Climate science

Climate science, or climatology, is the study of Earth’s climate. Climate scientists want to better understand our planet’s atmosphere and how it affects various ecosystems. Many equate climate with the weather. And indeed, the word climate is usually defined as the average weather conditions in a particular area over a long-term period, such as years or decades. But climate science touches far more than weather trends. It explores how climate conditions affect a variety of habitats such as oceans, rivers, forests, deserts, and grasslands, as well as the creatures living within those habitats.

Conducting climate science is essential to understanding the effects of global warming and climate change. In the 20th century, the global average surface temperature increased about 2 °F, and the warming rate per decade has significantly increased in the past 40 years. This warming has been driven by increasing atmospheric levels of greenhouse gases, so named because their heat-trapping properties create a “greenhouse effect.” Greenhouse gases include carbon dioxide, methane, and nitrous oxide, and their rising concentrations in the air have been driven by human activity such as burning fossil fuels.

Climate scientists measure changes to the planet using a variety of techniques. They study ice cores taken from the North and South poles to gauge changes to the environment over centuries. They sample air to see how concentrations of greenhouse gases are evolving and examine trees to chart how forest conditions have changed over time. They build computer models that predict changes to ecosystems based on historical data. These and other methods illuminate what causes changes to the climate, what effects those changes have on ecosystems, how they will affect wildlife and humans, what can be done to slow or reverse harmful climate trends, and how humans and animals might adapt to a changing world. Disciplines related to climatology include atmospheric science, hydrology, environmental microbiology, cloud physics, meteorology, and Earth system modeling.

Nearly every country in the world has agreed to reduce greenhouse gas emissions as part of the Paris Agreement, an international pact aimed at limiting global warming to at least 2 degrees Celsius—preferably 1.5. This agreement is informed by climate science. The Intergovernmental Panel on Climate Change (IPCC), which the United Nations established in 1988, delivers periodic reports that assess the latest scientific knowledge on climate change.

Hundreds of experts have convened to create these reports, which have provided crucial scientific consensus that the climate is changing rapidly because of human activities. This consensus is the backdrop for international action like the Paris Agreement. The sixth IPCC assessment report, which was released in 2021, warned that “human-induced climate change is already affecting many weather and climate extremes in every region across the globe.” The report further stated that it would take centuries to millennia to reverse many climate changes resulting from past and future greenhouse gas emissions, especially changes in the ocean, ice sheets, and global sea level.

The United States also conducts its own periodic assessment of climate science and impacts. The Fourth National Climate Assessment documented aspects of climate change, including changing precipitation patterns, rising sea levels, and the increasing frequency and intensity of extreme weather events such as heat waves and forest fires.

Climate science enables these insights. Because of Charles Keeling’s pioneering efforts to measure carbon dioxide in the atmosphere, for example, we now have a record spanning more than 60 years. In June 2021, the monthly average concentration of carbon dioxide in the air at the National Oceanic and Atmospheric Administration’s Mauna Loa Atmospheric Baseline Observatory peaked near 420 parts per million—more than 100 parts per million higher than in 1958 when Keeling measurements first began at the site. U.S. scientists have also documented shrinking sea ice and snow cover extent globally over the past several decades.

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