The United Nations science panel responsible for writing influential reports on climate change has exaggerated the likely amount of future global warming, and overstated its potential harm, scientists said in an alternative report released this week.
The new report, Climate Change Reconsidered II: Physical Science, is approximately 1,200 pages long and produced by the Nongovernmental International Panel on Climate Change, established in 2003 to counter the UN’s Intergovernmental Panel on Climate Change (IPCC).
In its most recent report, in 2007, the IPCC claimed “most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in [human-produced] greenhouse gas concentrations.” Policymakers from various countries have used the report to press for carbon cuts from the West and subsidies for developing nations. The green policies meant to curb global warming would amount to billions of dollars if implemented.
The alternative report, released on Tuesday by the Heartland Institute, points to scientific literature rebutting the UN’s claims. While acknowledging that “global temperature change is occurring, as it always does,” the authors conclude that “any human global climate [impact] is so small as to be embedded within the background variability of the natural climate system and is not dangerous.”
Climate Change Reconsidered II has chapters addressing temperature records, the hydrosphere, extreme weather, solar cycles, and climate models. The authors say global climate models, simulated on computers, are widely known to oversimplify climate complexity, and often produce inaccurate results. Mounting evidence suggests “climate sensitivity to CO2 is much lower than [IPCC] models assume.” For example, methane levels in the atmosphere are rising more slowly than expected, and increases in low-level clouds are likely to offset warming caused by greenhouse gases.
“We conclude the current generation of [global climate models] are unable to make accurate projections of climate even 10 years ahead, let alone the 100-year period that has been adopted by policy planners,” notes the report’s summary.
The authors say global warming that occurred in the late 20th century only seems extreme because of the narrow time period it represents. In fact, glacial and geologic records indicate global temperatures were warmer during the Egyptian, Minoan, Roman, and Medieval warm periods than at the end of the 20th century.
“Over recent geological time, Earth’s temperature has fluctuated naturally between about +4 C [7.2 F] and -6 C [10.8 F] with respect to 20th century temperature,” the report states. “Though a future warming of 2 C [3.6 F] would cause geographically varied ecological responses, no evidence exists that those changes would be net harmful to the global environment or to human well-being.”
Nearly two dozen scientists and professors helped write Climate Change Reconsidered II. The lead authors included Fred Singer, an atmospheric physicist who founded the Science and Environmental Policy Project; Craig Idso, founder of the Center for the Study of Carbon Dioxide and Global Change; and Robert Carter, a climate researcher. The entire report is available for free at ClimateChangeReconsidered.org.
The alternative analysis comes as the IPCC is preparing its fifth major climate change report for world leaders to review. Although mainstream news media have tended to laud IPCC conclusions, the panel’s habit of exaggerating facts is leading some reporters to take a more critical approach. A few days ago The Mail on Sunday criticized the IPCC’s climate models for predicting a rate of temperature increase four times higher than what has actually been observed.