by Sanjana Kulkarni
figures by Jovana Andrejevic
The average global temperature is increasing faster now than at any time in the last 2 million years. This has fueled record-breaking droughts, heat waves, and wildfires, and has intensified weather patterns, causing more extreme and damaging hurricanes and rainfall. Human activity is driving this change, primarily through the emission of carbon dioxide (CO2) and other greenhouse gases, which are released when fossil fuels like coal, oil, and natural gas are burned to produce energy.
When sunlight strikes the Earth’s atmosphere, around 30% of it is reflected back out to space, and 70% is incorporated into the climate’s energy system. The Earth radiates some of this absorbed heat out to space, but greenhouse gases in the atmosphere prevent it from escaping. Greenhouse gases are necessary to keep the planet warm enough for living things, but very high concentrations are increasing global temperatures beyond the normal range (Figure 1). Although the best way to slow climate change is to reduce greenhouse emissions by switching to clean energy sources like solar, wind, water, and nuclear energy, the CO2 already in the atmosphere can persist and continue to exert warming effects for centuries. Geoengineering, the large-scale modification of Earth’s climate, is worth exploring because countries have been cutting their emissions too slowly to make any near-term impact on climate change.
Giving Earth Some Shade
The greenhouse effect increases the amount of sunlight that the Earth absorbs, thereby heating the planet. To counter this, several methods have been proposed to cool the Earth by reducing the amount of sunlight that reaches the Earth in the first place. These light reflecting methods are collectively called solar geoengineering. One method involves spraying tiny particles called sulfate aerosols into the atmosphere to reflect away sunlight. Sulfate aerosols are naturally released from volcanoes and desert dust. They are also produced by burning fossil fuels and actually offset a portion of global warming caused by greenhouse gases. However, when released at ground level during fossil fuel combustion, they cause dangerous levels of air pollution. Scientists are experimenting with releasing sulfate aerosols into the stratosphere using airplanes or hot air balloons, where the aerosols can effectively increase sunlight reflectance but are too high to cause dangerous air pollution levels (Figure 2).
The main advantages of this method are speed, reversibility, and relative cost-effectiveness, as it is estimated to cost $2.5 billion per year. Additionally, sulfate aerosols are relatively well studied because they already exist in the atmosphere. However, the stratosphere contains a layer of ozone, a gas that absorbs the most harmful types of ultraviolet radiation from the sun, and it’s possible that sulfate aerosols could initiate ozone-destroying reactions, allowing more ultraviolet rays to reach the Earth.
Another cooling method involves brightening clouds above the oceans. In general, darker objects absorb light while brighter objects reflect it. Brightening clouds above oceans would cause the clouds to reflect more light away before it can be absorbed by the dark oceans below. A cloud’s brightness depends on the size of the water droplets that comprise it (smaller droplets have more surface area, so they scatter more light and appear brighter). To brighten clouds, tiny seawater aerosols could be sprayed over the oceans, so that small water droplets form around them. The smaller the aerosols, the smaller the droplets that stick to them. However, changing the droplet size could also affect how long the clouds last and how much water they can hold. Because clouds form in the lowest level of the atmosphere, called the troposphere, cloud brightening has a greater risk of affecting weather patterns than spraying sulfate aerosols high into the stratosphere.
Cloud brightening requires more investment up front to build the machines necessary to take in seawater, convert it to tiny droplets, and spray them into the air. The machines would likely be carried on boats to move to different parts of the ocean, but they must be able to withstand strong ocean currents and weather conditions. The estimated cost of building a large enough fleet of these boats is $3-5 billion, in addition to ongoing maintenance costs.
The primary knowledge gap of solar geoengineering is in how rapid sunlight changes will affect other aspects of climate besides temperature. This can be studied in climate models, but it is difficult to test in the real world. There is also concern that the drop in sunlight may decrease plant growth, thereby increasing the amount of atmospheric CO2 and reducing crop yields. These methods also fail to address the root cause of climate change.
Engineering the Oceans
Another major problem of too much CO2 in the atmosphere is ocean acidification, which occurs when CO2 dissolves into the ocean and makes carbonic acid. Acids dissolve the hard shells of many ocean animals like corals, killing them. Additionally, many animals without shells are also sensitive to changes in acidity and can’t survive outside a narrow range. Another problem with high ocean CO2 concentration is that it causes even more CO2 to accumulate in the atmosphere. Oceans currently absorb 25% of the CO2 that humans release into the atmosphere, but oceans are reaching a limit and are not able to absorb as much CO2 as before.
