by Daniel Brouse
The idea of climate geoengineering is gaining attention as the planet continues to warm. One proposal is cirrus cloud thinning: deliberately reducing high-level cirrus clouds to allow more infrared radiation to escape to space and temporarily offset some global warming.
I understand the logic. If the world remains on a trajectory toward 2.5–3°C of warming, the pressure to find additional ways to limit the damage will become enormous.
But I do not recommend geoengineering.
The fundamental problem is that we are dealing with an extraordinarily complex Earth system, not a thermostat.
Clouds Are Not a Thermostat
Clouds interact with atmospheric circulation, humidity, precipitation, aerosols, ocean temperatures, radiation, and the hydrological cycle. Changing one component can produce effects elsewhere that are difficult to predict or control.
Cirrus clouds are particularly important because their effects extend beyond simply reflecting or trapping radiation. Deliberately thinning them could alter atmospheric moisture, circulation, precipitation patterns, and interactions with other cloud layers.
We cannot assume that reducing one warming influence will produce only the desired result.
The climate system is interconnected.
Geoengineering Does Not Stop Global Warming
More importantly, cirrus cloud thinning would not remove the cause of the warming.
It would attempt to counteract one radiative effect while humanity continued adding CO₂ and other greenhouse gases to the atmosphere.
The atmospheric concentration of CO₂ would continue increasing. Ocean heat would continue accumulating. Ice would continue responding to the additional energy. Water vapor and other feedbacks would continue responding to the changing climate.
In other words:
Fossil-fuel combustion → greenhouse gases ↑ → energy imbalance ↑ → warming ↑
Cloud geoengineering does not break that chain.
It attempts to counteract one consequence of the chain while the forcing continues.
That is a fundamentally different strategy from solving the problem.
We Are Already Geoengineering the Planet
There is an important irony here.
Humanity is already conducting a massive uncontrolled geoengineering experiment.
We are changing the atmospheric composition of the planet by burning fossil fuels and releasing enormous quantities of greenhouse gases. We are changing atmospheric chemistry, ocean chemistry, land cover, aerosols, and the planetary energy balance.
Fossil-fuel combustion is humanity’s contribution to geoengineering.
The solution is not to develop another form of climate manipulation to counteract the first one.
The solution is to stop the geoengineering we are already doing.
The safest climate intervention available to us is therefore remarkably simple:
Stop adding the forcing.
The Cloud Problem Is More Complicated Than Cirrus Alone
There is another reason I am particularly cautious about cloud geoengineering.
Not all clouds have the same climate effect.
Low-level clouds generally produce a strong cooling effect because they reflect incoming solar radiation back into space. High-level cirrus clouds generally have a net warming effect because they trap outgoing infrared radiation.
That distinction is critical.
The climate system is already experiencing changes in cloud distribution, cloud altitude, cloud cover, atmospheric moisture, ocean temperatures, and radiation. Deliberately manipulating one cloud layer while these other components are changing could create new feedbacks that we do not fully understand.
We should not assume that the climate response will remain confined to the variable we intended to change.
The Most Dangerous Feedback May Be Societal
There is also a significant societal feedback that is already observable.
The promise of technological fixes such as carbon capture has been used to argue that continued fossil-fuel use can be accommodated while technologies are developed to remove or offset the resulting emissions.
That creates a dangerous feedback:
continued fossil-fuel combustion → technological-fix promises → reduced urgency to transition → continued fossil-fuel combustion
Geoengineering could amplify the same feedback.
If people believe we can simply manipulate clouds, remove carbon later, or otherwise engineer our way out of climate change, the perceived need to stop the underlying forcing is weakened.
This is particularly concerning when technological solutions become a justification for continuing the activity that created the problem.
The result is a feedback within the human system that reinforces the physical climate feedback:
continued emissions → continued warming → promises of technological correction → delayed transition → continued emissions.
That is not merely a theoretical concern. The debate over carbon capture already demonstrates how the promise of future technological solutions can become intertwined with arguments for maintaining fossil-fuel use.
We should be extremely cautious about extending that logic to deliberate manipulation of the atmosphere and cloud system.
The Goal Should Be to Stop the Experiment
Geoengineering may eventually become something humanity is forced to consider under extreme circumstances. But that is very different from treating it as a preferred solution.
Every additional intervention introduces another layer of uncertainty into an already highly coupled system.
We should not try to engineer the climate in the opposite direction while continuing to engineer it in the wrong direction.
The enormous scientific and engineering effort required for climate intervention would be far better directed toward rapidly replacing fossil-fuel combustion and eliminating the source of the forcing.
Once we stop adding the primary forcing, the climate system can begin responding to that change.
Until then, we are attempting to compensate for an accelerating problem while continuing to feed it.
The safest geoengineering strategy is therefore the simplest one:
Stop geoengineering the planet.
The Feedback Coupling Network
Here is a simplified diagram of the interconnected feedbacks already operating within the climate system. Deliberately altering any part of this network could trigger large and potentially dangerous teleconnections and unintended feedbacks:
http://membrane.com/global_warming/Feedback-Loop-and-Tipping-Point-Network.html#Feedback-Coupling