Climate change, in real time: specialists developed maps that allow us to know how it affects each region

The world is now 1.1°C warmer on average than it was in 1850, before widespread industrialization. But this number may cast a shadow over the lived experience of climate change: how we question whether this year was warmer than last, or how some regions of the world are warming faster than others.

The world is now 1.1°C warmer on average than it was in 1850, before widespread industrialization. But this number may cast a shadow over the lived experience of climate change: how we question whether this year was warmer than last, or how some regions of the world are warming faster than others.

A new online mapping tool called Climate Shift Index (CSI), developed by the US-based research and communications group Climate Central, illustrates how average daily temperatures in more than 1,000 cities around the world are more or less likely due to global warming.

In June, Climate Central made it possible to map the effect of climate change in the US in near real time. On one day in July, for example, areas from California to Florida, shaded in dark brown, showed temperatures drastically more likely from climate change.

Now, with the release of a global version of the index, people in Jakarta, Addis Ababa and Shanghai can also track how much human-induced climate change makes their days (and nights) warmer or strangely temperate in the colder months.

The Climate Central map.

“In a way, what we’re doing is keeping score,” said Andrew Pershing, director of climate science at Climate Central, adding, “You can think about what your experience with climate change has been, filtered through the lens of climate.”

Pershing and his team use data from the National Oceanic and Atmospheric Administration’s Global Forecast System to compare climate models with and without human-caused climate change, presenting the probability of the difference using a scale of -5 to 5, where 0 indicates no climate effect. For example, if Miami gets a 5 on a given day, the temperature there that day is at least five times more likely due to climate change. Or if Kathmandu is covered in gray at -2, the temperature there is twice as likely to occur on that date as a result of global warming.

The challenge of making climate change local is that the climate still fluctuates from day to day. When the weather is more variable, such as in autumn in the U.S., temperature changes can be masked, resulting in a relatively calm map. By contrast, during heat waves, the story of climate change becomes much more apparent, as happened in Europe and China this summer.

If I were to look closely at Mauritania, Morocco or Saudi Arabia on the CSI map, I would see climate footprints today. Just this week, climate change continued to influence temperatures in the equatorial region, particularly in small island states and coastal regions, which border the increasingly warming ocean.

Over the past year, from October 1, 2021 to September 30, 2022, climate change displaced temperatures to a greater extent in the Malay Archipelago (from Malaysia to Papua New Guinea), Brazil, Mexico, the Arabian Peninsula and the Horn of Africa, according to an analysis by Climate Central. The cities of Apia, Samoa and Ngerulmud, Palau scored highest overall, each with 90% of its days unusually out of sync with the temperatures they would have had before the climate crisis.

The researchers also adjusted their analysis to represent population centers, multiplying the number of days with relative climate impacts by the number of people in a place. While small island states appeared to be the most affected overall, a key finding for both adaptation and climate conservation, African cities, particularly Lagos, Nairobi, Dar es Salaam and Mogadishu, came to the fore for their highest total human exposure to rising local temperatures.

Victoria Keener, a senior researcher at the nonprofit East-West Center in Honolulu, said Climate Central’s findings are consistent with those of the 2021 Pacific Climate Change Monitor, an international collaboration that analyzed observed data from Pacific islands. Over the past decade, heat waves have increased in length across the Pacific, and states, including the Marshall Islands, have seen a significant increase in the number of hot days and nights.

Particularly in the context of the upcoming COP27 talks, where “loss and damage” is expected to be a central issue, coalitions of island nations could use the map to argue broadly the cost of climate change and the need for more climate finance from rich countries.

Source: Profile