Blocking Out The Sun Won't Fix Climate Change – But It Could Buy Us Time

Blocking Out The Sun Won't Fix Climate Change – But It Could Buy Us Time
Photo credit: Julius Silver

The Paris climate talks hoped to set out how we can reduce the amount of carbon we’re pumping into the atmosphere. But emissions cuts alone may not be enough. Atmospheric CO2 is the blanket that keeps our planet warm and any further emissions will mean more global warming. Observations in recent years show that warming is accelerating, that polar ice and glaciers are all melting, that sea level is rising … it all looks rather bleak.

Could we directly engineer the climate and refreeze the poles? The answer is probably yes, and it could be a cheap thing to achieve – maybe costing only a few billion dollars a year. But doing this – or even just talking about it – is controversial.

Some have suggested there is a good business case to be made. We could carefully engineer the climate for a few decades while we work out how to reduce our dependency on carbon, and by taking our time we can protect the global economy and avoid financial crises. I don’t believe this argument for a minute, but you can see it’s a tempting prospect.

Reflecting the sun

One option might be to reflect some of the sun’s energy back into space. This is known as Solar Radiation Management (SRM), and it is the most viable climate engineering technology explored so far.

For instance we could spray sea water up out of the oceans to seed clouds and create more “whiteness”, which we know is a good way to reflect the heat of the sun. Others have proposed schemes to put mirrors in space, carefully located at the point between the sun and the Earth where gravity forces balance. These mirrors could reflect, say, 2% of the sun’s rays harmlessly into space, but the price tag puts them out of reach.

Perhaps a more immediate prospect for cooling the planet is to spray tiny particles high up into the stratosphere, at around 20km altitude – this is twice as high as normal commercial planes fly. To maximise reflectivity these particles would need to be around 0.5 micrometres across, like the finest of dust.

We know from large volcanic eruptions that particles injected at high altitude cool the planet. The 1991 eruption of Mount Pinatubo in the Philippines is the best recent example. It is estimated that more than 10m tonnes of sulphur dioxide were propelled into the high atmosphere and it quickly formed tiny droplets of sulphuric acid (yes, the same stuff found in acid rain) which reflected sunlight and caused global cooling. For about a year after Pinatubo the Earth cooled by around 0.4℃ and then temperatures reverted to normal.

I was involved recently in the SPICE project (Stratospheric Particle Injection for Climate Engineering) and we looked at the possibility of injecting all sorts of particles, including titanium dioxide, which is also used as the pigment in most paints and is the active ingredient in sun lotion.

Blocking Out The Sun Won't Fix Climate Change – But It Could Buy Us Time The experiment to validate models of tether dynamics was cancelled. Hugh Hunt, CC BY-SA

The technology to deliver these particles is crazy – we looked at pumping them in a slurry up to 20km into the air using a giant hose suspended by a huge helium balloon. A small-scale experiment was cancelled because even it proved too controversial, too hot. Imagine if we demonstrate that this technology can work. Politicians could then claim there was a technical “fix” for climate change so there would be no need to cut emissions after all.

But this isn’t a ‘quick fix’

There are so many problems with climate engineering. The main one is that we have only one planet to work with (we have no Planet B) and if we screw this one up then what do we do? Say “sorry” I guess. But we’re already screwing it up by burning more than 10 billion tonnes of fossil fuels a year. We have to stop this carbon madness immediately.

Engineering the climate by reflecting sunlight doesn’t prevent more CO2 being pumped into the atmosphere, some of which dissolves in the oceans causing acidification which is a problem for delicate marine ecosystems.

There is therefore a strong imperative to remove the 600 billion tonnes of fossil carbon that we’ve already puffed into the air in just 250 years. This is known as Carbon Dioxide Removal (CDR).

We must work fast to cut our carbon emissions and at the same time we should explore as many climate engineering options as possible, simultaneously. However while reflecting sunlight may be an idea that buys us some time it is absolutely not a solution for climate change and it is still vital that we cut our emissions – we can’t use climate engineering as a get-out clause.The Conversation

About the Author

Hugh Hunt, Reader in Engineering Dynamics, University of Cambridge

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Related Books

The Uninhabitable Earth: Life After Warming Kindle Edition

by David Wallace-Wells
0525576703It is worse, much worse, than you think. If your anxiety about global warming is dominated by fears of sea-level rise, you are barely scratching the surface of what terrors are possible. In California, wildfires now rage year-round, destroying thousands of homes. Across the US, “500-year” storms pummel communities month after month, and floods displace tens of millions annually. This is only a preview of the changes to come. And they are coming fast. Without a revolution in how billions of humans conduct their lives, parts of the Earth could become close to uninhabitable, and other parts horrifically inhospitable, as soon as the end of this century. Available On Amazon

