Page last updated at 09:10 GMT, Tuesday, 1 September 2009 10:10 UK

Earth experiment could buy precious time

Alan Gadian
Alan Gadian

As the UK's Royal Society prepares to publish its conclusions on whether geo-engineering can help combat climate change, physicist Alan Gadian argues that geo-engineering techniques, in particular cloud whitening, must be properly tested - and soon.

Stratocumulus clouds
The research needs to be carried out; otherwise we will not know, five to 10 years from now, if we could have done anything to slow down the warming and the irreversible change in the Earth system

Planet Earth has become a huge science experiment, and the consequences will affect all of us.

"Global warming poses a greater threat than world terrorism and agreement must be reached within two years to mitigate global warming and minimise environmental catastrophe," Sir David King, the UK's chief scientist, wrote in 2007.

On 8 July this year, the G8 proposed a 50% reduction of global emissions of carbon dioxide by 2050. It remains to be seen whether this will be fast enough.

And carbon dioxide is not the only problem.

Methane is a greenhouse gas 21 times more potent, and the wastelands of Siberia are now releasing fountains of methane as the permafrost melts, adding to the greenhouse warming effect.

So how can geo-engineering help?

I define geo-engineering as man-made environmental change; and I would include in its definition the unprecedented burning of fossil fuels that has pumped large quantities of carbon dioxide into the atmosphere, and the massive increase in the number of farm animals with consequential methane production.

Changes in agriculture, in Africa for example, have resulted in the felling of large areas of forest and have removed the water storage capacity of the land. This has led to the rapid advance of the desert in the Sahel region.

The planet has been and is warming further. This will also lead to significant changes in precipitation, and flooding will remove prime agriculturally productive land.

Whiter clouds

In a 1990 paper in the journal Nature, John Latham, a scientist at the National Center for Atmospheric Research in Colorado, US, suggested that increasing the number of droplets in maritime layer clouds (stratocumulus) could significantly increase their reflectance.

Jars of glass beads (Stephen Salter)
Smaller glass beads, and smaller water droplets appear whiter

These clouds cover a third of the ocean.

The water droplets in clouds reflect solar radiation back to space. And the numbers of droplets they contain are largely controlled by the number of cloud condensation nuclei (CCN), such as specks of dust.

Many of these nuclei are produced over the land. Land-locked clouds therefore contain many hundreds of cloud droplets per cubic centimetre, whilst clouds that form over the sea contain substantially fewer.

Generally, the more droplets that are present in a cloud, the smaller they are.

For a given mass of water in a cloud, clouds with smaller droplets tend to be whiter. This was illustrated by the Edinburgh University scientist Stephen Salter's example of glass beads in a jar - the smaller the beads, the whiter they appear.

So the proposal is to inject a fine spray of sea salt from the ocean surface into the clouds; to artificially increase the number of drops, reduce their size and increase the reflectance of the clouds, making them whiter.

This one-off increase in reflectance - and the resulting cooling - could buy us precious time; maybe as much as 25 years.

Initial estimates suggest that we could complete the research for approximately £6m

But we need numerical models and field experiments to determine the ideal size of the sea-salt nuclei.

Results from climate models show that a modest increase of nuclei in marine stratocumulus clouds could produce the desired cooling.

Further research is required, but preliminary results suggest this could compensate for up to a doubling of atmospheric carbon dioxide from pre-industrial levels.

Initial results suggest that the biggest cooling would occur in the polar regions, which is consistent with theory, and is exactly the place where cooling is most needed.

The big advantages of this scheme are that it uses sea water spray, a naturally occurring substance, and that it can be turned off immediately if there are any undesirable consequences.

The technology

Professor Salter has even suggested a design for a fleet of about 2000 of wind-powered yachts, which incorporate a sophisticated spray mechanism that is now being developed.

My colleagues and I propose to carry out detailed research of the scheme and provide an answer on its viability within five years.

There are four elements to this research:

  • cloud physics modelling; there are many questions about the optimal size of sea-salt CCN and how the clouds will respond to their increased numbers
  • further climate modelling
  • developing and building Stephen Salter's test yachts
  • a field experiment; a limited-area field experiment is needed in a region of stratocumulus clouds, and we already have advanced-stage plans with potential collaborators in the US

The cost

Initial estimates suggest that we could complete the research for approximately £6m ($10m), and produce a result that will determine if the proposed scheme is viable or not.

Wind-powered yacht (J. McNeill)
Stephen Salter suggests a fleet of wind-powered yachts to inject sea salt into the clouds

The research needs to be carried out, otherwise we will not know, five to 10 years from now, if we could have done anything to slow down the warming and the irreversible change in the Earth system.

It is an insignificant sum compared to the cost of doing nothing.

As James Lovelock states: "There have been seven disasters since humans came on the Earth, very similar to the one that's just about to happen."

He argues that billions of people are likely to die in the ensuing famine. "Enjoy life while you can.

"Because if you're lucky it's going to be 20 years before it hits the fan".

We can do something to provide a breathing space. That something should start now.

Dr Alan Gadian is a senior research lecturer in the School of Earth and the Environment at the University of Leeds, UK

Dr Gadian would like to extend his thanks to collaborators Alan Blyth, John Latham and Stephen Salter

The Green Room is a series of opinion articles on environmental topics running weekly on the BBC News website

Do you agree with Alan Gadian? Do we need geo-engineering? Does the science behind these approaches need to be tested now? What are our other options?

