In 1991, a volcano in the Philippines sent 17 million tonnes of sulphur dioxide (SO2) into the atmosphere.

The gas turned into a mist that reflected sunlight and cooled the Earth. Now, scientists want to copy this effect to combat climate changeLong-term shifts in temperatures and weather patterns. Human action is a major cause of climate change..

It's called solar radiation management (SRM) and has funding from Bill GatesFounder and former CEO of Microsoft, the company responsible for popularising household computers in the 80s (and still one of the major global tech companies). His house on the shores of Lake Washington is called Xanadu 2.0. It took seven years to build and is seen as an early example of a smart home.. Planes injecting particles into the stratosphereA layer of the atmosphere which extends for 31 miles above the Earth's surface. could control global temperatures.

In California, the tech startup Make Sunsets is experimenting with small balloons. Founder Luke Iseman aims "to cool the Earth as quickly as we safely can".

The UN has warned we will not meet current targets to cut CO2 emissionsWhen a gas is let off from something, like a car, it is an emission. Carbon dioxide, or CO2, is a greenhouse gas that contributes to global warming..¹ And SRM is the "only" way to cool the planet in the short term.

Hundreds of climate scientists have signed open letters supporting the research. Expert Daniele Visioni says we should not reject a "tool to fight global warming".

But physicist Raymond Pierrehumbert calls it a "big distraction" from cutting emissions. Activists fear it gives polluters an excuse to ignore targets. Others warn it may cause extreme weather.

"You're setting the world up for a real catastrophe," Pierrehumbert warns. Once the aerosols disappear, temperatures will surge. To avoid disaster, we will need global cooperation for hundreds of years.

Who will be in control? Climate scientist Claudia Wieners says we must "stop crazy people doing crazy stuff". Acting alone, one country could radically change the atmosphere.

Expert Wake Smith says geoengineeringDeliberate attempts to intervene in the Earth's natural processes to counteract climate change on a large scale. is "inevitable" but will not fix climate change. It is a "fire extinguisher" for emergency use only.

July was the hottest month on record. Europe has seen the largest wildfire in its history. "The era of global boiling has arrived," says UN chief Antonio Guterres. Is it time to reach for the fire extinguisher?

Yes: Deliberately polluting the atmosphere with sulphur dioxide is a foolish act of desperation. We won't know the effects until it is too late. And meanwhile, we will grow complacentFeeling that you do not need to do anything about a situation. For example, somebody with very high grades at school might think they do not need to work hard any longer. about CO2 emissions.

No: Human activity is already putting aerosols into the air. It is responsible for offsetting a third of greenhouse gasGases in the Earth's atmosphere that trap heat, contributing to global warming. Carbon dioxide, methane, nitrous oxide and water vapour are all greenhouse gases. climate warming.² All SRM means is taking control of our atmosphere and our survival.

Or... All technology comes with risks. And doing nothing is also dangerous. That is why climate scientists demand further research, regulationWhen governments step in to control what (and how) people buy and sell things. and debate to find the best solutions to climate change.

Climate change - Long-term shifts in temperatures and weather patterns. Human action is a major cause of climate change.

Bill Gates - Founder and former CEO of Microsoft, the company responsible for popularising household computers in the 80s (and still one of the major global tech companies). His house on the shores of Lake Washington is called Xanadu 2.0. It took seven years to build and is seen as an early example of a smart home.

Stratosphere - A layer of the atmosphere which extends for 31 miles above the Earth's surface.

CO2 emissions - When a gas is let off from something, like a car, it is an emission. Carbon dioxide, or CO2, is a greenhouse gas that contributes to global warming.

Geoengineering - Deliberate attempts to intervene in the Earth's natural processes to counteract climate change on a large scale.

Complacent - Feeling that you do not need to do anything about a situation. For example, somebody with very high grades at school might think they do not need to work hard any longer.

Greenhouse gas - Gases in the Earth's atmosphere that trap heat, contributing to global warming. Carbon dioxide, methane, nitrous oxide and water vapour are all greenhouse gases.

Regulation - When governments step in to control what (and how) people buy and sell things.