Planet now at risk of heading toward 'hothouse Earth' state

August 6, 2018, Stockholm Resilience Centre
Credit: CC0 Public Domain

Keeping global warming to within 1.5-2 degrees C may be more difficult than previously assessed, according to researchers. An international team of scientists has published a study in the Proceedings of the National Academy of Sciences (PNAS) showing that even if the carbon emission reductions called for in the Paris Agreement are met, there is a risk of Earth entering what the scientists call "Hothouse Earth" conditions.

A "Hothouse Earth" climate will, in the long term, stabilize at a global average of 4-5 degrees C higher than pre-industrial temperatures with sea level 10 to 60 meters higher than today, the paper says. The authors conclude it is now urgent to greatly accelerate the transition toward an emission-free world economy.

"Human emissions of greenhouse gas are not the sole determinant of temperature on Earth. Our study suggests that human-induced of 2 degrees C may trigger other Earth system processes, often called feedbacks, that can drive further warming—even if we stop emitting ," says lead author Will Steffen from the Australian National University and Stockholm Resilience Centre. "Avoiding this scenario requires a redirection of human actions from exploitation to stewardship of the Earth system."

Currently, global average temperatures are just over 1 degrees C above pre-industrial and rising at 0.17 degrees C per decade.

The authors of the study consider 10 natural feedback processes, some of which are "tipping elements" that lead to abrupt change if a critical threshold is crossed. These feedbacks could turn from being beneficial, by storing carbon, to a source of uncontrollable emission in a warmer world. These feedbacks are permafrost thaw, loss of methane hydrates from the ocean floor, weakening land and ocean carbon sinks, increasing bacterial respiration in the oceans, Amazon rainforest dieback, boreal forest dieback, reduction of northern hemisphere snow cover, loss of Arctic summer sea ice, and reduction of Antarctic sea ice and polar ice sheets.

"These tipping elements can potentially act like a row of dominoes. Once one is pushed over, it pushes Earth toward another. It may be very difficult or impossible to stop the whole row of dominoes from tumbling over. Places on Earth will become uninhabitable if 'Hothouse Earth' becomes the reality," adds co-author Johan Rockström, executive director of the Stockholm Resilience Centre and incoming co-director of the Potsdam Institute for Climate Impact Research.

Hans Joachim Schellnhuber, director of the Potsdam Institute for Climate Impact Research, says, "We show how industrial-age greenhouse gas emissions force our climate, and ultimately the Earth system, out of balance. In particular, we address tipping elements in the planetary machinery that might, once a certain stress level has been passed, one by one change fundamentally, rapidly, and perhaps irreversibly. This cascade of events may tip the entire Earth system into a new mode of operation."

"What we do not know yet is whether the climate system can be safely 'parked' near 2 degrees C above preindustrial levels, as the Paris Agreement envisages. Or if it will, once pushed so far, slip down the slope towards a hothouse planet. Research must assess this risk as soon as possible."

Cutting greenhouse gases is not enough

Maximizing the chances of avoiding a "Hothouse Earth" requires not only reduction of carbon dioxide and other , but also enhancement and/or creation of new biological carbon stores, for example, through improved forest, agricultural and soil management; biodiversity conservation; and technologies that remove carbon dioxide from the atmosphere and store it underground, the paper says. Critically, the study emphasizes that these measures must be underpinned by fundamental societal changes that are required to maintain a "Stabilized Earth" where temperatures are ~2 degrees C warmer than the pre-industrial era.

"Climate and other global changes show us that we humans are impacting the Earth system at the global level. This means that we as a global community can also manage our relationship with the system to influence future planetary conditions. This study identifies some of the levers that can be used to do so," concludes co-author, Katherine Richardson from the University of Copenhagen.

Explore further: Study reveals what natural greenhouse emissions from wetlands and permafrosts mean for Paris Agreement targets

More information: Will Steffen el al., "Trajectories of the Earth System in the Anthropocene," PNAS (2018). www.pnas.org/cgi/doi/10.1073/pnas.1810141115

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12 comments

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V4Vendicar
4 / 5 (4) Aug 06, 2018
Here in America we are all entitled to our own reality, by the power of our God Given Constitution.
rodkeh
1.6 / 5 (7) Aug 06, 2018
Pure BS!
I wish I could get these frauds into a Court of Law. These so called scientists should all be behind bars, they are frauds and liars!
Old_C_Code
1.7 / 5 (6) Aug 06, 2018
10 to 60 meter sea level rise coming, yet Miami is still above water. 10 to 60 meter sea level rise sounds like something that could happen naturally in another millenium though.
Surveillance_Egg_Unit
1 / 5 (5) Aug 06, 2018
Here in America we are all entitled to our own reality, by the power of our God Given Constitution.
V4