Hmm, we need something to reflect back the suns rays? How about solar panels?
Ralph PAPA, Sydney Australia

Like many before me, I believe we need to rebalance ourselves & our planet. Test cloud seed by all means, but the fundamentals remain: capitalist, rather than socialist governments breeding envy, overconsumption of finite resources,deforestation,pollution and disease of mind. We need to revisit the basics or perish.
Susan Donohue, Mernda, Victoria, Australia - Our Wonderful planet

you want to know about environment..about the cloud?! you can refer at Al-Quran … surah al-dukhan.... USE THIS LINK. you must think profoundly . that are real. this were created centuries past . welcome on truth Islamic
kelainan , ipoh-melaka malaysia

Practically every aspect of our lives involves using resource that pollute. We are addicted to pollutants, like the smoker who has been told to quit the habit or it will be terminal, we promise, then relapse through lack of willpower, and clear understanding. Ill conceived Geo-engineering scheme's, are akin to closing the door; after the horse has bolted. And will do little to stem the tide of the global climate tsunami that is heading our way. Alternative energy promotion; plus the introduction, of fuel efficient eco-friendly hybrid automobiles; only scratch the surface of a deeper broader 150 year pollution trail, that Keelhauling our planets resource has left in it's wake, like, rapid global development; global land usage change, exponential fossil fuel usage, and aggressive adverse C o2 emission levels. This is a big ship for turning, It took 150 years of unbridled resource usage, to over-heat our planets Eco system; we cannot change direction with a quick tug on the wheel. Radical c o 2 emission level reduction is the only game in town and must have a timescale that allows for Global adaptation, coupled with nuclear and inclusive renewable sustainable Solutions, that measure up to the extent of the problem. Some Solutions for the mitigation of long-term radical adverse global Climate change) 1. Make sure emissions peak in 2012 and decrease as rapidly as possible towards zero after that. 2. Developed countries must make cuts of 50 percent on their 1990 carbon emissions by 2030 with mandatory regulation by United Nations. 3. Developing countries must slow the growth of emissions by 20 percent by 2040, with support from industrialized nations Our failure to coalesce, for the long term mitigation of radical adverse climatic change, will force the planet to make that decision for us, whatever action we take then, will ultimately benefit the planet. Long live, the planet.
philip clarkson, naxxar malta

It's about time that all those in favour of population control to control climate change do the rest us one big favour and start practising what you preach preferably on yourselves.
Shaun Turpin , London

My understanding of stratocumulus cloud is that they form under particular atmospheric conditions that are most prevalent over sub-tropical and polar oceans. They are formed below about 2400 metres by weak convection currents and do not develop vertically because the air above them is drier and therefore more stable. If we change the structure of these clouds with more condensation nuclei this might change the atmospheric conditions around the clouds and hence change how, when and if they form. These clouds are part of a global system and if we change them we could disrupt larger systems. On a very practical point; is it really possible to spray jets of sea water thousands of feet into the atmosphere and how much energy would be needed? Just a thought.
Keith Gwilym, Bristol UK

An interesting idea. However, unlike many people on this HYS it would appear, I have no idea how practical it would be. There is a sure-fire way to stop climate change, we all know what it is, but we just wont do it. So in the abscence of an intelligent human race we need to research possible geo-engineering routes. However, there are more problems than climate change that our current societies are responsible for such as habitat destruction and a loss of biodiversity. We need to focus on all these problems and keep the bigger picture in mind.
Chris, Bristol

Failure of Biosphere project shows how scientist are not aware about the subtle understanging of the dependencies between the different ecolayers. We have many examples of failures all around the globe from human intervention which tried to save the local ecosystem but leaded into major mistakes which worsened the situation. The recent failure from the tests of seeding the ocean with iron is another example about this context. Climatologists are not prepared to predict weather and are willing to do major transformation which can lead into major cataclismic event of global proportions. Nope. The answer is not manipulate the environment, not yet. The solution is work against the human expansion, the culture based in consumption and greed rather than equilibrium.
Carlos Frohlich, London

We are a consumer driven people. We like what we have, we like things cheaper and easier and more accessible. and as a direct reslut we have become lazy. I mean who can be bothered to take things to be recycled if it means taking 20 mins out of my precious personal time, If I have to drive in the opposite direction from where im going just to put a glass jar in a designated bin when I pass at least 50 or more regular bins on my way to the recycling area?. in order to change the planet and the downward spiral of problems WE have created we need to educate and change our entire philosophy and lifestyle. What we need to do is work hard, yes thats right! build up a sweat and actually do something about the issues. Why continue to add to the already evident, growing and existing problems by creating new artificial ones (some call them sollutions). granted, they may buy us a little extra time, and allow us to be lazy for longer while we grow rich and provide for "our families" consumer driven future. but at the end of the day what we need to do as a people is work together. we are all in this together, yes, granted, some have created the problems and have been less than open or honest about it and nor will they when they continue to gte rich from it which in the end will provide them with a better quality of life. We need to create more green spaces, plant more trees! we know they convert CO2. In fact do they not thrive on the stuff? instead of making artificial ones (why on earth would anyone want to make artificial trees. oh yes because someone will get very rich from sale of such things) plant real ones for goodness sake. Im not talking about local, community parks. But that would at least be a start. im talking about large scale forestation. it would provide jobs. more resources and lets not forget that it looks good, provides animals with shelter and a place in which to live but it does what we all want, it helps the planet and in doing so will help us. We have lots to do but we cant do it by bickering and arguing the best artificial means by which to fix a growing problem. the governments of the world need to put aside some of their land to develop into forest areas. Ok it wont fix all of the issues but what im trying to say is lets not think of a 'quick fix' we may have to get dirty, build up a sweat and actually start working together. But who will make us? why give up the glamerous life we are told we need to strive towards, by giving up access to the one thing we are told makes us better? money! what we need to do is change the way we think as a people. rant over!
milo smith, aberdee, uk

