Major science organisations on climate change

Anyone who thinks global warming has stopped has their head in the sand. The evidence is clear – the long-term trend in global temperatures is rising, and humans are largely responsible for this rise. Global warming does not mean that each year will be warmer than the last, natural phenomena will mean that some years will be much warmer and others cooler. You only need to look at 1998 to see a record-breaking warm year caused by a very strong El Niño. In the last couple of years, the underlying warming is partially masked caused by a strong La Niña. Despite this, 11 of the last 13 years are the warmest ever recorded.

Average global temperatures are now some 0.75 °C warmer than they were 100 years ago. Since the mid-1970s, the increase in temperature has averaged more than 0.15 °C per decade. This rate of change is very unusual in the context of past changes and much more rapid than the warming at the end of the last ice age. Sea-surface temperatures have warmed slightly less than the global average whilst temperatures over land have warmed at a faster rate of almost 0.3 °C per decade.

Over the last ten years, global temperatures have warmed more slowly than the long-term trend. But this does not mean that global warming has slowed down or even stopped. It is entirely consistent with our understanding of natural fluctuations of the climate within a trend of continued long-term warming.

The national science academies of the G8 nations and Brazil, China, India, Mexico and South Africa have signed a statement on climate change adaptation and the transition to a low carbon society. Adaptation is necessary if the worst impacts of climate change, now and in the future, are to be alleviated. Mitigation and adaptation can complement each other and if pursued together can significantly reduce the risks of climate change impacts.
The statement calls on world leaders, particularly those meeting at the G8 Summit in Toyako, Hokkaido, in July 2008 to:

• To make maximum efforts to commit to halving global greenhouse gas emissions by 2050.
• Agree, by 2009, a timetable, funding, and a coordinated plan for the construction of a significant number of Carbon Capture and Storage demonstration plants.
• Prepare for the challenges and risks posed by climate change by improving predictive and adaptive capacities at global, national and local level and supporting the developing world in carrying out vulnerability analyses and addressing their findings.
• Take appropriate economic and policy measures to accelerate transition to a low carbon society and to encourage and effect changes in individual and national behaviour.
• Promote science and technology co-operation, innovation and leapfrogging, e.g., by transfer of some basic critical low-carbon and adaptation technologies.
• Urge governments to support research on greenhouse gas reduction technologies and climate change impacts.

2008 Joint science academies' statement: Climate change adaptation and the transition of a low carbon society

Survey: Scientists Agree Human-Induced Global Warming is Real
While the harsh winter pounding many areas of North America and Europe seemingly contradicts that global warming continues unabated, a new survey finds consensus among scientists about the reality of climate change and its likely cause.

A group of 3,146 earth scientists surveyed around the world overwhelmingly agree that in the past 200-plus years, mean global temperatures have been rising, and that human activity is a significant contributing factor in changing mean global temperatures.

Peter Doran, University of Illinois at Chicago associate professor of earth and environmental sciences, along with former graduate student Maggie Kendall Zimmerman, conducted the survey late last year.

The findings appear today in Eos, the newspaper of earth and space sciences published by American Geophysical Union.

In trying to overcome criticism of earlier attempts to gauge the view of earth scientists on global warming and the human impact factor, Doran and Kendall Zimmerman sought the opinion of the most complete list of earth scientists they could find, contacting more than 10,200 experts around the world listed in the 2007 edition of the American Geological Institute's Directory of Geoscience Departments.

Experts in academia and government research centers were e-mailed invitations to participate in the on-line poll conducted by the website questionpro.com. Only those invited could participate and computer IP addresses of participants were recorded and used to prevent repeat voting. Questions used were reviewed by a polling expert who checked for bias in phrasing, such as suggesting an answer by the way a question was worded. The nine-question survey was short, taking just a few minutes to complete.

Two questions were key: have mean global temperatures risen compared to pre-1800s levels, and has human activity been a significant factor in changing mean global temperatures.

About 90 percent of the scientists agreed with the first question and 82 percent the second.

In analyzing responses by sub-groups, Doran found that climatologists who are active in research showed the strongest consensus on the causes of global warming, with 97 percent agreeing humans play a role. Petroleum geologists and meteorologists were among the biggest doubters, with only 47 and 64 percent respectively believing in human involvement. Doran compared their responses to a recent poll showing only 58 percent of the public thinks human activity contributes to global warming.

"The petroleum geologist response is not too surprising, but the meteorologists' is very interesting," he said. "Most members of the public think meteorologists know climate, but most of them actually study very short-term phenomenon."

He was not surprised, however, by the near-unanimous agreement by climatologists.

"They're the ones who study and publish on climate science. So I guess the take-home message is, the more you know about the field of climate science, the more you're likely to believe in global warming and humankind's contribution to it." [Bold and Italics mine - Martin]

Doran and Kendall Zimmerman conclude that "the debate on the authenticity of global warming and the role played by human activity is largely nonexistent among those who understand the nuances and scientific basis of long-term climate processes." The challenge now, they write, is how to effectively communicate this to policy makers and to a public that continues to mistakenly perceive debate among scientists.

Decades of scientific research have shown that climate can change from both natural and anthropogenic causes. The Geological Society of America (GSA) concurs with assessments by the National Academies of Science (2005), the National Research Council (2006), and the Intergovernmental Panel on Climate Change (IPCC, 2007) that global climate has warmed and that human activities (mainly greenhouse‐gas emissions) account for most of the warming since the middle 1900s. If current trends continue, the projected increase in global temperature by the end of the twentyfirst century will result in large impacts on humans and other species. Addressing the challenges posed by climate change will require a combination of adaptation to the changes that are likely to occur and global reductions of CO₂ emissions from anthropogenic sources.

