as a technical adjustment. For example, the SPM draft's "20 to 30% [of] species at increasingly high risk of extinction" as the world warms 1° or 2°C became "Up to 30% of species at increasing risk of extinction."

Perhaps the most substantial loss from the draft SPM was in the tables. The plenary session eliminated parts of a table that would have allowed a reader to estimate when in this century the various projected impacts might arrive. Also dropped was an entire table that laid out quantified impacts--such as annual bleaching of the Great Barrier Reef in the relatively near term--in an easily accessible, region-by-region format.

Toning-down aside, "it's still a decent report," says Schneider. "There are no key science points that didn't come through in the SPM," says ecologist Christopher Field of Stanford, a coordinating lead author. And all of the losses from the draft SPM are still available in the Technical Summary and the underlying chapters for the determined reader. However, anyone reading the SPM "should understand that the findings are stated very conservatively," says Field.

Conservative though it may be, the report holds one major first. "For the first time, we concluded anthropogenic warming has had an influence on many physical and biological systems," says impacts analyst and coordinating lead author Cynthia Rosenzweig of NASA's Goddard Institute for Space Studies in New York City. Media coverage of weird weather and its effects had come to imply that global warming was affecting things both living and inanimate, and individual studies pointed that way too, but no official body had given the link its imprimatur.

To make it official, IPCC authors considered 29,000 series of observations from 75 studies. Of those series, 89% showed changes--glaciers receding or plants blooming earlier, for example--consistent with a response to warming. Those responses so often fell where greenhouse warming has been greatest that it's "very unlikely" the changes were due to natural variability of climate or of the physical or biological system involved. "It's clear it's not all about future impacts," says Field. As an example, he cites the decline of more than 20% in snowmelt since 1950 as the U.S. Pacific Northwest has warmed. That puts a squeeze on everything from hydroelectric dams to salmon.

Like the ongoing effects of global warming, future impacts will vary greatly from region to region. Perhaps the most striking example is shifting precipitation. WGII authors started with WGI's model-based prediction of increasing dryness at low latitudes (the U.S. Southwest and northern Mexico; the Caribbean region, including northeast Brazil; and all around the Mediterranean) and increasing wetness at high latitudes (northern North America and northern Eurasia). They then drew on published studies of the effects of climate change on crops.

The results of a meta-analysis of 70 modeling studies "are compelling," says geographer William Easterling of Pennsylvania State University in State College, a coordinating lead author. "It's become very clear that in high latitudes, a warming of 1° to 3°C is beneficial for the major cereals--wheat, corn, and rice. At the same time, in low latitudes, even a little warming--1°C--results in an almost immediate decrease in yield." In the north, the added water accompanying warming boosts yields, but toward the equator, the added heat is too much for the plants. But "you can't warm the mid-latitudes forever without getting some negative response," says Easterling. "After a 3°C warming, you get this consistent downturn in cereal yield" even at higher latitudes. A 3°C warming is possible globally late in the century if nothing is done about emissions.

Other global warming impacts are even more localized. As glaciers melt in the next few decades in places such as the Andes and Himalayas, flooding and rock avalanches will increase at first. Then, as the glaciers continue to recede toward oblivion, water supplies will decrease. Sea-level rise from melting glaciers and ice sheets would flood low-lying coastal areas, threatening tens of millions of people living on the megadeltas of Africa and Asia, such as the Nile and Brahmaputra. Coral lives near its upper limits of temperature, so even modest warming is projected to lead to more frequent bleaching events and widespread mortality. Extreme heat waves would become more frequent and more deadly for people. Warming and drying would encourage forest pests, diseases, and fire, hitting forests harder as larger areas are burned. The IPCC list goes on and on.

