2025 in climate change

This article documents notable events, research findings, scientific and technological advances, and human actions to measure, predict, mitigate, and adapt to the effects of global warming and climate change—during the year 2025.

Global average surface temperatures, shown here for each January since 1940, reached a record high temperature of 1.75 °C in January 2025 despite the Earth being in a La Niña (regional cooling) phase.

Global sea ice reached a new all-time minimum in early February, and remained below the previous record of February 2023 for the rest of the month.

• 10 January: a summary from the Copernicus Climate Change Service stated that 2024 was the warmest year since records began in 1850, with an average global surface temperature reaching 1.6 °C above pre-industrial levels, surpassing for the first time the 1.5 °C warming target set by the Paris Agreement. The summary also stated that 2024 was the second consecutive year with the hottest global temperature, surpassing 2023 by +0.12 °C.
• 21 January: a study published in Nature Climate Change concluded that at least 30% of the Arctic has become a net source of carbon dioxide.
• 28 January: a study published in Environmental Research Letters reported that global mean sea surface temperature increases had more than quadrupled, from 0.06 K per decade during 1985–89 to 0.27 K per decade for 2019–23, and projected that the increase inferred over the past 40 years would likely be exceeded within the next 20 years.
• 3 February: a study co-authored by James Hansen published in Environment concluded that the IPCC had underestimated the effect of aerosols' planet-cooling radiative forcing, after enactment of international regulation of maritime aerosol emissions in the 2020s designed to improve air quality. This underestimation of aerosols' effect was said to cause underestimation of climate sensitivity, Hansen et al. writing that the reduction in aerosols explains the unexpectedly large global warming experienced in 2023-2024.
• 10 February: a study published in Nature Climate Change shows that the first single calendar year above 1.5 °C relative to pre-industrial levels in 2024 indicates that most probably Earth has already entered the 20-year period that will reach the Paris Agreement limit — that is, a 20-year period with average warming of 1.5 °C.
• 24 February: a study published by the non-profit Initiative on GHG Accounting of War estimated that the three years of the Russian invasion of Ukraine had caused 230 MtCO₂e (metric tons of carbon dioxide equivalent) emissions—citing warfare, buildings reconstruction, landscape fires, damage to energy infrastructure, refugee and civil aviation displacement.
• 7 March: a study by World Weather Attribution concluded that in a February 2025 heat wave, climate change made extreme heat at least 2 °C hotter and at least ten times more likely.
• 14 April: a study published in the Proceedings of the National Academy of Sciences concluded that since 1940, global warming has tripled the number of days per year that the oceans experience extreme surface heat conditions, and is responsible for a 1 °C increase in maximum intensity of marine heatwave events.

