As COP30 gathers, what’s the latest in climate science?

By Alison Withers and Katy Daigle

BELEM, Brazil (Reuters) – As the pace of climate change accelerates, extreme weather and other impacts are taking an increasing toll on people and the environment across the world. Here are some of the developments this year in climate science:

HOTTER, FASTER

Global temperatures aren’t just rising, they’re now climbing faster than before, with new records set for 2023 and 2024, and at times in 2025. The finding was part of a key study in June that updated baseline data used in scientific reports every few years by the Intergovernmental Panel on Climate Change.

The new study shows that the average global temperature is increasing at a rate of 0.27 degrees Celsius each decade – almost 50% faster than in the 1990s and 2000s – when the rate of warming was around 0.2 C per decade.

Sea levels are also rising faster today – about 4.5 millimeters per year over the past decade, compared to 1.85 mm per year measured in the decades since 1900.

The world is now on track to cross the 1.5°C warming threshold around 2030, after which scientists warn we will likely trigger catastrophic and irreversible impacts. According to the World Meteorological Organization, the planet has already warmed by 1.3 to 1.4°C since the pre-industrial era.

TIPPING POINTS

Warm-water corals are dying almost irreversibly from successive marine heat waves – marking what is believed to be the first so-called climate tipping point, when an environmental system begins to shift to a different state.

In October, researchers also warned that the Amazon rainforest could begin to die back and transform into a different ecosystem, such as savannah, if rapid deforestation continues as global warming exceeds 1.5°C, which is sooner than expected.

They said meltwater from the melting ice sheet atop Greenland could help cause an earlier collapse of the ocean current called the Atlantic Meridional Overturning Circulation, or AMOC, which keeps winters mild in Europe.

In Antarctica, where ice sheets are also under threat, scientists are concerned about the decline of sea ice surrounding the southernmost continent. Similar to what is happening in the Arctic, melting ice exposes dark waters that can absorb more solar radiation, amplifying the overall warming trend. It also jeopardizes the growth of phytoplankton, which consumes much of the world’s CO2.

EARTH ON FIRE

Along with heatwaves and drought, wildfires still threaten to be frequent and severe.

This year’s wildfire status report, led by a group of weather agencies and universities, counted some 3.7 million square kilometers (1.4 million square miles) burned between March 2024 and February 2025 – an area about the size of India and Norway combined.

This is slightly less than the annual average burned over the past two decades. But the fires produced higher CO2 emissions than before as more carbon-dense forests burned.

DEADLY HEAT

Researchers are working on ways to assess the health risks and consequences of heat, as the United Nations health and weather agencies estimate that about half the world’s population is already struggling.

The agencies also estimate that worker productivity falls by 2-3% for every degree above 20C, while another study published in the Lancet journal in October estimates global losses of more than $1 trillion from this loss of productivity last year alone.

There is no consistent international definition of a heat-related death, but technological advances are helping scientists fill data gaps and compare conditions from place to place.

For example, in Europe, a team from the United Kingdom’s Imperial College used mortality trends to estimate more than 24,400 deaths this summer linked to heat exposure in about 30% of the European population. They attributed up to 70% of these deaths to climate-induced heat, based on the same mortality trends applied to a model of Europe without global warming.

During last year’s record-breaking European summer, another team used computer modeling to examine mortality statistics along with temperature data and health metrics, estimating more than 62,700 heat-related deaths in 32 countries, or about 70% of the continent’s population.

SCIENCE UNDER ATTACK

The U.S. administration led by climate-denying President Donald Trump hopes to cut funding for agencies that collect and monitor climate and weather data, worrying a scientific community that says U.S. leadership will be difficult to replace.

Trump’s 2026 budget request, which has not yet been approved by Congress, proposes cutting NASA Earth Science’s annual budget in half to about $1 billion and cutting NOAA spending by more than a quarter to $4.5 billion while eliminating its climate research arm, among other cuts.

Elsewhere, however, government spending on science is increasing, with record budgets for scientific research in China, the United Kingdom, Japan and the European Union. The EU also opened real-time weather data monitoring to public access last month.

(Reporting by Ali Withers in Copenhagen and Katy Daigle in Belem; editing by Nia Williams)