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Missing 1.5 °C climate goal could double number of people at risk

17 May 2018
Map showing 2 °C global mean temperature warming scenario
Sectoral score (0–3) maps for 2 °C global mean temperature warming scenario. In the left column the individual indicators are shown, in the right column are the sectoral scores. (Courtesy: Edward Byers et al 2018 Environ. Res. Lett. 13 055012 CC-BY-3.0)

The number of people facing multiple climate change risks could double if global temperature rises by 2 °C rather than 1.5 °C. That’s according to a team from Austria, the US and the UK.

For a global average temperature rise of 1.5 °C, 16% of the world’s population in 2050 – 1.5 billion people – will have moderate-to-high levels of risk in two or more of the water, energy, and food and environment sectors. At 2 °C this figure nearly doubles to 29% of global population, whilst at 3 °C of warming it rises to half the population, or 4.6 billion people.

“Few studies have consistently investigated so many overlapping climate and development challenges,” said Edward Byers of the International Institute for Applied Systems Analysis (IIASA), Austria, in a press release. “The research considers both different global mean temperature rises, such as the differences between 1.5 °C and 2.0 °C, and uses new socioeconomic datasets of income levels and inequality, to identify where and to what extent the most vulnerable in society are exposed to these climate-development challenges.”

At lower temperature rises, hotspots of risk in two or more sectors were mainly in south and east Asia, Byers and colleagues found. At higher global temperatures, hotspots also broke out in Central America, west and east Africa, the Middle East and the Mediterranean.

Depending on the scenario used, 91–98% of the exposed and vulnerable population live in Asia and Africa. Sustainable development in hotspot areas could reduce the number of people who are exposed and vulnerable by an order of magnitude, from 1.5 billion to 100 million, compared to the high inequality scenario, according to the researchers.

“The research will be most relevant to policymakers and others looking to understand the benefits of keeping the average global temperature rise to 1.5 °C rather than 2 °C, as well as providing insights into the regions most at risk across different sectors,” said Astrid Hillers of Global Environment Facility, US. “The poorest and most vulnerable countries are most at risk and this work will aid to identify integrated, cross-sectoral approaches and target resources for maximum impact.”

The land mass affected, 3–16% depending on the scenario, was relatively small but the areas at highest risk tend to have high population densities.

Byers, Hillers and colleagues reported their findings in Environmental Research Letters (ERL).

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