Climate change 2025: What science knows today

The headlines are familiar: record temperatures, melting glaciers, extreme weather. But what exactly does science say today, beyond alarmism and downplaying? This article summarises the current state of climate research. No opinion, just data.

The sources are leading scientific institutions: the Intergovernmental Panel on Climate Change (IPCC), the World Meteorological Organization (WMO), the European Earth observation programme Copernicus and peer-reviewed specialist publications. The figures are as up to date as possible, as of autumn 2025.

2024 was the warmest year since systematic weather records began in 1850. The global average temperature was 15.10°C, or 1.60°C above pre-industrial levels (reference period 1850–1900).

This marked the first time that the symbolically important 1.5°C threshold of the Paris Agreement had been exceeded for an entire calendar year. The trend continued in 2025: over the first eight months, temperatures were 1.42°C above the pre-industrial average.

Europe is warming twice as fast as the global average, making it the fastest-warming continent on Earth. Antarctica recorded its warmest annual temperature since records began in 2025.

The concentration of carbon dioxide in the atmosphere reached a level in 2025 that had not occurred for more than two million years. In May 2025, 429.6 ppm (parts per million) was measured, the highest level in all of human history.

The increase is accelerating: between 2023 and 2024, CO2 concentration rose by 3.58 ppm, the highest annual increase ever recorded.

The oceans are the climate system’s great heat store, having absorbed more than 90% of the additional heat. The heat content of the upper 2,000 metres reached an unprecedented high in 2024.

In 2024, sea surface temperatures averaged 0.61°C above the 1981–2010 baseline. Marine heatwaves are becoming more frequent and more intense, with direct consequences for fisheries, coral reefs and coastal ecosystems.

Global sea level is rising faster than at any point in the past 3,000 years. In 2024, a rise of 5.9 mm was recorded, well above the average annual increase of 3.4 mm since 1970.

Arctic sea ice reached its lowest winter extent since satellite observations began 47 years ago in March 2025. At 14.33 million km², the area was 1.31 million km² below the 1981–2010 average and 800,000 km² below the previous record low in 2017.

Particularly stark: in the Northwest Passage through the Canadian Arctic Archipelago, sea ice cover fell to just around 3% of its total area by the end of September 2024, the lowest extent ever observed since 1960.

Scientists have identified around two dozen subsystems within the global climate that may have so-called tipping points, thresholds beyond which changes become irreversible and self-reinforcing.

The Global Tipping Points Report 2025 reaches a sobering conclusion: Earth has already crossed its first climate tipping point, the tropical coral reef system. Large-scale coral die-off can no longer be stopped.

In 2024, the highest number of climate-related displacements since 2008 was recorded. More than 617 extreme weather events were reported, 148 of which were classified as "unprecedented".

A scientific analysis of 29 weather events in 2024 found that climate change intensified 26 of them. These events killed at least 3,700 people and displaced millions.

The consequences of climate change are no longer future scenarios. They are affecting agriculture, water supplies and health now.

A recent study warns that, if warming exceeds 1.5°C, one third of global food production could be at risk. Particularly affected:

• Low latitudes: Up to 50% of crop production could be at risk under unsuitable climate conditions
• Tropical root crops: Yams and other crops important to low-income regions are particularly vulnerable
• Sub-Saharan Africa: If warming exceeds 3°C, almost three quarters of current production could be at risk

Rice, maize, wheat, potatoes and soya beans, the staple crops that provide more than two thirds of the world's food energy, are all severely affected.

The report "10 New Insights in Climate Science 2025" identifies several direct health impacts:

• Heat stress reduces labour productivity and particularly endangers outdoor workers
• Dengue outbreaks are increasing as rising temperatures support the spread of mosquitoes
• Falling groundwater levels put drinking water supplies at risk worldwide

The IPCC Synthesis Report 2023 summarises the scientific evidence and sets out clear thresholds:

The report "10 New Insights in Climate Science 2025", produced by more than 70 scientists from 21 countries, identifies the most important new findings:

The scientific data leave little room for interpretation:

• The Earth is warming faster than expected
• Emissions are still rising instead of falling
• The first tipping points have been crossed
• The impacts are already measurable today

That does not mean all is lost. Science also shows that every tenth of a degree of warming avoided makes a difference. The question is no longer whether climate change is real, but how we deal with it.

For anyone interested in the impact on mountain sports, the article Climate change in the Alps explains what this means in practical terms for glaciers, permafrost and alpine tours.