Climate Scenarios Project Temperature and Precipitation in the U.S. through 2100
Curious to ‘see’ how different greenhouse gas emission scenarios are expected to impact the United States? Two recently released animated NASA visualizations developed to support the forthcoming third US National Climate Assessment show projections of Earth’s temperature and precipitation patterns from today through the year 2100—revealing how “low” versus “high” emission scenarios would impact the planet’s climate.
“These visualizations communicate a picture of the impacts of climate change in a way that words do not,” said Allison Leidner, Ph.D., a scientist who coordinates NASA’s involvement in the National Climate Assessment. “When I look at the scenarios for future temperature and precipitation, I really see how dramatically our Nation’s climate could change.”
To develop these complex animations, a team of scientists used results from 15 global climate models, combined with data on monthly temperature and precipitation in the United States, to generate maps of projected conditions through the year 2100.
The visualizations present projections of temperature and precipitation changes from 2000 to 2100 - compared to the historical average from 1970-1999 - under two different scenarios of future CO2 emissions. The “higher emissions” scenario represents a fossil-fuel-intensive future in which concentrations of atmospheric CO2 exceed 800 ppm by the year 2100. The “lower emissions” scenario represents a less fossil-fuel-intensive future in which atmospheric CO2 concentrations level off at around 550 ppm by 2100.
Today, atmospheric CO2 concentrations stand at around 400 ppm.
Temperature in the U.S.
While NASA’s visualizations show significant warming in both scenarios, the projected average temperature change over the contiguous United States in the higher emissions scenario is nearly twice what is projected in the lower emissions scenario— at 8°F (versus just 4.5°F).
Dr. Kenneth E. Kunkel, Lead Scientist for Assessments at NOAA’s Cooperative Institute for Climate and Satellites, explained, “Looking at these visualizations, you see that reducing emissions does in fact have a big impact on the amount of warming by the end of the century.”
Another notable characteristic of the visualizations is that projected warming is generally greater over the North American continent, compared to the surrounding oceans. It takes longer for the oceans to warm up because the excess energy that is deposited in the oceans can be mixed over a fairly large depth, says Dr. Kunkel.
Dr. Kunkel also points out that the magnitude of temperature increase during the summer is much higher over the contiguous U.S. than in Canada and Alaska. This may be partially a result of decreasing soil moisture relating to increased evaporation, which increases as temperature rises.
How Will Precipitation Change?
Nationwide, changes in precipitation are expected to occur under both scenarios, but be more dramatic in the higher emissions scenario—with many dry areas getting dryer, while wet areas get wetter.
“The visualizations really bring home how regional variations tie back together,” Dr. Leidner said. “Words describe this, but when you see it, you get it.”
For instance, the visualizations show that New England precipitation projected to increase, while some areas of the Southwest can expect to see a 10% decrease in annual precipitation in the higher emission scenario.
To view the detailed visualizations on the NASA website, please visit the links below: