Special Journal Issue Meeting the UN Paris Climate Change Agreement

The journal of the Royal Society today publishes the science outcomes of the Conference in Oxford in September 2016, Meeting the Challenges of the Paris Agreement hosted by the Environmental Change Institute at Oxford University and co-sponsored by the Tyndall Centre for Climate Change Research. The special issue editors include Profs Jim HallMyles Allen and Corinne Le Quéré.

The Paris Agreement’s aim is to strengthen the global response to the threat of climate change by keeping a global temperature rise this century well below 2 degrees Celsius above pre-industrial levels and to pursue efforts to limit the temperature increase even further to 1.5 degrees Celsius.

The papers in this special issue of Philosophical Transactions of the Royal Society A provide new insights that limiting warming to 1.5°C, in the context of sustainable and equitable development, is still possible with urgent and rapid reductions of carbon dioxide emissions.

Researchers present and compare a range of projected changes for a world at 1.5°C and 2°C. Oman, Bangladesh, Mauritania and Yemen at 2°C are projected to reach unprecedented levels of vulnerability to food insecurity.

Scientists predict that the median GDP per capita will be 13% lower at the end of the century if climate change raises temperatures worldwide by 2°C, compared to if temperatures remained the same. The projected economic losses are greatest in low income countries suggesting increased inequality under future climate change.

Researchers find that an additional 5.5% and 14% of the globe could act as a climatic refuge for plants and animals if we limit global warming to 1.5°C compared to 2°C.

The Myriad Challenges of the Paris Agreement

Mitchell, Daniel http://rsta.royalsocietypublishing.org/lookup/doi/10.1098/rsta.2018.0066

The much awaited and intensely negotiated Paris Agreement was adopted on the 12th of December 2015 by the Parties to the United Nations Framework Convention on Climate Change (UNFCCC, 2015).The agreement set out a more ambitious long term temperature goal than many had anticipated, implying more stringent emissions reductions that have been under-explored by the research community. By its very nature a multidisciplinary challenge, filling the knowledge gap requires climate scientists, the Earth system science community, as well as economists, engineers, lawyers, philosophers, politicians, emergency planners and others to step up. To kick start cross-disciplinary discussions, the University of Oxford’s Environmental Change Institute (ECI) focused its 25th anniversary conference upon meeting the challenges of the Paris Agreement for science and society. This special issue consists of review papers, opinion pieces and original research from some of the presentations within that meeting, covering a wide range of issues underpinning the Paris Agreement

Changes in climate extremes, fresh water availability and vulnerability to food insecurity projected at 1.5°C and 2°C global warming with a higher-resolution global climate model

Betts, Richard; Alfieri, Lorenzo; Caesar, John; Chang, Jinfeng; Ciais, Philippe; Feyen, Luc; Friedlingstein, Pierre; Gohar, Laila; Koutroulis, Aristeidis; Papadimitriou, Lamprini; Tsanis, Ioannis; Wyser, Klaus http://rsta.royalsocietypublishing.org/lookup/doi/10.1098/rsta.2016.0452

Impacts of 2C global warming are larger than those of 1.5C. Temperature extremes increase by more than the global average warming. Hydrological impacts such as flooding and drought show complex changes but generally most models project wetter conditions in most areas, with increased flooding risk and, mostly, reduced drought risk.  However, increased drought risk is still projected by most models in some areas, and by a minority of models in many areas, so should not be overlooked. Vegetation productivity is projected to increase, especially if climate sensitivity is relative small and higher concentrations of CO2 are required to reach 1.5C or 2C global warming.

Stabilisation of global temperature at 1.5°C and 2.0°C: Implications for coastal areas

Nicholls, RobertBrown, Sally; Goodwin, Phil; Wahl, Thomas; Lowe, Jason; Solan, Martin; Godbold, Jasmin; Haigh, Ivan D; Lincke, Daniel; Hinkel, Jochen; Wolff, Claudia; Merkens, Jan-Ludolf http://rsta.royalsocietypublishing.org/lookup/doi/10.1098/rsta.2016.0448

Coastal areas benefit less from climate stabilisation following the Paris Agreement than other sectors. Most relevant climate variables such as ocean pH stabilise in about a century. However, sea-level rise is only slowed and continues to 2300 (and beyond). Hence while coastal impacts of sea-level rise are reduced by climate stabilisation, potential impacts continue to grow for centuries. Sea-level rise under stabilisation in 2300 exceeds unmitigated sea-level rise in 2100, threatening vulnerable populated coastal areas such as small islands, deltas and cities. Hence, long-term adaptation (linked to wider coastal development and planning) remains essential in coastal areas under climate stabilisation.

