Skip to content

Global warming levels

A global warming level (GWL) is a given rise of the global mean surface temperature above its pre-industrial level, taken as the 1850–1900 average: +1.5 °C, +2 °C, +3 °C or +4 °C, for instance. Instead of asking what the climate will be like in 2050 under a given scenario, a warming level asks what it will be like in a world 2 °C warmer, whenever that happens. The IPCC’s sixth assessment presents many of its regional results this way (IPCC, 2021).

How it is computed

Section titled “How it is computed”

For each climate model and scenario, the global mean temperature of the simulation is compared with the same model’s 1850–1900 average. The warming level is reached when the 20-year average of that difference crosses the level, and the local climate is then described over those 20 years (IPCC, 2021). Each model reaches a given level in its own years: models with a high climate sensitivity reach it earlier, and under a low-emission scenario some models never reach the higher levels before 2100.

Why use it

Section titled “Why use it”
  • Comparable results. Much of the difference between models comes from how fast they warm. Grouping them by warming level rather than by date removes that part of the spread, so the results of different models, and often of different scenarios, can be read together.
  • What happens, separated from when. For many quantities, such as hot extremes and heavy rainfall, the change in a region at a given warming level is largely the same whichever scenario leads there (IPCC, 2021). The question of when a level is reached is then left to the scenario choice.
  • The language of policy. The Paris Agreement sets its goals as warming levels: holding warming well below 2 °C and pursuing efforts to limit it to 1.5 °C (UNFCCC, 2015). Climate risk disclosures use the same terms: companies test their strategy against a 2 °C or lower scenario (TCFD, 2021) and, under the EU’s sustainability reporting standards, state whether their targets are compatible with 1.5 °C (EFRAG, 2025), and the central banks’ climate scenarios are defined by the warming they lead to (NGFS, 2024).

Some quantities do depend on the path and the timing: sea level, for instance, keeps rising long after the temperature has stabilised.

Where we are today

Section titled “Where we are today”

Global surface temperature was 0.99 °C above 1850–1900 over 2001–2020 (IPCC, 2021) and 1.26 °C over 2016–2025; the human-induced part reached 1.37 °C in the year 2025 (Forster et al., 2026). A single year above 1.5 °C, as 2024 was (Copernicus Climate Change Service, 2025), does not mean the 1.5 °C level has been reached: a warming level is a 20-year average.

In our data

Section titled “In our data”

Our hazard indicators can also be delivered by warming level: contact us.

References

Section titled “References”
© 2026 the climate data factorytheclimatedatafactory.comContactLinkedIn