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Scientists debate experimenting with climate hacking to prevent catastrophe

Posted on 1 June 2016 by dana1981

On his late-night talk show, Jimmy Kimmel recently invited climate scientists to explain that they’re not just messing with us about global warming.

In fact, climate scientists are so worried that we’re going to fail to prevent catastrophic consequences that some are studying how we can hack the climate, also known as “geoengineering.” This approach is essentially viewed as a last-ditch, “break glass in case of emergency” desperation option in the event of such a failure. Some climate scientists view this as a potentially reasonable way to deal with climate change, but others disagree. It’s a controversial topic.

Scientists have proposed various ways that we might use geoengineering to stave off a climate emergency, but one of the most popular involves pumping particles into the atmosphere. Volcanic eruptions spew tiny sulfur dioxide particles (aerosols) into the atmosphere, which reflect sunlight and act to temporarily cool the planet. If humans were to similarly pump aerosols into the atmosphere, in theory we could offset some global warming. This is known as albedo (whiteness) modification, because we would be modifying the Earth’s reflectivity.

If the idea of mimicking a continuous volcanic eruption makes you nervous, you’re not alone. A National Academies of Science (NAS) report warned that the potential side-effects of this type of climate hacking are not well understood or quantified. Moreover, it would not solve the problem of ocean acidification – sometimes referred to as “global warming’s evil twin” – a major threat to marine ecosystems that only 20% of the British public has ever heard of.

Hotter and more acidic oceans form a one-two punch that’s killing off coral reefs, for example with the mass bleaching event that’s currently ongoing. Coral reefs are home to 25% of marine fish species, so this is a critical concern. It’s carbon that’s causing the world’s oceans to become more acidic, so we can only solve the problem by cutting carbon pollution or by removing it from the atmosphere.

Recently the US Senate appropriations committee passed a spending bill that mysteriously included funding for the computational study of albedo hacking.

Climate hacking field experiments could be like nuclear weapons tests

Some are pushing not just for the computational experiments funded by the Senate appropriations bill, but also for field experiments. They cite the NAS report as supporting such field tests, but one of its authors, Ray Pierrehumbert explained that the report first calls for some sort of regulatory process to be put in place:

Our NRC report does have a cautious statement saying that under some circumstances small scale field trials may become necessary to address scientific questions, but that statement is loaded with caveats concerning the (as-yet undemonstrated) scientific payback from such experiments regarding the questions that most need to be answered, and the need for some form of governance process (“serious deliberative process”) which would define what would count as “small scale.” There has not yet been any “deliberative process” of any sort, open, serious or otherwise, and indeed nobody seems to know what such a process would look like.

The concern is that there are risks associated with these experiments, and without an international oversight framework in place, conflict could arise between nations with different ideas about the associated dangers:

The risk is of a sociopolitical nature: it opens the door to a process that is unregulated, and which nobody knows how to stop, for which there is no governance in place, and which some scholars (myself included) think is fundamentally ungovernable. It’s similar to a nation without nuclear weapons beginning underground weapons testing. It’s not the threat to the physical environment that is the chief source of concern, but rather that the tests breach a significant barrier on the path leading to deployment, and have a substantial risk of triggering escalation as other nations respond.

Moreover, this form of climate hacking is inherently riskier than researching technologies to remove carbon from the atmosphere:

It’s strange and alarming that they chose to highlight the most dangerous form of climate intervention (albedo hacking) instead of asking for a big push on carbon capture, which addresses the root cause of the problem and moreover is the key backstop technology for staying under 2°C in a way that doesn’t put the Earth in a perilous state.

Since the rising carbon pollution is also the root cause of ocean acidification, unlike albedo hacking, carbon capture technologies would address both problems. We may eventually reach a point where albedo hacking becomes necessary, but field experimentation poses its own risks unless an international oversight framework is first established.

President Trump might make climate hacking necessary

The international community has been making significant progress in cutting carbon pollution to prevent the need for an emergency geoengineering effort, particularly through the Paris climate accords. However, Donald Trump has said that if he’s elected US president, he’ll do what he can do undermine that agreement, for example by trying to undo President Obama’s Clean Power Plan, and enacting policies to burn as much fossil fuels as possible.

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Comments 1 to 11:

  1. I think that the f bomb was a little overboard. One round would have been enough and that without the child mouthing it.

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  2. I think what we really need is to hack our political system.

    Or rather un-hack it. It has already been hacked by the fossil fuel industries and their friends, preventing us from taking the proper steps to reduce CO2 emissions.

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  3. I think it is just great that we need to have comic actors do psa's because our political leadership are bought off and will only gently push the envelope from behind the scenes if they are aware of the scientific reality at all. I wish that I could transport back to us today scenes of this planet 30 years from now when the Arctic sea ice melts out in mid August, and perpetual drought, hunger, migrations, sea level rise and mass human and animal die-offs are the norm. It wouldn't be so F_ing funny then.