I assume you are referring to the article in a roundabout way. Constitution has nothing to do with the "alleged" coming heat of a burning-hot planet Earth.
On the other hand, the first world-wide destruction was the flood of Noah's time...water.
God can't use water again to kill off Life, so it would be reasonable to use FIRE instead and start all over again. There are evil men who should be taken out, and a large majority are in the US Democrat Party aka Socialists aka Communists aka Marxists whose goal is to raise taxes on the workers. Many rich politicians won't be raising taxes on their own incomes.
Surveillance_Egg_Unit
1 / 5 (4) Aug 06, 2018
10 to 60 meter sea level rise coming, yet Miami is still above water. 10 to 60 meter sea level rise sounds like something that could happen naturally in another millenium though.


When there are fish swimming in the streets of downtown Miami, I will be there with my fishing pole and tackle. Maybe even an airboat where we can have a fish-fry on board. :)
robd
5 / 5 (1) Aug 07, 2018
So many people in the USA seem to be so lacking in education or so lacking in respect for the educated and lacking in awareness of their surrounding environment that they are still in denial that the climate is changing or that we have an effect on this change. Like the Dodo if we keep sticking our heads in the sand we will be GONE.
howhot3
not rated yet Aug 07, 2018
So smelly_egg_unit is going fishing in Miami once the sea level rises; Funny, I wish him luck finding fish and not bodies.
rodkeh
1 / 5 (2) Aug 07, 2018
So many people in the USA seem to be so lacking in education or so lacking in respect for the educated and lacking in awareness of their surrounding environment that they are still in denial that the climate is changing or that we have an effect on this change. Like the Dodo if we keep sticking our heads in the sand we will be GONE.

And you are a prime example of the scientifically illiterate. And apparently ignorant of most things, it is the Ostrich that puts its head in the sand, not the Dodo and if you had a real education you would know that there is no real threat except from the stupidity of people like you!
rodkeh
1 / 5 (1) Aug 07, 2018
So smelly_egg_unit is going fishing in Miami once the sea level rises; Funny, I wish him luck finding fish and not bodies.

No worries, the fish will cleanup the bodies.
Johnpaily
not rated yet Aug 08, 2018
We need to face the truth - The leaders should know fire jumps, spreads in a non-linear manner and heat feeds the fire. With the exponentially increased amount of heat being released by the technological world into the environment, the scenario is set for more of the climatic disaster of all forms, unless we change our thinking and develop New technologies, we are doomed.
We should awaken to the fact that Our ecosphere and life are sustained by a parallel and multiple world design. It works on two vital ratios; one is energy to matter ratio and other is of O2 to CO2 ratio.
rodkeh
1 / 5 (1) Aug 08, 2018
We need to face the truth - The leaders should know fire jumps, spreads in a non-linear manner and heat feeds the fire. With the exponentially increased amount of heat being released by the technological world into the environment, the scenario is set for more of the climatic disaster of all forms, unless we change our thinking and develop New technologies, we are doomed.
We should awaken to the fact that Our ecosphere and life are sustained by a parallel and multiple world design. It works on two vital ratios; one is energy to matter ratio and other is of O2 to CO2 ratio.

Why do you think you can just make stuff up?
Anonym842258
not rated yet Aug 10, 2018
First the facts, earth has cooled due to the rise of the Himalayas, and the CO2 washed out of the atmosphere. This is acknowledged by ICCO. The response to cooling has been the development of C4 plants in the hot and dry regions, and C3C4 HYBRIDS in the cooler regions. C3C4 hybridization is expensive to the plants concerned, so they have epigenetic mechanisms to manage the C4, C3 being much more efficient in cooler and wet environments, which alter during ice ages is vital to survival. These processes of epigenetic adaptation in c3c4 plants are slow, they pace with glaciation, and avoid tracking short term warming effects, lack of volcanic activity, or high solar output. So the C3 and C3C4 plants won't immediately adapt to human created CO2. At least more than a few decades will be needed. main message is that the levels of co2 and global temperatures seen more than 40 million years ago, won't return to earth on a human timescale, we have c4 and C3C4 plants to delay this process.

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