Science
28 October 2016 Vol 354, Issue 6311
http://www.sciencemag.org/current.dtl
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EDITORIAL
Dealing with details in Marrakesh
Patricia Espinosa
Summary
Over the next few weeks, two major events will take place—the 2015 Paris Agreement on climate change will enter into force on 4 November, and 3 days later, nearly 200 countries will convene in Marrakesh, Morocco, at the 22nd United Nations (UN) Conference of the Parties (COP22) to decide on how to rapidly implement the agreement. Indeed, the agreement’s governing body will hold its first meeting during COP22. This swift action to commit and come up with climate action plans is a welcome departure for the international community, and it sends a clear message that success in tackling climate challenges requires more than just a historic political agreement.

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Policy Forum
Making climate science more relevant
By Charles F. Kennel, Stephen Briggs, David G. Victor
Science28 Oct 2016 : 421-422 Full Access
Better indicators for risk management are needed after Paris
Summary
For nearly three decades, the central goal in international climate policy had been to set the political agenda—to engage all countries on the need for action. So long as that was the goal, it was sufficient for policy-makers to focus on simple indicators of climate change, such as global average surface temperature With the 2015 Paris Agreement, governments launched a process that can move beyond setting agendas to coordinating national policies to manage the climate. Next month in Marrakesh, diplomats will convene to flesh out the Agreement. They need to focus on the infrastructure of data and analysis that will be needed as the Agreement becomes operational. The scientific community can help by identifying better lagging indicators to describe what has changed as policy efforts progress, and leading indicators to focus policy on the right risks as the planet warms.

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Climate change: The 2015 Paris Agreement thresholds and Mediterranean basin ecosystems
By Joel Guiot, Wolfgang Cramer
Science 28 Oct 2016 : 465-468 Restricted Access
Global warming above 1.5°C will likely change Mediterranean ecosystems in ways unprecedented in the Holocene record.
Editor’s Summary
A warming limit for the Mediterranean basin
Pollen cores from sediments provide rich detail on the history of vegetation and climate in the Mediterranean during the Holocene (the most recent ~10,000 years). Guiot and Cramer used this information as a baseline against which to compare predictions of future climate and vegetation under different climate-change scenarios. Vegetation and land-use systems observed in the Holocene records may persist under a 1.5°C warming above preindustrial temperature levels. A 2°C warming, however, is likely over the next century to produce ecosystems in the Mediterranean basin that have no analog in the past 10,000 years.
Abstract
The United Nations Framework Convention on Climate Change Paris Agreement of December 2015 aims to maintain the global average warming well below 2°C above the preindustrial level. In the Mediterranean basin, recent pollen-based reconstructions of climate and ecosystem variability over the past 10,000 years provide insights regarding the implications of warming thresholds for biodiversity and land-use potential. We compare scenarios of climate-driven future change in land ecosystems with reconstructed ecosystem dynamics during the past 10,000 years. Only a 1.5°C warming scenario permits ecosystems to remain within the Holocene variability. At or above 2°C of warming, climatic change will generate Mediterranean land ecosystem changes that are unmatched in the Holocene, a period characterized by recurring precipitation deficits rather than temperature anomalies.