Uncertain impacts on economic growth when stabilizing global temperatures at 1.5°C or 2°C warming
Pretis, Felix; Schwarz, Moritz; Tang, Kevin; Haustein, Karsten; Allen, Myles http://rsta.royalsocietypublishing.org/lookup/doi/10.1098/rsta.2016.0460

Using a new set of climate projections and empirical estimates of how climate affects economic growth, we assess economic outcomes under 1.5°C and 2°C warming following the Paris Agreement. Economic growth under 1.5°C warming is near indistinguishable from current climate conditions, while 2°C warming suggests lower growth rates for a large set of countries. Median projected global average GDP per capita is 5% lower at the end of the century under 2°C warming relative to 1.5°C, and 13% lower than under no additional warming. Projected economic losses are greatest in low income countries suggesting increased inequality under future climate change.

Impacts on terrestrial biodiversity of moving from a 2ᵒC to a 1.5ᵒC target
Smith, Pete; Price, Jeff; Molotoks, Amy; Warren, Rachel; Malhi, Yadvinder http://rsta.royalsocietypublishing.org/lookup/doi/10.1098/rsta.2016.0456

Efforts to hold warming to 1.5°C versus 2°C can reduce, by up to 50%, the number of species facing a potential loss of 50% of their climatic range. Further, there would be an increase of 5.5-14% of the globe that could potentially act as climatic refugia for plants and animals, an area equivalent to the current global protected area network. Efforts to meet the 1.5°C target through mitigation could largely be consistent with biodiversity protection / enhancement. Additional effort to meet the 1.5°C target by greenhouse gas removal presents some risks, particularly if inappropriately managed, but it also presents opportunities.

The impact of Earth system feedbacks on carbon budgets and climate response
Lowe, Jason; Bernie, Daniel http://rsta.royalsocietypublishing.org/lookup/doi/10.1098/rsta.2017.0263

This work highlights that it might be more difficult to limit global warming to below 1.5C or 2C than previously thought.

The Legal Character and Operational Relevance of the Paris Agreement’s Temperature Goal Rajamani, Lavanya; Werksman, Jacob http://rsta.royalsocietypublishing.org/lookup/doi/10.1098/rsta.2016.0458

Politically and symbolically, 1.5 °C goal reflects an acknowledgement by states that the planet’s most vulnerable countries and communities consider a temperature rise beyond that limit, as an existential threat. The operational links established between the Agreement’s purpose, its aims, its goals, and Parties’ nationally determined contributions, help to ensure the temperature goal has an operational role in guiding global and national discourse on the need for climate policy with greater ambition and urgency. However, the Paris Agreement falls short of converting the long-term temperature goal into a provision with specific legal force applicable to the actions of individual Parties. The existential aspirations of the most vulnerable countries that the goal represents will continue to rest on the quality of the political discourse the Paris Agreement is able to create – both internationally and domestically — and on our individual and collective conscience.

The utility of the historical record for assessing the transient climate response to cumulative emissions
Millar, Richard; Friedlingstein, Pierre http://rsta.royalsocietypublishing.org/lookup/doi/10.1098/rsta.2016.0449

The total amount of carbon dioxide emissions over all time has been shown to be an important predictor of future global warming. We investigate constraints on the amount of warming expected from a given amount of carbon dioxide emissions using observations of historical climate change. We find a best-estimate in the lower half of previously assessed ranges but with substantial uncertainty making it impossible to rule out a high response to carbon dioxide emissions. This indicates still large physical uncertainty in the size of the remaining carbon budgets compatible with the goal of the Paris Agreement.

Implications of possible interpretations of “greenhouse gas balance” in the Paris Agreement
Fuglestvedt, Jan Sigurd; Rogelj, Joeri; Millar, Richard; Allen, Myles; Boucher, Olivier; Forster, Piers; Kriegler, Elmar; Shindell, Drew http://rsta.royalsocietypublishing.org/lookup/doi/10.1098/rsta.2016.0445

The goal of the Paris Agreement is “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”. It points to the need to achieve “a balance between anthropogenic emissions by sources and removals by sinks of greenhouse gases”. “greenhouse gas balance” is subject to interpretation, and several clarifications are needed in order to make it operational for implementation in climate policies. We study possible interpretations from a scientific perspective and analyze their climatic implications to make Policymakers aware issues and choices.

