Authors: Derek Paul and Metta Spencer

This planet is gradually warming, mainly because of the burning of fossil fuels, which add heat-trapping gases to Earth’s atmosphere. The increased temperature changes the climate in other ways too, including the rise in sea levels; ice mass loss in Greenland, Antarctica, the Arctic and mountain glaciers worldwide; shifts in the times when flowers bloom; and extreme weather events.

Life on Earth is dependent on a layer of gases, primarily water vapor, in the lower atmosphere that trap heat from the sun, while radiating some of it back and keeping our planet at a temperature capable of supporting life.

The sunlight that remains trapped is our source of energy and is used by plants in photosynthesis, whereas the remainder is reflected as heat or light back into space. Climate forcing (or “radiative forcing”) is the differential between the amount of sunlight absorbed by Earth and the amount of energy radiated back to space.

Several factors determine the size and direction of this forcing; for example light surfaces are more reflective than dark ones, so geographical regions covered by ice and snow reflect back more than areas covered by dark water or dark forests; this variable is called the “albedo effect.”

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A consistent SRM story line from our groups:
Below is an imaginary conversation with an eminent politician or thought leader where we explain our reasoning for refreezing the Arctic using SRM.  Comments welcome. 
Don’t we have to accept that climate change is inevitable?
No. Climate change can probably be reversed if we act quickly.
Where is climate change the most critical?
The Arctic!
Can’t we reverse climate change in the Arctic by drastic emissions reduction?
No!  Any cooling from emissions reduction will come too little and decades too late to halt Arctic warming.  The Arctic is currently warming about four times faster than the global average. 
So how can we reverse climate change in the Arctic and refreeze it?
By the application of cooling intervention techniques, also known as Solar Radiation Management (SRM).
But aren’t these highly dangerous?
The risks associated with all the proposed SRM techniques are minimal compared to the risks from allowing the Arctic meltdown to continue.
Isn’t Stratospheric Aerosol Injection (SAI) particularly dangerous?
The risks from SAI have been studied.  One conclusion is that the application to refreezing the Arctic is less risky than the application for global cooling.  The main risk from either is ozone depletion and increasing the ozone hole over the Arctic.  But experts who have studied this problem say that this risk would certainly be manageable for subpolar SAI.
Suppose the experts are wrong?  Suppose there are serious unintended consequences?
SAI would be ramped up over several years, allowing early detection of problems.  Subpolar SO2 injection ensures a limited lifetime for the aerosol, so the SAI effects could be eliminated within a few months simply by stopping the injection.
What about public opinion against SRM and SAI in particular?
This may be the main barrier to SRM deployment – not anything physical.  The risks from SRM have been hyped up ever since it was first suggested for tackling global warming.  The anti-SRM lobby is well organised and well-funded.  And scientists working on the emissions reduction strategy, promoted by the IPCC, have been against SRM as “letting the fossil fuel industry off the hook”.  This is known as the “moral hazard” argument, and it is still being used against SRM.
Is the fossil fuel industry pro or anti SRM?
The fossil fuel industry wants to preserve the status quo.  While climate protestors are focussed on emissions reduction, the fossil fuel industry knows it can win the fight, as it has been for the past forty years: the COP meetings have made no dent in the curve of increasing emissions and the curve of increasing CO2 in the atmosphere.  Having an oil executive leading COP28 ensures that emissions will be sustained.  The International Energy Agency forecasts only a slight reduction in emissions by 2050.  The only conceivable way to achieve net zero (CO2e) by 2050 is by removing a trillion tons or more of CO2 from the atmosphere and suppressing other greenhouse gases on a similarly massive scale.  
What does the fossil fuel industry think about the use of SRM for refreezing the Arctic?
They have not been asked!  However it is clear that the fossil fuel industry is keen to exploit a low-ice Arctic for its material resources: oil, natural gas and minerals.  Furthermore some governments would like to exploit the sea routes opening up as the sea ice retreats.  There is even competition between governments to exploit the Arctic.  Thus, though never admitted, there must be huge financial and political pressure against refreezing the Arctic, despite the Arctic being central to the climate crisis.
Who is supporting the refreezing of the Arctic?
Other than ourselves, the main group we know of is the Centre for Climate Repair in Cambridge under the former government chief scientific adviser, Sir David King. 
Isn’t the moral hazard argument against SRM still valid?
No.  The moral hazard is that we leave the application of SRM too late to be able to reverse climate change, thereby leaving civilisation with the prospect of an ever worsening situation as regards climate, extreme temperatures, sea level rise and extreme flooding events.  Climate activists seem oblivious to this point and continue to denigrate SRM.
What about ecosystems and biodiversity?
Refreezing the Arctic would not only restore the Arctic ecosystem with its natural biodiversity but also help to restore ecosystems and biodiversity elsewhere.  Weather extremes are damaging to plants and animals as well as to humans.   
Isn’t the strategy of emissions reduction and adaptation enough to deal with this worsening situation?
No.  Emissions reduction can only make the situation worsen a bit slower over the coming decades.  Adaptation to an ever worsening situation means that you are always running to catch up.  The wealthiest people may feel themselves safe and able to cope: “I’m all right, Jack!”  But the strain on international relations, both from the unequal effects of this worsening situation on different countries and from the starvation and mass migration it would trigger or exacerbate, means that conflict could rise to the world war level, affecting everyone on the planet.  This is an existential risk for our very civilisation.
What about the governance of SRM?  
Cloud techniques such as Marine Cloud Brightening (MCB) pose a governance problem, because they cannot be confined to a single country.  There may be benefits for one country and adverse effects for another.  Subpolar SAI does not have this problem since the aerosol quickly spreads round the planet as it spirals towards the pole, driven rapidly eastward by high level winds and slowly northward by the Brewer-Dobson circulation.  Thus SAI necessarily produces a blanket cooling effect. Any country can do the injection: the cooling effect will be the same and everyone will benefit.
Would cooling the Arctic have an immediate effect on the climate crisis?
We believe it would have an immediate effect on the trend towards ever increasing extremes of weather and climate, because the Arctic would be cooled relative to global warming.  This would increase the temperature gradient between pole and tropics.  The gradient has been decreasing due to rapid Arctic warming, and this has disrupted jet stream behaviour, causing it to get stuck in blocking patterns which give us the persistent weather which amplifies the effects of that weather, hence the observed extremes.
How soon could the trend be halted and reversed?
The SRM would be ramped up until a fall in Arctic temperature was detected.  This could take as little as five years with determined effort. A few more years and a decrease in extreme weather events might be detected.
What about Arctic methane?
Methane emissions from terrestrial and subsea permafrost have grown over the past few decades as the permafrost thaws.  Continued thawing risks a massive outburst at the gigatonne level.  This could be enough to boost global warming and take the planet into a hot-house state, according to some researchers.  Refreezing the Arctic would avoid this risk.  
What about sea level rise (SLR)?
Continued global warming this century could cause a metre of SLR by 2100 through ocean expansion alone.  Far more serious is the accelerated SLR caused by melting and glacier discharge from Arctic and Antarctic ice sheets.  The Greenland Ice Sheet (GIS) is of particular concern, since it is contributing an accelerating amount of meltwater and glacier discharge, already amounting to hundreds of gigatonnes of water (a cubic kilometre of water weighs a gigatonne), and overtaking the SLR caused by ocean expansion.
Isn’t Antarctica even more dangerous?
Yes, in terms of potential SLR.  There is mutually reinforcing feedback between the Arctic and Antarctica.  When GIS melts, the local sea level is not affected nearly as much as in Antarctica, and vice versa.  This is due to gravitation and planetary dynamics.  The SLR in Antarctica which GIS produces has the effect of raising the termination of Antarctic glaciers, thus accelerating their discharge.  Thus by cooling the GIS and slowing its glacier discharge, we can improve the situation in Antarctica as well as slowing SLR more generally.
Is there any hope for climate restoration?  
Yes indeed.  Everyone we know who supports SRM also supports climate restoration.  But we also believe that refreezing the Arctic is an essential precursor to climate restoration.  However, using SRM of some kind for global cooling is also essential on a slightly longer timescale.  And greenhouse gas suppression and/or removal will be essential for long-term sustainability and to allow SRM to be phased out after a few decades.
What should we work towards?
The planet needs to be in a state with zero net warming and a slow rate of SLR.  It is conceivable that the planet could be restored close to such a state within 50 years, i.e. by 2073, given determined and focussed international effort.  This could prove a major force for peace.