 Some of both. Global warming will bring more precipitation (bluish) to high latitudes in both winter (left) and summer (right) and less precipitation (reddish) to low latitudes. Projected Patterns of Precipitation Changes

The report also briefly considers potentially catastrophic climate events. WGI had already found that in this century, the great "conveyor belt" of currents carrying warm water into the chilly far North Atlantic will only slow, not collapse. So Western Europe isn't about to freeze over. In fact, it would warm under the strengthening greenhouse. But WGII still sees likely North Atlantic-wide effects including lower seawater oxygen and changes in fisheries.

More ominous is the report's discussion of potentially large sea-level rise. The main statement is low-key: "There is medium confidence that at least partial deglaciation of the Greenland ice sheet, and possibly the West Antarctic ice sheet, would occur over a period of time ranging from centuries to millennia for a global average temperature increase of 1-4°C (relative to 1990-2000), causing a contribution to sea level rise of 4-6 m or more."

Four to 6 meters of sea-level rise would be globally catastrophic. New Orleans, south Florida, much of Bangladesh, and many major coastal cities would be inundated. Centuries to millennia might seem like plenty of time to deal with this still-uncertain prospect, but the "1-4°C" is a tip-off. Combine that with the table of greenhouse gas-emission scenarios dropped from the SPM, and it is evident that a 1°C warming would in all likelihood arrive by mid-century, assuming no action to cut emissions. A 3°C warming could be here by the end of the century. Although the sluggish ice sheets might not respond completely to that warming for centuries or millennia, before the century is up, the world could be committed to inundation of its lowlying coastal regions.

The world loses

So what's the bottom line? WGII did that calculation too. According to the SPM, "Global mean losses could be 1-5% [of] Gross Domestic Product (GDP) for 4°C of warming." That's a range from significant but bearable to truly burdensome. "There's too much uncertainty in that calculation" to take it too seriously, Yohe says. That's because it is a messy computation involving assumptions about all sorts of factors: how sensitive the climate really is to added greenhouse gases; what people alive today owe to future generations; how to balance the needs of greenhouse gas emitters and climate victims. And the calculation doesn't even include many nonquantifiable impacts, such as ecosystem losses and the conflicts resulting from climate refugees, that could double damage costs. The SPM's bottom line: "The net damage costs of climate change are likely to be significant."

Economists are "virtually certain," however, that whatever the global climate costs prove to be, not everyone will bear them equally. Some people will be exposed to more climate change than others. Some will be more sensitive to it. Some will be less able to adapt to it. And some will suffer on all three accounts. These people might live in countries that lie in low latitudes where drying will predominate. Their economies are likely based largely on agriculture that is susceptible to drought. And they are more likely to be developing countries without the wealth needed to adapt to climate change, say, by building irrigation systems.

Because such happenstances of geography, climate, and economics make some groups particularly vulnerable, Yohe says, "climate change will impede progress toward meeting Millennium Development Goals"--eight U.N.-sponsored goals, which include eradicating extreme poverty and hunger and ensuring environmental sustainability. "If you don't do something about climate, you're swimming upstream" trying to meet these goals across the world. Fortunately, says Yohe, many of the steps that would help communities adapt to climate change would also help meet the U.N. goals.

Although the report emphasizes the vulnerability of poorer, developing countries, it foresees no real winners. Every population has vulnerable segments, Oppenheimer points out. In the European heat wave of 2003 that killed perhaps 30,000, it was the elderly. When Hurricane Katrina hit New Orleans, Louisiana, killing 700, it was the poor. Adaptation--building levees in the case of New Orleans--has not worked out all that well so far.

And no one region seems exempt. In a paper published online by Science on 5 April (www.sciencemag.org/cgi/content/abstract/1139601), climate modeler Richard Seager of Lamont-Doherty Earth Observatory in Palisades, New York, and his colleagues look at 19 global climate models run for the IPCC. They expect the dryness of the 1930s Dust Bowl to return to the American Southwest by midcentury, for good. If the models are right, the western drought of the past decade is only the beginning. If the world's biggest emitter of greenhouse gases needed some prodding to take action on global warming, this could be it.

