Climate Variability and Change
Climate is the sum of weather over time, the average temperatures and rainfall of a place. Earth's climate—how hot our planet is on average—is set by the Sun. Anything that changes the amount of solar energy that enters the Earth system will change the temperature. By burning fossil fuels, people are loading the atmosphere with heat-absorbing gases, especially carbon dioxide, that trap solar energy that would otherwise be emitted to space (outgoing longwave radiation). As a result, Earth is warming up.
See Climate and Earth's Energy Budget on the Earth Observatory.
Rising temperatures melt ice, put more water vapor into the atmosphere, and may change clouds. These changes and others amplify warming or, in fewer cases, cause cooling. Called feedbacks, the changes and carbon dioxide together will warm Earth between two and ten degree Celsius over the 21st century. Climate change will also change weather patterns around the world.
See Global Warming on the Earth Observatory.
On shorter time scales, years to decades, Earth's temperature varies because of events like El Niño and La Niña. Studying year-to-year climate variability helps scientists understand the processes that connect the ocean, atmosphere, land, snow and ice, and climate. Understanding the connections in the Earth system will improve our ability to predict what will happen as Earth's climate changes.
In fact, NASA's goal in studying climate variability and change is to improve predictions from season to season and decade to decade. Such predictions will help communities prepare for extreme weather months ahead of time and plan infrastructure for long-term climate change.
Terra and Climate Change
The Terra satellite's five instruments provide important climate measurements that record how Earth's energy budget—the amount of energy flowing through the Earth system from the Sun—is changing. These measurements span more than a decade. Since climate is the average of Earth's temperature over decades, long-term measurements are necessary to track climate change. Terra's climate measurements become more and more valuable the longer the satellite is in orbit.
Clouds reflect energy from the Sun back into space, helping to shade and cool Earth. Four Terra instruments (ASTER, CERES, MISR, and MODIS) work together to monitor how clouds are changing, both in response to climate change and natural climate variability because of things like El Nino or changes in solar activity.
Aerosols, tiny particles in the atmosphere, reflect energy back into space, cooling the Earth. Dark-colored aerosols, like black carbon or soot, absorb energy and heat the atmosphere. Terra instruments (CERES, MISR, MODIS) monitor aerosols concentrations, identify aerosol types and sources, and monitor how aerosols are affecting the climate.
Snow and Ice
Snow and ice reflect energy, which helps keep the climate cool. Terra instruments record snow and ice extent (ASTER, MODIS) and track the amount of energy reflected into space from snow and ice (CERES).