A climate scientist has said he is ‘terrified’ of the futuristic technologies he is helping to develop in a bid to slow global warming.

British academics have spent £5.4 million ($8.5 million) in the last five years on taxpayer-funded ‘geoengineering’ projects to stop the effects of climate change.

Dr Matthew Watson, lead investigator of a £1.8million ($2.8 million) project to pump chemicals into the atmosphere to reflect the sun’s rays, said using such technologies will become inevitable if humanity fails to stop global warming.

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Dr Watson from Bristol University said we should be wary of interfering with nature on a planetary scale - known as geoengineering. It involves changing our planet to counteract effects of climate change. Earth is shown here pictured from space

The Bristol University academic has already suffered a major setback, when much-trumpeted plans to send a huge balloon into the air to test his scheme was scrapped over a patenting dispute.

Yesterday he admitted that despite the millions already spent on research, scientists are still decades from seeing their dreams turn into reality.

POTENTIAL SIDE EFFECTS OF FIVE GEOENGINEERING STRATEGIES 1. Afforestation: This technique would irrigate deserts, such as those in Australia and North Africa, to plant millions of trees that could absorb carbon dioxide. Drawback: This vegetation would also draw in sunlight that the deserts currently reflect back into space, and so contribute to global warming. 2. Artificial ocean upwelling: Engineers would use long pipes to pump cold, nutrient-rich water upward to cool ocean-surface waters. Drawback: If this process ever stopped it could cause oceans to rebalance their heat levels and rapidly change the climate. 3. Ocean alkalinisation: This involves heaping lime into the ocean to chemically increase the absorption of carbon dioxide. Drawback: Study suggests it will have of little use in reducing global temperatures. 4. Ocean iron fertilisation: The method involves dumping iron into the oceans to improve the growth of photosynthetic organisms that can absorb carbon dioxide. Drawback: Study suggests it will have of little use in reducing global temperatures. 5. Solar radiation management: This would reduce the amount of sunlight Earth receives, by shooting reflective sulphate-based aerosols into the atmosphere. Drawback: Carbon dioxide would still build up in the atmosphere. Advertisement

And he said they could indeed be dangerous.

The schemes could see rainfall patterns change, droughts spread across the world and the ozone layer damaged beyond repair.

‘Personally, this stuff terrifies me,’ he said.

‘Whilst it is clear that temperatures could be reduced during deployment, the potential for misstep is considerable.

‘By identifying risks, we hope to contribute to the evidence base around geoengineering that will determine whether deployment, in the face of the threat of climate change, has the capacity to do more good than harm.’

But he added that it would be ‘unethical’ not to try the technology.

‘If we ever deploy these technologies it will be the closest indication yet that we've failed as planetary stewards.

‘But there is a point at which not deploying some technologies would be unethical.

‘It's a watershed for our relationship with the Earth and with nature. It fundamentally changes the way seven billion people are going to interact with the world, and I'm not sure the system is going to be controllable in the way we want.’

Three taxpayer-funded schemes will today publish the results of five years of research into geoengineering.

Each report will confirm that we are many years away from seeing any project work outside the laboratory.

One of the touted projects includes spraying low-level clouds with sea salt to make them reflective to the sun; another would pump aerosols or sulphur particles into the atmosphere to disperse sunlight; and others would see greenhouse gases such as carbon dioxide sucked out of the air to reduce global warming.

One of the proposals to geoengineer our planet involves Solar Radiation Management (SRM), pictured, which would involve releasing small particles into the stratosphere that reflect some of the incoming solar radition. This would then allow Earth to cool instead of continuing to warm like it is now

One of the biggest risks is disrupting the delicate balance of land and sea weather influences.

The scientists admit that each technology they investigated could lead to damaging changes in rainfall patterns, leading to floods where there had previously been little risk, and droughts elsewhere.

Another danger specifically linked to sulphur particles is the destruction of atmospheric ozone, a vital barrier to harmful solar radiation that can trigger skin cancer and have damaging effects on plants and animals.

Dr Watson said the day may come when the use of such technologies cannot be avoided.

‘We are swimming, drowning, in a sea of ignorance. This terrifies me. But doing nothing is not an option.

‘Unless we're very wrong about climate change or quickly change our ways, at some point we're going to have to 'go outside' [with these technologies],’ he said.

Several proposals for geoengineering have been proposed, illustrated here, But Dr Watson said resorting to these measures amounted to us admitting we could no longer save the planet by managing our global emissions - and meant we had failed to look after Earth

He stressed that without drastic cuts in greenhouse emissions, global warming was on course to make the world 4°C (7.2°C) hotter by 2100.

‘That's going to have a profound effect on the planet,’ he added.

Professor Piers Forster from the University of Leeds, who has also investigated climate engineering projects, said: ‘Our research shows that the devil is in the detail.

'Geoengineering will be much more expensive and challenging than previous estimates suggest and any benefits would be limited.’

Professor Steve Rayner of Oxford University, who has researched the legal and ethical ramifications of geoengineering, said: ‘Mostly it is too soon to know what any of these technology ideas would look like in practice or what would be their true cost and benefit.

‘But it's almost certain that geoengineering will be neither a magic bullet nor Pandora's Box.’

He said that each technology would have to be shown to be safe, effective and affordable before it was trialled - but added: ‘They will probably be part of the tool box.’