The Inequality of Climate Change From 1.5 to 2°C of Global Warming

King, Andrew D.; Harrington, Luke J.

doi:10.1029/2018gl078430

Cited by 175 publications

(122 citation statements)

References 25 publications

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“…Such regional preference of hot spots in the tropics seems not quite surprising, considering the well-known smaller natural variability and less variable climates there (Stocker, 2014). Hence, previous univariate-based analyses similarly located climate change hot spots to hot extremes in the tropics as well, though they did not document influences of 0.5°C on emergence timings of hot extremes (King & Harrington, 2018;Mahlstein et al, 2011;Schleussner et al, 2016). However, using univariate-defined hot days (daily maxima ≥ 90th percentile), both the increase in frequency at individual warming levels and added frequency due to the 0.5°C rise would be underestimated by several folds there (Figure 5a).…”

Section: Comparisons With Univariate-based Estimatesmentioning

confidence: 77%

Half‐a‐Degree Matters for Reducing and Delaying Global Land Exposure to Combined Daytime‐Nighttime Hot Extremes

et al. 2019

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The Paris Agreement has motivated rapid analysis differentiating changes in frequency/intensity of weather and climate extremes in 1.5 versus 2°C warmer worlds. However, implications of these global warming levels on locations, spatial scales, and emergence timings of hot spots to extremes are more relevant to policy-making but remain strikingly under-addressed. Based on a bivariate definitional framework, we show that compared to 2°C, the 1.5°C target could avoid a transition of prevailing type of summertime hot extremes from daytime-/nighttime-only events to combined daytime-nighttime hot extremes in approximately 18% of global continents and protect 14-26% of land areas from seeing over threefold-totenfold increases in occurrence of combined hot extremes. This half-a-degree reduction also matters for around 21% of global lands, mostly within the tropics, in constraining historically unprecedented combined hot extremes from becoming the new norm within just one to three decades ahead. By contrast, previous analyses based on univariate-defined hot days substantially underestimate the magnitude, areal extent, and emergence rate of 0.5°C-caused aggravation of summertime hot extremes. These projected changes of bivariate-classified hot extremes, therefore, underline not only the imperative but also the urgency of striving for the lower Paris target.Plain Language Summary Since the milestone Paris Agreement, policymakers are eager to know the extent to which and the time when their own regions will suffer from consequences associated with pertinent global warming levels (1.5 and 2°C). We show that even the aspirational 1.5°C target would still be translated into huge threats from summertime hot extremes to the tropics, as manifested by a type transition toward health-damaging daytime-nighttime combined heat and threefold-to-tenfold increases in its occurrence. Further rise to 2°C would put an extra 20% of global continents at risk from similar transitions and increases. Unexpectedly, despite involving substantial reduction in carbon emissions, the 2°C-compatible development pathway would bring about a rapidly emerging novel era of hot extremes for most tropical countries, where historically unprecedented daytime-nighttime combined heat will be registered every other year within the next one to three decades and thereafter. Our results highlight that the extra 0.5°C of global warming, from 1.5 to 2°C, would impose the earliest and severest heat-related consequences on the least-developed regions, whose adaptive capacity is unfortunately very limited.

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Section: Comparisons With Univariate-based Estimatesmentioning

confidence: 77%

Half‐a‐Degree Matters for Reducing and Delaying Global Land Exposure to Combined Daytime‐Nighttime Hot Extremes

et al. 2019

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“…Keeping global warming to 1.5°C, rather than 2.0°C, limits these uneven distributions. King and Harrington (2018) indicated that the ratios of annual mean temperature differences (2.0°C minus 1.5°C) and the internal variability are larger in lower-income countries. Russo et al (2019) suggested that heatwave exposure and an illustrative heatwave risk index (the product of the probability of heatwave occurrence, exposure and a proxy for vulnerability) at the 1.5°C warming level for the population living in low development countries is expected to be greater than those at the 2°C warming level for the population living in very high development countries.…”

Section: Summary and Discussionmentioning

confidence: 99%

Limiting global warming to 1.5 °C will lower increases in inequalities of four hazard indicators of climate change

Shiogama

Hasegawa

Fujimori

et al. 2019

Environ. Res. Lett.

