Skip to main content

Cooling Solutions – Summary

Action to prevent dangerous climate change has been delayed too long. Impacts projected for the end of the century are happening now. Our climate culture of net zero emissions can no longer change our climate in time frames that matter. Emissions reduction and removal are not proceeding at a pace that will limit global average warming to less than the Paris Agreement targets of 2.0 degrees C above normal, much less the dangerous limit of 1.5 degrees C above normal from the Intergovernmental Panel On Climate Change 2018 report on 1.5 C warming.  Accelerating global warming is indicated by record high 2023–2024 monthly temperatures exceeding 1.5°C above pre-industrial levels. This amount of warming has triggered the activation of Earth system degradation or climate tipping reponses, that will not self-restore unless our climate is cooled from today.

Cooling must be at least to within the degrading Earth systems evolutionary boundaries, or the natural variation of our old climate, of less than 1 degree C warming above normal and this cooling must be completed before degradation becomes so extreme that the systems cannot self-restore.  This time frame for most of the activated tipping responses is about mid-century, or significant time above warming of 1.5 degrees C above normal of no more than decades. Because future emissions reductions or even complete elimination only limit future warming in time frames that matter, and because carbon dioxide and other greenhouse gas removal from our atmosphere may take longer than decades, only direct climate cooling solutions have the potential to cool our climate in time frames that matter, so that Earth systems degradation and tipping responses can stabilize, repeatedly unprecedented extreme weather can return to their former rare occurrences, and warming-caused injustice and inequity can be eliminated.  Strategically deployed at scale, starting with emergency urgency in the immediate future, several cooling measures have the potential to reduce or reverse global warming. Others can be implemented through learning by doing to minimize risk of negative or inadvertent side effects. There is no other choice. A risk-risk analysis of futures with and without direct cooling solutions reveals it is far less impactful to temporarily implement cooling, versus allowing  even existing warming to continue into the point of no return for activated tipping responses. The world needs an approach to climate change that extends beyond sole reliance on emission reductions and removal, that can overcome the risks of too-late actions of emissions elimination and greenhouse gas removal.  To read more about direct cooling solutions implemented by the same engineers that have kept our advanced culture safe in the face of dangerous futures for over 2,000 years, read on.

Trust Our Engineers To Keep Us Safe

Cooling Solutions
(How those that have kept us safe from pollution can do the same with climate)

Thirty years of delay and greenhouse gas concentrations have doubled, prematurely activating climate tipping. Our climate culture has failed and a coalition of international scientists now says urgent emergency action is needed that was previously proposed for the worst-case scenario 50 years from now. Earth’s temperature has exceeded the evolutionary boundaries of her systems, creating degradation, that will not stop unless the thing that caused the collapses to begin is removed. This is climate tipping, it is now active, and only cooling, or restoring our climate from today can stop it.

Even three decades after the Rio Earth Summit, global GHG emissions are still increasing. Emissions reduction is simply not proceeding at a pace nearly adequate to prevent the global average temperature increase from exceeding Paris Agreement warming targets. Despite progress, global warming has reached record high levels during 2023-24, with both years likely to exceed 1.5°C warming. Only climate intervention has the near-term potential to limit extreme weather, intolerable heat indices, and amplified sea level rise; slow permafrost thawing, ecosystem disruption, and biodiversity loss; and reduce climate change-caused injustice, inequity and distance from the Sustainable Development Goals.

Strategically deployed at scale, several cooling measures have the potential to start to counterbalance the warming influences of the elevated GHG concentrations. Depending on how deployed, their influences can emphasize local, regional, or global scales. To provide a greater likelihood of passing a less-disruptive climate and fewer millions of environmental refugees to future generations, a credible policy approach that extends beyond sole reliance on emission reductions is needed.

The Triad approach requires (i) researching, field testing and deploying one or more large-scale cooling influence(s) perhaps initially in polar regions and applying local and regional cooling measures that also support adaptation, (ii) accelerating emissions reductions with an early prioritization of short-lived climate drivers, and (iii) deploying large scale carbon removal to draw down legacy greenhouse gas.  These actions are all compulsory and require simultaneous implementation with emergency urgency to achieve a climate condition restored to within the boundaries of our Earth systems evolution, or the natural variation of our old climate by about mid-century.

