The IPCC Fifth Assessment Report: A Roadmap for Action

COP-20 comes on the heels of the release of the Fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change (IPCC). AR5 is the result of an extraordinary amount of rigorous research, with over 800 scientists participating as authors. To make this information accessible to policymakers and to the public, the IPCC engages in various outreach activities; a helpful synthesis video is available on the IPCC website. Yesterday, on the second day of COP-20, lead authors of the AR5 further presented a brief summary of their findings with the intent of informing policymakers as they commence negotiations. While much of the findings below come as no surprise to those involved in climate issues, it is important to remind negotiators of just what is at stake here in Lima and next year in Paris. The research is organized in four topics:

1) Observed Changes and their Causes

The authors present unequivocal evidence of anthropogenic climate change, and show that the observed changes since the 1950s are unprecedented. Moreover, the report shows how dishearteningly meagre efforts to mitigate emissions have been so far: from 2000 to 2010, global greenhouse gas emissions have been the highest in history, with total emissions from this decade equivalent to those of three previous decades.

2) Future Climate Changes, Risks and Impacts

The impacts of these emissions vary from region to region. Alarmingly, the effects of a rise in global temperature are most prominent in coldest places in world, where it would be most important to retain cooler temperatures. This is because changes in the cryosphere, or in snow and ice, have severe consequences for the rest of the world as more sunlight will be absorbed by the earth, not to mention the impacts on the hydrological cycle and sea-level rise caused by melting of glaciers. Of course, the cryosphere is just one area where the impacts of climate change are felt and multiplied; the main message of AR5’s Risks and Impacts chapter is that ecosystems overall are very sensitive to changes in climate. With greater changes, the risk of more severe impacts grows. Still, according to Dr. Chris Field, Co-Chair of Working Group II of the IPCC, we can still have a world where the impacts of climate change are manageable; but to do this, we will need to act now.

3) Future Pathways for Adaptation, Mitigation and Sustainable Development

To reduce these risks and keep impacts manageable, it is essential that we take comprehensive mitigation action going much further than present efforts, with all sectors participating. In this section, the report shows how different mitigation portfolios result in varying levels of future climate change, highlighting that without significant further mitigation efforts, the impacts of climate change are likely to be severe and irreversible. Professor Ottmar Ederhofer, Co-Chair of Working Group III of the IPCC, emphasized that we do have a choice; the level of mitigation efforts we engage in will determine whether we face a temperature increase of 2 degrees, 4 degrees, or higher. However, to achieve lower levels, such as the 1.5 degree goal of small island developing states, radical and immediate efforts would be required.

4) Adaptation and Mitigation

No matter how intense mitigation efforts are made, some impacts are unavoidable due to the accumulation of greenhouse gases in the atmosphere. Thus, adaptation has already begun to occur; seawalls, changes in agricultural practices, and climate-smart buildings are all examples of adaptive practices. The extent to which mitigation is undertaken will determine how far these adaptive measures can take us. AR5 underscores that successful adaptation and mitigation both require effective institutions and governance, innovation and investments in environmentally sound technologies and infrastructure, sustainable livelihoods, and behavioral and lifestyle choices, highlighting the sometimes overwhelming range of challenges societies face in addressing their own adaptation and mitigation strategies.


Laura Sundblad graduated from Columbia University’s School of International and Public Affairs in 2014. She currently works in New York in the field of access to clean energy and is a CUCSD COP-20 Delegation Member.