We can never stop climate change, If you look at the history of this planet and go back to the beginning of time, you will see this Earth was white hot and as the surface cooled (The core still hot)came the 1st of the many ice ages and as the 1st of the many globle warming followed, Then the melting ice formed the first ripplets of water into small streams, As each ice age and each globle warming came making the streams into rivers and rivers into lakes, Therefore over millions of years and countless ice ages and globel warmings, the lakes grew into seas and then oceans, The Earth is now covered in four fiths water and this will eventually cover the planet The Earth does not go round the Sun on the same path every year, but over a period of many years it slowly alters its orbit,moving slightly away to form an ice age and then over the same amount of years, it slowley returns to melt the ice, giving us the globle warming we are witnessing today
Colin E Robinson,

Probably one of the worst ideas out there. What impact will it have on weather patterns? We couldn't even begin to guess. Global warming is here and the people of earth will continue to refuse to change habits until the S*** hits the fan and the natural forces of the planet make us stop our insane way of life. cherio
Joe, HB, USA

Whether or not we are the cause of global warming, if " the wastelands of Siberia are NOW RELEASING fountains of methane as the permafrost melts, adding to the greenhouse warming effect," WE HAVE NO TIME TO WASTE.
Odile Brock, Kinshasa, RDC

Calling on the precautionary principle, I'd like to see irrefutable scientific proof that these proposed techniques will pose no danger of any sort. Let's also create "Geo-Technology Watch" quickly!
Hardy, Geneva, Switzerland

It saddens me when people write without even examining in detail the item they are discussing, viz Andy R, Frank Mitchell, Gill Pearce, John Byng, Richard and Lyndon Forster. No-one, and certainly not Alan Gadian,is going to ruin precious arable land with salt water. The majority of the salt water will fall back into the sea, what little is left will fall on the Andes, not really known for its grain poduction!
Sue, Birmingham

it's a good idea....but the application should not only be centralized to the developed countries who can invest or contribute on the warming is a global problem the attempt to solve the problem should also be global..
Sandeep Acharya, Nepal

Two questions that need to ba answered before we can conclude that Professor Salter has considered this with true scientific detachment: 1. Surely salt water sprayed into clouds will result in salty rainfall, not necessarily confined to the spraying area? 2. Siver iodide crystals sprayed on to cloude from the air will increase precipitation under the right conditions. Why will salt crystals not cause the same effect? The silver iodide trick used to be used in Calif. but I understand they quit doing it due to the damage caused by the resulting deluges.
Alex McKeon, Los Gatos, California

Around the 20's, the world did experiment with population control, America was a leading compenant with Eugenics. A system of sterilising people with less desirable genes to control population and improve genetics. Nearly all of the western countries supported this plan, until the Austrian leader of a extreme German political party took it too far.. but to every buffoon who has suggested population control as a viable means of fixing everything... do us a favour and lead by example
Samuel, Sydney, Australia

As a non-scientist I don't understand the problem with the extra rain here. At present, clouds are currently seeded by sea water and the rain it produces is perfectly acceptable. So artificially seeding clouds with extra seawater will simply enlarge or repeat the same process. If they choose to do it in clear skies, they'll just create extra clouds that will work in exactly the same way as existing clouds. Okay, so we don't actually know that this will be the outcome but we don't actually know it wont be. Presumably that is why the scientist is proposing spending the £6m on further research. Some of the commentors here are convinced this will give us salty rain and destroy argicultural land but their assertations are every bit as theoretical as Dr Gadian. He at least seems to have retained an open mind. Give the boy a chance to prove/disprove his theory. If he's wrong at least he is trying to be constructive and not just sitting about blaming everybody else for the problems. And just for the conspiracy theorist (at whom I had a hearty chuckle)... This research has probably already been done by the "controlling elite" and found not only to save the planet but increase life expectancy seven fold, end war, end famine and make every day a bank holiday with free ice cream for all. But they wont publish until they can sell it to us. Watch your back maaahn.
John H. Tully, Edinburgh, UK

The reason why we are in this predicament is because there are too many of our species on this planet. Instead of managing our resources as the planet evolves, we have squardered and plundered everything. We have upset the balance and nature will react to restore it, at our own cost. The only solution is to have fewer babies, and that should be everyones primary concern. Changing weather patterns to 'buy us more time' is simply going to postpone the inevitable. When will people finally wake up to understand this very inconvenient fact?
Cynic, Brisbane, Australia

