Dryland climate change: Recent progress and challenges

Reviews of Geophysics, Journal Year: 2017, Volume and Issue: 55(3), P. 719 - 778

Published: July 19, 2017

Abstract Drylands are home to more than 38% of the world's population and one most sensitive areas climate change human activities. This review describes recent progress in dryland research. Recent findings indicate that long‐term trend aridity index (AI) is mainly attributable increased greenhouse gas emissions, while anthropogenic aerosols exert small effects but alter its attributions. Atmosphere‐land interactions determine intensity regional response. The largest warming during last 100 years was observed over drylands accounted for half continental warming. global pattern interdecadal variability changes modulated by oceanic oscillations. different phases those oscillations induce significant land‐sea north‐south thermal contrasts, which affect westerlies planetary waves blocking frequency, thereby altering temperature precipitation. During 1948–2008, Americas became wetter due enhanced westerlies, whereas Eastern Hemisphere drier because weakened East Asian summer monsoon. as defined AI have expanded 60 projected expand 21st century. expansion has occurred semiarid regions since early 1960s. Dryland will lead reduced carbon sequestration increasing aridity, warming, rapidly growing exacerbate risk land degradation desertification near future developing countries.

Language: Английский

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Divergent consensuses on Arctic amplification influence on midlatitude severe winter weather

Nature Climate Change, Journal Year: 2019, Volume and Issue: 10(1), P. 20 - 29

Published: Dec. 23, 2019

Language: Английский

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Arctic amplification is caused by sea-ice loss under increasing CO2

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

Published: Jan. 4, 2019

Abstract Warming in the Arctic has been much faster than rest of world both observations and model simulations, a phenomenon known as amplification (AA) whose cause is still under debate. By analyzing data here we show that large AA occurs only from October to April over areas with significant sea-ice loss. largely disappears when sea ice fixed or melts away. Periods larger are associated loss, models bigger loss produce AA. Increased outgoing longwave radiation heat fluxes newly opened waters AA, whereas all other processes can indirectly contribute by melting sea-ice. We conclude necessary for existence need simulate realistically order correctly warming increasing CO 2 .

Language: Английский

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Warming amplification over the Arctic Pole and Third Pole: Trends, mechanisms and consequences

Earth-Science Reviews, Journal Year: 2021, Volume and Issue: 217, P. 103625 - 103625

Published: April 14, 2021

Language: Английский

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Warm Arctic episodes linked with increased frequency of extreme winter weather in the United States

Nature Communications, Journal Year: 2018, Volume and Issue: 9(1)

Published: Feb. 22, 2018

Recent boreal winters have exhibited a large-scale seesaw temperature pattern characterized by an unusually warm Arctic and cold continents. Whether there is any physical link between variability Northern Hemisphere (NH) extreme weather active area of research. Using recently developed index severe winter weather, we show that the occurrence in United States significantly related to anomalies pan-Arctic geopotential heights temperatures. As transitions from relatively state warmer one, frequency mid-latitudes increases through transition. However, this relationship strongest eastern US mixed even opposite along western US. We also during mid-winter late-winter recent decades, when warming trend greatest extends into upper troposphere lower stratosphere, weather-including both spells heavy snows-became more frequent States.

Language: Английский

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Weakened Potential Vorticity Barrier Linked to Recent Winter Arctic Sea Ice Loss and Midlatitude Cold Extremes

Journal of Climate, Journal Year: 2019, Volume and Issue: 32(14), P. 4235 - 4261

Published: April 12, 2019

Abstract A winter Eurasian cooling trend and a large decline of sea ice concentration (SIC) in the Barents–Kara Seas (BKS) are striking features recent climate changes. The question arises as to what extent these phenomena related. mechanism is presented that establishes link between SIC midlatitude cold extremes. Such potential weather linkages mediated by whether there weak north–south gradient background tropospheric vorticity (PV). strong PV gradient, which usually occurs North Atlantic Pacific Ocean midlatitudes, acts barrier inhibits atmospheric blocking southward air intrusion. Conversely, more persistent weakened regions over Eurasia, Greenland, northwestern America because energy dispersion intensified nonlinearity. small climatological gradients mid- high-latitude Eurasia have become weaker decades BKS temperatures show positive trends due loss, this has led Ural-region blocking. These factors contribute increased East Asia. It found, however, years when Asian extremes can even occur absence negative anomalies. Thus, magnitude an important controller Arctic–midlatitude linkages, but it plays no role if Ural not present. “PV barrier” concept presents critical insight into producing hypothesized set up such other locations.

