Summary

The average global temperature in 2024 was 1.6°C above preindustrial temperatures and 2025 is off to a very hot start. The speed and acceleration of warming has alarmed and surprised climate scientists. Global targets of 1.5°C and 2°C are quickly moving out of reach.

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The data

This visualization shows annual global temperature compared to historical temperatures before humans started emitting greenhouse gases in large quantities. Here’s how it works: 

The chart shows, for each year, how much Earth’s average temperature differed from pre-industrial times (1850-1900). We use this historical baseline to clearly show warming relative to global climate targets like the 1.5°C threshold established in the Paris Agreement.

The data covers the entire Earth (from 90° South to 90° North latitude, and all longitudes). Specifically, the metric being tracked is the surface air temperature, which is the temperature 2 metres above the ground or ocean surface.

The temperatures come from ERA5, which is the fifth generation ECMWF (European Centre for Medium-Range Weather Forecasts) reanalysis dataset. ERA5 combines actual observations with physics-based models to create a complete picture of global climate.

Each year’s value is calculated by:

- Pulling global temperature readings for each month of the year across the global

- Applying a weighted average that accounts for the fact that gridcells are not all equal in size (grid squares near the poles cover less actual area than squares near the equator) 

- Averaging these monthly readings to get an annual value

- Comparing this to the pre-industrial baseline using adjustment values from Copernicus Climate Change Service (C3S)

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Citation

Copernicus Climate Change Service (C3S) (2023): ERA5 monthly mean data on single levels from 1940 to present. Copernicus Climate Change Service (C3S) Climate Data Store (CDS). 10.24381/cds.adbb2d47.