It is rather funny how we in the First World always think about technical solutions and are not thinking about the cheapest yet still very sufficient way. And we are not thinking about giving work to those in need and willing to work for less than the rest of us. We can cool the earth by means of seawater and water buckets = bucket chains. There are enough hot coasts to put two Billion people to work, all payed for by the not yet famous TOBIN TAX. In the end cooling the system will be payed by those who heated it up most. This tax does not hurt the regular taxpayer, neither do those suffer where the money comes from, they have more than they can eat. The water is spread onto the coastline, evaporates, goes up, becomes clouds, falls as rain somewhere in the hinterlands. It takes 6 to 9 months to set up sufficient bucket chain lines, but then it will rain in the Sahara and at other dry and hot places. I will eat the famous broom by fork and knife if it does not work. One Million bucket will cost about 3 US$/pc. Who will spend the first Million? I´m thinking about Bill Gates and the like. There are so many Billionaires who want to be good. Let´s roll. With all those buckets we will have a nice day at the beach. Regards Tyll Ruhtenberg
Tyll Ruhtenberg, Hamburg Germany

Alan is selling the research he's interested in under the guise of climate mitigation, but to me it seems he's overstepping a threshold. I see here a combination of public doom-saying, science-fiction cartoons, open-ended speculation, inaccuracies, and even bad English ("consequential"), with the modest request for £6M - to save the planet... That's going to go down really well with fact-starved climate skeptics. The timing is perfect, too, to further muddle and confuse the difficult Copenhagen negotiations. This is not a great way of bidding for new research funds.
Thomas, Reading, UK

I see support for the CO2 theory losing ground dangerously fast unfortunately, and unless there isn't something done quick, this 23 year old theory may be lost but most certainly rear it's ugly head when the earth really does die because of us? Just type "global warming" in at Google News and see how much support for the climate change theory has dropped to about 50% now. Let's hope this winter is not as cold as the last three. But they say the Arctic is melting so as long as we keep warning people about that crisis, support for climate change should come back. We don't have any other options is the world's largest open forum on the Internet debating "Global Warming" and in real time too. So get out there and defend this theory!!!!!!!!! Current news on both sides of the issue are displayed at:
Meme Mine, Toronto Canada

i think why not using that budget to determine the sea water to produce the electrical energy!... design a method and mechanical / chemical / biological instrument to generate the elctrc by sea water. we can stop the combustion activity to generate electrict…
kelainan, ipoh-melaka,malaysia

Yet another article from an "expert" with a personal barrow to push. As an eminent American diplomat once said "Where a person stands on an issue depends on where he/she sits". Research scientists (I've been one) require funds to carry out research obviously and certainly research is desperately needed to get the world out of the messy future we are heading into but as the saying goes....lets get real.When we tamper with nature, who knows what can of worms we will open. Planet Earth is not a laboratory in which we can carry out controlled experiments. Climate change (MMCC) is not the problem it's a symptom. It is just one of the "trees" in the forest of man's greed. Just peruse GEO 4, and wonder what GEO 5 will come up with. Mankind on this planet (and there is no Planet B) depends on Nature in one form or other for everything.......yes, despite the leaps and bounds that man has achieved during our existence on Earth, everything has a source in Nature. "Nature can supply our needs but not our greed" ...quote by Mahatma Gandhi. Request to the BBC.....More articles please from Steven Wallace and the likes and less from "self professed "xspurts". Then again, reading the comments to this article, looks like it went down like a lead balloon in many peoples' opinion.
Mike Perkins, Whangarei, New Zealand

I do not believe anyone is sufficiently competent to try tinkering with the planet with these schemes. Also it would need the agreement of every nation for us to embark on such dubious projects that would affect everyone on the planet - I don't see that happening soon. There is one thing we can all do and that is limit the population like the Chinese. One child per family throughout the UK for a start. It is scandalous that successive governments in the UK have encouraged population growth through immigration.
Ken, Stroud

The notion of geo-engineering is fine, but any solutions proposed should have minimal risks. A small experiment would be fine, but I'm very skeptical--do we really have the knowledge and technology to cool our planet? I think we will end up needing to do harder and more expensive things, like sequestering methane and carbon. I also think we are going to suffer as a species, no matter what we do. It would be better to face the difficulty than to hope for magical solutions.
Victoria Else, New Jersey, US

It seems there are many people who realise that we as a whole are to blame, the population. We should make moves to reduce paranoia and increase our understanding of each other and of our home, earth. The problem is multi national corporations whose sole purpose is to make money and seek control. This is what wars are fought over. Sorry for this leap across subjects, but it all counts for our need to change and change fast. If we want our government to act we need to explain to them in their language. Money. Drop tools and stop work. Don't buy high tax consumables such as fuel or cigarettes (for those who smoke), alcohol will do too. If everyone did this for just one day the loss of tax revenue would be immense, and more than enough for the government to sit up and listen. The problem is you won't do it!! Is someone out there influential enough to organise a Tax boycott day????...
Phil, Manchester

Mark from exeter. It isn't a solution, it is a quick fix from what I understand. It won't solve the issue, but it may provide us with the time we need to come up with ways to combat the issue at hand. Considering population increase and the industrialisation of countries, we're in for a disaster of some sorts eventually. We're just delaying the inevitable.
Aaron, Lincoln