• 1 January: a study published in Science Advances concluded that faster flow of the Antarctic Circumpolar Current (ACC) at higher latitudes causes upwelling of isotopically light deep waters around Antarctica, likely increasing atmospheric carbon dioxide levels and thereby potentially constituting a critical positive feedback for future warming.
• 6 January: a study published in Nature Climate Change stated that a fungal pathogen (Entomophaga maimaiga) that had successfully controlled the defoliation of the spongy moth in North American forests was becoming less effective due to climate change producing hotter, drier conditions. The study predicts this will lead to significantly decreased forest biodiversity and productivity by spongy moths, evidenced by recent increases in defoliation.
• 7 January: NOAA's Arctic Report Card 2024 reported that, including the impact of increased wildfires, the Arctic tundra region had shifted from storing carbon in the soil to becoming a carbon dioxide source, and that the Arctic remained a consistent source of methane—both adding to planet-warming greenhouse gases in the air.
• 8 January: a study published in Nature concluded that one-quarter of 23,496 decapod crustaceans, fishes and odonates studied, some of which provide climate change mitigation, are threatened with extinction. One-fifth of threatened freshwater species are affected by climate change and severe weather events.
• 9 January: a study published in Nature Reviews Earth & Environment estimated that since the mid-twentieth century, global-averaged 3-month and 12-month "hydroclimate whiplash" events have increased by 31–66% and 8–31%, respectively. Such increases amplify hazards associated with rapid swings between wet and dry states, including flash floods, wildfires, landslides and disease outbreaks. (Hydroclimate volatility refers to "sudden, large and/or frequent transitions between very dry and very wet conditions".)
• 15 January: a study published in Weather reported that the terrestrial biosphere's rate of natural carbon dioxide sequestration has fallen since its 2008 peak at a rate of 0.25% per year, a decline that will accelerate climate change.
• 21 January: a study published in the Proceedings of the National Academy of Sciences reported an "abrupt, coherent, climate-driven transformation" from "blue" (more transparent) to "brown" (less transparent) states of lakes in Greenland after a season of both record heat and rainfall drove a state change in these systems. This change was said to alter "numerous physical, chemical, and biological lake features", and the state changes were said to be unprecedented.
• February (reported): though polar bears and grizzly bears traditionally occupy distinct habitats (marine and land), arctic warming has forced polar bears inland into grizzly bear habitats, where the two species mate to produce hybrid "grolar bears" that have characteristics poorly adapted to either marine or land habitats.
• 4 February: a study published in Environmental Research Letters concluded that, in addition to the 2023 marine heat wave, an extensive river plume caused a ~10–20 m (33–66 ft) thick strongly stratified barrier layer that contributed to Hurricane Idalia's rapid intensification (Category 1 to Category 4 in less than 24 hours).
• 26 February: a study published in Nature concluded that the Atlantic meridional overturning circulation (AMOC) is resilient to extreme greenhouse gas and North Atlantic freshwater forcings across 34 climate models, suggesting that an AMOC collapse is unlikely in the 21st century.
• 26 February: a study published in Science Advances concluded that short-, mid-, and long-term ambient outdoor heat can significantly accelerate epigenetic aging in older adults.
• 10 March: a study published in Nature Sustainability projected that climate change's cooling of the atmosphere occupied by space debris in low Earth orbit will reduce the atmosphere's drag on the debris, extending the debris' lifetime and potentially causing a 50–66% reduction in satellite carrying capacity at altitudes 200–1,000 km (120–620 mi).
• 19 March: an article published in Nature said that two major natural events occurred at the end of the last ice age: around 10,300 and 8,300 years ago, sea levels surged rapidly due to meltwater releases from the North American and Antarctic ice sheets, with peak rates of sea-level rise reaching nearly 9 mm/year — comparable to projections for the year 2100 under high-emissions scenarios.
• 25 March: an article published in Nature said that volcanic eruptions over the past 603 years have significantly impacted the strength and tilt of the Atlantic jet stream, which in turn influenced extreme weather events in Europe. These jet stream shifts contributed to increased droughts when moving north and heightened flood risks when shifting south.
• 10 April: NOAA published a statement that after a few months of La Niña conditions, the tropical Pacific was ENSO-neutral and was likely to remain so through autumn, stating the most recent La Niña phase was very brief.
• 21 April: NOAA confirmed the Earth was experiencing its fourth global coral bleaching event, which it called the biggest to date: from 1 January 2023 to 20 April 2025, bleaching-level heat stress had impacted 83.7% of the world’s coral reef area, and mass coral bleaching had been documented in at least 83 countries and territories.
• 30 April: a study published in Nature Communications described how melting of sea ice caused by global warming allows increased areas of open water—which passes a narrower spectrum of light than the smooth continuum of frequencies passed by sea ice—to "cause major changes in both the pigment and species composition of primary producers in polar ecosystems". These changes affect photosynthesis in ocean phytoplankton.

• 12 February: a study published in Bird Study found that solar farms can benefit bird abundance and biodiversity in arable-dominated landscapes, especially when managed with biodiversity in mind.
• 3 March: advising policy makers to assimilate uncertainty into decision making to increase decarbonization, a study published in the Proceedings of the National Academy of Sciences urged a "portfolio approach" of planting diverse species of trees, as that approach "reduces exposure to downside cost extremes".

• 20 January: within hours of his inauguration, U.S. President Donald Trump signed an executive order to withdraw the country from the 2015 Paris Agreement, joining only Iran, Libya and Yemen to become the only countries not party to the agreement.
• 4 March: the administration of U.S. President Donald Trump withdrew the country's representatives from the board of the United Nations' Loss and Damage Fund, which was formed to help poor and vulnerable nations cope with climate change-fueled disasters.
• 13 March: the Costa Rica-based Inter-American Court of Human Rights ordered the Ecuadorian government to protect Indigenous people from oil operations, to leave oil in the ground underneath their lands, and to ensure future oil operations do not impact Indigenous peoples living in voluntary isolation.
• 14 March: 440 Olympic athletes from 90 countries and 50 sports published an open letter to candidates for President of the International Olympic Committee, urging them to keep "the spirit of the Games alive by ensuring that sport remains accessible and safe for future generations".
• 24 March: the Supreme Court of the United States declined to hear the appeal in Juliana v. United States, ending the case in which youth plaintiffs asserted in their 2015 filing that the government had violated their constitutional rights by encouraging use of fossil fuels. Certain other lawsuits with similar strategies were more successful.
• 30 March: an open letter signed by 1900 researchers called on the administration of US President Donald Trump to stop its "wholesale assault on U.S. science", including its blocking of research on climate change, and causing researchers to live in a "climate of fear" amid the administration's flagging of terms such as climate change as objectionable.
• 28 April: U.S. President Donald Trump dismissed the scientists and experts who compile the National Climate Assessments that are required by the U.S. Congress, the next assessment having been planned for 2028.

