Scientists have devised a plan to survive a nuclear winter that might follow a massive volcanic eruption.

Experts say huge seismic disasters are inevitable – and we must use modern technology to limit the impacts of the very worst of them.

They have drawn up plans to pump millions of tonnes of greenhouse gas into the atmosphere to stabilise the climate after a huge eruption.

Scientists have devised a plan to survive a nuclear winter that might follow a massive volcanic eruption. Experts say huge seismic disasters are inevitable – and we must use modern technology to limit the impacts of the very worst of them. Pictured is the eruption ash cloud of Eyjafjallajokull Volcano, Iceland in 2010

The study authors, from Reading University and Norway, aimed to produce a plan that might help people survive an event on the scale of the eruption of the Indonesian volcano of Tambora 200 years ago.

That eruption - the biggest in the last 10,000 years - resulted in a 'year without summers'.

Clouds of sulphuric gas blocked out the sun, cooling the temperature of the Earth for months on end.

The Reading scientists, who worked with the Centre for International Climate and Environmental Research Oslo (Cicero), calculated that the climatic impact of a repeat could be controlled.

Producing huge quantities of a greenhouse gas called a hydrofluorocarbon, or HFC, would be sufficient to warm the atmosphere and balance the effect of the reduced temperature.

The HFC would stop warmth leaving the planet, making up for the lack of solar heat reaching the atmosphere in the first place.

The benefit of the plan is that HFCs are already produced industrially, to create plastics, although their manufacture would have to increase 100-fold to achieve the required effect

HOW CAN GEOENGINEERING CHANGE THE CLIMATE? 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. 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. 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. Ocean iron fertilisation: The method involves dumping iron into the oceans to improve the growth of photosynthetic organisms that can absorb carbon dioxide. Drawback: Studies suggest it will have of little use in reducing global temperatures. 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

The proposal, published in the journal Geophysical Research Letters, is the first significant geoengineering plan to avert disaster in the event of a volcanic eruption.

HFCs are similar to CFCs –destructive compounds which were banned in fridges and aerosol sprays in the 1980s. However, the specific type of HFC that the scientists propose using does not harm the ozone layer, unlike its chemical cousins, and disappears from the atmosphere after a few years, breaking down naturally.

The benefit of the plan is that HFCs are already produced industrially, to create plastics, although their manufacture would have to increase 100-fold to achieve the required effect.

The researchers suggest a specific gas called HFC-152a would be used, as it breaks down naturally after a few years, reducing the long-term effect.

Study author Professor Keith Shine, of the University of Reading, said: 'Unlike global warming, the climate impacts from a volcano eruption have a natural end-point beyond which we would not need to act further.

'However, the emissions of the short-lived gas we found to be needed are problematic in other respects.

'While a gas could in principle be found that has few associated detrimental environmental impacts, we estimate that large quantities would be needed. This would be very expensive, and would require a vastly expanded industrial production capacity.

'Society would have to decide whether the risks associated with such a large volcanic eruption could ever justify this expense.'

HFCs are similar to CFCs –destructive compounds which were banned in fridges and aerosol sprays in the 1980s. However, the specific type of HFC that the scientists propose using does not harm the ozone layer, unlike its chemical cousins, and disappears from the atmosphere after a few years, breaking down naturally

Co-author Dr Jan Fuglestvedt added: 'Considering such drastic action may appear far-fetched. But it would be unwise for the scientific community and policymakers not to think the issue through.

'Future, large volcanic eruptions are inevitable.'

'However, to our knowledge, no one had considered whether similar ideas could be applied to temporary global cooling from volcanic eruptions. We investigated, and found that yes, in principle, they can.'

The plan was welcomed by climate scientists yesterday.

Professor John Shepherd of the University of Southampton said: 'The possibility of deliberate intervention to 'engineer' our climate is undoubtedly scary, but climate change causes problems for both people and ecosystems, especially if it is large and rapid, whether it is warming or cooling.

'It is sensible and responsible to consider whether, and if so how, we could moderate such changes, and to think through the benefits, costs and risks of doing so, before we attempt to reach any decisions about whether or not such actions should ever be considered.

'We need to be prepared, so far as possible, and explorations like this are desirable, even if some people find them distasteful.'

Dr Matt Watson of the University of Bristol added: 'It is an interesting idea, with an appropriate level of careful caveats, and probably worthy of further investigation, not least because it broadens the debate on climate engineering to countering natural, as opposed to anthropogenic threat.