Coordinating AgMIP data and models across global and regional scales for 1.5 °C and 2.0 °C assessments
Rosenzweig, Cynthia; Ruane, Alex; Antle, John; Elliott, Joshua; Ashfaq, Muhammad; Chatta, Ashfaq; Ewert, Frank; Folberth, Christian; Hathie, Ibrahima; Petr, Havlík; Hoogenboom, Gerrit; Lotze-Campen, Hermann; Mason-D’Croz, Daniel; MacCarthy, Dilys; Mencos Contreras, Erik; Müller, Christoph; Perez-Dominguez, Ignacio; Phillips, Meridel; Porter, Cheryl; Raymundo, Rubi M.; Sands, Ron; Schleussner, Carl-Friedrich; Valdivia, Roberto; Valin, Hugo; Wiebe, Keith http://rsta.royalsocietypublishing.org/lookup/doi/10.1098/rsta.2016.0455

After significant work on the use of multi-model ensembles for individual crops, regional farming systems, and global economics, a new major focus of AgMIP is the creation of protocols for Coordinated Global and Regional Assessments. The shift from the intercomparison and improvement focus of AgMIP in general to a coordination and improvement across scales and disciplines will help to make CGRA research more relevant to agricultural science and stakeholders. CGRA results have direct implications for international climate policy, national mitigation and adaptation planning, and development aid.

Solar Geoengineering as part of an overall strategy for meeting the 1.5°C Paris target
MacMartin, Douglas; Ricke, Katharine; Keith, David http://rsta.royalsocietypublishing.org/lookup/doi/10.1098/rsta.2016.0454

Solar geoengineering refers to deliberately reducing radiative forcing by reflecting some sunlight back to space, in order to reduce anthropogenic climate changes; a possible such approach would be adding aerosols to the stratosphere. If future mitigation proves insufficient to limit global mean temperatures to less than 1.5C above preindustrial, it is plausible that some additional and limited deployment of solar geoengineering could reduce climate damages, as part of an overall strategy to manage climate change risks.  Model projections suggest that a 1.5C-climate achieved with geoengineering is closer to a 1.5C-climate achieved through mitigation alone than either is to a 3C-climate.

Can “loss and damage” carry the load?
Verchick, Rob http://rsta.royalsocietypublishing.org/lookup/doi/10.1098/rsta.2017.0070

Robert Verchick, a legal scholar at Loyola University New Orleans argues that if global warming rises beyond 1.5ºC above preindustrial levels, it could become much more difficult to realize the promise of addressing “loss and damage,” a term that describes significant negative impacts that cannot be avoided or adapted to. The most dramatic increases in such impacts are predicted to occur in tropical latitudes, where most of the world’s poor reside. Verchick argues that for the world to have a chance at addressing loss and damage in a meaningful way, all efforts must be made to keep warming near 1.5ºC.

Toward Legitimacy of the Solar Geoengineering Research Enterprise

Frumhoff, Peter; Stephens, Jennie C http://rsta.royalsocietypublishing.org/lookup/doi/10.1098/rsta.2016.0459

Mounting concerns over climate risks above the Paris Agreement temperature targets is increasing calls for atmospheric experiments to test the efficacy of solar geoengineering technologies to reflect sunlight and rapidly lower surface temperatures. This paper argues that researchers and funders eager to move forward with solar geoengineering field experiments should participate in and await the outcomes of meaningful processes of engagement on the risks and implications of solar geoengineering with a broad cross-section of civil society stakeholders and be explicitly open to multiple potential outcomes, including societal rejection of the solar geoengineering research enterprise.

Building Equity In: Strategies for Integrating Equity into Modeling for a 1.5 °C World

Klinsky, Sonja; Winkler, Harald http://rsta.royalsocietypublishing.org/lookup/doi/10.1098/rsta.2016.0461

Emission pathways consistent with limiting temperature increase to 1.5 °C raise pressing questions from an equity perspective. We develop a set of six elements for evaluating the equity implications of policy actions consistent with 1.5°C and use these to assess the adequacy of current modelling approaches in this context.  We find current practices face serious limitations across all six dimensions although the severity of these varies. Based on our assessment we identify strategies that may be best suited for enabling us to generate insights about each of the six equity elements in the context of assessing 1.5°C pathways

Mitigation Gamble: Uncertainty, Urgency, and the Last Gamble Possible

Shue, Henry http://rsta.royalsocietypublishing.org/lookup/doi/10.1098/rsta.2017.0105

A rejection by current generations of more ambitious mitigation of carbon emissions inflicts on future generations an inherently objectionable gamble about which they have no choice.  Any gains from less ambitious mitigation, which are relatively minor, would accrue to current generations, and all losses, which are relatively major, would fall on future generations.  This mitigation gamble is especially unjustifiable because it imposes a risk of unlimited losses until carbon emissions cease.  Ultimate physical collapses are possible.  Much more ominous is prior social collapse from political struggles over conflicting responses to threatened physical collapse.