HPAC makes no attempt to determine what measures or mix of measures is optimal. That will depend on modeling and learning by doing to limit or avoid adverse impacts and unintended side effects. What is important is emergency action as the point of no return is no longer the end of the century, but mid-century so as to eliminate any risk of irreversible Earth systems collapse tipping responses. Savings from reduced damage and death will more than pay for climate intervention without slowing progress on mitigation.

Rationale – Risk Versus Risk Analysis

Engineered climate cooling solutions have risks, but the risks of passing the point of no return of tipping responses are far more extreme. These responses are activated now with many Earth systems degraded and their carbon sequestration capacity reduced, eliminated or reversed. An example is the Amazon emitting, not absorbing, a gigaton of greenhouse gases annually before the last of five droughts of greater than 100-year extremeness since 2005. Another is emissions from thawing permafrost are now estimated to be above two gigatons per year. Many more examples can be found similar earth systems very likely behaving similarly to the Amazon and the Great North’s response to warming beyond evolutionary boundaries. These emissions will only grow, even with no additional warming as they create systems feedbacks that enhance and accelerate these feedback emissions. In addition, more than half of tipping elements have connections where when one systems is degraded, this degradation cascades into the other systems with the obvious effects again being the enhancement and acceleration of emissions where ultimately, these emissions will dwarf humankind’s. This future is now forgone unless we cool Earth back to within the natural variation of our old climate to stabilise tipping responses.

What we have to be concerned about with engineered cooling solutions is changes to regional weather patterns and termination shock. These effects are by no means minor and could be mortal to many and have outsized economic impacts, but the prospect of  natural feedback emissions dwarfing humankind’s cannot be ignored as this is a risk many times that of those of regional weather modification. And termination shock? This is a misplaced concept. When there is a world war in processes, if one side stopped warring, that side would lose.  This cannot be an issues that influences whether or not we deploy cooling solutions or not.

We Have Been Geoengineering for 2,000 Years

Since the Roman Era, at least, we have been implementing engineered solutions to our world for the betterment of our advanced civilization and to protect us from danger. Roads, aqueducts, sewers, landfills, mines… all were and still arem plus many more, engineered solutions to advance our culture and keep it safe.

Bright Aerosols, Sulfur in Fossil Fuels, 200-Years of Engineered Cooling Solutions

For over two centuries our human culture has been implementing geoengineering that has manipulated our climate and not just with global warming pollutants. All fossil fuels contain sulfur, this is a natural part of fossil hydrocarbon synthesis in wild geology. When that sulfur is burned as the fossil hydrocarbons are burned, it creates sulfates in the exhaust, right along side the greenhouse gases. These sulfates are called aerosols that have a couple of interesting and extremely important cooling mechanisms that offset warming that would have otherwise occurred if the fossil fuels had no sulfur content. They reflect light harmlessly back into space instead of it striking an object and changing to heat, and they enhance cloud formation and create whiter clouds, that like the aerosols themselves, reflect sunlight harmlessly back into space. As of the Intergovernmental Panel on Climate Change (IPCC) 6th Assessment Report, these global cooling aerosols that almost all come from burning fossil fuels, have masked about a third of warming that should have occurred meaning, if we remove the sulfur in fossil fuels, we remove the warming mask and experience a fifty percent increasing in actual warming.

This engineered solution is most likely what we will implement first as we have the most data on it from 200 years of observation and mitigation. We know exactly how many excess mortalities will results and we know exactly what regional weather patterns to expect, and we also know what to expect form thing like acid rain. These aerosols are very important to humanity in that, today, they create about 7,000 deaths per year from respiratory ailments. Since the 1970s, the West has required limits on sulfur in fossil fuels to reduce air pollution and respiratory ailments. Today, new regulations limiting sulfur are being implemented in China and India, and further regulations are still being implemented in the West.

