Climat : papiers de recherche moissonnés (26 juillet 2017)

Importance of the pre-industrial baseline for likelihood of exceeding Paris goals / Andrew P. Schurer, Michael E. Mann, Ed Hawkins, Simon F. B. Tett, Gabriele C. Hegerl, Nature Climate Change, 24 July 2017, 6 p. doi:10.1038/nclimate3345 http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate3345.html

During the Paris conference in 2015, nations of the world strengthened the United Nations Framework Convention on Climate Change by agreeing to holding ‘the increase in the global average temperature to well below 2°C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5°C’ (ref. 1). However, ‘pre-industrial’ was not defined. Here we investigate the implications of different choices of the pre-industrial baseline on the likelihood of exceeding these two temperature thresholds. We find that for the strongest mitigation scenario RCP2.6 and a medium scenario RCP4.5, the probability of exceeding the thresholds and timing of exceedance is highly dependent on the pre-industrial baseline; for example, the probability of crossing 1.5°C by the end of the century under RCP2.6 varies from 61% to 88% depending on how the baseline is defined. In contrast, in the scenario with no mitigation, RCP8.5, both thresholds will almost certainly be exceeded by the middle of the century with the definition of the pre-industrial baseline of less importance. Allowable carbon emissions for threshold stabilization are similarly highly dependent on the pre-industrial baseline. For stabilization at 2°C, allowable emissions decrease by as much as 40% when earlier than nineteenth-century climates are considered as a baseline.

Pathways to a Zero-Carbon Future / John C. Dernbach. The Environmental Forum, July/August 2017; Widener Law Commonwealth Research Paper No. 17-04. Available at SSRN: https://ssrn.com/abstract=2991223

This paper reviews major reports by the Deep Decarbonization Pathways Project and the World Bank that describe overall approaches at the global and national levels for meeting a decarbonization objective. Then it describes ways to identify and create legal pathways to that objective for the U.S., building on the insights of these two reports.

Legal Pathways to Deep Decarbonization: Lessons from California and Germany / John C. Dernbach. Last revised: 23 Jun 2017. 56 p. 82 Brooklyn Law Review 825; Widener Law Commonwealth Research Paper No. 15-40. Available at SSRN: https://ssrn.com/abstract=2811667

To achieve deep decarbonization, developed countries need to reduce their net greenhouse gas emissions by more than 80 percent from 1990 levels by 2050. As ambitious and even unachievable as that goal may seem, some developed country jurisdictions have already made considerable progress in conceptualizing and even adopting legal approaches for achieving decarbonization. This article describes the approaches being taken in two major developed country jurisdictions — California and Germany — and suggest lessons from that experience that could be useful to the United States. These lessons are no less important—and may even be more important—after President Trump’s decisions to withdraw the U.S. from active engagement on climate change.

Climate Change after the G-20 Summit / Mukul Sanwal. Economic & Political Weekly, vol. 52, n° 29, 22 Jul. 2017, pp. 24-26 http://www.epw.in/journal/2017/29/commentary/climate-change-after-g-20-summit.html

Global climate policy should now move away from its sole focus on reduction of emissions of carbon dioxide, which is a symptom of the problem, to discussing its causes and strategies. This article argues that, with the largest emitter opting out, the key issue is the broader response from the late developers, in particular India, reframing both the design and implementation of the climate regime.

Research for REGI Committee – Cohesion policy and Paris Agreement Targets / M. Nesbit, K. Paquel et A. Illes. Département thématique B « Politiques structurelles et de cohésion, section « Regional Development » de la Communauté Européenne, 2017, 74 p. https://ieep.eu/uploads/articles/attachments/c6717f0c-98bc-4ede-a662-edd0ce418a8b/Cohesion%20Policy%20and%20Paris%20Agreement%20targets%20report.pdf?v=63667241874

This study examines experience of the mainstreaming of climate policy objectives into cohesion policy in the current (2014-2020) and earlier programming periods, including with respect to its urban dimension, and to territorial cooperation. It identifies the implications of the Paris Agreement on climate change, and makes recommendations for further development of climate mainstreaming in cohesion policy in future programming periods.

Future summer mega-heatwave and record-breaking temperatures in a warmer France climate / Margot Bador, Laurent Terray, Julien Boé, Samuel Somot, Antoinette Alias, Anne-Laure Gibelin and Brigitte Dubuisson, Environmental Research Letters, vol. 12, n° 7, 19 July 2017 http://iopscience.iop.org/article/10.1088/1748-9326/aa751c

This study focuses on future very hot summers associated with severe heatwaves and record-breaking temperatures in France. Daily temperature observations and a pair of historical and scenario (greenhouse gas radiative concentration pathway 8.5) simulations with the high-resolution (~12.5 km) ALADIN regional climate model provide a robust framework to examine the spatial distribution of these extreme events and their 21st century evolution.
Five regions are identified with an extreme event spatial clustering algorithm applied to observed temperatures. They are used to diagnose the 21st century heatwave spatial patterns. In the 2070s, we find a simulated mega-heatwave as severe as the 2003 observed heatwave relative to its contemporaneous climate. A 20-member initial condition ensemble is used to assess the sensitivity of this future heatwave to the internal variability in the regional climate model and to pre-existing land surface conditions. Even in a much warmer and drier climate in France, late spring dry land conditions may lead to a significant amplification of summer extreme temperatures and heatwave intensity through limitations in evapotranspiration. By 2100, the increase in summer temperature maxima exhibits a range from 6 °C to almost 13 °C in the five regions in France, relative to historical maxima. These projections are comparable with the estimates given by a large number of global climate models.

Three years to safeguard our climate / Christiana Figueres, Hans Joachim Schellnhuber, Gail Whiteman, Johan Rockström, Anthony Hobley, Stefan Rahmstorf. Nature, 546 (7640), 28 June 2017, 3 p. https://www.nature.com/uidfinder/10.1038/546593a

Christiana Figueres and colleagues set out a six-point plan for turning the tide of the world’s carbon dioxide by 2020.

International Climate Policy: Trumping Trump / Hermann E. Ott, Lukas Hermwille, Wolfgang Obergassel. Wuppertal Institute for Climate, Environment and Energy, 2017, 8 p. (In brief n° 03/2017) https://wupperinst.org/fa/redaktion/downloads/publications/In_Brief_2017-3_en.pdf

The G20 summit in Hamburg on 7 and 8 July 2017 was the acid test at the highest level for global climate protection after the United States announced its withdrawal from the Paris Agreement. In an unprecedented act of isolating a single country, the remaining « G19 » states reaffirmed their commitment to the Agreement and also clearly stated that it was « irreversible ». With this, a new chapter in international climate policy has begun. Will the rest of the world succeed in coordinating an effective global climate policy despite the withdrawal of US President Trump? Might the international community even succeed in not just compensating for the American contribution, but also in seizing the momentum that has arisen following the decision by the US and perhaps in the end even defy Trump through more far-reaching measures?… read more


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