The human imperative of stabilizing global climate change at 1.5°C

Science, Journal Year: 2019, Volume and Issue: 365(6459)

Published: Sept. 19, 2019

Increased concentrations of atmospheric greenhouse gases have led to a global mean surface temperature 1.0°C higher than during the pre-industrial period. We expand on recent IPCC Special Report warming 1.5°C and review additional risks associated with levels warming, each having major implications for multiple geographies, climates, ecosystems. Limiting rather 2.0°C would be required maintain substantial proportions ecosystems clear benefits human health economies. These conclusions are relevant people everywhere, particularly in low- middle-income countries, where escalation climate-related may prevent achievement United Nations Sustainable Development Goals.

Language: Английский

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Advances in understanding large‐scale responses of the water cycle to climate change

Annals of the New York Academy of Sciences, Journal Year: 2020, Volume and Issue: 1472(1), P. 49 - 75

Published: April 4, 2020

Abstract Globally, thermodynamics explains an increase in atmospheric water vapor with warming of around 7%/°C near to the surface. In contrast, global precipitation and evaporation are constrained by Earth's energy balance at ∼2–3%/°C. However, this rate is suppressed rapid adjustments response greenhouse gases absorbing aerosols that directly alter budget. Rapid forcings, cooling effects from scattering aerosol, observational uncertainty can explain why observed responses currently difficult detect but expected emerge accelerate as increases aerosol forcing diminishes. Precipitation be smaller over land than ocean due limitations on moisture convergence, exacerbated feedbacks affected adjustments. Thermodynamic fluxes amplify wet dry events, driving intensification extremes. The deviate a simple thermodynamic in‐storm larger‐scale feedback processes, while changes large‐scale dynamics catchment characteristics further modulate frequency flooding increases. Changes circulation radiative evolving surface temperature patterns capable dominating cycle some regions. Moreover, direct impact human activities through abstraction, irrigation, use change already significant component regional importance demand grows population.

Language: Английский

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Enhanced future changes in wet and dry extremes over Africa at convection-permitting scale

Nature Communications, Journal Year: 2019, Volume and Issue: 10(1)

Published: April 23, 2019

Abstract African society is particularly vulnerable to climate change. The representation of convection in models has so far restricted our ability accurately simulate weather extremes, limiting change predictions. Here we show results from experiments with a convection-permitting (4.5 km grid-spacing) model, for the first time over an Africa-wide domain (CP4A). model realistically captures hourly rainfall characteristics, unlike coarser resolution models. CP4A shows greater future increases extreme 3-hourly precipitation compared convection-parameterised 25 (R25). also dry spell length during wet season western and central Africa, weaker or not apparent R25. These differences relate more realistic CP4A, its response increasing atmospheric moisture stability. We conclude that, accurate convection, projected changes both extremes Africa may be severe.

Language: Английский

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Later Wet Seasons with More Intense Rainfall over Africa under Future Climate Change

Journal of Climate, Journal Year: 2018, Volume and Issue: 31(23), P. 9719 - 9738

Published: Oct. 4, 2018

Abstract Changes in the seasonality of precipitation over Africa have high potential for detrimental socioeconomic impacts due to societal dependence upon seasonal rainfall. Here, first time we conduct a continental-scale analysis changes wet season characteristics under RCP4.5 and RCP8.5 climate projection scenarios across an ensemble CMIP5 models using objective methodology determine onset cessation season. A delay West Sahel 5–10 days on average, later southern Africa, is identified associated with increasing strength Saharan heat low late boreal summer northward shift position tropical rain belt August–December. Over Horn rainfall during “short rains” projected increase by 100 mm average end twenty-first century scenario. Average per rainy day increase, while number declines regions stable or declining (western Africa) remains constant central where increase. Adaptation strategies should account shorter seasons, intensity, decreasing frequency, which will implications crop yields surface water supplies.

Language: Английский

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Monsoons Climate Change Assessment

Bulletin of the American Meteorological Society, Journal Year: 2020, Volume and Issue: 102(1), P. E1 - E19

Published: May 6, 2020

Monsoon rainfall has profound economic and societal impacts for more than two-thirds of the global population. Here we provide a review on past monsoon changes their primary drivers, projected future changes, key physical processes, discuss challenges present modeling outlooks. Continued warming urbanization over century already caused significant rise in intensity frequency extreme events all regions (high confidence). Observed mean vary by region with decadal variations. Northern Hemisphere land as whole declined from 1950 to 1980 rebounded after 1980s, due competing influences internal climate variability radiative forcing greenhouse gases aerosol confidence); however, it remains challenge quantify relative contributions. The CMIP6 models simulate better precipitation CMIP5 models, but common biases large intermodal spreads persist. Nevertheless, there is high confidence that will increase, alongside an increasing risk drought some regions. Also, increase South Asia East confidence) northern Africa (medium confidence), decrease North America, be unchanged Southern Hemisphere. Over Asian–Australian region, daily scales. rainy season likely lengthened late retreat (especially Asia), shortened delayed onset.