Acid Rain From Global Cooling Atmospheric Sulfur Solutions

Acid rain is a big problem with sulfur in fossils fuels. Two important pieces of science about sulfur though, can almost completely mitigate for detrimental acid rain. One is that stratospheric aerosols injection uses only about five precent of the sulfur than we emit every day because when injected so high in the atmosphere, the bright aerosols are far more efficient because ther eis less atmosphere with dust in it for the sunlight and reflected sunlight to strike, to change the light energy into heat energy, before the light is safely reflected back into space. The other is tropospheric sulfur injection, that comes from burning fossil fuels close to the surface. Brand new regulations limiting sulfur in ship fuels by the International Maritime Organization (IMO) have unmasked at least 0.2 degrees C of warming in 2022 and 2023. If we temporarily pause these regulations, and require ships switch fuel tanks to low sulfur within 200 miles of shore, almost all of the sulfur is gone before winds can blow it to land.

Certainty of Perceived Risks

What we see now with perceived risks from engineered cooling solutions is not a product of certainty, but a product of uncertainty. Modeling of geoengineering is by no means robust because these efforts have just not been motivated to a substantial degree as of yet, and little else is available to drive our understanding…

Cooling Solutions
(The ‘Brightest’ Prospects)

Solar Radiation Modification (SRM): NOAA – Climate.gov State of the Science factsheet
http://climate.gov/news-features/understanding-climate/solar-radiation-modification-noaa-state-science-factsheet

Solar radiation modification is reflecting sunlight harmlessly back into space before it can strike an object on Earth or in our atmosphere and create warming. A common example is the warmth of the sun on our face, when a cloud passes by and the warmth disappears. Only a very small amount of sunlight needs reflected back into space to be effective. If SRM methods are implemented at large scales, the implementation then, is very small.

These reflection or shading methods reduce surface warming without addressing the fundamental cause of excess greenhouse gasses in our sky, or of future increases because of ongoing and rising global emissions. However, the reduction of our climate’s temperature caused by reflecting sunlight does decrease net warming because of natural feedback emissions. These natural greenhouse gas emissions are triggered by warming, with greater warming delivering nonlinearly more natural emissions. For example: forest mortality from drought releases greenhouse gases as trees decay and soils respire sequestered carbon. tese additional greenhouse gases create more warming, which further increases the intensity of drought and mortality. but this is only one feedback mechanisms. As trees die in a forest, more sunlight hits the forest floor because there are fewer shading leaves. this warms the forest floor creating further mortality and enhancing soil respiration of stored carbon, where about half of the carbon in a forest is contained in its soils.

Three methods of sunlight reflection and one of heat radiation enhancement are noteworthy as near-shovel ready strategies, and one very important method that is absolutely shovel ready.

Tropospheric Sulfur: Shovel Ready – the International Maritime Organization (IMO) has recently enforced new regulations for ship fuels that limit natural sulfur content. This sulfur, when burned, creates particles that reflect sunlight, that stay close to the ocean surface in our lower atmosphere – the stratosphere. These “bright aerosols” as they are called, are responsible for masking warming by reflecting a small amount of sunlight back into space. The amount of masking, or of reduced warming, is equal to about two-thirds of all warming that has taken place since 1850. In other words, if we were to remove all of the sulfates created when we burned natural sulfur in fossil fuels, instead of a current warming of about 1.5 degrees C, warming would be 2.5 degrees C.  Why did the IMO limit sulfur? When burned, the resulting sulfur oxides (mostly sulfates) are one of the main components of air pollution that create seven to eight million mortalities globally every year from respiratory illness. Western nations began limiting sulfur in fossil fuels in the 1970s, with increasing limits since. Developing nations have only recently begun limiting sulfur in the last ten years. There are further temporary relaxation of sulfur regulations that could provide further cooling from renewed atmospheric sulfur at a price of lives lost and other degradation from increased air pollution. This price must be balanced against the grave threat to humanity of existential outcomes if we do not reverse warming to stabilize tipping systems collapses.

