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Geoengineering - a climate get out of jail or risk to all humanity?

25 May 2022 7:15 PM
Digital technology

We need to do more reduce global warming, but this may come at a high cost.

Humans have for centuries set their behaviour according the weather and seasons. Some of the first gods regulated it, we never thought one day we would affect it and maybe even control it. Geoengineering is the science that may change that and save us from the worst of climate change, but there are costs and risks, so we are back in the realms of the fickle weather gods.

What is it?

An intervention to current conditions, typically weather related, to mitigate the impact of global warming. There options based in space, the oceans and the atmosphere.


The sun’s energy actually causes the Earth to warm, CO2 and other greenhouse gases trap the heat created by the warmed Earth causing overall temperature to rise.

Blocking the solar energy before it reaches the Earth would reduce the heating and so offset the degree greenhouse gases increase the temp. Sending something to work like a shade or a lens to reduce the light would need to be sent a long way from Earth (about 1 million km) and have to be quite large, depending on the method about 1000 km in diameter. Currently the James Webb telescope uses a shade to keep itself very cool, that is about the size of a tennis court. Fans of Mike Myers might enjoy the Pentaverate which features a space based solution to global warming.

Other options are based closer to Earth but need more coverage and a lot more work to keep in space.


The sea absorbs a lot of CO2 already, in fact the increased levels and warmer seas are causing coral reefs to die which themselves are massive carbon capture tools as the reef is made from CO2.

The solution suggested using the sea relies on the ability of plankton to absorb CO2 as part of their natural life cycle, when they die they would take that to the sea floor. Most of our oil was created this way so we know it works. The catch is how to do it and how to avoid the algal blooms killing the other animals in that part of the ocean.

The solution is to use iron in parts of the ocean that have very little activity, the assumption being that the naturally occurring plankton would be able to rapidly increase in volume and absorb a lot more CO2, as long as we keep adding iron we can sustain the algal bloom as it captures more CO2. Iron is cheap and the process would use it in relatively low density but it would need to be done for a very long time and a long way out to sea. Deciding exactly where and again who will be responsible for running the operation is to be decided.

Another long shot option is to spray sea water about 300 m in the air, it will more likely result in cloud formation which produces more shade and reflects more thanks to its albedo value (more on that later). Just where to set up 300m high water fountains able to maintain a fine mist somewhere in the middle of the ocean is going to be a big task and probably would not work so well in the same areas that the plankton farming is happening.


CO2 concentration in the atmosphere is 0.04% or 420 parts per million. That is a relatively small amount considering 78% of the air is nitrogen and 21% is oxygen, so 99% is just those two, of the remaining 1% CO2 is still only a small part. Unfortunately it does not take much to have a big impact.

The upside is that it might not seem like we need to remove much, but the reality is that you need to process a lot of air to capture just a little CO2.

Still, the direct capture machines especially if placed near outlets of more concentrated CO2 can help.

Not as much or as cost effectively as a tree though, but then the number of trees needed also need to be planted in places that we have removed them for grazing or farming, planting them where they are not already will probably not see them thrive.


Like the space options this seeks to lower the amount of light reaching the Earth or lowering the amount the Earth gets heated.

Different surfaces reflect or absorb light, those that are highly reflective tend to remain cooler and are said to have a high albedo value. The more reflective we can make surfaces the more we reduce the heating of the planet. Almeria in Spain has so many greenhouses that the light plastic roofs have resulted in lower temperatures to the region. Snow, ice caps and glaciers work well, but as the Earth warms and the ice recedes it heats even more.

Desserts, grasslands and cities have very low albedo numbers so introducing more trees and using more reflective paints for roofs and roads could help.


Following volcanic eruptions, especially two in the 80s and early 90s sent enough material into the air and that rose so high into the sky that it lowered global temperatures for the next few years. It sparked an idea that if we sustained the one or two percent volume of something to dim the light entering the Earth’s atmosphere it would offset the effect of global warming allowing us time to transition away from fossil fuels. It is the rate of transition at the moment that means we will miss the targets and exceed the safe limits which could trigger massive changes to weather.

The process to do this has been called SCoPEx or Stratospheric Controlled Perturbation Experiment. It got a lot of attention about a decade ago and looked set to begin testing a few years ago before it was put on hold. The plan is to still do the experiment but the questions about if it should be done are now getting a lot more attention.

While the volcanoes did result in lower temperatures, it also resulted in lower crop yields. Even if the experiment show that we can lower temperature practically and at a fair cost, how do we factor in the potential impact to agriculture or perhaps where it will affect agriculture.

The sun’s ray are most intense over the equator so you might want to focus the dimming in that area, but that is also the rainforests and we need the trees and the biodiversity, if we tried to seed in the tropics we cover desserts but also grasslands which is often farmland.

If we did buy extra time to transition from fossil fuels would we not just slow the transition, just like we chose to not use less plastic when the oil industry told us we could just recycle it.

Assuming the intervention works and we have global adoption for it, we would not be able to stop until fossil fuel use had dropped significantly, should we stop because the will to fund it or the operators simply can’t continue the heating will return but will not only rise to potentially higher levels, it will rise faster than it has before.

What to do

Experiments that will not have lasting effects should be encouraged, even if to confirm that we should never look to implement it.

We have completed one geoengineering project already, we used fossil fuels in such volumes that we have changed the climate. We were aware of the potential impact over a century ago, but were more focused on shorter term issues and actively encouraged to not believe there was a risk, some still try to make that argument.

The focus needs to remain on lowering CO2 output, but it does not look like alternatives are ready to replace fossil fuels. Political will and commercial interests may also not align with not using fossil fuels in which case having to also use other methods may be a final hope to avoid the worst of the disaster, but we don’t know enough to take small experiments to a global scale and manage to fund and implement it let along get the world to agree how it should best be done.

25 May 2022 7:15 PM
Digital technology

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