Increased concentrations of atmospheric greenhouse gases have led to a global mean surface temperature 1.0ºC higher that during the pre-industrial period.

In this article the authors of the recent IPCC Special Report on global warming of 1.5ºC expand on it and review the additional risks associated with higher levels of warming, each having major implications for multiple geographies, climates, and ecosystems.

This review shows that multiple lines of evidence indicate that the next 0.5ºC above today will involve greater risks per unit temperature than those seen in the last 0.5ºC increase.

The authors explore as well the elements of the costs and benefits associated with acting in response to climate change, and come to the preliminary conclusion that restraining average global temperature to 1.5ºC above the pre-industrial period would be much less costly than the damage due to inaction on global climate change.

The authors conclude that limiting warming to 1.5ºC rather than 2.0ºC would be required to maintain substantial proportions of ecosystems and would have clear benefits for human health and economies. The authors state that these conclusions are relevant for people everywhere, particularly in low- and middle-income countries where the escalation of climate-related risks may prevent the achievement of the United Nations Sustainable Development Goals.

https://science.sciencemag.org/content/365/6459/eaaw6974.editor-summary

Hoegh-Guldberg et al. (2019) The human imperative of stabilizing global climate change at 1.5ºC. Science 365:eaaw6974.