Key Indicators
Atmospheric Carbon Dioxide
Atmospheric concentration of carbon dioxide, as well as methane and nitrous oxide, are at the highest levels in the last 800,000 years.
Carbon dioxide concentrations in 2023 (the last year for which consolidated global annual figures are available) were 420.0 ± 0.1 parts per million (ppm), 2.3 ppm more than 2022 and 151% of the pre-industrial level (in 1750). 420 ppm corresponds to 3,276 Gt – or 3.276 trillion tonnes of CO₂ in the atmosphere.
Real-time data from specific locations show that levels of these three main greenhouse gases continued to increase in 2024. Carbon dioxide remains in the atmosphere for generations, trapping heat.
Global Mean Near-surface Temperature
In addition to 2024 setting a new record, each of the past ten years, 2015-2024, were individually the ten warmest years on record.
The record temperature in 2024 was boosted by a strong El Niño which peaked at the start of the year. In every month between June 2023 and December 2024, monthly average global temperatures exceeded all monthly records prior to 2023.
Record levels of greenhouse gases were the primary driver, with the shift to El Niño playing a lesser role.
Ocean Heat Content
Around 90% of the energy trapped by greenhouse gases in the Earth system is stored in the ocean.
In 2024, ocean heat content reached its highest level in the 65-year observational record. Each of the past eight years has set a new record. The rate of ocean warming over the past two decades, 2005-2024, is more than twice that in the period 1960-2005.
Ocean warming leads to degradation of marine ecosystems, biodiversity loss, and reduction of the ocean carbon sink. It fuels tropical storms and contributes to sea-level rise. It is irreversible on centennial to millennial time scales. Climate projections show that ocean warming will continue for at least the rest of the 21st century, even for low carbon emission scenarios.
Ocean Acidification
Acidification of the ocean surface is continuing, as shown by the steady decrease of global average ocean surface pH. The most intense regional decreases are in the Indian Ocean, the Southern Ocean, the eastern equatorial Pacific Ocean, the northern tropical Pacific, and some regions in the Atlantic Ocean.
The effects of ocean acidification on habitat area, biodiversity and ecosystems have already been clearly observed, and food production from shellfish aquaculture and fisheries has been hit as have coral reefs.
Projections show that ocean acidification will continue to increase in the 21st century, at rates dependent on future emissions. Changes in deep-ocean pH are irreversible on centennial to millennial time scales.
Annual global ocean heat content down to 2000 m depth for the period 1960–2024, in zettajoules (1021 J). The shaded area indicates the 2-sigma uncertainty range on each estimate.
Global Mean Sea Level
In 2024, global mean sea level was the highest since the start of the satellite record in 1993 and the rate of increase from 2015-2024 was double that from 1993–2002, increasing from 2.1 mm per year to 4.7 mm per year.
Sea level rise has cascading damaging impacts on coastal ecosystems and infrastructure, with further impacts from flooding and saltwater contamination of groundwater.
Glacier Mass Balance
The period 2022-2024 represents the most negative three-year glacier mass balance on record. Seven of the ten most negative mass balance years since 1950 have occurred since 2016.
Exceptionally negative mass balances were experienced in Norway, Sweden, Svalbard, and the tropical Andes.
Glacier retreat increases short-term hazards, harms economies and ecosystems and long-term water security.
Sea-ice Extent
The 18 lowest Arctic sea-ice minimum extents in the satellite record all occurred in the past 18 years. The annual minimum and maximum of Antarctic sea-ice extent were each the 2nd lowest in the observed record from 1979.
The minimum daily extent of sea-ice in the Arctic in 2024 was 4.28 million km2, the 7th lowest extent in the 46-year satellite record. In Antarctica, the minimum daily extent tied for the 2nd lowest minimum in the satellite era and marked the 3rd consecutive year that minimum Antarctic sea-ice extent dropped below 2 million km2. These are the three lowest Antarctic ice minima in the satellite record.
Extreme events and impacts
Extreme weather events in 2024 led to the highest number of new annual displacements since 2008, and destroyed homes, critical infrastructure, forests, farmland and biodiversity.
The compounded effect of various shocks, such as intensifying conflict, drought and high domestic food prices drove worsening food crises in 18 countries globally by mid-2024.
Tropical cyclones were responsible for many of the highest-impact events of 2024. These included Typhoon Yagi in Viet Nam, the Philippines and southern China.
In the United States, Hurricanes Helene and Milton in October both made landfall on the west coast of Florida as major hurricanes, with economic losses of tens of billions of dollars. Over 200 deaths were associated with the exceptional rainfall and flooding from Helene, the most in a mainland United States hurricane since Katrina in 2005.
Tropical Cyclone Chido caused casualties and economic losses in the French Indian Ocean island of Mayotte, Mozambique and Malawi. It displaced around 100,000 people in Mozambique.
