Climate Change Fact Sheet

This fact sheet summarizes the personal testimony provided by Dr. James E. Hansen on August 14, 2006, regarding climate change in the legal case of Association of International Automobile Manufacturers et. al. v. the Secretary of Vermont, Agency of Natural Resources et. al.

• The United States produces nearly four times the CO2 emissions of any other single country, with power plants and vehicle emissions serving as the two fastest growing and largest sources. Atmospheric concentrations of methane and CO2 have moved far beyond the ranges seen for hundreds of thousands of years; CO2 has risen from a pre-industrial level of 280 parts per million (ppm) to 382 ppm. At current rates of increase, CO2 concentrations are expected to double pre-industrial levels, reaching 560 ppm by 2050.
• Under 'Business-as-Usual' (BAU) scenarios, where CO2 concentration growth continues to increase by typically 2% per year, global warming of at least 5°C is projected by 2100. Warming in the range of 2-3°C is described as virtually certain to cause large-scale disastrous climate impacts for humans and other inhabitants, while 3°C of warming would result in "a different planet."
• Global warming threatens the stability of ice sheets in West Antarctica and Greenland. In 2005, satellite data showed both regions losing mass at approximately 200 cubic kilometers of ice per year. Between 1993 and 2005, 'ice quakes' (earthquakes with magnitudes between 4.6 and 5.1) occurred near Greenland's major ice stream outlets, with the annual frequency of these events quadrupling since 1993. If BAU warming of 2-3°C occurs, sea level rise of at least 25±10 meters is likely, though Dr. Hansen specifically expects about six meters of rise by 2100.
• The climate system is susceptible to abrupt changes that may be impossible to reverse on a civilization-relevant timescale. Dr. Hansen states there is a probability greater than 99% that an additional 2°C of global warming would push the Earth past a tipping point, leading to major regional climate disruptions, the extermination of a substantial fraction of plant and animal species, and sea level rise of at least several meters.
• An 'Alternative Scenario' to avoid the worst impacts would require CO2 concentrations to peak at approximately 475 ppm in 2100, with annual growth reaching zero by that year, keeping total warming below 1°C (relative to 2000). This scenario also requires reducing other greenhouse gases, such as methane, black carbon, and aerosols. Dr. Hansen notes that the window to make this scenario plausible is approximately ten years, and that emission standards proposed by the California Air Resources Board align with the vehicle-related goals of this scenario.

APA

Environmental and Energy Study Institute (2006). Climate Change Fact Sheet. https://www.eesi.org/files/hansen_climate_testimony_06.pdf

Chicago

Environmental and Energy Study Institute. Climate Change Fact Sheet. 2006. https://www.eesi.org/files/hansen_climate_testimony_06.pdf.

Wikipedia

{{cite report |author=Environmental and Energy Study Institute |title=Climate Change Fact Sheet |date=November 2006 |url=https://www.eesi.org/files/hansen_climate_testimony_06.pdf |access-date=17 August 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{environmentalandenergystudyinstitute2006climate, author = {{Environmental and Energy Study Institute}}, title = {{Climate Change Fact Sheet}}, institution = {Environmental and Energy Study Institute}, year = {2006}, month = nov, url = {https://www.eesi.org/files/hansen_climate_testimony_06.pdf}, urldate = {2026-08-17}, note = {Indexed by Climate Insights Directory} }