There are a number of comments that I agree with including Kay Eyezee, Chester and Barnes, Chelmsford but from those that I have read [I have not read all] I agree most with steve johnson, Nottingham. The most enlightening and frightening film that I viewed as a child was Pinocchio, a masterpiece of celluloid as only Walt Disney could produce. Could I suggest that ignorance is our greatest enemy? If you are told something is so by 'experts' often enough, you may become a victim caught in a cage of fear and respectful trust with no means to think through the arguments for yourself. Stones do not rise into the air without coming back down to earth. Carbon Dioxide is at least nearly 1.5 times heavier than the gases that you find in air. There is more, Carbon Dioxide enrichment encourages plant growth, our plants should be growing faster. There is more, a match or any flame should burn less effectively if CO2 is increasing. There is more, a lot more [find out for yourself]. Dr David Bellamy disagrees with the 'Carbon Dioxide/Global Warming'. I have great respect for Dr David Bellamy [only because to the very best of my very limited ability I have read, understand and agree with his arguments.
Gordon McGinn, Troon , Scotland

This sounds like it could be one of many possible solutions to slowing down enhanced global warming and at £6 to research, a bargain. This is pointless though useless we address our carbon footprints and those of emerging countries moving forward. Looking at the maths, technology we have today and resources available, there's no reason for governments not to be able to turn things around dramatically within the next 10-15 years if they work together. The problem always seems to be the same though... Politics. There's too much power in oil as it is still 'powering' the world. Once green energies become more readily available (and are made more efficient), the world economy will begin to look a lot different than it does today - frightening prospect for some. Cleaner though! :)
Lenny, Amsterdam

The usual scaremongering nonsense. "Billions of people are likely to die". Why does Gadian re-iterate this hysterical nonsense? Is he not aware that the Earth's temperature hasn't risen at all this decade?
charles, Birmingham

Well i agree with doing this on a small scale in the polar regions. If it means that the polar bears stop drowning because they can no longer find as at the nothern polar region.
brian alderson, earth

There is an island of plastic waste clogging up the sea. The plastic appears to be absorbing heavy metals which is a good thing but marine life is eating the waste, which is a bad thing. The size of this free plastic heap is big enough to employ several large ships over several years to process it in some way. Could the giant rubbish island be re processed at sea, to become something else which could aid the environment? After all our own body cells have an outer lipid layer to protect it. Could we not develop a plastic layer that works like our cell's lipid layer with embedded transport channels etc? Surely if we copy some of the brilliant mechanisms that occur in nature we could eventually sort out these problems. The trouble is who would be willing to invest money in the planet's future?

this geo-engineering idea sounds great - anything to hold off global climate change for afew years has got to be worth a try - and whats more it wont cause salination of rainwater over land by anything significant. the whole idea of getting salt water into clouds is so you get smaller droplets becuase theres more of those nucleii around for water to stick to - and if theres smaller droplets then its less likely to rain, because only big droplets are heavy enough to escape a clouds convection cycle and fall to the ground. so putting salt up there will reduce rainfall, and therefore reduce the salt falling back down. but this is only really significant over the sea; clouds over the sea have about 100 of these condensation nuclei per cubic cm, and putting salt water up there will increase that to 110 - but as soon as you get onto land with pollution and dust particles that number goes up to 1000. so the extra 10 units of salt will have a tiny effect on clouds over the land when you consider the 900 other nuclei were already putting up there at the moment. and whats more, because you need big droplets to make rain, and big droplets have lots of water relative to condensation nuclei, the absolute number of salt particules falling in rain over land will be tiny, about 1 part in 8 million with this new technique, which is an absolutely negligible number and wont lead to any any noticable salination of rain falling over land.
Dave, Manchester

More scare tactics to inflict fear into the population, Global Warming is a scam. Maybe the people calling for world depopulation of humans would like to be the first I didn't think so.
Elena Cowie, Hebburn, England.

Global Warming, you goddamn liars. There is none caused by carbon emissions, you freaks.
Mark Davies, uk

We've got to remeber its not the planet we are saving, it's ourselves. Earth has recovered from much higher fluctuations in climate and it will 'surive' this one, but the question is, will we?
Dan, Gloucester

Instead of spending money on yachta, why not use the thousands of Oil Platforms that dot the oceans and test from a statioary position? Cheaper, faster and maybe Exon or Shell would fund the project.
Joy Coleman, Missoula, Montana

Reading these comments it saddens me that there are still people out there who refuse to accept scientific evidence that the climate of the planet Earth is changing. The evidence points towards our industrial activities being the cause, but even if somehow this is false it will still be disastrous for us as a species if it continues. Therefore research into methods by which such climate change can be halted or minimised is extremely important and will hopefully give us a greater understanding of the world in which we live while helping to solve the problem.
Alistair, Durham

The albedo of the oceans reflect a huge amount of radiation compared to inland albedo's. If the human made clouds were to cover the ocean then the radiation reflected from the ocean would hit these "anthro-clouds" and reflect radiation back to the earth resulting in further possible warming. Research needs to look at whether this occurs at such a rate that is worth spending the money.
Simon R, Dudley, UK

