The Elephant
The climate change and environmental emergency: a comprehensive resource for journalists, politicians, policy makers, activists and citizens
The ElephantThe climate change and environmental emergency: a comprehensive resource for journalists, politicians, policy makers, activists and citizens
Visit: journals.ametsoc.org
Observational Evidence for a Regime Shift in Summer Antarctic Sea Ice
2024-04-08 (or before) in American Meteorological Society JournalsAbstract In recent years, the Southern Ocean has experienced extremely low sea ice cover in multiple summers. These low events were preceded by a multidecadal positive trend that culminated in record high ice coverage in 2014. This abrupt transition has led some authors to suggest that Antarctic sea ice has undergone a regime shift. In this study we analyze the satellite sea ice record and atmospheric reanalyses to assess the evidence for such a shift. We find that the standard deviation of the summer sea ice record has doubled from 0.31 million km2 in 1979–2006 to 0.76 million km2 for 2007–22. This increased varianc...
Tagged under: Oceans | Antarctic
Constraining the Pattern and Magnitude of Projected Extreme Precipitation Change in a Multimodel Ensemble
2024-01-08 (or before) in American Meteorological Society JournalsAbstract Projections of precipitation extremes over land are crucial for socioeconomic risk assessments, yet model discrepancies limit their application. Here we use a pattern-filtering technique to identify low-frequency changes in individual members of a multimodel ensemble to assess discrepancies across models in the projected pattern and magnitude of change. Specifically, we apply low-frequency component analysis (LFCA) to the intensity and frequency of daily precipitation extremes over land in 21 CMIP-6 models. LFCA brings modest but statistically significant improvements in the agreement between models in the spatial patte...
Effect of Wind Speed and Leads on Clear-Sky Cooling over Arctic Sea Ice during Polar Night
2023-12-27 (or before) in American Meteorological Society JournalsAbstract A simple analytical model of the atmospheric boundary layer (ABL) coupled to sea ice is presented. It describes clear-sky cooling over sea ice during polar night in the presence of leads. The model solutions show that the sea ice concentration and wind speed have a strong impact on the thermal regime over sea ice. Leads cause both a warming of the ABL and an increase of stability over sea ice. The model describes a sharp ABL transition from a weakly stable coupled state to a strongly stable decoupled state when wind speed is decreasing. The threshold value of the transition wind speed is a function of sea ice concentrat...
Tagged under: Russia | Arctic | Oceans
Significant West Antarctic Cooling in the Past Two Decades Driven by Tropical Pacific Forcing
2023-11-07 (or before) in American Meteorological Society JournalsAbstract During the second half of the twentieth century, the West Antarctic Ice Sheet (WAIS) has undergone significant warming at more than twice the global mean and thus is regarded as one of the most rapidly warming regions on Earth. However, a reversal of this trend was observed in the 1990s, resulting in regional cooling. In particular, during 1999–2018, the observed annual average surface air temperature had decreased at a statistically significant rate, with the strongest cooling in austral spring. The spring cooling correlates significantly with the second leading modes (EOF2) derived from empirical orthogonal func...
Tagged under: Global Warming | Sea Level | Antarctic
The Potential to Narrow Uncertainty in Regional Climate Predictions
2023-09-09 (or before) in American Meteorological Society JournalsFaced by the realities of a changing climate, decision makers in a wide variety of organizations are increasingly seeking quantitative predictions of regional and local climate. An important issue for these decision makers, and for organizations that fund climate research, is what is the potential for climate science to deliver improvements—especially reductions in uncertainty—in such predictions? Uncertainty in climate predictions arises from three distinct sources: internal variability, model uncertainty, and scenario uncertainty. Using data from a suite of climate models, we separate and quantify these sources. Fo...
Tagged under: Predictions | Climate Change
Sixfold Increase in Historical Northern Hemisphere Concurrent Large Heatwaves Driven by Warming and Changing Atmospheric Circulations
2023-07-16 (or before) in American Meteorological Society JournalsAbstract Simultaneous heatwaves affecting multiple regions (referred to as concurrent heatwaves) pose compounding threats to various natural and societal systems, including global food chains, emergency response systems, and reinsurance industries. While anthropogenic climate change is increasing heatwave risks across most regions, the interactions between warming and circulation changes that yield concurrent heatwaves remain understudied. Here, we quantify historical (1979–2019) trends in concurrent heatwaves during the warm season [May–September (MJJAS)] across the Northern Hemisphere mid- to high latitudes. We fin...
Tagged under: Climate Change | Health | Climate Change Impacts | Heatwaves
Why Are Arctic Linkages to Extreme Weather Still up in the Air?
2022-06-15 (or before) in American Meteorological Society JournalsAbstract Shifting weather patterns, particularly increasing extreme events, are observed in populous midlatitudes, and connections to climate change are becoming clearer. The specific roles of rapid Arctic warming and sea ice loss in this story are a topic of intense research and controversy. Instead of converging on answers however, the science seems as unsettled as ever. Many new studies find evidence supporting Arctic–midlatitude linkages, while others report no robust signals. This article presents my interpretation of recent literature to illuminate possible causes of this discrepancy, which include a low signal-to-no...
Tagged under: Extreme Weather | Arctic | Climate Change
Climate Science Needs to Take Risk Assessment Much More Seriously
2021-12-21 (or before) in American Meteorological Society JournalsAbstract For decision-makers, climate change is a problem in risk assessment and risk management. It is, therefore, surprising that the needs and lessons of risk assessment have not featured more centrally in the consideration of priorities for physical climate science research, or in the Working Group I contributions to the major assessment reports of the Intergovernmental Panel on Climate Change. This article considers the reasons, which include a widespread view that the job of physical climate science is to provide predictions and projections—with a focus on likelihood rather than risk—and that risk assessment is...
Tagged under: Predictions | Climate Change
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