Falling oxygen levels caused by global warming could be a greater threat to the survival of life on planet Earth than flooding, according to an estimate led by Sergei Petrovskii, Professor in Applied Mathematics from the University of Leicester's Department of Mathematics.

Their mathematical model estimates that an increase in the water temperature of the world's oceans of around six degrees Celsius, which the most aggressive claims (two degrees is the scientific consensus) say could occur as soon as 2100, could stop oxygen production by phytoplankton by disrupting the process of photosynthesis. 

"About two-thirds of the planet's total atmospheric oxygen is produced by ocean phytoplankton - and therefore cessation would result in the depletion of atmospheric oxygen on a global scale. This would likely result in the mass mortality of animals and humans," says Petrovskii.

He and his colleagues developed a new model of oxygen production in the ocean that takes into account basic interactions in the plankton community, such as oxygen production in photosynthesis, oxygen consumption because of plankton breathing and zooplankton feeding on phytoplankton. 

While mainstream research often focuses on the CO2 cycle, as carbon dioxide is the agent mainly responsible for global warming, few models have explored the effects of global warming on oxygen production.