🌡️ Climate science

Weather describes short-term atmospheric conditions, what is happening in the sky over hours or days, while climate describes the long-term statistical pattern of weather in a region, typically measured over multiple decades. Scientists studying climate look at averages, extremes, and trends across huge stretches of time, which lets them separate normal, expected variation from an actual long-term shift in a region's typical conditions. A record-breaking cold snap can happen even during an overall warming trend, since short-term weather always bounces around, sometimes wildly, on top of the slower-moving climate pattern underneath it.

El Niño is a natural, cyclical shift in ocean temperatures and wind patterns across the tropical Pacific Ocean, where warmer than usual water builds up and changes how heat and moisture move through the atmosphere, which then shifts weather patterns across huge parts of the globe. During an El Niño year, some regions tend to get unusually wet weather while others tend toward drought, and these shifts can last a year or more before conditions swing back the other way, a phase called La Niña. Scientists still cannot predict exactly when the next El Niño will begin, but they can track early warning signs in ocean temperature months in advance.

Deserts form for several different reasons, some sit in the rain shadow of tall mountain ranges, some sit under permanent high-pressure zones where air constantly sinks and dries out instead of rising to form rain clouds, and some sit so far from any ocean that moist air simply never reaches them. A desert is defined by how little rain it gets, not by temperature, which is why some deserts are bitterly cold rather than hot, since even icy places can technically be deserts if they receive very little precipitation. Understanding exactly why a desert exists where it does often means tracing back through mountain ranges, wind patterns, and ocean currents all working together.

Ocean currents act like giant conveyor belts, moving enormous amounts of warm and cold water around the globe, and since water holds and releases heat much more slowly than air, these currents help even out temperatures between the equator and the poles. Some coastal regions stay far milder than their latitude would otherwise suggest simply because a warm ocean current flows nearby, carrying tropical heat toward them, while other coastlines stay unusually cool thanks to cold currents flowing past. If a major ocean current were to slow down or shift, scientists believe it could dramatically reshape the climate of entire regions, sometimes within just a few decades.