Ocean fertilization is the best studied ocean geoengineering method and may be able to reduce both ocean acidification and global warming. It involves supporting the growth of phytoplankton, which convert CO2 into oxygen through photosynthesis. Microscopic phytoplankton perform around 50% of the world’s photosynthesis. Just like fertilizer can be added to gardens to help plants grow faster, different fertilizers can be added to oceans to help phytoplankton grow faster and consume more CO2. Iron is the main ocean fertilizer under consideration, and this process would be much cheaper and faster than planting more trees on land.
However, there are potential unintended consequences of this method. Overgrowth of phytoplankton could cause algae blooms that deplete oxygen from water, thereby harming marine animals. Additionally, although phytoplankton are crucial at the bottom of the marine food chain, a sudden increase in their population may shift the balance of different algal species, destabilizing the marine ecosystem. This is also more expensive, less efficient, and will take longer to set up than aerosol methods. The cost depends on the type of nutrient (iron or other) added to the ocean, but the average annual estimate is $450 billion.
Direct Carbon Capture
Direct carbon capture is an umbrella term for chemical reactions that filter CO2 from the air. Existing technology can store CO2 underground or funnel it to be used to make consumer goods. Carbon capture has fewer risks than the other methods, and it addresses the root problem of excess atmospheric CO2, but it requires more work upfront to research different techniques and build the necessary infrastructure than solar geoengineering.
Carbon capture methods have facilitated growth of a market for carbon trading, and several companies, such as Carbon Engineering, Global Thermostat, CarbonCure, and Climeworks have been working to commercialize their technologies. As opposed to the other methods, the costs of developing these technologies will most likely fall to the private sector, whereas public investment will be in the form of monitoring and regulation.
Geoengineering for the World
The primary challenges of geoengineering are conducting field experiments to accurately assess potential consequences and developing international agreements to safely deploy and monitor geoengineering technologies. If geoengineering were adopted, a combination of techniques would be used depending on cost, regional conditions, and the climate’s response. Different methods may have local or global effects, so regulatory policies need to be agreed upon by the international community. Therefore, many scientists have called for the creation of regulatory agencies to advise the United Nations and lay out plans for how geoengineering methods should be prioritized. Geoengineering could help us reverse climate change in a more controlled manner, buying us time to make our society more sustainable.
Sanjana Kulkarni is a first-year Ph.D. student in Virology at Harvard Medical School
Jovana Andrejevic is a fifth-year Applied Physics Ph.D. student in the School of Engineering and Applied Sciences at Harvard University
Cover image by cocoparisienne on Pixabay
For More Information:
- To read more about geoengineering, check out How to Cool the Planet by journalist Jeff Goodell and The Planet Remade by science writer Oliver Morton.
- Check out many other geoengineering methods not discussed in this post here.
- For a good summary about the lack of geoengineering research and the challenges of implementation, see this Nature article.
- For information about geoengineering research being conducted at Harvard, check out the Solar Geoengineering Research Program and the development of controlled stratospheric experiments.
- To learn more about ocean acidification and buffering, see this Nature Scitable article.
- For more information on global warming and its impacts on humans and other organisms, see journalist Elizabeth Kolbert’s writings.
Why is the MEER approach not mentioned?
This very promising method is straight forward and requires minimal development. It does not suffer from side effects that are difficult to address.
Why is the MEER approach not mentioned?
This straightforward method will require minimal development and has at worst minimal side effects.
Well, we have been geo-engineering our planet in a negative direction for 100 or so years and we can see the results: we know it cannot last. It looks like we can’t avoid some geo-engineering in a positive direction to try to bring us back to a sustainable equilibrium.
Research needs to be completed and unpopular decisions made if we are to persevere with our experiment in supporting large human populations.
If you believe in our First Amendment of the United States Constitution, you should allow my previous comment to be posted.
You do realize the 1st amendment only applies to government actors, right?
One more proof of what’s up with this Republic
This is misleading! Geoengineering, which realeases toxic and flammable nano particulate matter into the air, which reaches down to our very soil and into our lungs, is what’s drying up and heating up our weather, thus causing wildfires and extreme weather patterns. A self-imposed globalist evil agenda for the masses, is at play.
geoengineering, the large-scale manipulation of a specific process central to controlling Earth’s climate for the purpose of obtaining a specific benefit. Global climate is controlled by the amount of solar radiation received by Earth and also by the fate of this energy within the Earth system—that is, how much is absorbed by Earth’s surface and how much is reflected or reradiated back into space. The reflectance of solar radiation is controlled by several mechanisms, including Earth’s surface albedo and cloud coverage and the presence in the atmosphere of greenhouse gases such as carbon dioxide (CO2). If geoengineering proposals are to influence global climate in any meaningful way, they must intentionally alter the relative influence of one of these controlling mechanisms.
