Three views of two degrees

Jaeger, Carlo; Jaeger, Julia

doi:10.1007/s10113-010-0190-9

Cited by 78 publications

(37 citation statements)

References 36 publications

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“…These range from a high, business-as-usual, scenario (RCP8.5), two intermediate scenarios with maximum emissions occurring around 2080 (RCP6.0) and 2040 (RCP4.5), and a low-emission scenario (RCP2.6). RCP2.6 is constructed to be in line with the so-called two-degree target (Rijsberman and Swart 1990;Jaeger and Jaeger 2011). The observed CO 2 -emissions indicate that we are currently tracking the RCP 8.5 scenario (Quéré et al 2014).…”

Section: Global Temperature Variationsmentioning

confidence: 99%

Global and regional surface cooling in a warming climate: a multi-model analysis

Medhaug

Drange

2015

Clim Dyn

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to variations in global surface temperature. The likelihood of decadal-scale non-warming periods decrease with global warming, firstly at the low latitude region stretching eastward from the tropical Atlantic towards the western Pacific. The North Atlantic and Southern Oceans have largest likelihood of non-warming decades in a warming world. Keywords Hiatus · CMIP5 · Global warming · Decadal variability MotivationA central issue in climate research in recent years has been the apparent paradox that global surface temperature has not been increasing in tandem with increasing emissions of human-induced greenhouse gases. This paradox has generated a lot of attention among researchers (e.g., Easterling and Wehner 2009;Foster and Rahmstorf 2011;Katsman and van Oldenborgh 2011;Santer et al. 2011Santer et al. , 2014Trenberth and Fasullo 2013;Huber and Knutti 2014;Maher et al. 2014;Risbey et al. 2014;Watanabe et al. 2014) and the general public (Tollefson 2014). It has also been used to cast doubts about the reliability of climate research in general and climate models in particular (Showstack 2014) since the ensemble mean of the models do not reproduce the so-called surface temperature hiatus.A large suite of possible factors influencing the recent hiatus in the global surface temperature have been identified, including: the possibility of too-high model sensitivity to increased greenhouse gas (GHG) forcing (Flato et al. 2013); decadal-scale ocean uptake and storage of heat in the Pacific Ocean (e.g., Meehl et al. 2011;Kosaka and Xie 2013;Meehl et al. 2013;Trenberth and Fasullo 2013;England et al. 2014;Hu et al. 2015), in the Atlantic Ocean Abstract Instrumental temperature records show that the global climate may experience decadal-scale periods without warming despite a long-term warming trend. We analysed 17 global climate models participating in phase 5 of the Coupled Model Intercomparison Project (CMIP5), identifying the likelihood and duration of periods without warming in the four Representative Concentration Pathway (RCP) scenarios RCP2.6, RCP4.5, RCP6.0 and RCP8.5, together with the preindustrial control and historical simulations. We find that non-warming periods may last 10, 15 and 30 years for RCP8.5, RCP6.0 and RCP4.5, respectively. In the models, anomalous ocean heat uptake and storage are the main factors explaining the decadalscale surface temperature hiatus periods. The low-latitude East Pacific Ocean is a key region for these variations, acting in tandem with basin-scale anomalies in the sea level pressure. During anomalously cold decades, roughly 35-50 % of the heat anomalies in the upper 700 m of the ocean are located in the Pacific Ocean, and 25 % in the Atlantic Ocean. Decadal-scale ocean heat anomalies, integrated over the upper 700 m, have a magnitude of about 7.5 × 10 21 J. This is comparable to the ocean heat uptake needed to maintain a 10 year period without increasing surface temperature under global warming. On sub-decadal time scales the Atlantic, Pacific and Southern Oceans all have the a...

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Section: Global Temperature Variationsmentioning

confidence: 99%

Global and regional surface cooling in a warming climate: a multi-model analysis

Medhaug

Drange

2015

Clim Dyn

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“…T he 2°C climate target stipulates that globally averaged surface warming should be limited to less than 2°C above pre-industrial levels (Rijsberman and Swart, 1990;WBGU, 1995;Ott et al, 2004;Tol, 2007;Ramanathan and Feng, 2008;Randalls, 2010;Cointe et al, 2011;Jaeger and Jaeger, 2011;Moellendorf, 2011). The 2°C target has emerged as the most prominent candidate (Randalls, 2010;Cointe et al, 2011;Jaeger and Jaeger, 2011) for fulfilling the mandate by the United Nations Framework Convention on Climate Change (UNFCCC) to "prevent dangerous anthropogenic interference with the climate system" (UNFCCC, 1992).…”

