Some climate change impacts may appear sooner than expected

December 8, 2015 by John Toon, Georgia Institute of Technology
Rising Sea Level - Marshall Islands

For the 70,000 residents of the Marshall Islands, global climate change isn't a theoretical concern with far-off potential consequences. The island nation is nowhere more than six feet above the Pacific Ocean, and because sea levels are already rising, the nation's leaders have made plans to move to higher ground in the Fiji Islands.

Some impacts of global will appear much sooner than others – with only moderate increases in global temperature. While rising sea levels may one day threaten the commuter tunnels and subway lines of New York City, it will have effects much sooner in other parts of the world. Rising temperatures may one day make parts of the globe uninhabitable, but far lower temperatures may have already begun to decimate coral reefs. Agriculture may also begin to feel the effects well before temperatures rise more than a few degrees globally.

Only immediate and aggressive efforts to mitigate the effects of climate change can head off these accelerating near-term impacts, argues a commentary paper published this week in the journal Nature Geoscience. As more impacts occur, the incentives for addressing the causes of climate change will themselves change, the paper's authors warn.

"Our argument is that if you want to do something, you'd better do something now because over time, you are going to lose the ability to have an impact," said Juan Moreno-Cruz, an assistant professor in Georgia Tech's School of Economics and one of the paper's five co-authors. "If we delay action on climate change, the likelihood of doing something will be reduced because the damages will be accelerating. The incentives to address it are going to disappear as more damage occurs."

Climate impacts are often assumed to increase steadily with global temperature increases, but that's not true for all impacts. The scaling of many with temperature may have a nonlinear sigmoidal pattern, with a dramatic initial impact followed by a leveling off as warming continues, says the paper, which was co-authored by Katharine Ricke and Ken Caldeira at the Carnegie Institution for Science at Stanford, and Jacob Schewe and Anders Levermann at the Pottsdam Institute of Climate Impact Research.

At relatively low levels of warming, for instance, rising will impact low-lying nations such as the Marshall Islands and Bangladesh. Relatively modest water temperature increases may kill corals, while a relatively low temperature rise may affect agriculture in equatorial areas, the paper notes.

Once significant portions of the Marshall Islands or Bangladesh are destroyed by rising seas, the rate of damage will reach an inflection point, continuing at a decreasing rate so that further temperature increases have little additional effect. The authors call that "saturation" – a point at which most of the harm has already been sustained. The paper, authored by a team of climate scientists, economists and oceanographic experts, was intended to add this notion to the global climate policy discussion.

"Once the Marshall Islands are uninhabitable, there is not more damage that can be done there," Moreno-Cruz said. "For them to benefit, we should have had a climate agreement a long time ago. Once that level of saturation has been reached, they will not have an incentive to participate because they won't have anything more to lose."

For sectors or countries where come early and then begin to saturate, there may be two sets of optimum cost-benefit policies – at different levels of mitigation with different environmental and cultural preservation resulting, the paper notes. For these sectors, there may be strong incentives to limit emissions at low levels of warming before the bulk of the impacts occur.

And for certain levels of impact, humans may be able to adjust. For instance, New York City may be able to build walls to keep out the rising Atlantic Ocean, and some coastal communities may be able to move to higher ground. In some parts of the world, wealthy people will simply be able to install air conditioning to address rising temperatures.

Once those investments have been made, however, those who have protected themselves will have less incentive to address the causes of climate change because already made an investment, Moreno-Cruz said. For each of these impacts, there will be an optimal point of investing to protect existing capital. To find this optimal amount of protection, "we need to look at climate change impacts not as a total amount, but a rate," Moreno-Cruz said. "Everything changes at a particular pace. We need to understand those rates, not levels and overall amounts, because that's how climate change impacts are working."

As an economist, Moreno-Cruz is interested in the policy implications of these accelerating impacts. He is working with other scientists to develop a better understanding of the economic issues involved in climate change impacts.

"We have a relatively small window of opportunity in terms of economic incentives underlying the climate science," Moreno-Cruz said. "Once we pass a certain threshold, we won't be able to go back because we will lose the incentives to do so. We think it is time to re-think this problem from the ground up, and this paper is our effort to begin that."

Explore further: More aggressive climate policies are needed to save the future poor

More information: Nature Geoscience, DOI: 10.1038/ngeo2607

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13 comments

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gkam
2.5 / 5 (11) Dec 08, 2015
Perhaps we should send the Deniers to the Marshall Islands and make them STAY there.

No, . . sounds too much like Trump.
Shootist
1.7 / 5 (12) Dec 08, 2015
No one denies the climate changes, only that man is the fundamental cause.

