Climate explained: rising carbon emissions (probably) won't make the Earth uninhabitable - The Conversation AU

Even with all humanity’s carbon emissions to date, there’s a lot less carbon dioxide in Earth’s atmosphere than Venus, and Earth is further away from the Sun.

But if carbon emissions continue at the current rate, is there any risk of reaching a tipping point at which a runaway greenhouse effect takes over, making Earth uninhabitable for any form of life.

Some longwave radiation is absorbed in the atmosphere by heat-trapping gases, such as carbon dioxide.

Climate Explained: what Earth would be like if we hadn't pumped greenhouse gases into the atmosphere.

One consequence of increasing atmospheric carbon dioxide concentrations is that, as the atmosphere warms, it can contain more water vapour.

If the atmosphere becomes completely saturated with water vapour, the Earth’s surface and lower atmosphere warm up, but further increases in emission of longwave radiation are not possible.

This is termed a runaway greenhouse and would mean the Earth would become lethally hot and unable to cool itself by emitting heat to space.

But could we bring such a situation about on a shorter timeframe through continued carbon dioxide emissions.

Previous research has found that, due to differences in the properties of water vapour and carbon dioxide as greenhouse gases, adding carbon dioxide to the atmosphere is likely insufficient to trigger a runaway greenhouse.

Yet human emissions of carbon dioxide are considered insufficient to trigger a runaway greenhouse, given the fossil fuel reserves available.