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Warming patterns

Global warming does not mean the same amount of warming over the whole globe. There is a distinct spatial pattern to the long-term changes.

The first map below shows the total change in temperature since the early-industrial era, and the second map removes the global average warming to highlight regions of above and below average warming.

The largest warming is seen in the Arctic, and the land regions are clearly warming faster than the ocean. The striking blue area in the North Atlantic is a region of very little warming, and this is due to a decline in the strength of the Atlantic overturning circulation which brings warm water from the tropics to the northern latitudes.

All these features of the warming have been long predicted in climate model simulations, for example in IPCC AR4 and IPCC AR5.

Technical details: spatial pattern of warming uses approach described in Hawkins et al. (2020) using Berkeley Earth dataset, and the changes are relative to 1850-1900.

Arctic surprise

In 2007, IPCC AR4 produced this figure showing projections of changes in Arctic sea ice extent in the summer (July-September). The different colours represent a wide range of different scenarios for future emissions. Observations (1979-2020, added purple line) have decreased far more rapidly than projected in the CMIP3 models used at the time, when plotted on the same scale with the same reference period.

This demonstrates the concept of a climate-related ‘surprise’, or what might have been considered a low-likelihood event at the time.

The original figure is here. Also see Stroeve et al. (2012) for a CMIP5 comparison (Fig. 2a), and Notz et al. (2020) for a CMIP6 comparison (Fig. 2f).

What does a 1°C warmer world look like?

Global average temperature has risen by over 1°C since pre-industrial times, but the size of the change is not the same everywhere. The image below shows the temperature change observed in 5 individual years and for the 20-year average (2000-2019). For all of these examples the global average temperature was almost exactly +1°C warmer than the late 19th century.

In each individual year, the patterns can be quite different, with disparate regions of cooler and warmer temperatures. When averaging over 20-years, the overall pattern of warming is clearer: the Arctic is clearly warming much faster than the global average, and land areas are warming faster than ocean regions.

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