Section: Introductionmentioning

confidence: 99%

“…The 2°C target has emerged as the most prominent candidate (Randalls, 2010;Cointe et al, 2011;Jaeger and Jaeger, 2011) for fulfilling the mandate by the United Nations Framework Convention on Climate Change (UNFCCC) to "prevent dangerous anthropogenic interference with the climate system" (UNFCCC, 1992). However, meeting a temperature target alone cannot comprehensively avoid dangerous interference (Steinacher et al, 2013;IPCC, 2014); furthermore, some fundamental critique of the 2°C target has been levied (Shaw, 2010;.…”

Section: Introductionmentioning

confidence: 99%

“…This treatment introduces a more gradual and thus more realistic transition from a high to no risk of dangerous climate change. Furthermore, T 2 stresses the role of a climate target as a focal point for climate negotiations (Jaeger and Jaeger, 2011), by introducing a second focal point. The €80 focal point can be interpreted as a warming of 3°C above pre-industrial, assuming that climate change mitigation is proportional to the effort (see Methods in Supplementary Information).…”

Section: Introductionmentioning

confidence: 99%

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The level of climate-change mitigation depends on how humans assess the risk arising from missing the 2°C target

2017

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The established international 2°C target stipulates that global warming should be limited to below 2°C compared with pre-industrial periods; this has emerged as the most prominent interpretation of how to avoid dangerous climate change. The 2°C target was confirmed and made legally binding in the Paris agreement at the "climate summit" (Conference of Parties 21, COP21) in December 2015. But despite agreement on the target, greenhouse-gas emissions are unlikely to fall soon and fast enough to meet the target, raising the question of whether this target needs to be revised or reinterpreted, and also of why there is insufficient cooperation toward emissions reduction despite the risk of dangerous climate change. Previous theoretical and experimental research has suggested that cooperation towards emissions reduction is undermined by uncertainty about the threshold marking the transition to dangerous climate change. However, even if the threshold and hence the location of the target are known precisely, uncertainty ensues because of an unknown risk that arises from missing the collective target. How humans deal with this risk has not been investigated experimentally. Here we investigate how individuals behave under different risk scenarios if a collective target is missed. We perform economics experiments framed as a collective-risk social dilemma and directly examine the extent to which human subjects trade pay-out reduction for risk. We show that a reduced assessed risk arising from missing the collective target leads to reduced contributions towards the target; but that risk reduction causes the subjects almost to maximize their individual pay-out by balancing the effort to reach the target against the risk posed by missing it. We provide quantitative support for the argument that group contributions toward the collective target can be interpreted as proportional to mitigated warming. We conclude that reinterpretation of the 2°C target as less strict causes additional warming. However, our subjects deal effectively with a risk of dangerous climate change that they assess to depend gradually on global warming. Our results suggest that, if the additional warming is judged to be acceptable, a less strict interpretation of the 2°C target might support finding a trade-off between the effort put into climate mitigation and the risk of dangerous climate change.

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“…However, recent years have witnessed a rapid increase in developing countries' emissions, most prominently in China, which has not only become the world's largest emitter in 2006, but whose per--capita emissions are now already close to the EU average (7.2t vs. 7.5t of energy related CO 2 emissions in 2011, respectively, Olivier et al 2012). If other developing countries follow China's carbon--intensive growth pattern, ambitious climate stabilization targets -such as the 2°C target agreed by the world community (Jaeger and Jaeger 2011) -are likely to become infeasible even if industrialized countries were to drastically reduce their emissions (IEA 2011). For this reason, 'preventing dangerous anthropogenic climate change' (UNFCCC 1992) without undermining poor countries' growth prospects requires a fundamental structural break of the historical correlation between economic growth and GHG emissions.…”

Section: Introductionmentioning

confidence: 99%

Feasible mitigation actions in developing countries

et al. 2014

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Abstract'Preventing dangerous anthropogenic climate change' (UNFCCC 1992) will only be feasible with substantial emission reductions below the business--as--usual case in developing countries. Because of the central role of energy for economic development, reducing emissions in developing countries without undermining their development goals requires a fundamental structural break of the historical correlation between economic growth and GHG emissions. While possible in theory, such a transformation of the global energy system would impose considerable costs on developing countries. Even if these costs were fully covered by industrialized countries, mitigation measures could still be unattractive to developing countries due to a possible 'climate rent curse' through which financial inflows negatively affect recipients' economic performance. Mitigation measures could further meet resistance because of adverse distributional impacts and political economy reasons. Hence, we caution against overly optimistic expectations regarding the opportunities to drastically re--orient development paths towards low--carbon growth. Instead, we suggest that mitigation efforts in developing countries should focus on 'feasible mitigation actions' that seek to maximize mitigation as a positive co--benefit of policies with different objectives.2

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Three views of two degrees

Cited by 78 publications

References 36 publications

Global and regional surface cooling in a warming climate: a multi-model analysis

Global and regional surface cooling in a warming climate: a multi-model analysis

The level of climate-change mitigation depends on how humans assess the risk arising from missing the 2°C target

Feasible mitigation actions in developing countries

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