Multidecadal variability of Atlantic Meridional Overturning Circulation (AMOC) has been reconstructed by various proxies, simulated in climate models, and linked to multidecadal Arctic salinity variability. However, the mechanisms of the multidecadal AMOC variability and its two-way interaction with the Arctic salinity anomaly, as well as the factors affecting the periods and amplitudes of the multidecadal AMOC variability are not well understood from the theoretical perspective using simple conceptual models. Read More…
Multiple large ensembles of climate simulations are used to explore 21st century climate response to greenhouse gases, including the response to significant reductions in greenhouse gases beginning in 2040. The authors explore the extent to which future climate changes could be reversed by reduced emissions of greenhouse gases. Read More…
Research reveals how pollution control measures in Europe and the United States over the past 40 years led to significantly decreased anthropogenic aerosols. During the same time period, economic and industrial growth in South and East Asia led to increased anthropogenic aerosols in those regions. The impact of these changes suggests effects on both the frequency of global tropical cyclones (hurricanes and typhoons), as well as a shift in the global wind circulation.. Read More…
Ocean acidification (OA) is a consequence of the absorption of anthropogenic carbon emissions and it profoundly impacts marine life. Arctic regions are particularly vulnerable to rapid pH changes due to low ocean buffering capacities and high stratification. This research applied unsupervised machine learning methodology to simulations of surface Arctic acidification using two state-of-the-art coupled climate models. The authors identified four sub-regions whose boundaries are influenced by present-day and projected sea ice patterns. The regional boundaries are consistent between the models and across lower and higher carbon emissions scenarios. Read More…
Potential future changes in the genesis frequency and distribution of tropical cyclones are important for society, yet uncertain. Confidence in model projections largely relies on whether we can physically explain why the models projected such changes. After analyzing climate simulations from multiple models, the authors find that future changes in the patterns and frequency of tropical cyclone genesis are largely governed by dynamic effects—that is, by human-induced changes in the atmospheric circulation. Read More…
Prediction on weather and seasonal timescales has become routine, but the “subseasonal” time scale of a few weeks has proven difficult. The Madden-Julian oscillation (MJO), a large complex of tropical thunderstorms, is the dominant subseasonal phenomenon over the tropics, and its prediction is critical for subseasonal prediction of tropical cyclones, atmospheric rivers, and other extreme events. Read More…
Record-setting fires in the western US over the last decade caused severe air pollution, loss of human life, and property damage. Enhanced drought and increased biomass in a warmer climate may fuel larger and more frequent wildfires in the coming decades. The air quality impact of increased wildfires in a warming climate has often been overlooked in current model projections, owing to the lack of interactive fire emissions of gases and particles responding to climate change in Earth System Model (ESM) projection simulations. Read More…
In Western North America, 30% of the annual precipitation is determined by atmospheric rivers (ARs) that occur during less than 15% of the winter season. ARs are beneficial to water supply but can also produce extreme precipitation hazards when making landfall. Consequently, ARs exert significant socioeconomic impacts on this region. Read More…
In the tropical Pacific, year-to-year changes in chlorophyll, a proxy for the phytoplankton base of ocean food webs, is dominated by the El Niño–Southern Oscillation. El Niño, triggered by westerly wind anomalies and subsequent redistributions of upper ocean heat content, can sharply reduce the regional supply of nutrients, limiting phytoplankton growth. GFDL’s new Earth System Model (ESM4.1) captures not only the onset and extent of chlorophyll anomalies during El Niño events, but also a pronounced post-El Niño “chlorophyll rebound” that produces positive equatorial Pacific chlorophyll anomalies in the summer following El Niño events. Read More…
Coastal oceans host diverse ecosystems and serve as important habitats for marine fish species. Over the past century, anthropogenic activities have resulted in substantial climatic and land use changes that stress coastal environments, often leading to eutrophication, harmful algal blooms, and deoxygenation. Rivers are a primary source of eutrophication, supplying an increasing amount of anthropogenic nitrogen to the coastal ocean over the past century. Read More…
