Ted's governance concerns deserve serious attention, but the argument remains too asymmetrical.
Ted treats continued climate warming as broadly manageable through adaptation, while evaluating solar climate intervention through the most extreme imaginable scenario: large-scale deployment, decades of dependence, institutional failure and abrupt global termination. That is not a balanced comparison of risks.
It also ignores the escalating costs of doing nothing—or doing too little.
Inaction is not a neutral baseline. It means accepting rising expenditure on heat-related illness, crop losses, water scarcity, wildfire, flood protection, coastal retreat, infrastructure damage, insurance withdrawal, ecosystem collapse, disaster relief and displacement. These costs accumulate year after year, while losses to nature, public health and social stability are often irreversible or never fully reflected in financial accounts.
The relevant comparison is therefore not between a risky intervention and a cost-free natural world. It is between different intervention pathways in a climate system that humanity has already altered.
“Termination shock” is also too often presented as though it were an inherent property of every cooling intervention. It is not. It is a specific failure scenario in which substantial greenhouse warming is masked for a prolonged period and the cooling influence is then stopped suddenly, without phase-out, replacement capacity, carbon removal or sufficient emissions reduction.
The warming revealed after termination is not created by the intervention. It comes from the greenhouse gases already accumulated in the atmosphere. A more accurate term would be rapid rebound warming following abrupt withdrawal of large-scale climate masking.
This distinction is especially important for marine cloud brightening. MCB could potentially be modular, regional, seasonal, adjustable and based on short-lived sea-salt particles. A bounded or regional intervention cannot logically produce a massive global termination event, because the rebound cannot exceed the cooling influence being withdrawn.
Humanity is also already experiencing warming unmasking as harmful aerosol pollution is reduced and part of its accidental cloud-cooling effect disappears. Cleaning the air is essential, but the loss of that cooling influence is physically real. It is inconsistent to accept the disappearance of accidental cloud cooling while rejecting research into whether a cleaner, controlled and reversible marine influence could temporarily reduce climate risk.
None of this proves that MCB or other forms of solar climate intervention are safe. Cloud responses, precipitation, regional circulation, ecological effects, governance and justice all require rigorous study.
But uncertainty cuts both ways.
There are uncertainties around intervention, but also profound uncertainties around unchecked warming, tipping points, compounding disasters and the capacity of institutions, insurers and public budgets to absorb mounting losses. Treating the risks of intervention as unacceptable while discounting the much larger cumulative risks and costs of non-intervention is not precaution. It is selective risk accounting.
The real choice is not geoengineering versus decarbonisation. A credible stabilisation strategy requires emissions reduction, carbon removal, adaptation, ecosystem and ocean restoration, and careful research into reversible methods of reducing excess planetary heating.
Research is not deployment. A controlled experiment is not a permanent planetary commitment.
The greater danger may be allowing climate damage and its associated economic, ecological and human costs to grow beyond society’s capacity to manage them, while refusing to investigate tools that could reduce those losses.
The burden of proof should therefore apply not only to intervention, but also to those advocating continued delay. They must explain why the risks and costs of inaction—which may far exceed the costs of responsible climate action and carefully governed intervention—should be accepted.
Thank you Paul, Nordhaus fails to appreciate that if humanity is collectively too stupid to deploy the global infrastructure required to maintain climate stability, that means we are too stupid to sustain a global civilization. The success of the Montreal Protocol in ending the use of ozone depleting substances is an excellent model for the successful collaboration between business, science and government required to establish an Albedo Accord, initially through business lobbying to convene a coalition of first mover nations. The Montreal precedent cannot work for carbon, which is a wicked problem, but it can work for albedo governance. Reflectivity has fallen by 2% this century, from 100 to below 98 w/m2 on CERES data, and shows every indication that this dangerous slide into planetary darkening is accelerating, with the rate of decline doubling each decade. As you note, nothing we do about carbon can reverse this trajectory on a practical time scale. I really liked your point from Irvine that cooling infrastructure should be made robust against opposition. We cannot afford to go back into the Dark Ages, but that would be the effect of following Nordhaus's advice.
Ted's governance concerns deserve serious attention, but the argument remains too asymmetrical.
