From measuring changes to Earth’s surface and oceans, to examining ice cores to gauge atmospheric composition over centuries, to developing computer models that predict how ecosystems will change and human-induced climate trends may play out, scientists use a range of tools to keep tabs on climate. Their findings help us understand how and why the planet is changing, such as by identifying warmer temperatures or expanding areas of drought. This knowledge can guide efforts to slow or reverse harmful trends, and to adapt to unavoidable ones.
The work of climate scientists has a long history, beginning with the recognition that carbon dioxide in the atmosphere can affect temperature through its ability to trap infrared radiation. Svante Arrhenius first envisioned this effect in 1908, and by the 1980s scientists such as NASA scientist James Hansen were sounding alarms. The global scientific community now recognizes that human activities are substantially altering the Earth’s climate.
PNNL scientists develop computational models that simulate and predict Earth’s climate. These models include equations that describe everything from how the winds blow to how sea ice reflects sunlight and how forests take up carbon dioxide. Models are designed to replicate real-world conditions as closely as possible and to incorporate the knowledge gained through observations.
When analyzing observations of the Earth’s climate, scientists often try to detect changes that are due solely to external factors such as greenhouse gases and aerosols. Detection requires an estimate of how much variation could have been expected in the absence of such external forces, as well as a confidence level on the estimated magnitude of the observed change.
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