"Global warming is, and always has been, COMPLETELY NATURAL." But combustion of hydrocarbons in an internal combustion engine is not and never has been NATURAL. CO2 creating a warmer earth if increased is COMPLETELY NATURAL. Combustion of Hydrocarbons in an oxygen rich atmosphere produces CO2 NATURALLY. But our burning of 7 billion tons a year of oil is not natural and never has been.
Mark, Exeter, UK

Hmm. A "solution" that a) doesn't remove the problem b) requires continual repeat treatments c) stopping treatment means it is much worse Sounds like a crack dealer scam. Tell me, what does this do to solve the problem of excessive CO2?
Mark, Exeter, UK

The problem is not incoming sunlight, it is trapped infrared. Sunlight powers the biosphere. If we block sunlight, we will reduce plant growth - ask any gardener how much grows in the shade - risking reduced food production and ecological problems. Agrichar is a possible way forward. If water is available, atmospheric CO2 is an opportunity to make poor lands fertile enough to grow forests.
Clive, Cardiff

This is a band-aid on the cancers of pollution and fossil fuel consumption. Combined with some other feats of geoengineering, all of which could interact, we could end up with unforseen reactions and interactions of positive and negative feedback loops. A global sized experiment!
Ligija, Vancouver

We are living on a planet where everything is well designed and connected in an automatic cycle. Neither we think to take birth nor do we desire to reach at the end. If one thing goes, automatically other things come. It's an impeccable design. There is a no beginning and no end. More we go away from this circle, more we find ourselves in a difficult position because ours is not a cyclic development. Natural cycle has got its own rules, quite different from the existing norms of any country, religion, or any profit making profession. Dr.Gadian is trying to seek breathing space with geo-engineering experiments of cloud whitening. There is nothing wrong in conducting these experiments but its results should not give cushion to the present trends as nothing substantial is going on crucial issues like check and reduction of human population, habitat development for other species of the planet, afforestation, environment literacy and alike. There are infinite human rights but there is no universally accepted environment action plan. I strongly believe that we have more than enough water on this planet. The need is to 'free' this water in to natural cycle and not to restrict it. There is more than enough land on this planet. The need is to redefine the space for every creature in proper proportions. There is more than enough breathing space. The need is to recreate forest at appropriate levels. Restrict the consumption of fossil fuel before we get converted to fossils. If we keep ourselves within the boundaries of natural cycle we may think of light years not of few years. Generate a healthy environmental set up and life style and stick to it irrespective of any nationality and religion.
Sanjay Singh Thakur, Indore,India

Global warming is, and always has been, COMPLETELY NATURAL. It will happen regardless what we do, all were doing it making the world a worse place to live by trying to change whats working perfectly fine. Pumping sulphur into the air over cities and residential area's is probably doing more harm than good, how about you put 6m into stopping aeroplane fuel companies creating chemtrails above our childrens parks rather than poisoning the clouds to stop a few rays.
Kay Eyezee, Chester

As many people have commented, our population and consumption levels are the problem, they are already more than our planet can cope with. However, I'm not sure that we can find enough human lemmings, prepared to sacrifice themselves for the good of the few! The best that any of these well meaning experiments can do is delay the inevitable and at the worst they will bring forward the "final solution". Unfortunately, only a massive natural disaster, which reduces our numbers to a "managable level", is going to solve this problem. Lets just hope that there will be someone left at the end of it!
Vince Corbin, Canterbury Kent

How nice of John Byng to volunteer some Africans (or anyone else disproportionately affected by drought) to die for the cause of the planet. The flaw in his reasoning, quite apart from its moral repulsiveness, is that those Africans most likely to die have a miniscule carbon footprint. I'm sure Mr. Byng could create a far larger impact by removing himself from the carbon cycle.
Patrick Nevins, Mooresville, NC, USA

£6m for research to find out if geo-engineering is viable? Ronaldo just went for £60m. That £6m is a penny compared.
Stew Rogers, Canada

Probably the most stupid set of ideas ever to be articulated by someone calling themselves a scientist ..... totally impractical, unnecessary - especially if it turns out climate change is natural - politically impossible, will be a hundred times more expensive than thought, and even if it works technically will have unimagined negative dire consequences. Thank god for the democracies we live in that will prevent such lunacy.
Imran, Brunei

Research definitely needs to be done, meanwhile we have proven methods-but they involve changes in personal and CORPORATE behavior. Mostly we already know what needs to be done.
kath, aberystwyth

what happens when these clouds rain? Do we get salty water falling on land? If so isnt that a problem?
andy R,

global warming, terrorism - these are politcal creations with a political agenda, global warming/climate change was created by the club of rome think tank after the west lost communism as their public 'enemy'. The whole idea of there being too many humans is also erroneous - every human on the planet could fit into texas - the truth is the controlling elite are afraid that the cat is out of the bag and we the public will soon turn on them for poisoning us, lying to us, committing illegal wars and stealing our money and resources - this is why they are putting all their efforts into brainwashing and radicalising us against one and other yet again - remember the entire worlds media is controlled by a handful of humans who are chosen to further the agenda of mass depopulation so the elite can enjoy 'their' utopian dream without us the people that they have enslaved for millenia, educate yourselves - dont take anything at face value - we are in a war here for our existence.
steve johnson, nottingham