National Science Foundation Statement

Climate change is real

There will always be uncertainty in understanding a system as complex as the world’s climate. However there is now strong evidence that significant global warming is occurring1. The evidence comes from direct measurements of rising surface air temperatures and subsurface ocean temperatures and from phenomena such as increases in average global sea levels, retreating glaciers, and changes to many physical and biological systems. It is likely that most of the warming in recent decades can be attributed to human activities (IPCC 2001)2. This warming has already led to changes in the Earth's climate.

The existence of greenhouse gases in the atmosphere is vital to life on Earth – in their absence average temperatures would be about 30 centigrade degrees lower than they are today. But human activities are now causing atmospheric concentrations of greenhouse gases – including carbon dioxide, methane, tropospheric ozone, and nitrous oxide – to rise well above pre-industrial levels. Carbon dioxide levels have increased from 280 ppm in 1750 to over 375 ppm today – higher than any previous levels that can be reliably measured (i.e. in the last 420,000 years). Increasing greenhouse gases are causing temperatures to rise; the Earth’s surface warmed by approximately 0.6 centigrade degrees over the twentieth century. The Intergovernmental Panel on Climate Change (IPCC) projected that the average global surface temperatures will continue to increase to between 1.4 centigrade degrees and 5.8 centigrade degrees above 1990 levels, by 2100.

Reduce the causes of climate change

The scientific understanding of climate change is now sufficiently clear to justify nations taking prompt action. It is vital that all nations identify cost-effective steps that they can take now, to contribute to substantial and long-term reduction in net global greenhouse gas emissions.

Action taken now to reduce significantly the build-up of greenhouse gases in the atmosphere will lessen the magnitude and rate of climate change. As the United Nations Framework Convention on Climate Change (UNFCCC) recognises, a lack of full scientific certainty about some aspects of climate change is not a reason for delaying an immediate response that will, at a reasonable cost, prevent dangerous anthropogenic interference with the climate system.

As nations and economies develop over the next 25 years, world primary energy demand is estimated to increase by almost 60%. Fossil fuels, which are responsible for the majority of carbon dioxide emissions produced by human activities, provide valuable resources for many nations and are projected to provide 85% of this demand (IEA 2004)3. Minimising the amount of this carbon dioxide reaching the atmosphere presents a huge challenge. There are many potentially cost-effective technological options that could contribute to stabilising greenhouse gas concentrations. These are at various stages of research and development. However barriers to their broad deployment still need to be overcome.

Carbon dioxide can remain in the atmosphere for many decades. Even with possible lowered emission rates we will be experiencing the impacts of climate change throughout the 21st century and beyond. Failure to implement significant reductions in net greenhouse gas emissions now, will make the job much harder in the future.

Prepare for the consequences of climate change

Major parts of the climate system respond slowly to changes in greenhouse gas concentrations. Even if greenhouse gas emissions were stabilised instantly at today’s levels, the climate would still continue to change as it adapts to the increased emission of recent decades. Further changes in climate are therefore unavoidable. Nations must prepare for them.

The projected changes in climate will have both beneficial and adverse effects at the regional level, for example on water resources, agriculture, natural ecosystems and human health. The larger and faster the changes in climate, the more likely it is that adverse effects will dominate. Increasing temperatures are likely to increase the frequency and severity of weather events such as heat waves and heavy rainfall. Increasing temperatures could lead to large-scale effects such as melting of large ice sheets (with major impacts on low-lying regions throughout the world). The IPCC estimates that the combined effects of ice melting and sea water expansion from ocean warming are projected to cause the global mean sea-level to rise by between 0.1 and 0.9 metres between 1990 and 2100. In Bangladesh alone, a 0.5 metre sea-level rise would place about 6 million people at risk from flooding.

Developing nations that lack the infrastructure or resources to respond to the impacts of climate change will be particularly affected. It is clear that many of the world’s poorest people are likely to suffer the most from climate change. Long-term global efforts to create a more healthy, prosperous and sustainable world may be severely hindered by changes in the climate.

