July 22 Sets Record For World Hottest Day Ever

On July 21, 2024, the world experienced its hottest day on record. Remarkably, just 24 hours later, this record was surpassed, making July 22 likely the hottest day in thousands of years. Such extreme temperature readings, though seemingly extraordinary, are confirmed through advanced scientific techniques developed to handle the challenges of global climate monitoring. The EU’s Copernicus Climate Change Service, responsible for these findings, employs a method known as “reanalysis” to provide a comprehensive view of global climate conditions. This technique integrates temperature data with sophisticated climate models to create an accurate, near real-time picture of Earth’s climate. The reanalysis process involves aggregating data from various sources, including temperature readings from satellites, weather stations, airplanes, and ships, to cover roughly every 30-square-kilometer area of the planet’s surface.

Reanalysis data from Copernicus, which dates back to 1940, allows scientists to identify and verify new temperature records with confidence. The data reveals that 2023 was the hottest year ever recorded, with every calendar month over the past 13 months being the hottest on record. This pattern underscores the alarming trend of rising global temperatures, a significant indicator of ongoing climate change. Despite the lack of thermometers in every location around the world, Copernicus manages to compile extensive weather data. According to Carlo Buontempo, Director of the Climate Change Service at the European Centre for Medium-Range Weather Forecasts (ECMWF), the center receives around 100 million weather readings daily from a variety of sources. This data includes information on temperature, wind, precipitation, and other climate variables.

The model used for this analysis, known as ERA5, combines historical climate information with real-time data to fill gaps and correct errors. This model addresses challenges such as incomplete data coverage and varying weather conditions that can affect satellite observations. ERA5’s methodology involves testing predictions against actual weather observations from various sources, including ocean currents and atmospheric circulation patterns. This iterative process ensures that the climate models are as accurate as possible, enabling scientists to confidently declare records like the hottest day in human history. Globally, five major weather services contribute to temperature assessments using similar techniques. These include the US’s National Oceanic and Atmospheric Administration (NOAA) and NASA, the ECMWF, the China Meteorological Administration, and the Japan Meteorological Agency. While each organization uses slightly different models, their findings converge on similar conclusions about recent record heat. This consensus reflects a broader, corroborated understanding of global temperature trends.

Historical temperature data, while useful, poses its own set of challenges. The longest-running temperature series, the Central England Temperature record, began in the 17th century. For periods before systematic temperature monitoring, scientists rely on proxies like gas bubbles trapped in glacial ice and tree rings. Though these sources do not provide precise temperature readings, they offer valuable insights into long-term climate trends. According to Copernicus, recent temperatures are likely the highest in about 100,000 years, based on these historical data sources. The alarming records set in July 2024 highlight the ongoing impact of climate change. The accuracy and reliability of modern climate models, coupled with extensive global data collection, allow scientists to track and understand these extreme weather events. As the planet continues to warm, these records serve as a stark reminder of the urgent need for climate action and mitigation strategies.