The problem with all these technical solutions is that we, as a global society, have come to the end of the Growth era and in 2009 have entered the Decline era. Why? Because world oil production has peaked. Because oil has to be discovered first and discoveries of new oil fields have peaked in 1962, 47 years ago and because nowadays we consume five times more oil then we discover. World oil production has started to decline this year after four years of stagnation, and it will continue to decline for the foreseeable future. That will drive a 30 or 40 year spiral of decline across the world, which may only stop when our energy consumption is forcibly reduced to some 25% of current energy consumption - a level capable of being supplied from renewables. And that means that all our resources will be wasted on attempts to slow down or reverse the Decline, which are of course bound to fail - at least until we reach the renewables level.
Paul Sousek, Cornwall

For £6 million why not, money well spent. Good luck i'd say.
Richard Johnston, South Croydon

We may as well 'all' already be dead. How about planting billions and billions of trees everywhere instead of watching them all burn down? Simple fix, world wide contributions of tree planting every day?
M. Weeks, worcestershire uk

Surely this must be one of the stupidest ideas yet. Where will the salt land? Presumably with rainwater making the water undrinkable and the soil it lands on sterile.
Frank Mitchell, Nuneaton, UK

This project is an excellent idea. Regardless of whether it succeeds or fails, we should be encouraging more research into geo-engineering solutions by diverting funds from defence and propping up the banks to much more worthwhile and valuable causes for humanity and the planet.
Neil, Mahboula, Kuwait

So the clouds will rain salt water onto the land and cause the crops to fails. Reserviours will become saline and undrinkable and famine and thirst will ensue
Gill Pearce, Devon

Science Fiction authors have long used 'terra-forming' technologies within their plots and alien worlds, and before anyone scoffs, please remember that it was a science-fiction author, Arthur C. Clarke, who foresaw satellites being used in global communications. I do not believe that any single course of action will prevail to stabilise our warming planet, because we simply do not know what percentage of change is a natural shift, and how much is caused by human impact. What we can do is minimise our impact with better house-keeping, but this often requires trust or faith in authorities, and there is a lot less trust around. Meaningful actions need to start at 'grass-roots' and become popular for them to succeed. This will require some evidence of success and better education to overcome the inertia of international nimby-ism (not in my back-yard). Before we seed the skies with salt, improving our efficiency with energy generation and its use could also help to cool down the problem and provide more space to understand and address the issues surrounding climate change.
Simon Mehlman, Manchester, England

As usual, typical pie-in-the-sky thinking from those who think they understand climate change but in reality don't. Whitening clouds - great idea. Do you have any idea of what long-term knock-on effects to our detriment that such a move may have? Probably not. Maybe some of that salt will start falling on land - what will that do to agriculture? The last thing we need is more tinkering. One of the problems we have is over-population on this planet and a famine is the very thing which the earth will do to restore the balance.
John Byng, York, UK

Nothing but pure scaremongering! There is so much contradictory research produced by so many different institutions that no one in the general public can find clear, concise, unbiased or unweighted information. All these scientists with their grand designs and goals should look to the present issues with famine and the solutions required for that, rather than attempting to convince millions of people, with a level of general ignorance, that we are all going to die from something far worse than what the last person 'confirmed' would destroy us all.
Barnes, Chelmsford

Before settling on geoengineering, lets take out the politics and the vested interests. Solutions seem to be biased towards big company solutions! The public is sidelined and personal efforts marginalised. Domestic renewable energy has been held up by 5 years of failed promises for feed-in-tariffs. The solar thermal industry is now in decline, largely due to govt indifference and a failed grant scheme. We have just seen Vestas close the only major wind turbine factory in the UK and to now talk about carbon sequestration! Dare I suggest that only big projects are considered due to the lack of potential for directorships and kudos when looking at the domestic scale solution! We as people are the problem, we need to be the solution.
Simon Mallett, Maidstone Kent

Geo-engineering is one thing, but the simplest steps are usually the best, and the simplest steps are (unfortunately) curbing the damage done by each individual, and curbing the number of indivuals.
Andrew, Ashford, Kent

While the concept is interesting and may well be a part of the solution, there are some key ethical questions posed as this will mealy delay the inevitable. Would this desensitise us into inaction? This topic and important question were addressed two years ago at TED in a very good talk: Regards
Richard Gould, London

Why not just lob a load of dust into the atmosphere, just as Mount St Helens did a while back? It shouldn't be hard, a large explosion inside the top of a mountain that no one wants. Or we could stop trying to remove particulates from vehicle exhausts; when nature has a big fire, there's lots of smoke and ash to go with it, blocking the sun's rays and compensating for the CO2 produced by the fire. With our clean vehicle exhausts and power station scrubbers, we're dumping the CO2 into the atmosphere without the accompanying blockers.
Dave, Cambridge, UK

Most plants can't handle salty water. So what happens when the salty clouds produce salty rain over crops and other plants trying to soak up our CO2? Could this actually make things worse?
Richard, Southampton

A great idea in principle but could it produce 'salty rain'? Given the worries of food production over the next 30 years the last thing we need to do is poison agricultural land (and our drinking water) with salt.
Peter, Notts

