Driving the news: Scientists are well acquainted with feedback loops, but the often wonky topic doesn’t break through into the mainstream despite its importance to how much the world warms and how much we respond to that warming.
- As we soak up the last of these hot summer days, and extreme weather hits parts of the country, today seems a fitting time to break this down for those of us without a Ph.D.
Here are six feedback loops in science and beyond.
Air conditioning
How it works: Climate change is making our summers hotter, so we use more air conditioners, which emit greenhouse gases, which heats up our planet more, so we use even more AC, which heats up our planet even more ... You get the cycle.
- This is an easy-to-understand feedback loop, but it’s not going to have a big impact> on our emissions, says Zeke Hausfather, a climate scientist at the research group Breakthrough Institute.
- The bigger impact is likely to be population growth in developing countries in hot parts of the world, like India, getting AC to survive their ever-hotter weather.
Water evaporation
This one’s more technical but far more consequential for Earth’s temperature than the AC example.
How it works: The atmosphere heats up as we emit heat-trapping greenhouse gases.
- This warmer air leads to more water evaporation from water and land.
- This evaporation results in water vapor, which itself is a greenhouse gas and traps heat.
- The increased amount of water vapor in the atmosphere retains ever more heat, which leads to more water evaporation, which results in more water vapor, which....
Between the lines: This type of feedback loop more than doubles the amount of global warming, says Hausfather.
Permafrost
This is a type of feedback that has only recently begun to be included in climate models, says Philip Duffy, climate scientist and president of the nonprofitWoodwell Climate Research Center.
How it works: It’s like a massive freezer thawing atop the world, Duffy says. Nearly a quarter of Northern hemisphere land has permafrost underneath it.
- As the warm worlds, organic matter — plants and dead animals frozen for tens of thousands of years — starts to decompose. “Those decomposition processes emit greenhouse gases,” Duffy said.
- Scientists estimate that there's twice as much carbon locked up in permafrost as is already in the atmosphere, Duffy says. "The potential to amplify warming is huge.”
Albedo feedback
This is similar to permafrost. It’s why you feel hotter in black clothes compared to white clothes.
How it works: Lighter surfaces reflect heat more, so as ice and other cold places get warmer (i.e., the Arctic and other permafrost), their ability to reflect heat diminishes and they soak up more heat.
- “As the world warms, expect a lot of ice and snow to melt, which uncovers darker surfaces, which will result in more warming,” said Hausfather.
Between the lines: This phenomenon, combined with the permafrost one, helps explain why the planet's poles warm faster than the rest of the world.
Wildfires
How it works: Trees, by definition, embody carbon. So when wildfires burn them down, carbon dioxide is emitted.
- As the world warms, temperatures get hotter and places get drier, creating tinderboxes for when wildfires do start.
- The hotter the world gets, the bigger wildfires will be (in some places like California), the more CO2 emitted into the atmosphere, which heats up the world more, which will exacerbate wildfires more ...
Policy and economic paralysis
Unlike most policy challenges, climate change gets worse the longer we take to address it.
How it works: The longer we wait to address climate change with major government action, the bigger the policy needed and the bigger economic impact that policy will have.
- But the bigger the policy and economic hit get, the harder the politics get.
- So we wait longer still, making the required policy and economic impact ever bigger, which makes the politics even more difficult.
Yes, but: Plausible future scenarios also exist where the impacts of a warming world grow so intense and/or clean-energy technologies become so cheap that eventually these aforementioned feedback loops are broken.
Geopolitics
How it works: It takes global cooperation to address climate change, given its global nature. But climate change impacts different countries differently, so they're more likely to act on their own, and in their own self-interest.
- But if there's no global cooperation, climate change continues to get worse — prolonging the adverse impacts on different countries, and giving them even less incentive to cooperate with other countries and more incentive to act on their own.
The bottom line:
“The possible scenario that is a real nightmare is if we don’t control human emissions, nature takes over and we lose control of the warming, because of these emissions from natural systems.”
Philip Duffy, climate scientist
