Andrew Yang, the Democratic Presidential candidate most well known for his so-called “freedom dividend,” has proposed building giant space mirrors in order to combat climate change.

Yang released his plan to tackle the environment on his website on Monday, with a section on large scale “geoengineering” projects that sound like total science fiction.

Under a section entitled, “emergency options,” Yang said that the country has to be prepared “with options that have potential side effects that are more desirable than… climate collapse,” with one being “space mirrors”:

Space mirrors would involve launching giant foldable mirrors into space that would deploy and reflect much of the sun’s light. This method would be extremely expensive, which is why it should be investigated as a last resort. However, since we would be able to “undo” the mirror after deployment if needed, it’s less permanent.

He also suggested launching sulfur dioxide into the atmosphere via a process known as “stratospheric aerosol scattering”:

When volcanoes erupt, they spew sulfur dioxide into the sky and reflect sunlight particles away from the earth… If scientists can find a way to burn sulfur in the stratosphere, then they could mimic the positive effects of volcanoes eruptions on climate change and their ability to help keep the earth cool. Bill Gates has recently backed a study to explore the feasibility of this method, but there are many dangers to it, which is why it (and other, similar methods) require research.

Yang said that he would provide $800 million to NASA, the National Oceanic and Atmospheric Administration, and the Department of Defense to “research, experiment with, and test” these geoengineering methods.

Steven Cohen, director of the research program on sustainability policy and management at Columbia University’s Earth Institute, told The Verge that he was sceptical of Yang’s ideas:

I think that he’s essentially on the right track to focus on science and technology, but I think that his faith in technology may be a little bit misplaced… It’s one thing to do the research… but another thing to count on it to save the world.

Yang’s plans to get the country to net-zero carbon emissions do include more normal proposals, like boosting nuclear energy capacity and ramping up renewable energy production.

In fact, the mostly costly element of his $4.87 trillion climate change plan are the loans for household renewable energy, which would cost $3 trillion over 20 years.