Language: Английский

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The Greening of the Sahara: Past Changes and Future Implications

One Earth, Journal Year: 2020, Volume and Issue: 2(3), P. 235 - 250

Published: March 1, 2020

In the future, Sahara and Sahelian regions could experience more rainfall than today as a result of climate change. Wetter periods, termed African humid occurred in past witnessed mesic landscape place today's hyperarid semiarid environment. Such large changes raise question whether near future might hold store similar environmental transformations, particularly view growing human-induced climate, land-use, land-cover changes. last decades, geoengineering initiatives (in form active re-greening projects Sahel) have been proposed significant effects on region. Here, we synthesize literature projected hydroclimate Sahelian-Saharan region associated feedbacks. We further address current state knowledge concerning Saharan afforestation their consequences. Our review underscores importance vegetation land-atmosphere-ocean feedback processes far-field impacts northern ecosystem

Language: Английский

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Rainfall trends in the African Sahel: Characteristics, processes, and causes

Wiley Interdisciplinary Reviews Climate Change, Journal Year: 2019, Volume and Issue: 10(4)

Published: June 4, 2019

Abstract Sahel rainfall is dynamically linked to the global Hadley cell and regional monsoon circulation. It therefore susceptible forcings from remote oceans land alike. Warming of enhances stability tropical atmosphere weakens deep ascent in Sahara nearby changes structure position shallow circulation allows more intense convective systems that determine seasonal rain accumulation. These processes can explain observed interannual multidecadal variability. Sea surface temperature anomalies were dominant forcing drought 1970s 1980s. In most recent decades, amounts have partially recovered, but rainy season characteristics changed: intermittent wetting concentrated late away west coast. Similar subseasonal subregional differences trends characterize simulated response increased greenhouse gases, suggesting an anthropogenic influence. While uncertainty future projections remains, confidence them encouraged by recognition mean depends on large‐scale drivers atmospheric circulations are well resolved current climate models. Nevertheless, observational modeling efforts needed provide refined changes, expanding beyond total accumulation metrics intraseasonal risk extreme events, coordination between scientists stakeholders generate relevant information useful even under uncertainty. This article categorized under: Paleoclimates Current Trends > Modern Climate Change

Language: Английский

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Evidence of crop production losses in West Africa due to historical global warming in two crop models

Scientific Reports, Journal Year: 2019, Volume and Issue: 9(1)

Published: Sept. 6, 2019

Abstract Achieving food security goals in West Africa will depend on the capacity of agricultural sector to feed rapidly growing population and moderate adverse impacts climate change. Indeed, a number studies anticipate reduction crop yield main staple crops region coming decades due global warming. Here, we found that production might have already been affected by change, with significant losses estimated historical past. We used large ensemble simulations derived from an atmospheric general circulation model two process-based models, SARRA-H CYGMA, evaluate effects change Africa. generated ensembles 100 yields sorghum millet corresponding conditions for each model. One is based realistic simulation actual climate, while other does not account human influences systems (that is, non-warming counterfactual condition). last simulated decade, 2000–2009, approximately 1 °C warmer accounting more frequent heat rainfall extremes. These altered led regional average reductions 10–20% 5–15% models. annual across 2000–2009 associated relative condition pre-industrial climate), accounted 2.33–4.02 billion USD 0.73–2.17 sorghum. The estimates presented here can be basis loss damage date useful estimating costs adaptation region.

Language: Английский

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What can we know about future precipitation in Africa? Robustness, significance and added value of projections from a large ensemble of regional climate models

Climate Dynamics, Journal Year: 2019, Volume and Issue: 53(9-10), P. 5833 - 5858

Published: July 20, 2019

We employ a large ensemble of Regional Climate Models (RCMs) from the COordinated Regional-climate Downscaling EXperiment to explore two questions: (1) what can we know about future precipitation characteristics over Africa? and (2) does this information differ that derived driving Global (GCMs)? By taking into account both statistical significance change models' agreement on its sign, identify regions where projected climate signal is robust, suggesting confidence will change, those changes in statistics are non-significant. Results show that, when spatially averaged, RCMs median usually with GCMs ensemble: even though seasonal mean may differ, some cases, other (e.g., intensity, frequency, duration dry wet spells) same tendency. When robust (i.e., value averaged only land points it robust) compared between RCMs, similarities striking, indicating although uncertainty geographical extent, project consistent future. Potential added downscaling projections non-negligible fine-scale absent lower resolution simulations) found for instance Ethiopian highlands, RCM shows decrease contrast results. This discrepancy be associated better representation topographical details missing scale GCMs. The impact heterogeneity GCM–RCM matrix results has been also investigated; most indices, or non-significant, they so independently choice GCM. However, there especially Central Africa parts West Africa, uncertain, i.e. statistically significant but do not agree sign. In these clearly clustered according RCM, simple way subsampling model order reduce infer more result.

Language: Английский

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The formation, character and changing nature of mesoscale convective systems

Nature Reviews Earth & Environment, Journal Year: 2020, Volume and Issue: 1(6), P. 300 - 314

Published: June 2, 2020

Language: Английский

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