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Clarifying characteristics of hazards and risks of climate change at 2°C and 1.5°C global warming is important for understanding the implications of the Paris Agreement. We perform and analyze large ensembles of 2°C and 1.5°C warming simulations. In the 2°C runs, we find substantial increases in extreme hot days, heavy rainfalls, high streamflow and labor capacity reduction related to heat stress. For example, about half of the world's population is projected to experience a present day 1-in-10 year hot day event every other year at 2°C warming. The regions with relatively large increases of these four hazard indicators coincide with countries characterized by small CO 2 emissions, low-income and high vulnerability. Limiting global warming to 1.5°C, compared to 2°C, is projected to lower increases in the four hazard indicators especially in those regions.

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“…The projected surface temperature increase in the 21st century over Africa is estimated to be faster than the global average increase, specifically in more arid regions (Engelbrecht et al, 2015;Niang et al, 2014). The continent is not only warming more rapidly than most regions elsewhere, but the smaller interannual temperature variability which African regions experience, especially in the tropics, lead to higher signal-to-noise ratios, hence resulting in such areas becoming even more vulnerable to climate change (Harrington et al, 2016;King & Harrington, 2018). A 3-5°C temperature increase is projected over the tropical regions of Africa by the end of the 21st century relative to current climate (Engelbrecht et al, 2015) under the low mitigation scenario (A2: Intergovernmental Panel on Climate Change, IPCC, 2000).…”

Section: Introductionmentioning

confidence: 99%

“…Specifically, West Africa on average is projected to experience a 3 to 6°C summer temperature increase between 1981-2000and 2031-2050(Diallo et al, 2012 under the A1B emission scenario (IPCC, 2000). Consequently, heat-related extreme events are also estimated to increase more rapidly in most parts of Africa, which also suffer from low adaptive capacities (IPCC, 2012; King & Harrington, 2018;Niang et al, 2014). ©2019.…”

Section: Introductionmentioning

confidence: 99%

High‐Temperature Extreme Events Over Africa Under 1.5 and 2 °C of Global Warming

et al. 2019

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With anthropogenic global warming, heat‐related extreme events are projected to increase in severity and frequency. Already vulnerable regions like Africa will be hard‐hit. Therefore, such regions could benefit from low global warming levels. Using the Community Earth System Model low warming simulations, we investigate changes in temperature extremes across Africa as a function of global mean temperature in the context of the implications of the Paris Agreement's targets. A significant warming across Africa is projected at the 1.5 °C warming world and is amplified at the 2 °C world, exceeding the mean global warming rate. Specifically, North Africa and East Africa regions are projected to have the highest and lowest temperature changes of 0.63 °C (0.60–0.67 °C) and 0.50 °C (0.47–0.54 °C), respectively, between the 1.5 and 2 °C warmer worlds. Consequently, hot events are also estimated to increase with global warming. We showed that limiting warming to 1.5 °C instead of 2 °C may lead to 29% (27–31%) to 35% (33–37%) reduction in severity of hot events and to 31% (30–33%) to 42% (39–48%) reduction in the frequency of the threshold‐based high‐temperature events across Africa. The highest reductions are projected over North Africa. Furthermore, restricting warming to 0.5 °C lower than 2 °C might also result in 28% (34–40%) to 37% (25–34%) reduction in severity of once‐in‐10/20‐year heat events across Africa with North Africa having the highest benefits than tropical regions. Thus, restricting warming to low levels may indeed translate to substantial benefits of reduced intensity and frequency of extreme heat events across Africa.

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The Inequality of Climate Change From 1.5 to 2°C of Global Warming

Cited by 175 publications

References 25 publications

Half‐a‐Degree Matters for Reducing and Delaying Global Land Exposure to Combined Daytime‐Nighttime Hot Extremes

Half‐a‐Degree Matters for Reducing and Delaying Global Land Exposure to Combined Daytime‐Nighttime Hot Extremes

Limiting global warming to 1.5 °C will lower increases in inequalities of four hazard indicators of climate change

High‐Temperature Extreme Events Over Africa Under 1.5 and 2 °C of Global Warming

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