Emissions could make Earth uninhabitable

Greenhouse gases could tip the Earth – or at least a planet like Earth, orbiting a star very like the Sun – into a runaway greenhouse effect, according to new research.

The new hothouse planet would become increasingly steamy, and then start to lose its oceans to interplanetary space. Over time, it would become completely dry, stay at a temperature at least 60°C hotter than it is now, and remain completely uninhabitable, even if greenhouse gas levels could be reduced.

Max Popp, postdoctoral researcher in climate instabilities at the Max Planck Institute for Meteorology, Germany, has been playing with models of clouds, sunlight, carbon dioxide and oceans for a while now.

Such research could not only help with a deeper understanding of global warming and climate change as a consequence of the human combustion of fossil fuels, but also with the possible dynamics of other planets, orbiting distant stars.

Baked to a crisp

He and colleagues report in Nature Communications that there may be no need to wait five billion years until the Sun becomes a Red Giant and bakes the inner planets to a set of crisps.

Notionally, humans could achieve much the same effect by simply quadrupling the proportions of carbon dioxide in the atmosphere to around 1,520 parts per million, and possibly as little as 1,120 ppm.

Right now, the ratio of CO2 has risen from 280 ppm to 400 ppm, and planetary average temperatures have risen by 1°C. So there is still a long way to go.

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