Last updated: October 2026
Key takeaways
- 2025 was the third warmest year on record, and the 10 most recent years are the 10 warmest ever measured.
- Global sea level has risen 8 to 9 inches since 1880, and NOAA projects 3.5 to 7 feet of rise along the US coast by 2100 if emissions are not curbed.
- Greenland and Antarctica are losing about 400 billion tons of ice a year, roughly 160 million Olympic swimming pools of water.
- The ocean soaked up a record amount of heat in 2025, and about 84% of the world’s coral reef area faced bleaching level heat stress between 2023 and 2025.
- Global greenhouse gas emissions reached a record 55 billion tonnes of CO2 equivalent in 2025.
- We can’t undo what has already happened, but cutting emissions limits how much worse it gets.
What has changed since this post was first published
- Hotter: NASA’s analysis shows 2025 ran 2.14°F above its 1951 to 1980 baseline, and 2023 through 2025 were the three warmest years in its 146 year record.
- Record ocean heat: The upper ocean gained a record 23 zettajoules of heat in 2025, the ninth record year in a row.
- Record coral stress: A fourth global coral bleaching event has hit about 84% of reef area, beating the old record of 68.2%.
- Record emissions: Global greenhouse gas emissions climbed 0.9% in 2025 to a new high of 55 billion tonnes of CO2 equivalent.
1. Sea Level Is Rising, and the Pace Has Picked Up
Global sea level has risen 8 to 9 inches since 1880, and the rate of rise has more than doubled since satellite records began in the early 1990s. It averaged about 3.8 millimeters a year between 1999 and 2025. Along the US coast, NOAA projects 10 to 12 inches of additional rise by 2050 and about 2 feet by 2100 from emissions to date, rising to a total of 3.5 to 7 feet by 2100 if emissions are not curbed. And it won’t stop there. Sea level will keep rising after 2100. The 2025 rise was one of the slowest in years, a short term dip tied to natural variability such as La Niña, not a change in the long term trend.
2. The Planet Keeps Setting Temperature Records
NASA’s analysis found that 2025 was effectively tied with 2023 and just behind 2024, the hottest year on record, at 2.14°F above its 1951 to 1980 baseline. NOAA, Berkeley Earth, the UK Met Office, and Copernicus all ranked 2025 as the third warmest year. Measured against preindustrial levels, 2025 was about 1.3°C (2.3°F) warmer, according to NOAA, as covered in our guide to global warming. About two thirds of the warming since 1880 has come since 1975, which highlights that human activity, mainly greenhouse gas emissions, is a big factor.
3. The US Is a Small Share of People and a Big Share of Emissions
The US has a little over 4% of the world population, yet it produced about 11.1% of global greenhouse gas emissions in 2025, second only to China at 29.5%, according to the EU’s EDGAR database. Transportation is the largest US source, making up about 28% of US greenhouse gas emissions, followed by electric power at about 24%. You can see the biggest sources in our list of the top 10 contributors to CO2 pollution in the US, and learn more about the consequences of burning fossil fuels.
4. The Big Ice Sheets Keep Shrinking
Greenland and Antarctica are together losing roughly 400 billion tons of ice a year, about 264 billion tons from Greenland and 135 billion tons from Antarctica between 2002 and 2025, according to NASA satellite data. To put that in perspective, it is enough water to fill roughly 160 million Olympic swimming pools every year. Greenland lost about 139 billion tons in 2025, below its recent average because heavy snowfall buffered the melt, but it was still the 29th year in a row of net loss. Together, the two ice sheets hold about two thirds of all the fresh water on Earth. Ice is also vanishing on land that stays frozen year round, which we cover in our post on permafrost.
5. Deforestation Is a Major Source of Emissions
Land use change released about 4.1 billion tonnes of CO2 in 2025, roughly 10% of human CO2 emissions, and permanent deforestation remains the largest source, according to the Global Carbon Budget. Carbon dioxide is released when forests are cleared for agriculture and when soils degrade. On the other side of the ledger, healthy forests take carbon in, and tree planting and natural carbon removal can help. But the world lost about 8.1 million hectares of forest in 2024, and tree planting pledges are far behind their goals, so protecting the forests we already have matters just as much. Forests also shelter wildlife, as we explain in our guide to biodiversity.
6. Cattle Are a Surprisingly Big Source of Greenhouse Gases
Cattle are the number one agricultural source of greenhouse gases worldwide. A single cow releases about 220 pounds of methane a year. Methane traps roughly 27 to 30 times as much heat as CO2 over 100 years and about 80 times as much over 20, though it breaks down faster, as we explain in what happens to gases in the atmosphere. Livestock overall are responsible for about 14.5% of human caused greenhouse gas emissions, according to FAO estimates. Scientists are now exploring ways to make cows less gassy, including feed additives such as seaweed.
7. Extreme Weather Is Costing More
Warmer air holds more water vapor, about 7% more for every 1°C of warming, and that extra moisture makes heavier downpours and catastrophic floods more likely. The United States recorded 23 separate weather and climate disasters costing at least $1 billion each in 2025, with total damages near $115 billion, the third highest year on record. The January 2025 Los Angeles wildfires alone caused about $61.2 billion in damage. Putting a dollar figure on this kind of harm is what the social cost of carbon tries to do.
8. The Ocean Is Getting Acidic, and Corals Are Struggling
The ocean absorbed about 29% of human CO2 emissions over the past decade, which makes seawater more acidic. Ocean acidity is up roughly 30% since the Industrial Revolution, and the ocean became about 17% more acidic between 1985 and 2025, according to the Copernicus Ocean State Report. More acid makes it harder for corals, shellfish, and some plankton to build shells and skeletons, and the damage works its way up to some groups of small fish that lose habitat and food supply. Heat adds to the problem: about 84% of the world’s coral reef area experienced bleaching level heat stress between January 2023 and September 2025, the most on record, according to NOAA Coral Reef Watch. That figure measures heat exposure, not the number of corals that died. The same forces are at work in the carbon cycle, which the ocean is helping to balance.
9. The Ocean Is Soaking Up Almost All the Extra Heat
Oceans aren’t just becoming more acidic. About 90% of the extra heat trapped by greenhouse gases ends up in the ocean, which makes its temperature climb quickly. In 2025 the upper ocean gained a record 23 zettajoules of heat, the ninth record year in a row and roughly 37 to 40 times the energy humanity used that year. Heat makes water expand, which pushes sea level up, and it fuels marine heatwaves and changes the ocean’s health and biochemistry.
10. Snow Is Disappearing Earlier Each Spring
Northern Hemisphere June snow cover has shrunk by about 13% per decade since satellite records began in 1967, and snow is now melting even earlier. Snow reflects sunlight back into space, which helps regulate Earth’s temperature, so losing it warms the surface further. Less snow also means drier soil, a higher risk of wildfire, and less meltwater for drinking and irrigating crops. Wildfire smoke adds to the problem, as we explain in our post on