With the capitalistic fervour evident in China, subsidized by the West, and the self-gratifying stupor North Americans exercise, something of an educated effort must be made by those who know, and care to finance it. I know Humans are in for a spectacular show, as the changes, now indicating the future, become more frequent and intense, yes, I agree with Alan Gadian. We should be so lucky, that the effort would bear positive fruit. More power to him. Ed G. Gil/Photographer
Ed G. GIL, Toulouse, France

Good idea to test. But there is even a cheaper and risk free way - Attitudinal change and speaking forth the "Holy word"
Tanko, Tema/Ghana

Well intentioned interference is likely to be more dangerous than global warming itself. Creating a more reflective cloud cover may trigger a new ice age with infinitely more damage to human (and animal) existence than global warming poses. Once triggered, a new ice age could not necessarily be 'turned off immediately'. There is a huge arrogance amongst scientists and, at the very least, their experimentation should be subject to a popular referendum.
John, Tiverton, Devon

In my lifetime; since the early 1970's, the human population has doubled. Even worse than that, the impact of those people on the planet has also gone off the graph. CO2 emissions is only one sympton of the damage we are doing. This cloud seeding is a desperate attempt to "carry on business as usual" It does nothing to repair any of the other damage done by 6billion people ripping up the planet. We should have started on the problems of human activity, way back in the 1960's; 40 years ago. So we reflect some heat into space; so what ? Unless we fix the fundamental problem; too much human activity; these are simply seeds of delusion thrown into the sky from a sail boat of fantasy . . . . I mean; by the time the money guys get on to this; the reality will probably some rusty old oil tanker with a clapped out pump We need to scrub off 80% of the human impact on the planet if it is to have any chance of repairing itself and continue as a home for us. We need to talk about what to do about "us" - not go off on some fantasy cruise aboard a glistening white yatch, lounging on the decks all day, and pointing at the fluffy white clouds coming out of the funnels. What are going to call this boat; "the good ship lolipop" - or perhaps "Titanic" So the clouds look nicer; whiter and fluffier ? But what are going to do about the problem; "us" Cheers Steven
Steven Walker, Penzance

As much as I respect Dr. Gadian's sentiments in wanting to do something to curb global warming, it seems to me that not only does this seem like a desperate stab in the dark, it could also potentially cause more problems than it solves. its fine if the sprayed clouds move out to sea, but say they travel onto a land mass before releasing their rain drops. would this not add insult to injury to those many areas of the world hoping and praying for long awaited rain to eventually recieve it, but not only is it undrinkable, but also ruins the soils that they are trying to cultivate. it is clear from many, many past examples that although we may think we know how this planet and its atmosphere works, we really don't understand the bigger picture. The only real change will occur once humanity stops screwing this planet like an old whore.
lyndon forster, Bournemouth, England

dear sirs, Increasing cloud cover as a means of improving solar reflectivity is by no means a new idea however Alan Gadians twist, of using NaCl as nuclei boarders on lunacy and is actually unnecessary. All fresh water originates from rain which in turn originates from the oceans. Whilst the water is evaporated it isn't totally distilled and does carry some salts, (the tiny traces of Molybdenum in our soils, an essential nutrient for plants is renewed through rainfall)l. However the slight increase in water density of this 'contamination' causes the cloud to shed its load early resulting in soils in coastal areas have higher relative levels of the trace element than inner continental soils. Increasing this density further through seeding of Na will result in aggravating premature cloud burst which in turn will lead to less rainfall occurring in central continental lands and exacerbating inland droughts. Furthermore the rain that does penetrate will be contaminated and it's presence will impact adversely on the remaining glaciers. What is by far a better method is the use of solar chimneys to generated updrafts which can then be fed with water vapour. The vapour carried on the updraft is then subject to rapid cooling to produce tiny very opaque ice crystals which are extremely efficient at reflecting solar radiation (you can see this effect everyday; vapour trails left by aircraft are a consequence of the rapid cooling of water vapour generated by jet engines). You can also see a proposal to use this in a youtube video presentation
malcolm mcewen, jersey u.k.

yes this is worth doing its cost is trivial but we should also reduce the number of diesel engined cars because although they generaly produce less CO2 than petrol cars they also produce much more NITROUS OXIDE than petrol card
richard t ratcliffe, worksop uk

Cue all the fundamentalists from the Church of Human Environmental Impact Denial.
Ryan, Glasgow

Unlike many proposed geoengineering schemes, cloud seeding is inexpensive, easily expanded, and can be easily stopped when needed. This research ought to be funded without delay - we all know the politicians aren't going to be able to deliver anything other than token results any time soon!
Andrew, Glasgow, UK

Frankly, until mankind as a whole addresses population growth and makes a serious attempt to redress the imbalance nothing is going to change although every effort should be made to slow the process of climate change. We have to understand that support of the world population at its current level, never mind projected growth forecasts and correcting climate change is unattainable since there are just not sufficient resources available to sustain the rate of population growth.
Richard Long,

Go for it. We need this and we need it soon.
Bradley Sneddon, Melbourne, Australia

Every time man has messed around with nature there have been unforeseen consequences. The solution is to STOP producing greenhouse gases completely rather than cutting them down. Leave the planet alone!
John McKay, Northampton UK

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