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.

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]...

This image shows the distribution of aboveground forest biomass across North America, measured as milligrams of biomass per hectare (mg/ha).

The Second State of the Carbon Cycle Report (SOCCR2), released by USGCRP in November 2018, is a state-of-the-science assessment of the carbon cycle in North America and its connection to climate and society. Authored by more than 200 experts from the United States, Canada, and Mexico, SOCCR2 focuses on U.S. and North American carbon cycle processes and their interactions with global-scale carbon budgets and climate change impacts over the last decade.

The report includes an assessment of...

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...

Figure shows how methane production changes with temperature in (a) surface and (b) deep peat samples that were anaerobically (without oxygen) incubated

Researchers are experimentally warming northern peatlands to understand carbon cycling in the climate of the future.

Northern peatlands hold large stocks of organic carbon in their soils that are vulnerable to release into the atmosphere as the greenhouse gases carbon dioxide and methane as the climate warms. Emissions of methane, which has about 28 times the warming power...

Spatial distribution of A, annual carbon loss and gain across upland Alaska 1950–2009 and B, historical fire scars from 2000–2009 among the five Landscape Conservation Cooperative (LCC) regions.

An assessment of carbon stocks in Alaska’s soils and vegetation helped set a baseline for monitoring future change.

Alaska’s soils and vegetation store vast quantities of carbon. Increases in temperature throughout the 21^st century may increasingly expose these stores to loss from increased wildfire, permafrost thaw, and other changes that could turn Alaska’s ecosystems into a net source of carbon to the atmosphere. However, much of Alaska has previously not been considered in any major national...

AmeriFlux FLUXNET2015 data collection sites overlaid on a map of global land cover types.

A global data collection network has built a strong foundation for carbon cycle understanding.

The AmeriFlux Network, which is supported by the Department of Energy, connects scientists from across the Western Hemisphere studying the exchange of carbon, water, and energy between ecosystems and the atmosphere. Since its launch in 1996, AmeriFlux has built a data record from 213 sites worldwide, called...

A warmed TRACE plot in the USDA-Forest Service Luquillo Experimental Forest in Puerto Rico.

Field research provides new data advancing our ability to project how tropical forests will respond to a changing climate.

Tropical forests store vast amounts of carbon and play a key role in regulating Earth’s climate. As climate changes, these ecosystems have the potential to become a net contributor to global warming if they shift to releasing more carbon to the atmosphere than they absorb^[1]. However, how these forests will be affected by a warming climate and changing atmosphere is still uncertain¾and is critical...

Mangrove forests store large amounts of carbon, protect the coastline from erosion, and provide shelter for many species.

A new research network aims to accelerate discoveries in the science of these important natural carbon sources and sinks.

Coastal wetlands provide protection from wind and waves, support habitats and fisheries, and store large amounts of atmospheric carbon dioxide for centuries to millennia. These ecosystems can also be sources of greenhouse gas emissions to the atmosphere; wetlands that do not have the capacity to keep pace with sea-level rise, for example, can erode and release soil carbon rapidly to the atmosphere. Freshwater and brackish wetlands also emit methane, a...

Modeling Permafrost Response to Climate Change

Vast quantities of carbon—twice the size of the current amount in the atmosphere—are stored in frozen permafrost soils in Arctic regions. The Arctic climate is warming much more rapidly than the global average, leaving these carbon pools highly vulnerable to release into the atmosphere as carbon dioxide and methane as soils thaw and decompose, leading to a feedback cycle of further warming and increasing carbon release. The potential for these carbon stocks to increase global-warming rates, and the rapid changes already observed in the permafrost region, have captured the attention of...

Improving Predictions of Changing Arctic Ecosystems

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...

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Highlights

Scientists investigate the effects of carbon emissions from thawing permafrost soils

A major interagency assessment evaluates carbon cycle science and impacts on society

Understanding carbon cycling in Arctic ecosystems

Understanding carbon cycling in warming northern peatlands

Assessing Alaska’s carbon resources

Supporting twenty years of carbon cycle understanding

Predicting the future of tropical forests

Understanding carbon flows in vulnerable coastal wetlands

Modeling Permafrost Response to Climate Change

Improving Predictions of Changing Arctic Ecosystems