Language: Английский

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Trends and variability in polar sea ice, global atmospheric circulations, and baroclinicity

Annals of the New York Academy of Sciences, Journal Year: 2021, Volume and Issue: 1504(1), P. 167 - 186

Published: July 27, 2021

Abstract We analyze the polar sea ice distribution and global level pressure (SLP) baroclinicity distributions over “satellite” period of 1979–2020. In Arctic, there are statistically significant extent (SIE) decreases in all calendar months, annual mean has lost 2.22 million km 2 four decades. The Antarctic SIE, marked contrast, increased up to 2014, then commenced a remarkable retreat (the decreased by 2.03 3 years 2017), subsequently near its long‐term average value 2020. shifts seasonal‐mean SLP patterns consistent with warming planet. At synoptic scale, we diagnose changes baroclinicity, mechanism which cyclones, fronts, other weather systems generated. Through novel presentation, give an overview relative roles vertical shear static stability influencing trends baroclinicity. both Arctic regions, is shown have each season (with sole exception summer). This increase, coupled midlatitude results poleward storm tracks.

Language: Английский

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Seasonal Cumulative Effect of Ural Blocking Episodes on the Frequent Cold events in China during the Early Winter of 2020/21

Advances in Atmospheric Sciences, Journal Year: 2022, Volume and Issue: 39(4), P. 609 - 624

Published: Jan. 7, 2022

Abstract Starting in mid-November, China was hit by several cold events during the early winter of 2020/21. The lowest temperature observed at Beijing station on 7 January reached −19.6°C. In this paper, we show that outbreak record-breaking extreme event can be attributed to a huge merging Ural blocking (UB) ridge over Eurasian region. sea-ice cover Kara and East Siberia Seas (KESS) autumn its value since 1979, which could have served as precursor signal. Further analysis shows successive UB episodes occurred from 1 September 2020 10 2021. persistent late September/early October may made an important contribution historical minimum sea ice KESS Our results also that, after each episode winter, significant upward propagation wave activity around 60°E, resulted weakening stratospheric vortex. Meanwhile, caused reduction extent westerly jet mid–high-latitude Eurasia. Results suggest Arctic vortex, is supposed enhance seasonally, became weaker more unstable than climatic mean under seasonal cumulative effects episodes, warming, long-lasting negative-phase North Atlantic Oscillation (NAO–). Those effects, combined with impact La Niña led frequent occurrence events.

Language: Английский

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Extreme Cold Events in North America and Eurasia in November-December 2022: A Potential Vorticity Gradient Perspective

Advances in Atmospheric Sciences, Journal Year: 2023, Volume and Issue: 40(6), P. 953 - 962

Published: Feb. 9, 2023

Language: Английский

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Changes in Atmospheric Blocking Circulations Linked with Winter Arctic Warming: A New Perspective

Journal of Climate, Journal Year: 2018, Volume and Issue: 31(18), P. 7661 - 7678

Published: June 18, 2018

Abstract Winter atmospheric blocking circulations such as Ural (UB) have been recognized to play an important role in recent winter Eurasian cooling. Observational analyses performed here reveal that the warming Barents–Kara Seas (BKS) related decline of sea ice concentration (SIC) has accompanied by a large increase mean duration UB events. A new energy dispersion index (EDI) is designed help physics behind this association and show how BKS can influence This EDI mainly reflects meridional potential vorticity (PV) gradient persistence it characterizes changes nonlinearity strength blocking. The PV combines relative (related nonuniform shear zonal wind) wind strength. It revealed leads significant lengthening because weakened intensified through reduced gradient. Furthermore, found depend more strongly on than westerly strength, although includes effect Thus, better indicator change Arctic index.

Language: Английский

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