Scientists believe the targets set by the Paris Climate Agreement may be unobtainable – and could be exceeded much sooner than previously thought.
A new study has looked at the impact thawing permafrost will have on the levels of greenhouse gases emitted into the planet’s atmosphere.
The methane and carbon dioxide trapped in the now-disappearing ice is expected to speed up global warming far beyond what previous models predicted.
These reservoirs of warming gases have thus far been unaccounted for when statisticians and scientists have built climate change models.
When the vast amount of carbon dioxide stored in permafrost is introduced into a mathematical model, scientists claim we are much closer to surpassing the long-term target set by the Paris Climate Agreement than previously expected.
Previous estimates suggest Arctic soils lock away billions of tonnes of methane and carbon dioxide – an enormous reservoir of potent greenhouse gas that could cause global temperatures to rocket if released into the atmosphere.
Reservoirs of gases in permafrost have previously been unaccounted for when generating predictive methods for climate change and policymakers have focused their efforts on the linear rise in carbon dioxide emissions due to human activity and global temperature (stock)
The new study from scientists at the International Institute for Applied Systems Analysis (IIASA) in Austria explains why the rise in global temperatures means previously year-round frozen soil is melting faster than thought.
Permafrost is soil that has been frozen for at least two years.
As a result of this prolonged cryogenic state, the land stores large amounts of carbon and other nutrients from organic matter.
It represents a ‘large carbon reservoir’, according to the scientists, which is slowly released into the atmosphere as the permafrost thaws.
Previous research into the make-up of the world’s permafrost suggests it contains more than 1,000 billion tonnes of carbon.
Widespread melting of the icy soil could a catastrophic release of billions of tonnes of carbon dioxide and deadly methane into the atmosphere.
These emissions are rarely considered in projections for potential future global warming.
Policymakers have so far focused efforts on the linear rise in carbon dioxide emissions due to human activity and the global temperature.
The new study reveals the flaw in this line of thinking and hopes to bring about a change in environmental legislature.
The Paris Agreement is an international collaboration with almost every nation and state in the world (174 countries and the European Union) to limit global warming to less than 2°C (3.6ºF) ‘and to pursue efforts to limit the temperature increase to 1.5°C (2.7°F)’.
In June 2017, President Trump announced his intention for the US, the second largest producer of greenhouse gases in the world, to withdraw from the agreement.
The Paris Agreement is an international collaboration with almost every nation and state in the world (174 countries and the European Union )In June 2017, President Trump (pictured) announced his intention for the US, the second largest producer of greenhouse gases in the world, to withdraw from the agreement
Dr Thomas Gasser, a researcher with the IIASA Ecosystems Services and Management Programme said: ‘Permafrost carbon release from previously frozen organic matter is caused by global warming, and will certainly diminish the budget of CO2 we can emit while staying below a certain level of global warming.
‘It is also an irreversible process over the course of a few centuries, and may therefore be considered a “tipping” element of the Earth’s carbon-climate system that puts the linear approximation of the emission budget framework to the test.’
The study also shows the effect can become even more significant for overshooting trajectories, which means first exceeding the targeted level, and then going back down to the target.
A further 1°C (1.8°F) increase (pictured) past Paris Agreement targets could cause a 500% increase in number of record-breaking hot days. Credit:Kurt Hickman/Stanford News Service
The Paris Agreement explicitly acknowledges an overshooting trajectory, peaking first at ‘well-below’ 2°C (3.6ºF) and then pursuing efforts to get back to 1.5°C (2.7°F).
But during the overshooting period, rising temperatures will lead to further permafrost carbon thaw, scientists say.
Dr Gasser said: ‘Overshooting is a risky strategy and getting back to lower levels after an overshoot will be extremely difficult.
‘However, since we are officially on an overshooting trajectory, we have to prepare ourselves for the possibility that we may never get back to safer levels of warming.
‘Policymakers should understand that there is no elementary proportionality between cumulative CO2 emissions due to human activity and global temperature, as previously believed, and that overshooting may have serious consequences.’
The study was published in Nature Geoscience.