Climate change maps usually fall into one of two categories: maps that show changes in precipitation, and maps that show changes in temperature. Unfortunately, focusing on one of these factors only tells half of the story. For example, a map of global temperature increase would show a warming Arctic, but it would not show the decrease in rainfall predicted to impact West Africa. Now, researchers at the University of Cincinnati have created a map that shows both.

‘Our goal was to create a web-based app that is relatively easy to use by everyone,’ says Tomasz Stepinski, geography and geospatial professor at the university. ‘When people think about climate change, they think about temperature – global warming. But climate has many components, including precipitation.’ The new map, called ClimateEx, combines precipitation and temperature from the WorldClim project. It shows how local climates have changed since the beginning of the Holocene (6,000 years ago) and how they are predicted to change until the year 2070.

Using the map in its most basic form shows how the impact of climate change is unequal across the planet. Brown and white colours show where most change will happen – such as the southern tip of Greenland, Central America and South East Asia. Meanwhile, the green hues across much of the northern hemisphere indicate less change in those regions.

Regions with white and brown colour show the most climate change between 2000 and 2070

When the user looks at specific locations, the map shows climates with circular illustrations. Each dot represents the monthly rainfall and temperature for the location (with green dots showing January, to mark a comparative starting point). The annual climates of different locations can be compared by testing the similarity of these shapes. For example, here is the predicted climate of Cardiff in 2070 compared to the very different climate of Lagos, Nigeria:

But if we search the entire globe, we can find Cardiff’s climate ‘twins’, such as locations in British Columbia, Canada, the eastern United States, areas of eastern Argentina, and parts of southeast Australia and New Zealand (displayed in brown):

Areas of the world with a similar climate to Cardiff in the year 2070

Areas of Australia and New Zealand showing a similar climate to Cardiff in 2070

Stepinski demonstrates how this can be used to search for specific climate types, such as those which are susceptible to tornadoes. ‘I know that Oklahoma is at the centre of the “Tornado Valley” region,’ he explains. ‘By doing a spatial search I may identify other regions in the world prone to tornadoes. The resulting map reveals that a region stretching across northern Argentina, Paraguay and southern Brazil is climatically similar. This region is indeed known to be prone to tornadoes.’

Areas probably prone to tornados, based on climate similarity with Oklahoma, US

Stepinski hopes the tool can be used to educate the public about how local climates are changing relative to each other, and that it is happening quickly. ‘The climate is always changing,’ he says. ‘But it usually changes on a geological timescale. It’s not surprising that the climate today is different from the climate a half-million years ago. But now we’re experiencing changes on a scale of 100 years. That’s a completely different thing.’

Before ClimateEx, Stepinski created new, high-detailed maps of the United States, which revealed persistent racial segregation in cities.

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