Climate Change

March 11, 2021

Climate models generally project wetter winters for the US Southwest under global warming. Dong et al. discovered a strong relationship between a common model bias with future precipitation changes over this region. More specifically, models with excessive double-ITCZ biases tend to exaggerate the future precipitation increase.

Are long-term changes in mixed layer depth influencing North Pacific marine heatwaves?
February 26, 2021

A new study by Amaya and co-authors in the Special “Explaining Extremes of 2019 from a Climate Perspective” Issue of BAMS now reveals that the record thin ocean mixed layer depth (MLD) that drove a Blob 2.0 in the northeast Pacific Ocean was exacerbated by a multi-decadal shoaling of the mean MLDs in this region since 1980.

Contrasting recent and future changes  in the Intertropical Convergence Zone
January 28, 2021

Under global warming, the ITCZ is projected to shift towards the equator, leading to squeeze in the annual-mean tropical ascent and far-reaching impacts on global circulation. Zhou and coauthors researched the observed and projected ITCZ changes based on a variety of observation and reanalysis datasets and ensemble projections of climate models, and found that the observed ITCZ changes are largely opposite to the projected future changes.

Uncertainty for drifter GMSL and GMSL trend estimates.
December 11, 2020

In a recently published Geophysical Research Letters paper, Elipot demonstrates how a new ocean observing system for measuring local and global sea level changes could piggy-back on the existing array of freely drifting buoys.

Box-plots for the future phase changes (units: days) in the precipitation annual cycle
November 9, 2020

A recent study by Song et al. discovered contrasting phase changes of the precipitation annual cycle between land and ocean under global warming, with land delay and ocean advance by examining simulations from 37 CMIP5 models and five large ensembles. They found that the seasonal delay of lands is mainly attributable to the increased effective heat capacity, while there exists a competing mechanism against the impact of increased capacity for the ocean precipitation.

Sources of uncertainty in climate projections and their relative importance for different variables, regions and seasons
June 29, 2020

A new collection of single model initial-condition large ensembles (SMILEs) can test statistical assumptions with a cleaner separation between sources of uncertainty in climate projections. In particular, the potential bias at regional scales or for variables with a lot of internal variability can be greatly reduced.

Time of emergence of the anthropogenic signal in storm-related extreme sea level at New York in the GFDL CM4 simulations.
June 1, 2020

Yin and coauthors use the new GFDL CM4 and CM4HR models to consider a series of climate change experiments under the CMIP6 protocol to study characteristics of extreme sea level events and their future evolution in a fully coupled weather, climate, sea level, and storm surge modeling system. They found that even in the absence of global warming, the Gulf Coast is most vulnerable to hurricane-induced storm surge.

Zonally averaged multi-model average shortwave low cloud feedbacks
March 25, 2020

Zelinka and coauthors compared ECS values derived from CO2 quadrupling experiments conducted with CMIP6 and CMIP5 models and found that the latest models warm more than their predecessors by about 0.5˚C. The primary culprit for the enhanced warming was shown to be clouds.

Multi-model mean evolution of the Hadley cell edge (defined by streamfunction at 500 hPa) in the 1 percent CO2 increase simulations. Copyright AGU.
January 14, 2020

Under exclusive CO2 forcing, climate models predicted twice as much Hadley cell expansion in the Southern Hemisphere as in the Northern Hemisphere. The finding was robust across models and all seasons except boreal fall.

Schematic representation of proposed dynamical mechanisms in summer
September 13, 2018

Researchers conduct a comprehensive review of research on summer weather stalling, focusing on the influence of Arctic amplification and how it could interact with other factors influenced by climate change.

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