Skip to main content
U.S. flag

An official website of the United States government

How do we know the climate is changing?

The scientific community is certain that the Earth's climate is changing because of the trends that we see in the instrumented climate record and the changes that have been observed in physical and biological systems. The instrumental record of climate change is derived from thousands of temperature and precipitation recording stations around the world. We have very high confidence in these records as a whole. The evidence of a warming trend over the past century is unequivocal.  

Many types of instrumental records point to a climate warming trend. Our streamflow records show an earlier peak in spring runoff; borehole temperature records in Alaskan permafrost as well as water temperature records on land and sea show the warming trend. The physical and biological changes that confirm climate warming include the rate of retreat in glaciers around the world, the intensification of rainfall events, changes in the timing of the leafing out of plants and the arrival of spring migrant birds, and shifting of the range of some species.  

Related

Filter Total Items: 22
Image: Climate Change and Snowshoe Hares Winter White Fur
Climate Change and Snowshoe Hares Winter White Fur
Climate Change and Snowshoe Hares Winter White Fur
Image: Climate Change and Snowshoe Hares Winter White Fur

Climate Change and Snowshoe Hares Winter White Fur

Climate Change and Snowshoe Hares Winter White Fur

Snowshoe hare experiencing camouflage mismatch in the spring at the Seeley Lake, MT, study site.

By
Climate Adaptation Science Centers, Communications and Publishing
Image: Climate Change and Snowshoe Hares Winter White Fur

Climate Change and Snowshoe Hares Winter White Fur

Climate Change and Snowshoe Hares Winter White Fur

Snowshoe hare experiencing camouflage mismatch in the spring at the Seeley Lake, MT, study site.

By
Climate Adaptation Science Centers, Communications and Publishing
Filter Total Items: 19

U.S. Geological Survey Climate and Land Use Change Science Strategy—A Framework for Understanding and Responding to Global Change U.S. Geological Survey Climate and Land Use Change Science Strategy—A Framework for Understanding and Responding to Global Change

Executive Summary The U.S. Geological Survey (USGS), a nonregulatory Federal science agency with national scope and responsibilities, is uniquely positioned to serve the Nation’s needs in understanding and responding to global change, including changes in climate, water availability, sea level, land use and land cover, ecosystems, and global biogeochemical cycles. Global change is among...
Authors
Virginia Burkett, David Kirtland, Ione Taylor, Jayne Belnap, Thomas Cronin, Michael D. Dettinger, Eldrich Frazier, John Haines, Thomas R. Loveland, Paul C.D. Milly, Robin O'Malley, Robert Thompson, Alec Maule, Gerard McMahon, Robert Striegl
By
Earth Resources Observation and Science (EROS) Center

Changing Arctic ecosystems - measuring and forecasting the response of Alaska's terrestrial ecosystem to a warming climate Changing Arctic ecosystems - measuring and forecasting the response of Alaska's terrestrial ecosystem to a warming climate

The Arctic Coastal Plain of northern Alaska is a complex landscape of lakes, streams, and wetlands scattered across low relief tundra that is underlain by permafrost. This region of the Arctic has experienced a warming trend over the past three decades, leading to thawing of on-shore permafrost and the disappearance of sea ice at an unprecedented rate. The loss of sea ice has increased...
Authors
John Pearce, Anthony DeGange, Paul Flint, Tom Fondell, David Gustine, Leslie Holland-Bartels, Andrew Hope, Jerry Hupp, Joshua Koch, Joel Schmutz, Sandra Talbot, David Ward, Mary Whalen
By
Ecosystems Mission Area, Alaska Science Center

Polar bear and walrus response to the rapid decline in Arctic sea ice Polar bear and walrus response to the rapid decline in Arctic sea ice

The Arctic is warming faster than other regions of the world due to positive climate feedbacks associated with loss of snow and ice. One highly visible consequence has been a rapid decline in Arctic sea ice over the past 3 decades - a decline projected to continue and result in ice-free summers likely as soon as 2030. The polar bear (Ursus maritimus) and the Pacific walrus (Odobenus...
Authors
Karen Oakley, Mary Whalen, David C. Douglas, Mark Udevitz, Todd Atwood, C. Jay
By
Ecosystems Mission Area, Alaska Science Center