The task of devising and implementing strategies to adapt to the consequences of climate change will require worldwide collaborative inputs from a wide range of experts, including physical and natural scientists, engineers, social scientists, medical scientists, those in the humanities, business leaders and economists.

Conclusion

We urge all nations, in the line with the UNFCCC principles4, to take prompt action to reduce the causes of climate change, adapt to its impacts and ensure that the issue is included in all relevant national and international strategies. As national science academies, we commit to working with governments to help develop and implement the national and international response to the challenge of climate change.

G8 nations have been responsible for much of the past greenhouse gas emissions. As parties to the UNFCCC, G8 nations are committed to showing leadership in addressing climate change and assisting developing nations to meet the challenges of adaptation and mitigation.

We call on world leaders, including those meeting at the Gleneagles G8 Summit in July 2005, to:

· Acknowledge that the threat of climate change is clear and increasing.

· Launch an international study5 to explore scientifically-informed targets for atmospheric greenhouse gas concentrations, and their associated emissions scenarios, that will enable nations to avoid impacts deemed unacceptable.

· Identify cost-effective steps that can be taken now to contribute to substantial and long-term reduction in net global greenhouse gas emissions. Recognise that delayed action will increase the risk of adverse environmental effects and will likely incur a greater cost.

· Work with developing nations to build a scientific and technological capacity best suited to their circumstances, enabling them to develop innovative solutions to mitigate and adapt to the adverse effects of climate change, while explicitly recognising their legitimate development rights.

· Show leadership in developing and deploying clean energy technologies and approaches to energy efficiency, and share this knowledge with all other nations.

· Mobilise the science and technology community to enhance research and development efforts, which can better inform climate change decisions.

Original PDF including graphics.

More Recent information from SCIENCE

Originally published in Science Express on 1 February 2007
Science 4 May 2007:
Vol. 316. no. 5825, p. 709

Recent Climate Observations Compared to Projections

Stefan Rahmstorf,1 Anny Cazenave,2 John A. Church,3 James E. Hansen,4 Ralph F. Keeling,5 David E. Parker,6 Richard C. J. Somerville5

We present recent observed climate trends for carbon dioxide concentration, global mean air temperature, and global sea level, and we compare these trends to previous model projections as summarized in the 2001 assessment report of the Intergovernmental Panel on Climate Change (IPCC). The IPCC scenarios and projections start in the year 1990, which is also the base year of the Kyoto protocol, in which almost all industrialized nations accepted a binding commitment to reduce their greenhouse gas emissions. The data available for the period since 1990 raise concerns that the climate system, in particular sea level, may be responding more quickly to climate change than our current generation of models indicates.

1 Potsdam Institute for Climate Impact Research, 14482 Potsdam, Germany.

2 Laboratoire d'Etudes en Géophysique et Océanographie Spatiales, 31400 Toulouse, France.

3 Marine and Atmospheric Research and Antarctic Climate and Ecosystems Cooperative Research Centre, Commonwealth Scientific and Industrial Research Organisation, Hobart Tasmania, 7001, Australia.

4 NASA Goddard Institute for Space Studies (GISS), New York, NY 10025, USA.

5 Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093, USA.

6 Hadley Centre, Met Office, Exeter EX1 3PB, UK.

Observations of the climate system are crucial to establish actual climatic trends, whereas climate models are used to project how quantities like global mean air temperature and sea level may be expected to respond to anthropogenic perturbations of the Earth's radiation budget. We compiled the most recent observed climate trends for carbon dioxide concentration, global mean air temperature, and global sea level, and we compare these trends to previous model projections as summarized in the 2001 assessment report of the Intergovernmental Panel on Climate Change (IPCC) (1). The IPCC scenarios and projections start in the year 1990, which is also the base year of the Kyoto protocol, in which almost all industrialized nations accepted a binding commitment to reduce their greenhouse gas emissions. Although published in 2001, these model projections are essentially independent from the observed climate data since 1990: Climate models are physics-based models developed over many years that are not "tuned" to reproduce the most recent temperatures, and global sea-level data were not yet available at the time. The data now available raise concerns that the climate system, in particular sea level, may be responding more quickly than climate models indicate.

