Atmospheric composition and circulation over the tropical western Pacific Ocean play important roles in the Earth’s climate system. In this remote region, rising air heated by some of the warmest seawater in the world moves gases produced by ocean organisms and other chemicals to higher altitudes, where water vapor and ozone exert their strongest influence on the climate. As the climate warms, the intensity of this transport mechanism will increase and may contribute to large-scale changes in atmospheric composition. Details of these dynamics, including how they vary over time and space,...
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Since 1989, the U.S. Global Change Research Program (USGCRP) has submitted annual reports to Congress called Our Changing Planet. The reports describe the status of USGCRP research activities, provide progress updates, and document recent accomplishments
In particular, Our Changing Planet highlights progress and accomplishments in interagency activities. These highlights represent the broad spectrum of USGCRP activities that extend from Earth system observations, modeling, and fundamental research through synthesis and assessment, decision support, education, and public engagement.
Over the Great Plains region of the United States, summertime thunderstorms often occur after sunset. Much of this nighttime rainfall is caused by large, organized storm systems and plays a critical role in the hydrology and agriculture of the region, especially over the more arid western Great Plains. During the summer months, these nighttime storm systems provide 30-70% of the region’s precipitation and can also cause severe weather, including flash floods, intense damaging winds, and large hail. Current weather and climate models have difficulty predicting the onset, location, frequency...
Founded in 2001, the Global Carbon Project (GCP) is an international scientific collaboration investigating the biophysical and human components of the global carbon cycle, the interactions between them, and their response to a changing climate. The GCP tracks sources and sinks of carbon dioxide and methane, the two most important greenhouse gases directly emitted by human activities—providing annual updates on emissions trends, atmospheric concentrations, and sources of uncertainty, in a format accessible to policymakers....
Recent evidence has revealed that the Antarctic and Greenland ice sheets are not as static as once thought. Accelerated ice loss from the Greenland Ice Sheet, disintegrating ice shelves around Antarctica, and signs that several marine-terminating glaciers in Antarctica have begun an irreversible retreat all signal that changes are taking place faster than was thought possible. Ice sheets are projected to contribute significantly to global sea-level rise, which poses dramatic risks for coastal communities and island nations worldwide. In response to these rapid changes, several USGCRP...
As climate change increasingly impacts society and ecosystems, demand for reliable information about climate conditions now and in the future is growing. Climate research is conducted by two distinct communities, one working on climate forecasts for the near-term future and the other on climate-change projections over decades to centuries. Despite these different foci, the boundaries between these two communities increasingly overlap, and they share many common methods and challenges. Enhanced collaboration across modeling centers and communities can help create more valuable climate-...
The El Niño/Southern Oscillation (ENSO) phenomenon is a periodic fluctuation of sea-surface temperatures and atmospheric pressure across the tropical Pacific Ocean. During the El Niño phase of the cycle, the eastern tropical Pacific Ocean warms substantially. This can cause significant short-term increases in global-average surface temperatures, and through atmospheric teleconnections, a strong El Niño event can affect weather patterns around the globe. A particularly strong El Niño emerged during the winter/spring season of...
A key challenge for Earth System Models is accurately representing land surface and subsurface processes and their complex interactions in a warming climate. This is true for ecosystems across the globe, but particularly critical for Arctic ecosystems, which are projected to warm at a rate twice that of the global average by the end of the 21st century. The Next-Generation Ecosystem Experiments in the Arctic (NGEE-Arctic) project is addressing this challenge by integrating process studies, ecosystem observations, and computational...
The Arctic tundra is a cold, desert-like biome, with a layer of permanently frozen soil and organic matter below the surface containing vast stocks of carbon. As Arctic tundra soils warm in response to climate change, methane emissions from decomposing organic material could increase dramatically, representing a potentially significant positive feedback on climate warming. However, seasonal and climatic influences on methane emissions from these systems are not well understood outside of the summer months, representing a major uncertainty for the Arctic methane budget. To help address a...