Share

Facebook logo Twitter logo Google+ logo LinkedIn logo Reddit logo

Climate Change

Sunset

 

Earth’s climate is now changing faster than at any point in the history of modern civilization, primarily as a result of human activities. Global climate change has already resulted in a wide range of impacts across every region of the country and many sectors of the economy that are expected to grow in the coming decades. 
 
The Fourth National Climate Assessment (NCA4), developed by the U.S. Global Change Research Program (USGCRP), is a state-of-the-science synthesis of climate knowledge, impacts, and trends across U.S. regions and sectors to inform
decision making and resilience-building activities across the country. It is the most
comprehensive and authoritative assessment to date on the state of knowledge
of current and future impacts of climate change on society in the United States. 
 
Explore the physical science of climate change in NCA4 Volume I, the Climate Science Special Report.
 
Understand the impacts of climate change on regions and sectors across the United States in
NCA4 Volume II: Impacts, Risks, and Adaptation in the United States. 

What's Happening & Why

Iceberg

Thousands of studies conducted by researchers around the world have documented increases in temperature at Earth’s surface, as well as in the atmosphere and oceans. Many other aspects of global climate are changing as well. Human activities, especially emissions of heat-trapping greenhouse gases from fossil fuel combustion, deforestation, and land-use change, are the primary driver of the climate changes observed in the industrial era.

 

Learn More

Impacts on Society

Farmer working a field of crops

Impacts related to climate change are evident across regions and in many sectors important to society—such as human health, agriculture and food security, water supply, transportation, energy, ecosystems, and others—and are expected to become increasingly disruptive in the coming decades.

Learn More

Response Options

Wind farm

The impacts of global climate change in the United States are already being felt and are projected to intensify in the future, especially without further action to reduce climate-related risks. As the impacts of climate change grow, Americans face decisions about how to respond. 

Learn More