Climate research aims to understand and describe the Earth’s complex, interrelated weather and climate conditions. Scientists have been making observations and recording weather conditions since the Scientific Revolution, aided by inventions such as thermometers and barometers, and systematic recordkeeping grew rapidly in the nineteenth and twentieth centuries. Today, global networks of observing stations report daily surface temperatures, pressures and humidity over the entire planet. These data are carefully corrected, synthesized and transformed into long-term global datasets. Learn more about the process of building these datasets in our Climate Data Primer.
In addition to using observations, scientists study climates of the past by studying proxies for the conditions that were experienced (IPCC-Glossary: 2245). Proxy indicators include variations in the ratio of different isotopes of oxygen in deep ice cores, carbon-14 in tree rings, fossilized shells and lake sediments, among others. These proxies can be used to reconstruct past atmospheric and oceanic conditions, which then can be compared with contemporary observed weather and climate phenomena.
A growing body of evidence indicates that human activities are causing the atmosphere to warm, with global average surface temperatures already higher than at any other time in recorded history. This warming is largely the result of increased greenhouse gas concentrations in the air. Scientists are assessing the impact of this warming on the natural environment and on people’s well-being.
As they seek explanations and understanding, scientists use models to represent the workings of the climate system. These model-based analyses and projections serve several purposes: They can supplement and test observations; they help identify what is difficult to learn from available observational data through simple physical reasoning (e.g., Arrhenius 1908); and they can serve as experimental systems manipulated by scientists to explore the quantitative plausibility of explanatory hypotheses.