Climate News Network

Emissions could make Earth uninhabitable

February 27, 2016, by Tim Radford

Baked earth caused by severe water shortage in Senegal, West Africa.
Image: United Nations Photo via Flickr

Share on FacebookShare on Google+Tweet about this on TwitterShare on LinkedIn

Researchers predict that the hothouse effect of runaway greenhouse gases would ultimately boil our planet dry and make it incapable of sustaining life.

LONDON, 27 February, 2016 – 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.

But, until now, researchers have wondered whether carbon dioxide alone could ever raise temperatures high enough to boil a planet dry. The Popp study suggests that it could − and in much lower proportions than others have suggested

“A planet in this state would eventually become
uninhabitable as all water is lost to space”

Venus, covered in clouds of sulphuric acid and with a surface hot enough to melt lead, has been proposed as a victim of the runaway greenhouse effect.

Research such as this is a bit like a computer game: compose an ideal planet, much like Earth, and run it through a series of extreme tests.

Dr Popp and his team simplified their Earth-like planet as much as they could. They started with a world covered entirely by ocean, and then eliminated the ice caps.

They made it 6°C on average warmer than it is now – and climate models predict that a 6°C planetary average temperature rise is possible under a business-as-usual emissions scenario – and then let the greenhouse gases start to build up.

Other researchers have hypothesised that clouds would also build up, and reflect sunlight away from Earth, to contain the warming.

But this team found a different effect: water vapour would increase in the atmosphere, which would in any case expand. As the water vapour climbed ever higher, it would become increasingly vulnerable to radiation.

This would break up H2O into hydrogen and oxygen. Hydrogen, being the lightest of the elements, would start to ooze away into space. And without hydrogen, there is no water.

Increasingly impossible

By the time that started to happen, this laboratory aqua-planet would be in a moist greenhouse state. Sea surface temperatures would be at least 50 to 70°C higher than now – that is, at the temperature needed to pasteurise milk – and life would become increasingly impossible.

Ominously, even if somehow the CO2 levels could be lowered dramatically, the planet would stay in this steam bath condition, increasingly parched. And the clouds above would simply trap the heat and make things worse.

“A planet in this state would eventually become uninhabitable as all water is lost to space,” the authors say.

They add: “To conclude, we have demonstrated with a state-of-the-art climate model that a water-rich planet might lose its habitability as readily by CO2 forcing as by increased solar forcing through a transition to a Moist Greenhouse and the implied long-term loss of hydrogen.” – Climate News Network

Print Friendly, PDF & Email
2 comments Show discussion Hide discussion
  • Little publicized data (Arctic News) indicates human life on earth faces near-term extinction. Tipping points may threaten our lives within 5 years. With luck we may have 7-15 years. Replacing 80% of fossil fuels as fast as is humanly possible – 5 years at the outside (as unlikely as that seems) may be the key to survival of ourselves and everyone we care about.

    “The monster is atmospheric methane. A potent greenhouse gas, methane leaking emanating from the Arctic Ocean alone is likely to add between 5C (41F) and 11C (52F) degrees of warming within one or two decades. Methane is a misbehaving bull in a fully stocked China shop.” Guy Mcpherson

    Without breakthrough technologies moving forward 24/7/365 survival will prove impossible! After 9 years of work by Chris Hunter, a Ford engine ran without fuel at 1,300 rpm. Propane filled the sealed engine, acting as a refrigerant and providing the temperature differential required for the engine to run using atmospheric heat. Frost formed on the engine exterior.

    Hunter’s brilliant achievement confirmed an earlier thermodynamic analysis reflected in a U.S. Patent, presentations at three Scientific Conferences, and papers by Ken Rauen. See aesopinstitute.org

  • This is the most dire planetary emergency in history and it is treated like a tiny problem that we can pass on to our children. If you have grandchildren, or expect to have them, you should be pressing your community to get completely off of fossil fuels now. We should be making very visible awards in every community for “climate conscious citizens.”

    We need a different ethos. When you see a faucet running and nobody using the water, you turn it off, even if you do not own the faucet or pay the water bill. We need to all accept the idea that when you see a light burning, and nobody using the illumination, you should turn it off. There is no use for street lights, vanity lighting, decorative lighting or luxury lighting. Everyone’s wasteful habits hurt all of us.

    Take responsibility to instal solar panels on your own roof and drive a plug-in electric car, stop flying, shift all your bulbs to LEDs and get everyone you know to do the same as quickly as possible. These steps are feasible and affordable. We need a community award program that puts a big “gold star” in the front yard of everyone who significantly reduces their carbon footprint, with additional “gold stars” for every further reduction.

Add a comment