Climate research uses scientific data accumulated over time, plus mathematical and statistical models to help understand past, present and future climates. It explores interactions between a changing climate and ecosystems, human societies and the economy, including food and water security. It also seeks to inform national and international policy, including assessing national pledges to limit greenhouse gas emissions (known as Nationally Determined Contributions or NDCs).
Observational climate science focuses on monitoring the current climate through networks of weather stations spanning the globe. Thousands of individual station records are merged, subjected to quality control, homogenized and transformed to a common grid in the process of producing global temperature datasets. This process, which can take years, requires a great deal of expertise and technical capacity.
Other observational research focuses on the climates of the past, using various types of proxy indicators — biophysical properties that are interpreted as representing variations in a variable such as temperature — from materials like ice cores, tree rings, corals, lake sediments and boreholes. Paleoclimatic investigations use these proxy data to study everything from changes in temperature to hurricane frequency over millennia.
Climate scientists are also increasingly seeking to quantify how much a particular extreme event was made more likely or intense due to human influences, such as warming temperatures or anthropogenic aerosols. This is known as probabilistic event attribution, and it involves comparing the frequency of the event under pre-industrial conditions to the frequency under present-day greenhouse gas levels.