Changing Arctic ecosystems--research to understand and project changes in marine and terrestrial ecosystems of the Arctic Changing Arctic ecosystems--research to understand and project changes in marine and terrestrial ecosystems of the Arctic

Ecosystems and their wildlife communities are not static; they change and evolve over time due to numerous intrinsic and extrinsic factors. A period of rapid change is occurring in the Arctic for which our current understanding of potential ecosystem and wildlife responses is limited. Changes to the physical environment include warming temperatures, diminishing sea ice, increasing...
Authors
Joy Geiselman, Anthony DeGange, Karen Oakley, Dirk Derksen, Mary Whalen
By
Ecosystems Mission Area, Alaska Science Center

The USA National Phenology Network; taking the pulse of our planet The USA National Phenology Network; taking the pulse of our planet

People have tracked phenology for centuries and for the most practical reasons: it helped them know when to hunt and fish, when to plant and harvest crops, and when to navigate waterways. Now phenology is being used as a tool to assess climate change and its effects on both natural and modified ecosystems. How is the timing of events in plant and animal life cycles, like flowering or...
Authors
Jake F. Weltzin

Sea level change: lessons from the geologic record Sea level change: lessons from the geologic record

Rising sea level is potentially one of the most serious impacts of climatic change. Even a small sea level rise would have serious economic consequences because it would cause extensive damage to the world's coastal regions. Sea level can rise in the future because the ocean surface can expand due to warming and because polar ice sheets and mountain glaciers can melt, increasing the...
Authors
Water Resources Division U.S. Geological Survey

Climate variation and its effects on our land and water : Part A, Earth science in climate research Climate variation and its effects on our land and water : Part A, Earth science in climate research

To better coordinate information being generated by the U.S. Geological Survey, a workshop was convened near Denver, Colo., on December 7-9, 1976, to exchange ideas about research that is oriented toward climate, climate variation, and the effects of climate on the Nation 's land and water resources. This is the first circular of a three-part report resulting from that workshop...
Filter Total Items: 13
Climate Change Accelerates Hybridization between Native and Invasive Species of Trout

Climate Change Accelerates Hybridization between Native and Invasive Species of Trout

Scientists have discovered that the rapid spread of hybridization between a native species and an invasive species of trout in the wild is strongly...

Read Article

Related

Filter Total Items: 22
Image: Climate Change and Snowshoe Hares Winter White Fur
Climate Change and Snowshoe Hares Winter White Fur
Climate Change and Snowshoe Hares Winter White Fur
Image: Climate Change and Snowshoe Hares Winter White Fur

Climate Change and Snowshoe Hares Winter White Fur

Climate Change and Snowshoe Hares Winter White Fur

Snowshoe hare experiencing camouflage mismatch in the spring at the Seeley Lake, MT, study site.

By
Climate Adaptation Science Centers, Communications and Publishing
Image: Climate Change and Snowshoe Hares Winter White Fur

Climate Change and Snowshoe Hares Winter White Fur

Climate Change and Snowshoe Hares Winter White Fur

Snowshoe hare experiencing camouflage mismatch in the spring at the Seeley Lake, MT, study site.

By
Climate Adaptation Science Centers, Communications and Publishing
Filter Total Items: 19

U.S. Geological Survey Climate and Land Use Change Science Strategy—A Framework for Understanding and Responding to Global Change U.S. Geological Survey Climate and Land Use Change Science Strategy—A Framework for Understanding and Responding to Global Change

Executive Summary The U.S. Geological Survey (USGS), a nonregulatory Federal science agency with national scope and responsibilities, is uniquely positioned to serve the Nation’s needs in understanding and responding to global change, including changes in climate, water availability, sea level, land use and land cover, ecosystems, and global biogeochemical cycles. Global change is among...
Authors
Virginia Burkett, David Kirtland, Ione Taylor, Jayne Belnap, Thomas Cronin, Michael D. Dettinger, Eldrich Frazier, John Haines, Thomas R. Loveland, Paul C.D. Milly, Robin O'Malley, Robert Thompson, Alec Maule, Gerard McMahon, Robert Striegl
By
Earth Resources Observation and Science (EROS) Center