Ted treats continued climate warming as broadly manageable through adaptation, while evaluating solar climate intervention through the most extreme imaginable scenario: large-scale deployment, decades of dependence, institutional failure and abrupt global termination. That is not a balanced comparison of risks.
It also ignores the escalating costs of doing nothing—or doing too little.
Inaction is not a neutral baseline. It means accepting rising expenditure on heat-related illness, crop losses, water scarcity, wildfire, flood protection, coastal retreat, infrastructure damage, insurance withdrawal, ecosystem collapse, disaster relief and displacement. These costs accumulate year after year, while losses to nature, public health and social stability are often irreversible or never fully reflected in financial accounts.
The relevant comparison is therefore not between a risky intervention and a cost-free natural world. It is between different intervention pathways in a climate system that humanity has already altered.
“Termination shock” is also too often presented as though it were an inherent property of every cooling intervention. It is not. It is a specific failure scenario in which substantial greenhouse warming is masked for a prolonged period and the cooling influence is then stopped suddenly, without phase-out, replacement capacity, carbon removal or sufficient emissions reduction.
The warming revealed after termination is not created by the intervention. It comes from the greenhouse gases already accumulated in the atmosphere. A more accurate term would be rapid rebound warming following abrupt withdrawal of large-scale climate masking.
This distinction is especially important for marine cloud brightening. MCB could potentially be modular, regional, seasonal, adjustable and based on short-lived sea-salt particles. A bounded or regional intervention cannot logically produce a massive global termination event, because the rebound cannot exceed the cooling influence being withdrawn.
Humanity is also already experiencing warming unmasking as harmful aerosol pollution is reduced and part of its accidental cloud-cooling effect disappears. Cleaning the air is essential, but the loss of that cooling influence is physically real. It is inconsistent to accept the disappearance of accidental cloud cooling while rejecting research into whether a cleaner, controlled and reversible marine influence could temporarily reduce climate risk.
None of this proves that MCB or other forms of solar climate intervention are safe. Cloud responses, precipitation, regional circulation, ecological effects, governance and justice all require rigorous study.
But uncertainty cuts both ways.
There are uncertainties around intervention, but also profound uncertainties around unchecked warming, tipping points, compounding disasters and the capacity of institutions, insurers and public budgets to absorb mounting losses. Treating the risks of intervention as unacceptable while discounting the much larger cumulative risks and costs of non-intervention is not precaution. It is selective risk accounting.
The real choice is not geoengineering versus decarbonisation. A credible stabilisation strategy requires emissions reduction, carbon removal, adaptation, ecosystem and ocean restoration, and careful research into reversible methods of reducing excess planetary heating.
Research is not deployment. A controlled experiment is not a permanent planetary commitment.
The greater danger may be allowing climate damage and its associated economic, ecological and human costs to grow beyond society’s capacity to manage them, while refusing to investigate tools that could reduce those losses.
The burden of proof should therefore apply not only to intervention, but also to those advocating continued delay. They must explain why the risks and costs of inaction—which may far exceed the costs of responsible climate action and carefully governed intervention—should be accepted.
Extremely well said, thank you!
Well done.
Great analysis, Paul. Towards the end I mistook "lever this large" for "fever this large". My febrile Earth moment.
Nicely argued, thanks.
Thank you Paul, Nordhaus fails to appreciate that if humanity is collectively too stupid to deploy the global infrastructure required to maintain climate stability, that means we are too stupid to sustain a global civilization. The success of the Montreal Protocol in ending the use of ozone depleting substances is an excellent model for the successful collaboration between business, science and government required to establish an Albedo Accord, initially through business lobbying to convene a coalition of first mover nations. The Montreal precedent cannot work for carbon, which is a wicked problem, but it can work for albedo governance. Reflectivity has fallen by 2% this century, from 100 to below 98 w/m2 on CERES data, and shows every indication that this dangerous slide into planetary darkening is accelerating, with the rate of decline doubling each decade. As you note, nothing we do about carbon can reverse this trajectory on a practical time scale. I really liked your point from Irvine that cooling infrastructure should be made robust against opposition. We cannot afford to go back into the Dark Ages, but that would be the effect of following Nordhaus's advice.