Projecting the impacts of climate change

February 14, 2018 by Mark Dwortzan, Massachusetts Institute of Technology
Air pollution in Bangladesh and Northern India. Credit: Jacques Descloitres, MODIS Rapid Response Team, NASA/GSFC

How might climate change affect the acidification of the world's oceans or air quality in China and India in the coming decades, and what climate policies could be effective in minimizing such impacts? To answer such questions, decision makers routinely rely on science-based projections of physical and economic impacts of climate change on selected regions and economic sectors. But the projections they obtain may not be as reliable or useful as they appear: Today's gold standard for climate impact assessments—model intercomparison projects (MIPs)—fall short in many ways.

MIPs, which use detailed and models to assess environmental and economic effects of different climate-change scenarios, require international coordination among multiple research groups, and use a rigid modeling structure with a fixed set of climate-change scenarios. This highly dispersed, inflexible modeling approach makes it difficult to produce consistent and timely climate impact assessments under changing economic and environmental policies. In addition, MIPs focus on a single economic sector at a time and do not represent feedbacks among sectors, thus degrading their ability to produce accurate projections of climate impacts and meaningful comparisons of those impacts across multiple sectors.

To overcome these drawbacks, researchers at the MIT Joint Program on the Science and Policy of Global Change propose an alternative method that only a handful of other groups are now pursuing: a self-consistent modeling framework to assess climate impacts across multiple regions and sectors. They describe the Joint Program's implementation of this method and provide illustrative examples in a new study published in Nature Communications.

The Joint Program method is essentially a next-generation Integrated Assessment Model (IAM). IAMs typically come in two forms—either as simple climate models coupled with algorithms that translate increases in average global surface temperature into environmental and economic damages known as the social cost of carbon; or as more detailed Earth-system models with continually improving representation of physical impacts, coupled with economic models. The Joint Program IAM integrates a geospatially resolved physical representation of climate impacts into a coupled human and Earth system modeling framework.

Developed over the past 26 years, the MIT Integrated Global System Modeling (IGSM) framework allows researchers to custom-design climate-change scenarios and assess climate impacts under those scenarios. For a given climate change , they can use the framework to analyze the chain of physical changes at the regional and sectoral levels, and then estimate at those levels.

"The IGSM framework makes it possible to do multisectoral climate impact assessment within a single modeling framework within a single group," says Erwan Monier, lead author of the study and a principal research scientist at the Joint Program. "It's responsive to changes in environmental policies, internally consistent, and much more flexible than multimodel international exercises."

In the study, Monier and his co-authors applied the IGSM framework to assess climate impacts under different climate-change scenarios—"Paris Forever," a scenario in which Paris Agreement pledges are carried out through 2030, and then maintained at that level through 2100; and "2C," a scenario with a global carbon tax-driven emissions reduction policy designed to cap global warming at 2 degrees Celsius by 2100. The assessments show that "Paris Forever" would lead to a wide range of projected climate impacts around the world, evidenced by different levels of ocean acidification, air quality, water scarcity, and agricultural productivity in different regions. The "2C" scenario, however, would mitigate a substantial portion of these impacts. The researchers also explored additional scenarios developed by Shell International regarding the potential development of low-carbon energy technologies.

"These examples showcase the responsiveness, consistency and multisectoral capability of our approach, which we believe represents a promising direction for the modeling community," says Sergey Paltsev, a co-author of the study and deputy director of the MIT Joint Program, as well as a senior research scientist at the MIT Energy Initiative and the MIT Center for Energy and Environmental Policy Research. "Unlike traditional IAMs and MIPs, the improved coupled human-Earth system models like the IGSM framework enable researchers to design new emissions scenarios in a matter of months rather than years, avoid inconsistencies among different model components and scenarios, and analyze multiple sectors all at once."

Explore further: Global warming poses substantial flood risk increase for Central and Western Europe

More information: Erwan Monier et al. Toward a consistent modeling framework to assess multi-sectoral climate impacts, Nature Communications (2018). DOI: 10.1038/s41467-018-02984-9

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CCMcCombs
1.8 / 5 (5) Feb 14, 2018
This is a big issue, especially when we are making policy decisions based on projections and simulations which may have boundary conditions that change in yearly or decadal time frames, not to mention the resolution of these simulations which is not a fair representation of actual biogeochem (or socio-economic) processes in the real world. These MIPs are not forecasts nor are they predictive and the danger lies in using the assumptions in these models as forecasts or predictive assessments. I prefer papers that state what we know for certain, what can be experimentally derived.
rrwillsj
1 / 5 (1) Feb 15, 2018
Theology is deductive. Providing definite conclusions and final answers.

The Scientific Method is abductive. Working from observation to theory. When scientists discover an answer ? Usually the result is a whole lotta new questions.

Uncertainty is not just a principle of quantum physics. But, also describes our emotional state as we are confronted with the conflict between our doubts and our curiosity.
PTTG
5 / 5 (2) Feb 15, 2018
@CCMcCombs

That's the exact same propoganda the tobbacco industry used to show that the studies showing that smoking caused cancer were not, in their words, "sound science."

cantdrive85
2 / 5 (4) Feb 15, 2018
There is another article mentioning predictions like this are about as accurate as looking into the crystal ball. Spot on!
snoosebaum
2.3 / 5 (3) Feb 15, 2018
''"2C," a scenario with a global carbon tax-driven emissions reduction policy designed to cap global warming at 2 degrees Celsius by 2100. The assessments show that "Paris Forever" would lead to a wide range of projected climate impacts around the world, evidenced by different levels of ocean acidification, air quality, water scarcity, and agricultural productivity in different regions. The "2C" scenario, however, would mitigate a substantial portion of these impacts.''

Ah yes, more tax , that will solve everything, especially bailing out various economic bungles
barakn
5 / 5 (3) Feb 16, 2018
Ah yes, more tax , that will solve everything, especially bailing out various economic bungles
....says the guy whose country's road system is crumbling due to fuel taxes that haven't been increased since the '90s.
rrwillsj
3 / 5 (2) Feb 16, 2018
Anyone want to cover a bet? That the deniers are the prats driving erratically after imbibing enthusiastically. And after they run into you? It'll turn out they don't have any insurance. "Cause man, that's my beer money!"

As all good scouts know "Be Prepared!" Cause shit happens to all of us. Denying reality is just setting Humanity up for extinction.

The deniers are proof that big skulls are no sign of intelligence.
leetennant
not rated yet Feb 18, 2018
Theology is deductive..


This is true. True deduction requires perfect knowledge of the universe and those stone age goat herders knew EVERYTHING
milnik
not rated yet Feb 23, 2018
Climate change, and especially global warming, are not the consequences of a human factor. It has not yet come to understand how temperature can change on planets, because they all imagined that people are causing these changes, but do not realize that this is impossible in the general space of the planet. A human factor can cause atmospheric pollution locally. Climate change and warming is a consequence of the interaction between the planets and the sun, and here the most important factor is magnetism. How? That nuke did not take her into consideration.

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