Carbon dioxide concentration follows the projections almost exactly (Fig. 1), bearing in mind that the measurements shown from Mauna Loa (Hawaii) have a slight positive offset due to the slightly higher CO2 concentration in the Northern Hemisphere compared with the global mean. The level of agreement is partly coincidental, a result of compensating errors in industrial emissions [based on the IS92a scenario (1)] and carbon sinks in the projections.

The global mean surface temperature increase (land and ocean combined) in both the NASA GISS data set and the Hadley Centre/Climatic Research Unit data set is 0.33°C for the 16 years since 1990, which is in the upper part of the range projected by the IPCC. Given the relatively short 16-year time period considered, it will be difficult to establish the reasons for this relatively rapid warming, although there are only a few likely possibilities. The first candidate reason is intrinsic variability within the climate system. A second candidate is climate forcings other than CO2: Although the concentration of other greenhouse gases has risen more slowly than assumed in the IPCC scenarios, an aerosol cooling smaller than expected is a possible cause of the extra warming. A third candidate is an underestimation of the climate sensitivity to CO2 (i.e., model error). The dashed scenarios shown are for a medium climate sensitivity of 3°C for a doubling of CO2 concentration, whereas the gray band surrounding the scenarios shows the effect of uncertainty in climate sensitivity spanning a range from 1.7° to 4.2°C.

Since 1990 the observed sea level has been rising faster than the rise projected by models, as shown both by a reconstruction using primarily tide gauge data (2) and, since 1993, by satellite altimeter data (3) (both series are corrected for glacial isostatic adjustment). The satellite data show a linear trend of 3.3 ± 0.4 mm/year (1993–2006) and the tide gauge reconstruction trend is slightly less, whereas the IPCC projected a best-estimate rise of less than 2 mm/year. Sea level closely follows the upper gray dashed line, the upper limit referred to by IPCC as "including land-ice uncertainty." The rate of rise for the past 20 years of the reconstructed sea level is 25% faster than the rate of rise in any 20-year period in the preceding 115 years. Again, we caution that the time interval of overlap is short, so that internal decadal climate variability could cause much of the discrepancy; it would be premature to conclude that sea level will continue to follow this "upper limit" line in future. The largest contributions to the rapid rise come from ocean thermal expansion (4) and themelting from nonpolar glaciers as a result of the warming mentioned above. Although the ice sheet contribution has been small, observations are indicating that it is rapidly increasing, with contributions both from Greenland and Antarctica [e.g., (5)].

Overall, these observational data underscore the concerns about global climate change. Previous projections, as summarized by IPCC, have not exaggerated but may in some respects even have underestimated the change, in particular for sea level.

References

1. IPCC, Climate Change 2001: The Scientific Basis (Cambridge Univ. Press, Cambridge, 2001).

2. J. A. Church, N. J. White, Geophys. Res. Lett. 33, L01602 10.1029/2005GL024826 (2006). [CrossRef]

3. A. Cazenave, R. S. Nerem, Rev. Geophys. 42, 20 (2004).

4. J. K. Willis, D. Roemmich, B. Cornuelle, J. Geophys. Res. 109, C12036 10.1029/2003JC002260 (2004). [CrossRef]

5. A. Cazenave, Science 314, 1250 (2006); published online 18 October 2006 (10.1126/science.1133325).[Abstract/Free Full Text]

6. J. C. Moore, A. Grinsted, S. Jevrejeva, Eos 86, 226 (2005).

Received for publication 27 October 2006. Accepted for publication 25 January 2007.

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