Read more about how the global surface temperature record is built in our Climate Data Primer. This process provides a consistent, reliable method for monitoring changes in Earth's surface temperature over time. Each value is then used to calculate a global temperature average. Multiple independent research groups across the world perform their own analysis of the surface temperature data, and they all show a similar upward trend.Īcross inaccessible areas that have few measurements, scientists use surrounding temperatures and other information to estimate the missing values. Because their goal is to track changes in temperature, measurements are converted from absolute temperature readings to temperature anomalies-the difference between the observed temperature and the long-term average temperature for each location and date. To calculate a global average temperature, scientists begin with temperature measurements taken at locations around the globe. However, the concept of a global average temperature is convenient for detecting and tracking changes in Earth's energy budget-how much sunlight Earth absorbs minus how much it radiates to space as heat-over time. To speak of the "average" temperature, then, may seem like nonsense. This means that some parts of Earth are quite cold while other parts are downright hot. Temperatures vary from night to day and between seasonal extremes in the Northern and Southern Hemispheres. After all, at this very moment, the highest and lowest temperatures on Earth are likely more than 100☏ (55☌) apart. The concept of an average temperature for the entire globe may seem odd. NOAA map, based on data from NOAA Centers for Environmental Information. Only a few locations, most of them in Southern Hemisphere oceans, cooled over this time period. Most of the planet is warming (yellow, orange, red). Trends in global average surface temperature between 19 in degrees Fahrenheit per decade. As the map below shows, most land areas have warmed faster than most ocean areas, and the Arctic is warming faster than most other regions. That extra heat is driving regional and seasonal temperature extremes, reducing snow cover and sea ice, intensifying heavy rainfall, and changing habitat ranges for plants and animals-expanding some and shrinking others. The roughly 2-degree Fahrenheit (1 degrees Celsius) increase in global average surface temperature that has occurred since the pre-industrial era (1880-1900) might seem small, but it means a significant increase in accumulated heat. Given the tremendous size and heat capacity of the global oceans, it takes a massive amount of heat energy to raise Earth’s average yearly surface temperature even a small amount. NOAA graph, based on data from the National Centers for Environmental Information. Blue bars indicate cooler-than-average years red bars show warmer-than-average years. Yearly surface temperature compared to the 20 th-century average from 1880–2022.
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