"Generally speaking, I'm much more of a conformist, but it happens I have strong views about climate because I think the majority is badly wrong, and you have to make sure if the majority is saying something that they're not talking nonsense." - Freeman Dyson.

As a general rule, if Freeman Dyson says your science is rubbish, it probably is.

SamB
1.8 / 5 (10) Dec 08, 2015
Ho-Hum heard it all before.. Call me when they are 6 ' under water and I will re-look at the religion of Global Warming.
thefurlong
4.2 / 5 (10) Dec 08, 2015
No one denies the climate changes, only that man is the fundamental cause.

Even if you were correct about that, which you aren't, you are making the mistake of assuming that whatever is natural is beneficial.

Asteroids are natural, but I assume you wouldn't be so blase if you knew of an imminent impact.

Viruses are also natural, but certainly, you wouldn't be unconcerned if Ebola became airborne.
As a general rule, if Freeman Dyson says your science is rubbish, it probably is.

You guys are so desperate for validation.

It would be funny if you weren't busy dragging the rest of us, in your stubborn ignorance, towards a future of famine, water scarcity, unbearable heatwaves, and sea-level rise.

In the meantime, maybe you should actually read the contents of this article and look into how the Marshall islands are CURRENTLY being affected by climate change, instead of proselytizing your religion here.
MalAdapted
3.2 / 5 (11) Dec 11, 2015
Shootist: "As a general rule, if Freeman Dyson says your science is rubbish, it probably is. "

No. Feynman said "The first principle [of Science] is you must not fool yourself, and you are the easiest person to fool!" Intersubjective Verification, or "peer review", is one of two foundations of Science, so if Dyson says one thing and one hundred equally well-trained and disciplined scientists say another, Dyson is most likely fooling himself.

Empiricism, the other foundation of Science, means that competence in the subject is also crucial. As brilliant as Dyson is, he admits he hasn't put the time in to study the multiple lines of evidence for anthropogenic global warming. The overwhelming consensus among competent (measured by publication record) climate experts is summarized by the US National Academy of Sciences (emphasis in the original): AGW "IS THE DEFINING ISSUE OF OUR TIME".
gkam
1.6 / 5 (7) Dec 11, 2015
As the impacts hit us, I wonder how many Deniers will admit it?
antigoracle
1.4 / 5 (9) Dec 11, 2015
I am reminded of that other cult, who have endured centuries of disappointment, awaiting the second coming. They are at least hopeful for glory and not doom and gloom like their AGW Cult counterparts.
24volts
3 / 5 (2) Dec 13, 2015
As the impacts hit us, I wonder how many Deniers will admit it?


Well, I've had to cut my grass in Jan for the last two years and will have to again this year. That's not a normal occurance where I live so yea, it's warming up a bit. Hard to argue with 'growing evidence'
Shootist
1 / 5 (5) Dec 14, 2015
Yes, the Climate Changes. And there is nothing, short of building an orbiting sun shade, that anyone can do about it. Well, you might try painting all your roofs and roadways white (just to see what happens).
antialias_physorg
5 / 5 (4) Dec 14, 2015
And there is nothing, short of building an orbiting sun shade, that anyone can do about it.

And you base this assertion that we can't do anything on...what exactly?
Is it based on the same lack of knowledge that 'supported' your "the climate isn't changing" argument?

Why don't you stop being part of the problem and be part of ...nothing. And let people with brains deal with problems and come up with solutions.
thefurlong
5 / 5 (4) Dec 14, 2015
Yes, the Climate Changes. And there is nothing, short of building an orbiting sun shade,

Ugh. Yes, let's consider the highly unrealistic scenario of engaging in an engineering project centuries beyond our current level of technology, instead of that much more realistic scenario in which we reduce carbon emissions, and start phasing existing technology into our infrastructure to replace outdated fossil fuels. You must be full of good ideas.
that anyone can do about it. Well, you might try painting all your roofs and roadways white (just to see what happens).

Like...the Earth's natural albedo currently does? The one that used to be more effective before we started melting the polar ice caps? The one that will continue reducing in efficacy as we continue pumping carbon into the atmosphere at unprecedented levels?

Like I said, you must be full of good ideas.
jeffensley
3 / 5 (2) Dec 14, 2015
Primitive man had the advantage of being nomadic back when sea levels were REALLY rising. Unfortunately for short-sighted us, we built cities along costs that we naively thought were permanent.
JamesWebbsSpaceScope
1 / 5 (3) Dec 14, 2015
antialias_physorg

Have you heard of carbonengineering? If we take that tech, scale up massively powered by fission ( or one day fusion ) we can bring down c02 to 280 PPM.

If not that then what?

I'm sick and fu!cing tired of the debate.

I'm sick of the only solution being to cut emissions.

Why the hell are people not talking about better solution, like the example I gave? Or something else.

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