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  4. Looking back, somewhere in the 1980's, this would have been very exciting.   Now it could be ironic epitaph.  Kids, you will have great struggles ahead. 

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  5. I shudder to think of us controling the heating of the atmosphere by some engineering feat while still spewing Carbon dioxide into the atmosphere,  The funds run out or some other factor stops the ongoing injection of sulphur into the stratosphere.  Mean time we are up at 500 or 600 ppm Carbon dioxide.  The longer before the brown stuff hits the wind pusher the worse the situation would be.  As fast as the changes are at present that we  observe, the rate of change in such a scenario would be devestating.

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  6. "…we can only solve the [ocean acidification] problem by cutting carbon pollution OR by removing it from the atmosphere."

         The "OR" should be "AND" — the task of preserving the oceans calls for far more than "Go thou and sin no more." To preserve the oceans, we must preserve the climate.

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  7. Perhaps the moment has come when we (more precisely, those scientists in the relevant disciplines - including  Guy McSpherson and Paul Beckwith -  should collectively disband the IPCC and tell the world leaders to their face what a useless bunch of tosspots they really are. Having done that I  suggest that a sober investigation into just how far away from extinction the human species really is would be really nice to know and if it is avoidable or not.

    I cannot think of any other course of action that stands a chance of bringing them to their senses.

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  8. funglestrumpet@7,

    Your "sober" approach that considers the "extinction the human species" and ignores everything else is akin to destroying the entire global civilisation - all 7b individuals - leaving just a few thousand hunters-gatherers - all that is required to maintain our species. You probably don't realise the meaning of your post overwise you would not have posted it. Please try to realise next time.

    Reading, needless to say arguing with such nonsense is a waste of everybody's time.

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  9. Irreversible rapid climate change and ocean acidification and warming is under way. Reducing the rate of emission of fossil fuels with only slow down the increase in these processes. Adapting measures to cope with the consequences, such as sea level rise, should be a widely adopted policy.

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  10. Suggesting earth can be cooled by emitting surfur dioxide into the atmosphere and by brighting clouds neglects evidence that the thick layer of sulfur dioxide in the upper regions of Venus, making Venus the most reflective (and hottest overall) object in the solar system is at least partially responsible for heating the surface of Venus to 462oC.

    While the sun produces much more radiation over a wider spectrum than the surface, it is limited to a cosine pattern from 6am to 6pm earth day relative time, with a net positive heating effect occuring between 9am and 3pm in general.  It is further reduced by latitude and tilt of the sphere as well as slant path through the atmosphere.  To maintain a stable temperature earth radiates to space over the remaining 15 hours.  Space at close to a 0 absolute temperature (-270oC) is just as powerful in rejecting since it is a constant rate independent of latitude, tilt, and slant path length even though over a narrower infrared band. Adding sulfur dioxide to the atmosphere will stop that nighttime rdiative cooling effect and cause the planet to warm abruptly. If SRM can be limited to daylight hours, reducing the peak daily temperature, it may be benificial.  However, the highest, driest deserts can experience a 27oF swing in temperature (Kufra, Libya) since the nighttime cooling rate is faster in dry thin atmpsheres than in moist, low altitude environments where temperature change from day to night is less than 10oF  (New Orleans, La).  My hypothesis is that if Sulfur Dioxide were added to the atmosphere above Kufra, Libya both during the day and night temperatures would rise abruptly. While less peak energy would be available to heat the surface, the deminished nighttime cooling effect would last all night. Radiative heat is a driving force, but unlike linear pressure changes, pressure radiation flux goes up as the 4th power of temperature [Stephan Boltzman's Law], so higher midday surface temperatures drop faster at night, than cooler solar shaded daytime surfaces.


    • Space is an equally effective cooling mechanism over the entire nighttime interval in stable climates.
    • Space cooling is not subject to seasons or latitude.
    • Space cooling drops faster from higher temperatures than lower temperatures giving more time to reject heat.
    • A reduction of nighttime radiative cooling has a larger impact that a reduction of daytime radiative heating.

    Therefore, SRM, if allowed to affect nighttime radiant cooling  is a particularly contraproductive approach to achieving stable climates. 

    A better approach would be to 1) reduce water vapor and cloud cover at night using 100,000 per day commercial air flights to affect weather modification and tto 2) remove high latitude polar winter sea ice using year-round Arctic Shipping.  This approach is feasible as it could improve the cooling effect by 50 W m-2 over 4% of the earth and completely offset the 12.5 ZJ per year global warming to achieve active thermal control.  

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  11. Aaron Davis,

    On this current thread people are discussing how volcanoes cool the Earth.  Volcanoes cool the Earth by releasing large amounts of SO2 into the stratosphere.  The experiment has been done and SO2 cools the Earth. 

    Your claim that SO2 does not cool the Earth is uninformed ranting.  Look at the data  that thread if you have any questions.

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