Fintan Hughes , human physiology researcher 1 , Jack Hodkinson , PhD candidate 2 , Hugh Montgomery , director 1 1Institute of Sport Exercise and Health, University College London, London, UK 2Department of Physics, University of Cambridge, Cambridge, UK Correspondence to: F Hughes fintan.hughes@ucl.ac.uk

Doctors must advocate for less use of fossil fuel, write Fintan Hughes, Jack Hodkinson, and Hugh Montgomery, if the harms to public health seen in this year’s hurricane season are not to become more regular occurrences

Throughout the 60 million years of the carboniferous period, which ended 300 million years ago, carbon dioxide was drawn down from the atmosphere and sequestered in fossil fuels. These fuels have only recently been burnt at scale. Cars first outnumbered horses in New York City just over 100 years ago, but there are now 1.2 billion vehicles on the road worldwide, and airlines carry over 400 000 passengers every hour. Burning fuels has increased atmospheric carbon dioxide substantially from 280 to 406 ppm since 1850.

In 1896, Nobel Laureate and physical chemist Svante Arrhenius predicted that such rises could increase global surface temperatures. By 1970 climate scientists widely recognised this causal relation. In 2016, the average land surface temperature was 1.42°C higher than the 20th century average, with an increase in average global temperature of 1.1°C.1

Food shortages and the spread of disease resulting from climate change have been well described.2 However, the oceans have also been affected: water and ice have absorbed 93% of the net global energy gain caused by carbon dioxide and other greenhouse gases, and their surface temperatures have risen by 0.7°C since preindustrial times.3 Polar sea ice is melting—its surface area 2 000 000 km2 smaller in 2017, the minimum Arctic sea ice extent in September being 44% lower than the 1981-2010 average—and sea levels are rising by 3.4 cm a decade.