Representatives from 196 countries have signed off on a historic climate pact in Paris, one that aims to keep the planet from warming by more than 2 degrees Celsius (3.6 degrees Fahrenheit) above preindustrial levels.
"The Paris agreement on climate change is a monumental success for the planet and its people," said U.N. Secretary-General Ban Ki-moon on Saturday (Dec. 12), according to news reports.
But even if the planet is inexorably warming, it's not for want of ideas. Scientists have proposed some wild schemes for curbing climate change.
"Although riskier ideas to lessen the amount of energy absorbed from the sun should not be considered for deployment, they should be studied so that we can provide answers if someday these ideas begin to be considered in attempts to avert catastrophe," Ralph J. Cicerone, National Academy of Sciences president, said in response to a February report on some of these crazy ideas. [Top 10 Craziest Environmental Ideas]
If the worst happens, it may be time to revisit some of those risky "climate hacks." From creating faux-volcanoes to sucking carbon from the air to make fancy building materials, here are some of the craziest climate fixes around.
1. It's a bird! It's a plane! It's a … volcano plane?
Climate change results from an increase in the amount of heat-trapping greenhouse gases in the atmosphere. These gases, like carbon dioxide and methane, absorb heat from the sun's rays and then, instead of reflecting that energy back into outer space, re-emit it back to the planet. Normally, that's a good thing: Thank the atmosphere for keeping the planet much toastier than Mars. But excess atmospheric CO2 is too much of a good thing.
However, sulfur dioxide plays the opposite role: It tends to rise into the stratosphere, the layer of the atmosphere between 6 miles and 30 miles (10 to 50 kilometers) above the Earth's surface. There, the substance combines with water to form sulfuric acid. These miniscule droplets reflect light from the sun, cooling the planet. In fact, anytime a volcano erups and spews out tons of sulfur dioxide into the atmosphere, it creates a measurable global cooling effect that typically wanes after a year or two.
Some researchers have proposed flying planes loaded with sulfuric acid aerosols into the sky and injecting those aerosols into the atmosphere to temporarily halt global warming. The catch? The excess sulfur would lead to more deaths from air pollution. And it wouldn't do anything to solve the underlying levels of greenhouse gas in the atmosphere, Bloomberg News reported.
2. Beano for cows
Methane is actually a much more potent greenhouse gas than is carbon dioxide, and the 1.5 billion cows living on the planet at any given time all release huge amounts of the gas in their belches and farts. This contributes anywhere between 11 and 17 percent of all the world's methane, according to a 2009 paper in the Journal of Dairy Science.
To combat this aerial assault, scientists have developed an equivalent of "beano" for cows. When administered to Holstein cows for 12 weeks, the methane inhibitor, called 3-nitrooxypropanol (3NOP), slashed the animals' methane output by about 60 percent per pound. Though 3NOP didn't affect milk production or composition, it did spur the cows to pack on extra pounds, the researchers reported in a 2014 paper in the Journal of Dairy Science.
3. Whiter whites?
If the greenhouse gases can't be prevented at one end, perhaps they can be curtailed at another, by modifying the amount of light reflected, or albedo, of clouds by making clouds optically brighter. Because whites (such as in snow) reflect more sunlight than darks, making clouds brighter could reflect more heat out into space.
Unfortunately, that won't do anything to curb ocean acidification, which is caused by the excess CO2 in the atmosphere, not just the temperature, according to a report published in 2015 by the National Academies. And changing cloud cover could have far-reaching and unintended consequences on weather patterns and rainfall, the report concluded.
4. Stratospheric shield
In a slight twist on the cloud-brightening plan, some scientists suggest injecting light-reflecting aerosols into the stratosphere to act as a kind of "albedo shield" that covers the planet. Like other albedo modification schemes, this would be a short-term fix, whereas the excess carbon in the atmosphere will linger for millennia, according to a 2013 study published by the National Academies of Sciences, Engineering and Medicine. That means that to really get a handle on the carbon emissions, people need to figure out how to remove carbon from the atmosphere.
5. Carbon sucks
In that vein, another scheme would literally suck the excess carbon out of the air, with a bonus of creating a superstrong building material that is ordinarily quite pricy to produce. This method, which was described in August in the journal Nano Letters, uses solar energy to create molten lithium carbonate. When a voltage is placed across it, the mixture separates into lithium oxide, carbon and oxygen. The lithium oxide attracts more carbon dioxide, creating a loop. The leftover carbon fibers are useful for many applications, from making cars to rocket ships. And nanoscale carbon fibers, like those the chemical reaction would create, have unique electrical properties.
Of course, the authors describe the method as "one-pot synthesis," and scientists would need much more than one pot of the stuff to make a dent in global emissions. If an area about one-tenth the size of the Sahara Desert was deployed for this purpose, the Earth would return to its pre-industrial carbon levels within a decade, even with continued greenhouse gas emissions, MIT Technology Review reported. That level of synthesis would create a huge stockpile of carbon fibers, far in excess of what is currently needed, however.