The End of Ice: Bearing Witness and Finding Meaning in the Path of Climate Disruption

by Dahr Jamail
1620972344After nearly a decade overseas as a war reporter, the acclaimed journalist Dahr Jamail returned to America to renew his passion for mountaineering, only to find that the slopes he had once climbed have been irrevocably changed by climate disruption. In response, Jamail embarks on a journey to the geographical front lines of this crisis—from Alaska to Australia’s Great Barrier Reef, via the Amazon rainforest—in order to discover the consequences to nature and to humans of the loss of ice.  Available On Amazon

Our Earth, Our Species, Our Selves: How to Thrive While Creating a Sustainable World

by Ellen Moyer
1942936559Our scarcest resource is time. With determination and action, we can implement solutions rather than sit on the sidelines suffering harmful impacts. We deserve, and can have, better health and a cleaner environment, a stable climate, healthy ecosystems, sustainable use of resources, and less need for damage control. We have so much to gain. Through science and stories, Our Earth, Our Species, Our Selves makes the case for hope, optimism, and practical solutions we can take individually and collectively to green our technology, green our economy, strengthen our democracy, and create social equality. Available On Amazon

From The Publisher:
Purchases on Amazon go to defray the cost of bringing you InnerSelf.comelf.com, MightyNatural.com, and ClimateImpactNews.com at no cost and without advertisers that track your browsing habits. Even if you click on a link but don't buy these selected products, anything else you buy in that same visit on Amazon pays us a small commission. There is no additional cost to you, so please contribute to the effort. You can also use this link to use to Amazon at any time so you can help support our efforts.

 

enafarzh-CNzh-TWnltlfrdehiiditjakomsfaptruesswsvthtrurvi

LATEST VIDEOS

What if Greenland Melted?
by Atlas Pro
Isostatic rebound isn't expected to be too great over Greenland, and instead is greatest over parts of Canada,…
Can We Terraform the Sahara to Stop Climate Change?
by Real Engineering
Is terraforming the Sahara of the solutions to Stop Climate Change? We'll explore this idea in this video.
Allergens Are On The Rise In Canada's Urban Centres
by CBC News: The National
Canadians across the country say their allergies are getting worse.
Bill Nye And The Climate Crisis
by MSNBC
On a special show before a live studio audience, Bill Nye the science guy discusses the climate crisis with Chris Hayes.
How Greenland's Massive Ice Melt Will Totally Transform The World
by Channel 4 News
Remember that heatwave back in August? Well, the Arctic remembers it too. Record rates of ice melt have been recorded…
China Is Positioned To Lead On Climate Change As The US Rolls Back Its Policies
China Is Positioned To Lead On Climate Change As The US Rolls Back Its Policies
by Kelly Sims Gallagher and Fang Zhang
As the effects of climate change become more widespread and alarming, U.N. Secretary-General António Guterres has…
What Happens When The Permafrost Thaws?
by Official W5
Almost half of Canada sits on permanently frozen land called permafrost, but climate change is causing it to thaw and…
We Are Striking to Disrupt the System: An Hour with 16-Year-Old Climate Activist Greta Thunberg
by Democracy Now!
In her first extended broadcast interview in the United States, we spend the hour with Greta Thunberg, the 16-year-old…

LATEST ARTICLES

How People Can Best Make The Transition To Cool Future Cities
How People Can Best Make The Transition To Cool Future Cities
by Abby Mellick Lopes
It is difficult to remember when we are in the midst of winter, but keeping cool in summer is a big issue for some…
What if Greenland Melted?
by Atlas Pro
Isostatic rebound isn't expected to be too great over Greenland, and instead is greatest over parts of Canada,…
Clean, Green Machines: The Truth About Electric Vehicle Emissions
Clean, Green Machines: The Truth About Electric Vehicle Emissions
by Jake Whitehead
Despite the overwhelming evidence that electric vehicle technology can deliver significant economic, environmental and…
How To Build A City Fit For 50℃ Heatwaves
How To Build A City Fit For 50℃ Heatwaves
by Adrian Pitts
The Persian Gulf is already one of the hottest parts of the world, but by the end of the century increasing heat…
Can We Terraform the Sahara to Stop Climate Change?
by Real Engineering
Is terraforming the Sahara of the solutions to Stop Climate Change? We'll explore this idea in this video.
Hope And Mourning In The Anthropocene: Understanding Ecological Grief
Hope And Mourning In The Anthropocene: Understanding Ecological Grief
by Neville Ellis and Ashlee Cunsolo
We are living in a time of extraordinary ecological loss. Not only are human actions destabilising the very conditions…
Healthy, Happy And Tropical – World's Fastest-growing Cities Demand Our Attention
Healthy, Happy And Tropical – World's Fastest-growing Cities Demand Our Attention
by Karine Dupré, et al
What does it take to be a happy and healthy city? In any city, myriad factors go into the mix – and of course we are…
The Government Is Right To Fund Energy Storage: A 100% Renewable Grid Is Within Reach
The Government Is Right To Fund Energy Storage: A 100% Renewable Grid Is Within Reach
by Andrew Blakers, et al
In a speech to the National Press Club yesterday, Prime Minister Malcolm Turnbull declared that the key requirements…