Present-day geoengineering proposals have focused on the global scale, particularly as evidence has mounted of increasing atmospheric CO2 concentrations and thus the prospect of global warming. Two fundamentally different approaches to the problem of global climate change have arisen. The first approach proposes the use of technologies that would increase the reflectance of incoming solar radiation, thus reducing the heating effect of sunlight upon Earth’s surface and lower atmosphere. However, altering Earth’s heat budget by reflecting more sunlight back into space might offset rising temperatures but would do nothing to counter the rising concentration of CO2 in Earth’s atmosphere. The second geoengineering approach focuses on this problem, proposing to remove CO2 from the air and store it in areas where it cannot interact with Earth’s atmosphere. This approach is more appealing than the first because it has the potential to counteract both rising temperatures and rising carbon dioxide levels. In addition, reducing CO2 in the air could address the problem of ocean acidification. Vast amounts of atmospheric CO2 are taken up by the oceans and mixed with seawater to form carbonic acid (H2CO3). As the amount of carbonic acid rises in the ocean, it lowers the pH of seawater. Such ocean acidification could result in damage to coral reefs and other calcareous organisms such as sea urchins. Reducing the concentration of CO2 would slow and perhaps eventually halt the production of carbonic acid, which in turn would reduce ocean acidification.
This sounds like another grand experiment from the technocrats who have no clue what the long term risks could be. Similar to the current experiment with the covid vaccines.
We do know with a high degree of certainty that if some efficacious cooling technique is not employed that the global average temperature will just go up to a temperature which is unlivable for human beings and most other species . We must stop the overheating of the planet if we hope to survive .
Agreed!
This is a very well written piece
I would be nervous of the law of unintended consequences though as well as letting the folks that caused the problem science the problem away
Perhaps we can look at a more gras roots approach For example
Agriculture has the potential to provide enormous positive benefits and can be instituted in a macro fashion at a micro level with a little government support for practices that grow soil organic matter (carbon)
Construction can go away from concrete and revert to gravel, wood or stone where possible
Government needs to reward sequestering (and reducing) carbon activities and discourage those which they currently support
Thanks…Gord
thank you gord!
You’re right. We MUST stop GEOENGINEERING!!! The agenda is proven to be about financial gain at any cost; including our health, pain, and suffering both short and long term. Thank you for proving our point that we need to stand up for what’s right, instead of accepting cash to publish false information. Thank you
Why everything was just fine until the Theory of Global Cooling started in 1970’s?
Is it possible that Scientists Playing withGeoengeenearing are the Humans causing the opposite of Global Cooling?
Why the underwater vulcanos in Antarctica are never pointed out for maybe warming the waters and melting icebergs?
Do you know about summing inside volcanic craters in Antarctica?
Why Billionaires and Mega Millionaires keep investing and buying Prime RealState Land in locations they are predicting to be Doomed by Global Warming?
Maybe Geoengeneering should be looking into what is happening in the lobbying of the Political Weather change before they are blamed for not paying attention in what they are being deceived into doing….and….after considering the political side… conecting the dots…
How the same people predicting the devastation of the Present and Future are investing in the same locations they are predicting to be the ones affected the most?
Do they know something we do not know?
I think these guys are simply lunatics that can’t handle anything being outside of their control, including the weather. Kind of like a strict high school teacher on a global scale.
The interesting reality is that technocrats are mostly Capitalist. For example, Elon Musk who proposes a microchip in the brain which would not help humans with anything whereas, the nuance is that vaccines are backed by experienced scientific professionals and doctors around the world. Solutions to pandemics is technocratic whereas, the better example of technocratic is Elon Musk and Andrew Yang.
Some uses of the word refer to a form of meritocracy, where the ablest are in charge, ostensibly without the influence of special interest groups.[5] Critics have suggested that a “technocratic divide” challenges more participatory models of democracy, describing these divides as “efficacy gaps that persist between governing bodies employing technocratic principles and members of the general public aiming to contribute to government decision making”.[6]
Yeah, I am not at all confident in any sort of “experiments” when it comes to playing around with the earths atmosphere or oceans. The earth’s ecosystems are far more complex than we can model, and just because we feel that we must lower the temperature, doesn’t mean we should try. Since we have no idea if the “side” effects of our experimentation will be worse than the “supposed” problem.
What if your attempt to shade the earth causes a massive global cooling? Or what happens if it gets weaponized, and can be targeted over certain areas.
Geoengineering should be banned, as it’s literally playing with our lives.
Are you comfortable with inevitable starving to death or burning to death from wet bulb conditions? Pay attention. China, the USA, and Europe are experiencing severe drought and wet bulb conditions. Fresh water is quickly disappearing and so are crops. Human habitat is rapidly being destroyed. Forget 2100, as if that is a magic date or something. The scientific models were deeply flawed. Phenomenon predicted to occur in 2100 is happening now. Climate is unraveling now and we are lucky if another human being is standing in 2026. Yes..it is happening that fast. Do the research, provided you have the courage and inner strength to look at the awful truth.
