U.N. Report States Climate Mitigation Must Start Now

On April 13, Working Group III (WGIII) of the Intergovernmental Panel on Climate Change (IPCC) released its report on what can be done to mitigate climate change across sectors. Four years of research and analysis culminated in a week-long meeting in Berlin, during which scientists from developing and industrialized nations discussed mitigation strategies and goals. The 2,000-page report avoids recommending specific policy goals, but instead focuses on providing policy options for different levels of government (nations, regions, cities…) and economic sectors. This publication is the third and final part of the IPCC's fifth assessment report (AR5), an update to the fourth assessment report published in 2007. The Working Group I report found that climate change is unequivocal, and is caused by humans, while the Working Group II report detailed the risks of climate change to society.

Greenhouse gas (GHG) emissions have risen faster in the last 10 years than they have in the preceding 30-year period. Between 1970 and 2000, GHG emissions rose at an annual rate of 1.3 percent; now, they are rising at a rate of 2.2 percent per year, largely due to an increase in coal usage from developing countries. The scientists contributing to the IPCC argue that clean technologies will need to overtake traditional fossil fuels in order to address climate change. With urban populations expected to triple by 2030, energy efficiency, smart infrastructure, and retrofits to buildings will all need to be implemented as part of a global mitigation strategy.

Also discussed in the WGIII report are some risky technologies for removing carbon dioxide from the atmosphere, which some scientists believe could help with mitigation. But the authors wrote that these are not yet viable options and could potentially be a “distraction” from more feasible renewable energy options, such as wind and solar.

Scientists are still optimistic that the world can stay below a global rise of 2 degrees Celsius (3.6 degrees Fahrenheit) compared to pre-Industrial levels. However, to stay below this threshold—which scientists have established as the “danger-threshold”—business-as-usual scenarios of fossil fuel burning will not be able to continue. Fossil fuel burning would need to peak in the near future and then fall to between 40 to 70 percent of 2010 levels by 2050 and then continue falling until 2100, in order to stay within a 2-degree Celsius rise.

Those who say action against climate change will drastically harm the economy are mistaken, according to this report. The IPCC reports that the most ambitious mitigation plan would only reduce growth by about 0.06 percentage points per year. This doesn’t even take into account the co-benefits of climate action, such as public health and increased energy efficiency savings, which could further reduce the impact to the global economy and perhaps even lead to a net benefit.

Two hundred eighty-five authors from 58 countries, along with 900 peer reviewers, contributed to this report. Rajendra K. Pachauri, one of the co-chairmen of WGIII, argued for the need for cooperation among countries to limit global temperature rise, saying that “what comes out very clear from this report is that the high-speed mitigation train needs to leave the station soon, and all of global society needs to get on board.” U.S. researchers, including Leon Clarke, senior research economist at the Pacific Northwest National Laboratory and one of the report's lead authors, seconded this feeling with the sentiment that, “the longer we wait, the harder this is going to get.”