Scientists develop feedback technique to manage uncertainties in solar geoengineering

May 02, 2014

(Phys.org) —In reality, there is no climate reset button. But climate models, unlike the real world, allow do-overs. Scientists at Pacific Northwest National Laboratory, Caltech and Lancaster University took advantage of this "what-if" proving ground by inserting a unique feedback loop into a climate model to react to theoretical climate engineering techniques. Like using a steering wheel to keep a car on course, their feedback technique reacts and adjusts to conditions resulting from designed climate engineering. And, it is much better at achieving climate objectives—whatever those might be—compared to predicting the amount of geoengineering required ahead of time. In this way, researchers can manage a large set of uncertainties inherent in understanding how these techniques may work in the real world.

"There are uncertainties in the climate system due to the amount of carbon dioxide, and adds inherent uncertainties on top of that," said Dr. Ben Kravitz, and modeler at PNNL. "Some of these uncertainties can't be reduced, so if society decides to use geoengineering to help meet climate objectives, it will be done in the presence of uncertainty. Our method allows us to manage some of those uncertainties."

Some postulate that if societies are unable to reduce the greenhouse gas warming effects through emissions reduction, and communities are unable to fully adapt to changing conditions, then using a technology to reduce climate warming would buy society some time. Geoengineering is a category of deliberate technologies proposed by some to reduce the effects of greenhouse gases. Scientists are using model-based analysis to understand how the climate might react to engineered solutions, the amount of carbon dioxide they offset, and how they could be adjusted to keep the climate at a desired state. Modeling investigations are important, because testing these techniques in the real world has a host of issues that need to be resolved first.

"After start-up, if the amount of geoengineering deployed to achieve a climate objective is wrong, we wouldn't get to start over and try again," said Kravitz.

The research team used two in the study: one to design a geoengineering strategy, and one in which geoengineering was implemented (a real-world proxy). They implemented the design model as often as they wished, but conducted each simulation in the real-world proxy exactly once. This process parallels the situation that society might face if geoengineering is used to achieve climate goals. Through "what-if" scenarios, they turned up the sun's energy if the climate got too cold or dialed it down if the climate got too warm. Their research showed how using a deliberate feedback mechanism was effective in helping manage some of those uncertainties.

This study developed tools that can be more broadly used to understand feedbacks in the system.

Explore further: Is nuclear power the only way to avoid geoengineering?

More information: Kravitz B, DG MacMartin, DT Leedal, PJ Rasch, and AJ Jarvis. 2014. "Explicit Feedback and the Management of Uncertainty in Meeting Climate Objectives with Solar Geoengineering." Environmental Research Letters 9:044006. DOI: 10.1088/1748-9326/9/4/044006

add to favorites email to friend print save as pdf

Related Stories

Is nuclear power the only way to avoid geoengineering?

Apr 23, 2014

"I think one can argue that if we were to follow a strong nuclear energy pathway—as well as doing everything else that we can—then we can solve the climate problem without doing geoengineering." So says Tom Wigley, one ...

Effects of sea spray geoengineering on global climate

Feb 14, 2012

Anthropogenic climate warming is leading to consideration of options for geoengineering to offset rising carbon dioxide levels. One potential technique involves injecting artificial sea spray into the atmosphere. The sea ...

New approach needed to deal with increased flood risk

Apr 17, 2014

Considering the impacts of climate change on flood risk may not be effective unless current risk is managed better, according to new research from the University of Bristol published today in the Journal ...

Climate change: Can geoengineering satisfy everyone?

Sep 15, 2010

Reflecting sunlight from the Earth by geoengineering would undoubtedly cool the climate, but would different countries agree on how much to reflect? Research by climate scientists at the University of Bristol ...

Recommended for you

Russia battles to contain Black Sea oil spill

Dec 25, 2014

A Russian Black Sea city declared a state of emergency Thursday after a burst pipeline spewed oil into the landlocked water body, with stormy weather hampering cleanup efforts.

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

Bob Osaka
not rated yet May 04, 2014
The best climate models thus far have proven untrustworthy. If this one can accurately forecast the real world weather infallibly, then it would be something other than a climate video game. I know it's frustrating. Keep at it, we might get it right sometime.

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.