How Can We Avert Dangerous Climate Change?

TL;DR

This paper emphasizes the urgent need to keep atmospheric CO2 below 450 ppm to prevent dangerous climate tipping points, highlighting feasible actions and the importance of equitable responsibility and policy changes.

Contribution

It outlines scientifically feasible strategies to limit CO2 and global warming, emphasizing the importance of policy and responsibility distinctions between countries.

Findings

CO2 levels above 450 ppm risk irreversible climate tipping points

Reducing non-CO2 forcings offers limited mitigation benefits

Achieving low CO2 levels is technically feasible with policy changes

Abstract

Recent analyses indicate that the amount of atmospheric CO2 required to cause dangerous climate change is at most 450 ppm, and likely less than that. Reductions of non-CO2 climate forcings can provide only moderate, albeit important, adjustments to the CO2 limit. Realization of how close the planet is to "tipping points" with unacceptable consequences, especially ice sheet disintegration with sea level rise out of humanity's control, has a bright side. It implies an imperative: we must find a way to keep the CO2 amount so low that it will also avert other detrimental effects that had begun to seem inevitable, e.g., ocean acidification, loss of most alpine glaciers and thus the water supply for millions of people, and shifting of climatic zones with consequent extermination of species. Here I outline from a scientific perspective actions needed to achieve low limits on CO2 and global warming. These changes are technically feasible and have ancillary benefits. Achievement of needed changes requires overcoming the spurious argument that developed and developing countries have equivalent responsibilities, as well as overcoming special interests advocating minimalist or counterproductive actions such as corn-based ethanol and liquid-fuel-from-coal programs.