Making whiter clouds or shooting particles into the air to combat global warming. These are examples of geo-engineering or climate engineering, or intervening in the natural systems of the earth. The aim is to combat climate change. Sounds futuristic, but it may soon no longer be.
TU Delft is starting the year with major research into climate engineering. Together with the British University of Cambridge, they will spend the next six years researching how they can make clouds whiter.
The theory is that whiter clouds reflect more sunlight. This would cool the earth. “We are going to investigate whether it works and what the effects and risks are of these technologies,” says professor of atmosphere research Herman Russchenberg of TU Delft.
A cloud can consist of many small droplets, or a smaller number of large droplets. “Sunlight falling on a cloud with much smaller droplets is reflected better than sunlight on a cloud with fewer but larger droplets,” Russchenberg explains.
The professor wants to use his research to change clouds above the sea. “You could pump salt crystals out of the sea, atomize them and then blow them into a cloud,” says Russchenberg. This way you get more smaller droplets in a cloud, making it whiter and more reflective than in a natural situation. This is how you cool the earth. This is called marine cloud brightening.
In the coming years, they will investigate whether this really works in Delft. “We want to see whether it is technically possible, with salt crystals. Then we want to see whether it really has a cooling effect and whether there are any unintended side effects,” says Russchenberg. For example, it could be that rain patterns change due to human intervention.
In the United States, the government has also just launched a major research program. Over the next five years, research will also be carried out there into technologies to combat the consequences of climate change.
This concerns, for example, so-called stratospheric aerosol injections, in which sulfur particles are introduced into the stratosphere, kilometers above the earth.
“They spread around the earth and block sunlight. About 1 to 2 percent of the sunlight, causing the temperature on earth to drop,” says Claudia Wieners, researcher at the Institute for Marine and Atmospheric Research at Utrecht University. “Those particles stay in the stratosphere for about a year. Then you have to do it again, otherwise the effect is gone.”
Stratospheric aerosol injections have not yet been experimented with. “Once a test was set up by Harvard scientists. They wanted to put a balloon with two kilos of lime dust into the atmosphere to see how the particles would spread,” says Wieners. “But that experiment was stopped because there was a lot of resistance to it.”
‘The year without summer’
The idea of sunlight reflection comes from volcanic eruptions. A well-known example is the eruption of Tambora in 1815. It sent a gigantic cloud of ash into the air, up to 40 kilometers in height.
The particles blocked the sunlight, first over Indonesia and months later also over Europe. The average temperature on Earth fell by a few degrees. From China to England, the winter of 1815 was unprecedentedly harsh. 1816 became “the year without a summer”, causing crop failure worldwide.
Now that there is more research into new possibilities, the resistance against them is also growing. Hundreds of scientists signed a plea to agree internationally not to use climate engineering. “We can never fully map the risks of these technologies,” says Frank Biermann, professor of Global Sustainability Governance at Utrecht University and one of the initiators of the petition.
“Who decides whether we are going to use it? We have no structure for that at all,” says Biermann. Many people are also afraid that there will be no motivation to stop using fossil fuels if climate engineering becomes common.
“This is certainly not the solution to the climate problem,” says Wieners. “We need to stop greenhouse gases, but we also need to explore how we can combat the consequences, global warming.”
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Herman Russchenberg thinks that research should be done before you shoot ideas. “If you soon have an earth that is much too hot to live on and you have not researched the solutions, you will be left empty-handed.”
According to him, if the theory is correct, the temperature can be lowered by one degree with cloud brightening. “These techniques are more of a tool to keep the Earth livable in the future.”
They will first start with theoretical studies in Delft, with the first experiments possibly in 2024. That would be the first time that the theory of marine cloud brightening is put into practice. If the results are promising, the question arises as to how this can be used in the future.
“Science provides the knowledge, administrators have to think about how to use that knowledge,” says Russchenberg. “But if these kinds of methods exist and the earth gets hotter, people will want to use them.”