Paris climate targets could be exceeded sooner than expected

September 17, 2018, International Institute for Applied Systems Analysis
Credit: CC0 Public Domain

A new study has for the first time comprehensively accounted for permafrost carbon release when estimating emission budgets for climate targets. The results show that the world might be closer to exceeding the budget for the long-term target of the Paris climate agreement than previously thought.

Emissions budgets represent the upper limit of total carbon dioxide (CO2) emissions associated with remaining below a specific global average temperature. The simplicity of the concept has made it an attractive tool for policymakers to use in efforts to remain below dangerous levels of warming, even though it is strongly dependent on the assumption of a linear relationship between rise and cumulative CO2 emissions due to human activity. In their study, the researchers investigated how current budgets are impacted by the non-linear feedback phenomenon of CO2 and methane emissions caused by permafrost thaw.

Permafrost is soil that has been frozen year round for at least two years. Due to the long periods that it remains frozen, the soil stores large amounts of carbon and other nutrients from organic matter, and thus represents a large carbon reservoir, which is seldom considered in projections of potential future . The upper layer of permafrost (the active layer) periodically thaws in the summer, but in recent years, the active layer of permafrost has gradually been expanding due to increasing temperatures. This means that more permafrost is thawing and thus releasing the previously trapped carbon into the atmosphere.

"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," explains Thomas Gasser, a researcher with the IIASA Ecosystems Services and Management Program and lead author of the study published in Nature Geoscience.

This is the first time that such a tipping process is adequately accounted for in emission budgets, and according to the researchers, doing so shows that the world is closer to exceeding the budget for the long-term target of the Paris Agreement than previously thought.

Worryingly, the study also shows that the effect can become even more significant for overshooting trajectories. Overshooting means first exceeding the targeted level, and then going back down to the target. The Paris Agreement explicitly acknowledges an overshooting trajectory, peaking first at 'well-below' 2°C and then pursuing efforts to get back to 1.5°C. During the overshoot period however, rising temperatures will lead to further carbon thaw, which will in turn lead to more released that will need to be removed from the atmosphere for global temperature to decrease.

"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," says Gasser.

The researchers hope that their work will impact the scientific community by demonstrating that emission budgets are not as simple a tool as first thought and that it will also help to inform policymakers in designing future climate mitigation strategies.

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

More information: T. Gasser et al, Path-dependent reductions in CO2 emission budgets caused by permafrost carbon release, Nature Geoscience (2018). DOI: 10.1038/s41561-018-0227-0

Related Stories

Thawing permafrost microbiomes fuel climate change

July 16, 2018

A University of Queensland-led international study could lead to more accurate predictions or the rate of global warming from greenhouse gas emissions produced by thawing permafrost in the next 100 years.

Recommended for you

Oceans of garbage prompt war on plastics

December 15, 2018

Faced with images of turtles smothered by plastic bags, beaches carpeted with garbage and islands of trash floating in the oceans, environmentalists say the world is waking up to the need to tackle plastic pollution at the ...

A damming trend

December 14, 2018

Hundreds of dams are being proposed for Mekong River basin in Southeast Asia. The negative social and environmental consequences—affecting everything from food security to the environment—greatly outweigh the positive ...

Data from Kilauea suggests the eruption was unprecedented

December 14, 2018

A very large team of researchers from multiple institutions in the U.S. has concluded that the Kilauea volcanic eruption that occurred over this past summer represented an unprecedented volcanic event. In their paper published ...

The long dry: global water supplies are shrinking

December 13, 2018

A global study has found a paradox: our water supplies are shrinking at the same time as climate change is generating more intense rain. And the culprit is the drying of soils, say researchers, pointing to a world where drought-like ...

5 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

Old_C_Code
2 / 5 (4) Sep 17, 2018
CO2 is not a poison, and it's effect so far has not been determined.
V4Vendicar
2.5 / 5 (2) Sep 17, 2018
Republi-Dung is a natural plant food, so we need not fear having dung in our drinking water.

The effect of Republi-Dung in drinking water has not yet been determined.
leetennant
5 / 5 (3) Sep 18, 2018
This is really not a surprise. The idea we could stick to 1.5 degrees or even 2 degrees without anybody doing anything was insane. We needed to act fast and aggressively 10 years ago. Now? We're mostly just fucked.
antigoracle
1 / 5 (1) Sep 19, 2018
This is really not a surprise. The idea we could stick to 1.5 degrees or even 2 degrees without anybody doing anything was insane. We needed to act fast and aggressively 10 years ago. Now? We're mostly just fucked.......HAWW...HEE...HAWW....HEEE

What a surprise, the leetenant jackass brays, yet again.
This is the jackass who boasted about, his CO2 spewing pleasure cruise to watch the ice melt in the Antarctic and his plans to do the same to the Arctic. He then has the audacity to come here and bray at the heretics. This is the plan from this jackass to save the world......fast and aggressive and definitely fucked.
howhot3
5 / 5 (1) Sep 19, 2018
To sum up the article;
This is the first time that such a tipping process is adequately accounted for in emission budgets, and according to the researchers, doing so shows that the world is closer to exceeding the budget for the long-term target of the Paris Agreement than previously thought.
they are referring of course to the added CO2 emissions released by the thawing permafrost around the globe from global warming. Something that previously accounted for in the Paris models. So basically we need to find a solution a lot faster than what we planned for in the Paris Accords.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.