Changing Arctic ecosystems - measuring and forecasting the response of Alaska's terrestrial ecosystem to a warming climate Changing Arctic ecosystems - measuring and forecasting the response of Alaska's terrestrial ecosystem to a warming climate

The Arctic Coastal Plain of northern Alaska is a complex landscape of lakes, streams, and wetlands scattered across low relief tundra that is underlain by permafrost. This region of the Arctic has experienced a warming trend over the past three decades, leading to thawing of on-shore permafrost and the disappearance of sea ice at an unprecedented rate. The loss of sea ice has increased...
Authors
John Pearce, Anthony DeGange, Paul Flint, Tom Fondell, David Gustine, Leslie Holland-Bartels, Andrew Hope, Jerry Hupp, Joshua Koch, Joel Schmutz, Sandra Talbot, David Ward, Mary Whalen
By
Ecosystems Mission Area, Alaska Science Center

Polar bear and walrus response to the rapid decline in Arctic sea ice Polar bear and walrus response to the rapid decline in Arctic sea ice

The Arctic is warming faster than other regions of the world due to positive climate feedbacks associated with loss of snow and ice. One highly visible consequence has been a rapid decline in Arctic sea ice over the past 3 decades - a decline projected to continue and result in ice-free summers likely as soon as 2030. The polar bear (Ursus maritimus) and the Pacific walrus (Odobenus...
Authors
Karen Oakley, Mary Whalen, David C. Douglas, Mark Udevitz, Todd Atwood, C. Jay
By
Ecosystems Mission Area, Alaska Science Center

Changing Arctic ecosystems--research to understand and project changes in marine and terrestrial ecosystems of the Arctic Changing Arctic ecosystems--research to understand and project changes in marine and terrestrial ecosystems of the Arctic

Ecosystems and their wildlife communities are not static; they change and evolve over time due to numerous intrinsic and extrinsic factors. A period of rapid change is occurring in the Arctic for which our current understanding of potential ecosystem and wildlife responses is limited. Changes to the physical environment include warming temperatures, diminishing sea ice, increasing...
Authors
Joy Geiselman, Anthony DeGange, Karen Oakley, Dirk Derksen, Mary Whalen
By
Ecosystems Mission Area, Alaska Science Center

The USA National Phenology Network; taking the pulse of our planet The USA National Phenology Network; taking the pulse of our planet

People have tracked phenology for centuries and for the most practical reasons: it helped them know when to hunt and fish, when to plant and harvest crops, and when to navigate waterways. Now phenology is being used as a tool to assess climate change and its effects on both natural and modified ecosystems. How is the timing of events in plant and animal life cycles, like flowering or...
Authors
Jake F. Weltzin

Sea level change: lessons from the geologic record Sea level change: lessons from the geologic record

Rising sea level is potentially one of the most serious impacts of climatic change. Even a small sea level rise would have serious economic consequences because it would cause extensive damage to the world's coastal regions. Sea level can rise in the future because the ocean surface can expand due to warming and because polar ice sheets and mountain glaciers can melt, increasing the...
Authors
Water Resources Division U.S. Geological Survey

Climate variation and its effects on our land and water : Part A, Earth science in climate research Climate variation and its effects on our land and water : Part A, Earth science in climate research

To better coordinate information being generated by the U.S. Geological Survey, a workshop was convened near Denver, Colo., on December 7-9, 1976, to exchange ideas about research that is oriented toward climate, climate variation, and the effects of climate on the Nation 's land and water resources. This is the first circular of a three-part report resulting from that workshop...
Filter Total Items: 13
Climate Change Accelerates Hybridization between Native and Invasive Species of Trout

Climate Change Accelerates Hybridization between Native and Invasive Species of Trout

Scientists have discovered that the rapid spread of hybridization between a native species and an invasive species of trout in the wild is strongly...

Read Article
Updated Date: February 7, 2025
Was this page helpful?