Cost-Effectiveness of Carbon-Dioxide Removal Methods

Costs determine scalability, and costs vary by a factor of 30,000 

Peter Fiekowsky and Carole Douglis, June 2023


Humanity has a moral obligation to future generations to restore a safe climate  that humans have actually survived long term.  
Carbon-dioxide removal (CDR) has two uses: to provide carbon offsets to emitters, and to restore the climate for future generations.
Government and industry are investing billions in CDR methods that today cost $500 – $1,000 to remove a ton of CO2. These “carbontech” methods provide the carbon offsets sought by carbon-intensive companies as society tries to reduce emissions. Although intended to be climate solutions, offsets cannot actually reduce CO2 levels because each ton removed is traded for and replaced by an extra ton emitted.
Restoring the pre-industrial climate will require lowering CO2 levels from today’s 420 parts per million (ppm) to below 300 ppm. Nature performs massive carbon-dioxide removal (CDR) –130 ppm– before ice ages, and occasionally at very rapid rates. We know how to do the same thing, at a cost of pennies per ton of CO2 removed.
Concerned individuals are starting to invest in climate-restoration solutions that cost thousands of times less than carbontech—a few cents per ton of CO2. These solutions, based on natural processes, have the potential to scale sufficiently to actually restore pre-industrial greenhouse-gas (GHG) levels and temperatures.  
Intermediate solutions such as solar photovoltaics (PV) and synthetic limestone have an important role in reducing future CO2 levels as well. (Solar PV avoids emissions, while synthetic limestone sequesters CO2.) These are both self-financing and can help achieve net-zero emissions 100 times faster per dollar invested than new tech CDR. 
Climate restoration could be funded by compassionate grandparents and future grandparents for whom a liveable planet is paramount—while carbon offsets and subsidies continue to fund expensive CDR projects.

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