On Sunday, 2 November 2014 the IPCC made public the Synthesis Report of its latest assessment round on the science, impacts and solutions of climate change: the Fifth Assessment Report (AR5).
The Synthesis Report draws together the most significant findings from each of the three Working Groups’ reports and the two Special Reports to provide new insights relevant to policymakers. The Summary for Policymakers is approved line-by-line by governmental representatives from the member countries of the intergovernamental panel.
The IPCC sets forth, with greater certainty than its previous assessments, the fact that warming of the climate system is unequivocal, and that greenhouse gas emissions and other anthropogenic drivers have been the main causes. Since the 1950s many of the observed changes are unprecedented over decades to millennia, the report said. “Our assessment finds that the atmosphere and oceans have warmed, the amount of snow and ice has diminished, sea level has risen and the concentration of carbon dioxide has increased to a level unprecedented in at least the last 800,000 years,” said Thomas Stocker, Co-Chair of IPCC Working Group I.
The continuation of this warming trend will have increasingly profound impacts that affect all levels of society and the natural world. The impact will be felt most strongly by people in the least developed countries and vulnerable communities because of their limited ability to cope with the change. Adaptation has a fundamental role to play decreasing the risks associated with a warming planet while also enabling economic development. Nevertheless, the Synthesis Report maintains that substantial and sustained reductions of greenhouse gas emissions are the key to limiting the risks of climate change. “Human influence on the climate system is clear and growing, with impacts observed on all continents. If left unchecked, climate change will increase the likelihood of severe, pervasive and irreversible impacts for people and ecosystems. However, options are available to adapt to climate change and implementing stringent mitigations activities can ensure that the impacts of climate change remain within a manageable range”, experts said the official statement.
Multiple pathways are available to achieve emission reduction within the next few decades, with a greater than 66 percent change of keeping warming within the 2°C target agreed by governments. Further, such mitigation efforts would not strongly affect global economic growt, the report finds. In business-as-usual scenarios, consumption (a proxy for economic growth used by the Working Group III to estimates mitigation costs) grows by 1.6 to 3 percent per year over the 21st century. Ambitious mitigation would reduce global consumption by about 0.06 percent. “Compared to the imminent risk of irreversible climate change impacts, the risks of mitigation are manageable” said Youba Sokona, Co-Chair of IPCC Working Group III. The IPCC stresses that these economic estimates of mitigation costs do not account for the benefits of reduced climate change, nor do they account for the numerous co-benefits associated with human health, livelihoods, and development.
Timing is of the essence for both mitigation and its cost. To have a good chance of staying within the 2°C limit and avoiding excessive cost, emissions need to fall globally by 40-70% from 2010-2050 and to zero by 2100.
“We have the means to limit climate change,” said R. K. Pachauri, Chair of the IPCC. “The solutions are many and allow for continued economic and human development. All we need is the will to change, which we trust will be motivated by knowledge and an understanding of the science of climate change”.
(Image: Opening Ceremony of the Fortieth Session of the IPCC, Copenhagen, Denmark, 27 October 2014. Photo credit: IPCC/Flickr)