Social/Political Action You Can Do To Love Greener
Changes in individual behavior, by themselves, will not hold off catastrophe, but will reduce emissions, spread awareness of the climate-change crisis among people we come in contact with, and, if our numbers are great enough, exert pressure on corporations and government.

"Target Atmospheric CO2: Where Should Humanity Aim?" A Scientific Report published 31 March 2008. By James Hansen, Makiko Sato, Pushker Kharecha, David Beerling, Valerie Masson-Delmotte, Mark Pagani, Maureen Raymo, Dana Royer, James C. Zachos.

. . . Human activities are altering Earth's atmospheric composition. Concern about global warming due to long-lived human-made greenhouse gases (GHGs) led to the United Nations Framework Convention on Climate Change with the objective of stabilizing GHGs in the atmosphere at a level preventing "dangerous anthropogenic interference with the climate system." The Intergovernmental Panel on Climate Change (IPCC) and others used several "reasons for concern" to estimate that global warming of more than 2-3°C may be dangerous.

The European Union adopted 2°C above pre-industrial global temperature as a goal to limit human-made warming. Hansen et al. argued for a limit of 1°C global warming (relative to 2000, 1.7°C relative to pre-industrial time), aiming to avoid practically irreversible ice sheet and species loss. This 1°C limit, with nominal climate sensitivity of 3/4°C per W/m 2 and plausible control of other GHGs, implies maximum CO2 ~ 450 ppm.

Our current analysis suggests that humanity must aim for an even lower level of GHGs. Paleoclimate data and ongoing global changes indicate that ‘slow' climate feedback processes not included in most climate models, such as ice sheet disintegration, vegetation migration, and GHG release from soils, tundra or ocean sediments, may begin to come into play on time scales as short as centuries or less. Rapid on-going climate changes and realization that Earth is out of energy balance, implying that more warming is ‘in the pipeline', add urgency to investigation of the dangerous level of GHGs.

A probabilistic analysis concluded that the long-term CO2 limit is in the range 300-500 ppm for 25 percent risk tolerance, depending on climate sensitivity and non-CO2 forcings. Stabilizing atmospheric CO2 and climate requires that net CO2 emissions approach zero, because of the long lifetime of CO2.

We use paleoclimate data to show that long-term climate has high sensitivity to climate forcings and that the present global mean CO2, 385 ppm, is already in the dangerous zone. Despite rapid current CO2 growth, ~2 ppm/year, we show that it is conceivable to lower CO2 this century to less than the current amount, but only via prompt policy changes. . . . (p. 1)

Present policies, with continued construction of coal-fired power plants without CO2 capture, suggest that decision-makers do not appreciate the gravity of the situation. We must begin to move now toward the era beyond fossil fuels. Continued growth of greenhouse gas emissions, for just another decade, practically eliminates the possibility of near-term return of atmospheric composition beneath the tipping level for catastrophic effects.

The most difficult task, phase-out over the next 20-25 years of coal use that does not capture CO2, is herculean, yet feasible when compared with the efforts that went into World War II. The stakes, for all life on the planet, surpass those of any previous crisis. The greatest danger is continued ignorance and denial, which could make tragic consequences unavoidable. (p. 12)

(The full report--35 pages--is available as a download from a wide variety of sources. Go to www.columbia.edu/~jeh1/2008/TargetCO2_20080407.pdf, or simply do a search on the title of the report. It's ALL OVER THE WEB.)