In order to forestall global warming, a new team led by British academics are working towards recreating an artificial volcano that would inject particles into the stratosphere and cool the planet. The team plans to use a tethered balloon with a size equivalent to Wembley stadium and suspend it 20 km (13 miles) above Earth while linking it to the ground by a giant hose.

The scientists expect to unveil their project next month in the world's first major field test of "geo-engineering."

The aim is to reproduce the cooling effect that volcanoes have when they inject particles into the stratosphere that bounce some of the sun's energy back into space, mitigating the effects of manmade climate change, the Guardian reported.

The team will first send a scaled-down version of the balloon to a height of 1 km over an undisclosed location to pump water into the air, allowing climate scientists and engineers to determine the engineering feasibility of the plan.

Another aim of the project is to test the impact of sulphates and other aerosol particles when they are sprayed directly into the stratosphere.

The team from Cambridge, Oxford, Reading and Bristol universities has said that if it can overcome challenges of scale from the size of the balloon, they then intend to move to full-scale solar radiation tests.

One of the leading members of the team, Bristol University lecturer Matthew Watson, said the experiment was inspired by volcanoes and the way they can affect the climate after eruptions.

"We will test pure water only, in sufficient quantity to test the engineering. Much more research is required," The Guardian quoted him as saying.

"The whole weight of this thing is going to be a few hundred tonnes. That's the weight of several double-decker buses. So imagine how big a helium balloon do you need to hold several double-decker buses - a big balloon. We're looking at a balloon which is possibly 100-200m in diameter. It's about the same size as Wembley stadium," Hugh Hunt, an Oxford engineering lecturer, said in an interview earlier this year.

"This hose would be just like a garden hose, 20 km long and we pump stuff up the pipe. The nice thing about it is that we can really have a knob, if you like, which we can control to adjust the rate at which we inject these particles," added Hunt.

While the project has mainly received a warm welcome, environmental activists warn that the government's experiment could affect rainfall and food supplies, also adding that even if it successfully cools the planet by bouncing some of the sun's energy back into space, it would do nothing for the build-up of CO<sub>2 in the atmosphere, which leads to increased ocean acidity

Other leaders of the government-funded Stratospheric Particle Injection for Climate Engineering (SPICE) project have investigated using missiles, planes, tall chimneys and other ways to send thousands of tonnes of particles into the air but have concluded that a simple balloon and hosepipe system is the cheapest option, according to The Guardian.