Scientific advances in the first decade of the 21st century have greatly reduced previous uncertainties about the amplitude and causes of recent global warming.

NEAR-TERM EMISSIONS CHOICES COULD LOCK IN CLIMATE CHANGES FOR CENTURIES TO MILLENNIA; REPORT ESTIMATES IMPACTS FROM VARIOUS LEVELS OF WARMING

WASHINGTON— Choices made now about carbon dioxide emissions reductions will affect climate change impacts experienced not just over the next few decades but also in coming centuries and millennia, says a new report from the National Research Council.Because CO2 in the atmosphere is long lived, it can effectively lock the Earth and future generations into a range of impacts, some of which could become very severe.

Policy choices about emissions can be informed by recent advances in climate research that quantify the relationships between atmospheric CO2 and warming levels, and between warming levels and future impacts.Drawing upon this research, the report estimates changes in precipitation, streamflow, wildfires, crop yields, and sea level rise that can be expected with different degrees of warming.It also estimates the average temperature increases that would be likely if CO2 were stabilized in the atmosphere at various target levels.However, the report does not recommend any particular stabilization target, noting that choosing among different targets is a policy choice rather than strictly a scientific one because of questions of values regarding how much risk or damage to people or to nature might be considered too much.

Increased Confidence About Future Impacts

Although some important future effects of climate change are difficult to quantify, there is now increased confidence in how global warming of various levels would relate to several key impacts, says the report.It lists some of these impacts per degree Celsius (or per 1.8 degrees Fahrenheit) of global warming, for example (these apply for 1 C to 4 C of warming):

• 5 percent to 10 percent less total rain in southwest North America, the Mediterranean, and southern Africa per degree Celsius of warming.
• 5 percent to 10 percent less streamflow in some river basins, including the Arkansas and Rio Grande, per degree Celsius of warming.
• 5 percent to 15 percent lower yields of some crops, including U.S. and African corn and Indian wheat, per degree Celsius of warming.

While total rain is expected to decrease in some areas, more of the rain that does occur is expected to occur in heavy falls in most land areas (3 percent to 10 percent more heavy rain per degree Celsius).In addition, warming of 1C to 2 C (1.8 F to 3.6 F) could be expected to lead to a twofold to fourfold increase per degree in the area burned by wildfire in parts of western North America, the report says.Warming of 3 C (5.4 F) would put many millions more people at risk of coastal flooding and lead to the loss of about 250,000 square km of wetlands and drylands.And warming of 4 C (7.2 F) would lead to far warmer summers; about nine out of 10 summers would be warmer than the warmest ever experienced during the last decades of the 20th century over nearly all land areas.

Stabilizing Atmospheric CO2 Requires Deep Emissions Cuts

Currently the concentration of CO2 in the atmosphere is about 390 parts per million volume (ppmv), the highest level in at least 800,000 years.Depending on emissions rates, that level could double or nearly triple by the end of the century, greatly amplifying future human impacts on climate, the report says.

Because the amount of human-caused CO2 emissions already far exceeds the amount that can be removed through natural carbon "sinks" such as oceans, keeping emissions rates the same will not stabilize the concentration of CO2 in the atmosphere.Even if emissions held steady, the CO2 concentration in the atmosphere would increase, much like the water level in a bathtub when water is coming in faster than it is draining.Emissions reductions larger than about 80 percent, relative to whatever peak global emissions rate may be reached, would be required to approximately stabilize carbon dioxide concentrations for a century or so at any chosen target level.

Further, stabilizing atmospheric concentrations does not mean that temperatures will stabilize immediately.Warming that occurs in response to a given increase in the CO2 concentration is only about half the total warming that will ultimately occur.For example, if the CO2 concentration stabilizes at 550 ppmv, the Earth would warm about 1.6 C on the way to that level; but even after the CO2 level stabilizes, the warming would continue to grow in the following decades and centuries, reaching a best-estimate global "equilibrium" warming of about 3 C (5.4 F).Waiting to observe impacts before choosing a stabilization target would therefore imply a lock-in to about twice as much eventual crop loss, rainfall changes, and other impacts that increase with warming.

The report offers likely ranges and best estimates of the equilibrium warming that can be expected from various levels of CO2 in the atmosphere:

Table 1: Relationship of Atmospheric Concentrations of Carbon Dioxide to Temperature

The report was sponsored by the Energy Foundation and the U.S. Environmental Protection Agency.The National Academy of Sciences, National Academy of Engineering, Institute of Medicine, and National Research Council make up the National Academies.They are independent, nonprofit institutions that provide science, technology, and health policy advice under an 1863 congressional charter.Committee members, who serve pro bono as volunteers, are chosen by the Academies for each study based on their expertise and experience and must satisfy the Academies' conflict-of-interest standards.The resulting consensus reports undergo external peer review before completion.For more information, visit http://national-academies.org/studycommitteprocess.pdf.A committee roster follows.

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Copies of Climate Stabilization Targets: Emissions, Concentrations, and Impacts Over Decades to Millennia are available from the National Academies Press; tel. 202-334-3313 or 1-800-624-6242 or on the Internet at http://www.nap.edu.Reporters may obtain a copy from the Office of News and Public Information (contacts listed above).

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[ This news release and report are available at http://national-academies.org ]

NATIONAL RESEARCH COUNCIL