2026 on Track to Rank Among Four Hottest Years Ever Recorded

The ocean absorbs about 90% of that excess heat. Ocean heat content in the upper 2,000 meters (6,600 feet) reached its highest observed value in 2025 and has kept rising through July 2026, making 2026 the tenth straight year of record ocean warmth. Sea-surface temperatures set monthly records or near-records through June, July and August.

Warming rates have climbed sharply over the past two decades, harming marine ecosystems, biodiversity and the ocean's ability to absorb carbon. That warming is projected to continue for hundreds to thousands of years.

What happened to ice, seas and fresh water?

• Sea level hit a record high in 2026. June, July and August saw their highest readings since satellite altimetry began in 1993, a jump possibly tied to El Niño shifting rainfall from land to ocean in the western tropical Pacific.
• Antarctic sea ice reached its third-lowest annual maximum in the satellite era, which dates to 1979. The Arctic maximum was the lowest or second lowest.
• Glaciers lost more than 400 gigatons of ice in 2025—enough to fill five Olympic pools every second all year, and equal to roughly 1 mm of sea-level rise. It was the fourth consecutive year in which all 19 glaciated regions worldwide lost ice.
• Freshwater stored on land—in groundwater, soil, rivers, reservoirs, glaciers and snow—has declined globally since 2014. In 2025, 42% of the assessed global land area had below-normal terrestrial water storage, versus a long-term average of 25%.

What were the human costs?

Extreme events hit lives, food security and livelihoods across multiple regions. European heat waves, drought and wildfires caused more than 30,000 excess deaths in preliminary estimates, with national temperature records broken in at least eight countries. An April 2026 heat wave exposed an estimated 146.5 million people in India to extreme heat.

In late August, a Himalayan glacier collapse and catastrophic flash flood in Nepal killed more than 1,300 people and dealt a massive blow to the country's economy. Tropical cyclones caused devastation and loss of life in many countries as well.

"We have entered a new age of climate extremes. A supersized El Niño is colliding with a planet already superheated by man-made climate change," U.N. Secretary-General António Guterres said. He called on leaders to cut emissions faster, speed a just transition from fossil fuels, and deliver the finance and protection vulnerable countries need.

What comes next?

Greenhouse gases reached record levels in 2025. Carbon dioxide has risen 53% since 1750, from roughly 278 ppm to about 426.8 ppm. Methrose climbed 167% to 1,948 ppb, and nitrous oxide rose 26% to 339.1 ppb. Benchmark stations such as Mauna Loa in Hawaii and Kennaook/Cape Grim in Australia show the increase continued into 2026.

The WHO has, for the first time, classified the anticipated health impacts of El Niño as a health emergency. Risks include heat illness, wildfire smoke, malnutrition, and water- and insect-borne diseases such as cholera, malaria and dengue. Agriculture is already under strain, especially in regions dependent on rain-fed farming.

One bright spot: countries with multi-hazard early warning systems grew from 56 in 2015 to 136 in 2025.

The update includes data only through September 2026, so it misses El Niño's most recent effects. The full State of the Global Climate 2026 report, drawing on dozens of national weather services and U.N. partners, arrives in March 2027.