Highlights

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. Highlights describe the state of science at the time of publication of each yearly report, and may not reflect more recent advances in understanding. The date of publication of the source report is noted on each highlight page.

Researchers used interagency modeling and observational capabilities to understand the impacts of reduced pollution related to the COVID-19 pandemic on Earth’s energy balance.

Lockdown measures enacted to control the spread of COVID-19 led to a worldwide reduction in emissions of tiny atmospheric particles known as aerosols. Through their interactions with solar energy and clouds, aerosols play a significant role in shaping Earth’s energy balance (or the balance between incoming energy from the sun and outgoing energy from the Earth) and climate that is still inadequately...

The U.S. research centers that develop climate and Earth system models and the U.S. scientific community are key participants in long-running collaborative efforts to improve knowledge on climate change. A number of major interagency activities supporting improvements in climate modeling took place in 2019.

Most prominently, the World Climate Research Programme Coupled Model Intercomparison Project (CMIP) is currently in its sixth phase (CMIP6). The earlier phases of CMIP experiments have provided the research community...

Methane emitted from thawing permafrost below an Arctic thermokarst lake is trapped in bubbles of many different sizes and shapes as the ice grows during the winter.

Long-frozen northern soils known as permafrost contain one of the world’s largest stores of organic carbon. This reservoir is stable while soils are frozen, but as permafrost thaws, decomposition of biomass by microbes produces the heat-trapping gases carbon dioxide and methane, returning soil carbon to the atmosphere where it contributes to climate change. Permafrost carbon stores are expected to be increasingly vulnerable to decomposition as the climate continues to change, leading to a feedback cycle of further warming and permafrost thaw.^[1]...

Coordinated experiments run across major Earth system models help improve model projections and advance climate science understanding.

Projections of the future state of the Earth system can differ significantly across models, with various potential sources of uncertainty. To better understand the sources of difference and where fundamental scientific understanding can be improved, the Earth system modeling community uses a set of experiments run across many models known as the ...

Model runs of CMIP5 models without greenhouse gas forcing (orange lines) demonstrate natural variability in average annual global surface temperatures expected without human influence on the climate.

Earth system models allow researchers to evaluate the size and strength of various influences on the climate system and identify the human contribution to the warming trend.

Earth system models allow researchers to distinguish “internal” climate variability (natural climate cycles) from the effects of “external” influences on the climate, both human and natural (including variations in incoming solar energy, volcanic eruptions, and greenhouse gas emissions from human activities). Model simulations of natural variability from the...

Regional comparisons of submarine (1958–1976 and 1993–1997), ICESat (2003–2007), and CryoSat-2 (2011–2016) ice thickness data, showing declines in ice thickness over time.

Satellite observations of sea ice thickness provide an opportunity to improve seasonal predictions of Arctic sea ice cover.

Arctic sea ice grows and melts each year with the seasons, reaching its low point in September. Summer sea ice cover has shrunk significantly over the past thirty years, although variation from year to year means that the downward trend is not uniform. Arctic sea ice plays a critical role in regulating weather and climate in and beyond the region. Sea ice decline activates a feedback loop in the climate system: as highly...

Map shows the average active layer thickness (ALT) at the end of the growing season for the Barrow, Alaska region that contains the NGEE Arctic study site.

Scientists are gaining new understanding of processes that control greenhouse gas emissions from Arctic permafrost, a potential driver of significant future warming.

Rapid warming in the Arctic is causing carbon-rich soils known as permafrost, previously frozen for millennia, to thaw. As thawing soils decompose, the greenhouse gases carbon dioxide and methane are released into the atmosphere in varying proportions depending on the conditions under which decomposition occurs. Permafrost emissions could contribute significantly to future warming...

Collaboration across the modeling community supports critical experiments and scientific advancement.

U.S. climate modeling centers play a central role in understanding and predicting global change on seasonal to centennial timescales. They are engaged in the Coupled Model Intercomparison Project (CMIP), which produces climate projections underpinning the assessments conducted by the Intergovernmental Panel on Climate Change and the U.S. National Climate Assessment. Models developed by these centers are designed for different purposes, from providing operational forecast...

Modeling efforts provide new data on the effects of climate change in Antarctica.

Between 1998 and 2016, warming in Antarctica has been rapid and significant. Recent observations also reveal increases in snowfall in western Queen Maud Land, East Antarctica that are unprecedented over the past two millennia. To investigate these changes, a team of NSF-sponsored researchers and NASA scientists merged observation-based NSF-funded research with global modeling efforts that benefited from NASA satellite and airborne-based data^[1]...

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...

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Highlights

Measuring the atmospheric impacts of COVID-19-related emissions reductions

Modeling efforts drive advances in projections of future climate change

Scientists investigate the effects of carbon emissions from thawing permafrost soils

Collaborative modeling experiments to improve understanding of the future of the Earth system

Exploring human and natural influences on climate

Advancing seasonal predictions of Arctic sea ice

Understanding carbon cycling in Arctic ecosystems

Enhancing coordination among U.S. modeling centers

Modeling ice sheet change in Antarctica

Studying Thunderstorms by Night