Why is government not taking strict action and ban everything that is harmful for nature?
Because TheUnitedStates is a Republic Governed by We The People and We The People are being duped/deceived to think TheUS is a Democracy Governed by Politicians.
Republic = Several States United 50 Constitutions ( 1 per State) 1 Federal Constitution ( Organized as a Condominium)
Democracy = 1 Unit Governed by The Federal Government ( 1 Constitution or Law for the entire Country ruling all the population as a bridge toSlavery)
Above is just a “short cut” to explain what is reality and what is perceived as reality.
The Government of the Republic of The United States for America, is not doing anything because they are “We The People”, very confused and under the impression that The Government are NOT “We The People”. This shift the Power towards the control of Politicians and other “Not Elected Branches” of the “Condominium”, to do what is best for them and theirs pocket, because the people that “employ” them forgot theirs power, theirs local Constitution, theirs inalienable rights, Human rights, etc…
Right and Left talks about Democratic process without explanation in context.
All parties like the idea of being in Power and Gaslighting “We The People”.
Why “We The People” are not demanding the people “payed” to do theirs job in the “Condominium” called Government to do what they where chosen to do trough a “preference” called vote, after theirs presentation during election ( live résumé)?
Why “We The People” keep repeating the word Democracy… but forget about Democratic Election to choose “Employees Representative”.
Why we the people can easily be fired from a job, but the “Condominium of the Country Employees” changed laws making it almost impossible to get removed ….even if caught doing nefarious actions or looking the other way or helping to hide the truth?
Now… I will be in the list for having an opinion.
I tried to reply,
but “moderators” didn’t allowed me to.
Your article on geoengineering is all wrong. Geoengineering has already been going on for many decades.
Check out Geoengineeringwatch.org and watch the new movie THE DIMMING THE GLOBAL CLIMATE
ENGINEERING
COVER UP. Lab tests prove this.
Yes! Check out this website. We all need to wake up!
Interesting read. Will certainly be eager to review the literature on spraying of sulfate aerosols.
Using nuclear energy is safe for the world???
switching to clean energy sources like solar, wind, water is Good.but nuclear plants are not safe i think.
Our planet is important.
Brand Sentrik
The greenhouse effect it’s caused by HAARP and geongeneering: the leyer the dimmer of chem trails full of metal nano particles “to reflect back the sun reyes”, spreading every day back and for by airplaines, is creating the greenhouse effect! They are dissolving cumulus clouds because it disturbs radar, radio communications, In Europe doesn’ rain but they keep dissolving rain clouds: look the WEF program: thry want the weather control before 2025 and they are creating the greenhouse effect for their agenda, starting by Covid, virus + vax production, food and water land control, we will have to pay and switch to OGM… it’s full of HAARPS in many countries, all bombarding the ionosfere with artificial suns, magnetic waves that encrease tempersture in the ionosphere, Listen to Dane Wigington ‘geoengeneering watch’ YT
What University or academic source did you get that from?
The real joke of this whole thing is that plastics will make the planet uninhabitable long long before climate change
More like population control. Why do a handful of people get to screw with the SKY???
The interesting thing about population control is that oil Corporations, gas Corporations and Capitalism is doing that right now with economic isolation of the workers and children who exploited by the wealthy who oppose unions and instead use Imperialism and neocolonialism to interfere with other countries as well as worsening War crimes like against the Palestinians which worsens food shortages, global warming and inflation.
Yup. *this*. A small group of non elected private stakeholder corporations are busy deciding the fate of the planet, and thus, all of us Human CARBON BASED lifeforms.
And disguising it as a “climate crisis” doesn’t actually work when the genuine science disproves their lies.
“You can fool some of the people all of the time, and all of the people some of the time, but you can not fool all of the people all of the time.” ― Abraham Lincoln.
The bulk of us are done being fooled by this BS.
Due To Capitalism, that is happening along with global warming being part of the equation that is increasing inflation, global warming, crime rate And the cost of living. Poverty worsens the plastic and trash problem that is due to the wealth gap, Imperialism and colonialism.
Nuclear energy has actually been proven to be incredibly safe, thousands are running daily and with new technology the likelihood for a meltdown is incredibly low. The Chernobyl disaster is what people usually point too as a justification however the type of nuclear plant that was in Chernobyl (RBMK) is only operational in Russia and there are only 10. As of now all modern nuclear plants are considered to be the safest and most efficient form of energy in the world.
In what way is nuclear not safe? If you look at several graphs and data, the amount of deaths per year from nuclear plant accidents are very, very minimal below even wind.
Bill gates created a reason to think nuclear is safe now. No melt down risks I hear.
Nuclear energy involves fusing two atoms together which produces a lot of heat that is then used to create steam to turn turbines. There’s no emission of harmful gases.