Reaching a 1.5C target: Socio-technical challenges for a rapid transition to low carbon electricity systems
Eyre, Nick; Darby, Sarah; Grunewald, Philipp; McKenna, Eoghan; Ford, Rebecca http://rsta.royalsocietypublishing.org/lookup/doi/10.1098/rsta.2016.0462

A 1.5C global average target implies that we should no longer focus on merely incremental emissions reductions from the electricity system, but rather on fundamentally re-envisaging a system that, sooner rather than later, becomes carbon free. We argue that transition towards a system that can fully displace carbon sources will require expanding the focus of our efforts beyond technical solutions to include social dimensions of change which interact strongly with the technical system. This paper sets out a socio-technical review, covering electricity infrastructure, citizens, business models and governance, which describes some of the socio-technical challenges that need to be addressed for the successful transition of existing electricity systems.

Climate extremes, land-climate feedbacks, and land-use forcing at 1.5°C
Seneviratne, Sonia; Wartenburger, Richard; Guillod, Benoit P.; Hirsch, Annette L.; Vogel, Martha M.; Brovkin, Victor; van Vuuren, Detlef; Schaller, Nathalie; Boysen, Lena; Calvin, Katherine; Davin, Edouard L.; Doelman, Jonathan; Greve, Peter; Petr, Havlík; Humpenoeder, Florian; Krisztin, Tamas; Mitchell, Daniel; Popp, Alexander; Riahi, Keywan; Rogelj, Joeri; Schleussner, Carl-Friedrich; Sillmann, Jana; Stehfest, Elke http://rsta.royalsocietypublishing.org/lookup/doi/10.1098/rsta.2016.0450

We provide analyses of changes in climate extremes at 1.5°C global warming, showing that estimates of two well established approaches yield similar results. We then highlight the role of land use forcing and land-climate interactions for these projections, and their importance for the modelling of scenarios of sustainable development pathways.

Pathways limiting warming to 1.5°C: A tale of turning around in no time?
Kriegler, Elmar; Luderer, Gunnar; Bauer, Nico; Baumstark, Lavinia; Fujimori, Shinichiro; Popp, Alexander; Rogelj, Joeri; Strefler, Jessica; van Vuuren, Detlef http://rsta.royalsocietypublishing.org/lookup/doi/10.1098/rsta.2016.0457

We ask the question to what extent it is still feasible to limit warming to 1.5°C by the end of the century. We find that the lower bound of future cumulative CO2 emissions from fossil fuel combustion over the 21st century is 570 billion tCO2 even if we push all levers to reduce emissions to the extreme.This means that in all but the most optimistic assumptions about the remaining 1.5°C CO2 budget the deployment of CDR will be necessary to keep the 1.5°C limit within reach.

Climate and Development: Enhancing Impact Through Stronger Linkages in the Implementation of the Paris Agreement and SDGs
Gomez-Echeverri, Luis http://rsta.royalsocietypublishing.org/lookup/doi/10.1098/rsta.2016.0444

The extraordinary global achievements of the SDGs and the Paris Agreement provide a historic opportunity for strengthening the linkages between climate and development. The evidence is quite clear. It is impossible to reach the ambitious targets of the Paris Agreement without attending to the development implications.  And it would be impossible to reach the SDG goals and targets with worsening impacts of climate change.  New methodologies are making the task of assessing these linkages more accessible. A new family of scenarios tries to bring together analysis of biophysical as well as economic and social changes and incorporates qualitative analysis.

Negative emissions technologies and CCS to achieve the Paris Agreement commitments
Haszeldine, R; Flude, Stephanie; Johnson, Gareth; Scott, Vivian http://rsta.royalsocietypublishing.org/lookup/doi/10.1098/rsta.2016.0447

Fossil fuels stock billions of tonnes CO2 each year into the shared global atmosphere. Annual emissions continue to increase, and the world humans know is already changing. In 2015, governments worldwide signed-up to net-zero emissions. (Re) capture of emissions and secure storage deep below ground can protect the atmosphere, but that is happening 100x too slowly. Rather than blaming consumers, the producers of fossil carbon can help cleanup. A simple yet very powerful method is to assign a Certificate of Storage onto each tonne of fossil carbon. Producers pay to securely store an ever-increasing carbon percentage. The world can rapidly change climate change to net zero, by mid-century.

The full special issue is here

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