• March: the OECD's Investing in Climate for Growth and Development concluded that accelerated climate action provides economic gains, specifically, that under an Enhanced NDCs scenario, global GDP in 2040 would be 0.2% higher than under the Current Policies Scenario.

• 9 March: US Secretary of Defense Peter Hegseth posted on social media website X that "The (US Department of Defense) does not do climate change crap", though a 2018 Pentagon study found that nearly half of all U.S. military sites were threatened by weather linked to climate change. Hegseth also called for a review of mission statements and military planning documents to ensure there are no "references to climate change and related subjects", though not prohibiting the Pentagon from "assessing weather-related impacts on operations, mitigating weather-related risks (or) conducting environmental assessments". The Defense Department had announced cancellation of 91 studies, including research on climate change impacts and global migration patterns, to save about 0.03% of the department’s budget in 2024.

• 6 January: A study published in Scientific Reports comparing projected heat-related deaths from climate change with COVID-19 mortality rates across 38 global cities found that in half, annual heat-related deaths would likely exceed COVID-19 death rates within 10 years if global temperatures rise by 3.0 °C above pre-industrial levels. The study projected that cities in North America and Europe, particularly in Mediterranean and Central European regions, would have most dramatic increases in projected heat mortality.
• 3 February: climate risk financial modeling company First Street Foundation projected that by 2055, 70,026 U.S. neighborhoods (84% of all census tracts) may experience $1.47 trillion in net climate-related property value losses, citing insurance pressures and shifting consumer demand.
• 4 February: a review article published in Nature Reviews Earth & Environment, linking physical climate science with heat mortality risk, projected that human-caused global warming reaching 2 °C above preindustrial levels will cause tripling of global land area that is "uncompensable" (beyond which human core body temperature rises uncontrollably) for young adults.
• 26 February: a study published in Nature concluded that the Atlantic meridional overturning circulation (AMOC) is resilient to extreme greenhouse gas and North Atlantic freshwater forcings across 34 climate models, suggesting that an AMOC collapse is unlikely in the 21st century.
• 28 February: based on the Earth's orbital characteristics (precession, obliquity, and eccentricity), a study published in Science concluded that glacial-interglacial periodicity has been largely deterministic in a ~100,000 year cycle, and projected that in the absence of human-caused forcing, the next ice age would start in ~10,000 years.
• 5 March: a paper published in Nature cited the International Energy Agency as stating that data centers caused 1–1.3% of world electricity demand in 2022, but that, with electricity consumption expected to grow by more than 80% by 2050 owing to all sources, data centers were projected to "account for a relatively small share of overall electricity demand growth".
• 10 March: a study published in Nature Sustainability projected that climate change's cooling of the atmosphere occupied by space debris in low Earth orbit will reduce the atmosphere's drag on the debris, extending the debris' lifetime and potentially causing a 50–66% reduction in satellite carrying capacity at altitudes 200–1,000 km (120–620 mi).

• Moon, Twila A.;Druckenmiller, Matthew L.;Thoman, Richard L., editors."Arctic Report Card 2024" (PDF). National Oceanic and Atmospheric Administration (NOAA) Office of Oceanic and Atmospheric Research. doi:10.25923/b7c7-6431. Archived (PDF) from the original on 11 March 2025.

• 2025 in science
• Climatology § History
• History of climate change policy and politics
• History of climate change science
• Politics of climate change § History
• Timeline of sustainable energy research 2020–present

• The Intergovernmental Panel on Climate Change (IPCC)
• World Meteorological Organization (WMO)
• Climate indicators at the U.S. Environmental Protection Agency
• Copernicus Climate Change Service (C3S)