Earth’s climate experienced its hottest year in 2024. Extreme flooding in April killed hundreds of people in Pakistan and Afghanistan. A year-long drought has brought water levels in the Amazon River to record lows. And in Athens, Greece, the ancient Acropolis was closed in the afternoon to protect tourists from dangerous heat.
A new report from the EU’s Copernicus Climate Change Office confirms that 2024 was the first year on record when global average temperatures exceeded pre-industrial levels by 1.5 degrees Celsius. All continents except Australia and Antarctica experienced their hottest year on record, with 11 months of the year exceeding the 1.5°C level.
In recent years, global temperatures have been at record levels and continue to rise. The previous hottest year on record was 2023. The 10 hottest years on record have all occurred within the past 10 years. However, this is the first time in a calendar year that temperatures have exceeded the 1.5°C threshold.
Status in 2024: Earth’s average surface temperature graph
Although 2024 was the first calendar year to exceed 1.5 degrees Celsius above pre-industrial levels, the five-year average remains below this threshold. Copernicus Global Climate Highlights Report 2024
It’s getting hot
Copernican scientists used reanalyses to calculate temperature increases and estimate changes due to extreme events. Reanalysis occurs in real time, combining observations from as many sources as possible, including satellites, weather stations, and ships, with state-of-the-art weather prediction models to build a complete picture of weather around the world. Throughout the past year. The resulting dataset is one of the key tools used by scientists around the world to study weather and climate.
Limiting sustained global warming to 1.5°C is a key goal of the Paris Agreement, a 2015 international treaty aimed at mitigating climate change. The 195 signatories pledged to “continue our efforts” to limit long-term average temperature rise to below 1.5°C.
Although reaching 1.5°C in 2024 is a milestone, exceeding 1.5°C in a single year does not mean we have exceeded the Paris threshold. Weather fluctuates from year to year, so even if temperatures exceed 1.5°C in a single year, the long-term average can still be below. It is this long-term average temperature that is referred to in the Paris Agreement. The current long-term average temperature is approximately 1.3℃.
Read more: Human-induced warming exceeded 1.5C this year (only different from Paris Agreement measurements)
Natural factors, such as a strong El Niño, contributed to warmer temperatures in 2024. El Niño is a climate phenomenon that affects weather patterns around the world, causing increases in ocean temperatures in the tropical Pacific Ocean. Global average temperatures will rise, increasing the likelihood of extreme events in some parts of the world. Although these natural fluctuations drove anthropogenic climate change in 2024, they may act to cool the Earth in other years, reducing the observed temperature increase in a given year.
Although targets focus the attention of policy makers, it is important not to get too attached to targets, which from a scientific point of view are rather arbitrary. Research shows that catastrophic effects, such as the rapid and irreversible melting of the Greenland ice sheet, are more likely to occur with every bit of warming. These effects can occur even if the threshold is exceeded only temporarily. So every tenth of a degree of warming is important.
unprecedented extremes
What ultimately impacts humans and ecosystems is how global climate change manifests in local climate and weather. The relationship between Earth’s climate and weather is nonlinear. Global warming of 1.5°C could cause individual heat waves that are much hotter than the rise in global average temperatures.
Europe had its hottest year on record in 2024, with severe heatwaves occurring particularly in southern and eastern Europe. Wildfires burned large areas of pine forests and homes in parts of Greece and the Balkans.
The new report shows that 44% of the planet experienced strong or higher heat stress on July 10, 2024, which is 5% above the average annual maximum. Particularly in low-income countries, this can lead to poor health outcomes and excess deaths.
Flash floods in Valencia, Spain in October 2024 killed hundreds of people and caused extensive property damage. Vicente Sargus/Shutterstock
℃
The report also highlights that atmospheric moisture (precipitation) in 2024 was 5% higher than the recent average. Warmer air can hold more moisture, and water is a powerful greenhouse gas, trapping more heat in the atmosphere.
More worryingly, this increased moisture content means extreme rainfall events could become even more intense. In 2024, many regions will experience devastating floods, such as the one that occurred in Valencia, Spain last October. This is not as simple as increasing moisture content leading to more extreme rainfall. Wind and pressure systems that drive the weather also play a role and may be affected by climate change. This means that in some areas, rain can intensify even faster than the amount of moisture in the atmosphere.
To keep global warming from exceeding 1.5°C in the long term and avoid the worst impacts of climate change, we need to rapidly reduce greenhouse gas emissions. It is also important to adapt infrastructure and protect people from the unprecedented extreme conditions caused by current and future levels of warming.
It remains to be seen whether 2025 will be as hot as 2024 due to the cooler climate of the tropical Pacific. But this new record highlights the huge impact humans are having on the climate and should serve as a wake-up call for us all.
Don’t have time to read as much as you want about climate change?
Get our weekly roundup in your inbox instead. Every Wednesday, The Conversation’s environment editor writes a short email, “Imagine,” that digs a little deeper into just one climate issue. Join over 40,000 readers who have already subscribed.
