Background
Climatology is the science of climate, or the study of long-term atmospheric conditions across Earth.
Unlike meteorology, which uses data to predict weather over several days, climate science focuses on identifying patterns across 55 essential climate variables over periods of 30 or more years.
These patterns help climatologists better understand the interactions between Earth’s systems and refine computational models to predict future phenomena.
History
The word “climate” comes from the Greek term "klima," which refers to the slope or curvature of the Earth. Philosophers in ancient Greece knew the Earth was round and defined regional bands—later called "climata"—based on their latitude.
These philosophers developed the earliest form of climatology—climatic determinism—and argued that where a person lived dictated whether they sought intelligence or subjugation based on how much solar energy they received.
In the 1600s, the field began incorporating numeric data with the inventions of the thermometer and the barometer, which measured air pressure (watch explainer). Other devices were also used, such as anemometers to measure wind speed and hygrometers to measure humidity.
While this data was being collected across continents and elevations, determining the best trade routes for navigators during the early modern era drove the mapping of trade winds, monsoons, and the recurrence of other atmospheric phenomena.
By the 20th century, radar and satellite technologies transformed regional climatology into a global discipline where air, land, sea, and solar data from observation networks were collected in real time (learn more).
Paleoclimatology
Paleoclimatologists use climate proxies—materials that preserve past climate conditions—to obtain climate data from periods before modern instrumentation.
Comparing the results from analyzing these materials with collected data from recent centuries helps calibrate proxies toward accurately determining variables in the distant past.
Tree rings develop in yearly layers as trees grow and reveal precipitation and temperature conditions based on ring thickness.
Ice cores are long columns drilled from glacial ice sheets formed during the accumulation and compaction of thousands of years of winter snowfall. The compaction traps air bubbles that reveal past atmospheric composition, temperature, precipitation, and volcanic activity.
Sediment cores similarly trap information in layers of mud, sand, pollen, and dead animals and plants. Scientists can reconstruct the climate from when the layer formed by finding overlaps in the environmental conditions each organism needed when it was alive.
Speleothems—stalagmites, stalactites, and other rock formations—are formed from mineral deposits left behind by water as it drips into caves, indicating times of drought or heavy rain.
Elemental analysis in these and other proxies, including determining the ratios of different oxygen isotopes, can also provide data on various climate variables (watch explainer).
Modeling
Climate models apply the laws of physics to predict Earth’s climate at different points in time.
The simplest models only use energy balance—radiation received from the sun equals radiation emitted by Earth’s surface—while the most complex, known as general circulation models, incorporate interactions between all of Earth’s systems at high resolutions and can only be solved on supercomputers (watch explainer).
Models are tested via hindcasting—running them from one point in the past with known historical data to see if they reproduce known historical trends—before being run to project future climatic conditions.
These projections can incorporate human activities and forecast their impacts, including climate change, to help inform policy decisions such as mitigation efforts and disaster preparedness in vulnerable regions.
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