Marine Cloud Brightening (MCB) is what sulfur does over the ocean when burned in ship’s fuels. the aerosols not only reflect sunlight harmlessly back into space, they enhance cloud formation that shades, and the clouds tend to be brighter white, reflecting more sunlight than less white clouds. MVCB can be accomplished not only with sulfur in fuels, but by burning other elements too, like iron-rich clays. this strategy not only cools by reflection and shading and brighter clouds, but as the iron falls into the ocean it creates a slight fertilization effect that can partially offset the loss of nutrients in our ocean from humans overfishing. MCB can also be accomplished with snowmaking machines on ships modified to deal with salt water, with very similar effects of cloud formation enhancement and sunlight reflection.

Stratospheric aerosol injection (SAI) is exactly what happens when a volcano erupts. Much of the climate cooling after a major volcanic eruption is caused by sulfur oxides from the eruption that are injected into the stratosphere that starts at the upper boundary of the troposphere at  about 50,000 feet high at the equator, falling to 30,000 feet at the poles. Like human-implemented SAI, the sulfates are heavier than air and only last a year or two before they are rained out, fall back to earth by gravity, or are chemically neutralized by natural reactions in our atmosphere. It takes much longer for the sulfates to go away when injected into the stratosphere than in the troposphere because of less precipitation, fewer chemical reactions and the greater height that the particles must fall before they return to earth and can no longer reflect light back into space.

Cirrus Cloud Thinning (CCT) is basic cloud seeding strategies practiced since the Great Depression, only in the stratosphere. Excess cirrus cloud formation is responsible for half to double the warming caused by air transportation’s condensation trails. Simple re-routing air flights to avoid weather conditions favorable to condensation trail formation is also a viable solution. (Note: Chem trails are fiction as delivered by the anti-climate science community, but based on the reality of cloud seeding. Cloud seeding is a real strategy that can slightly enhance local rainfall in individual clouds with inert iodine crystals where the effects last only for hours. Somehow, the myth-monsters have created the nefarious mind-control chem trailsc created by ill-meaning liberal governmental factions from this simple cloud seeding strategy)

See our Long History of Geoengineering for much more information on IMO regulations, stratospheric aerosols and marine cloud brightening.

(Image Description: McKay et al., Exceeding 1.5 C global warming could trigger multiple climate tipping points, Science, September 9, 2022. There are many other tipping systems defined in other works based on different criteria but these will do for illustration. Tipping science is still developing, this has never happened before and physical evidence is extremely rare. Therefor modeling must suffice and modeling is challenging at best. These data however, do reflect generally the current state of climate tipping systems from other works. Note how many systems tipping ranges begin at the maximum warmth of the Holocene at about 1 degrees C above normal. Note how the Amazon is not yet into its tipping range but we know that it is already emitting and not sequestering because of mortality from five, greater than 100-year droughts since 2020 – link to paper.)

Trust In Engineers

Only by including properly researched intervention “tourniquets” to our “bleeding” Earth can we start to pull back from brink of irreversible tipping. Our advanced civilization relies upon our engineers to keep us safe from danger, to treat pollution so we incur no harm, to design a world where we can live free from undue risk, literally, to geoengineer our world for the betterment of mankind. This geoengineering is all around us and has been for a 2,000 years. Everywhere one looks, engineers have changed Earth for the betterment of humankind. Geoengineering is not a problem as our engineers are trained to keep us safe. The problem is perceived fear of the unknown. If more people knew what geoengineering actually is and how long we have been practicing it and that it is responsible for humankind’s population advancing from 1 billion to 8 billion souls, engineered cooling solutions fear would not be an issue.

The Moral Hazard

A primary argument has been that, pursuing engineered cooling solutions constitutes a “moral hazard” because implementation might well slow GHG emissions reduction efforts and this would be “morally wrong.” Now that effects from warming are becoming repeatedly unprecedented, and that tipping elements have activated and they do not self-restore unless we cool our climate from today, and future emissions reductions cannot cool our climate at all in time frames that matter, and considering warming in the pipeline that even with complete emissions cessation that we continue to warm because of warming in the pipeline that our cool oceans and ice sheets (and aerosols) have been masking;  the real “moral hazard” then,  is the failure to pursue cooling approaches that can stop irreversible tipping responses, and reduce ecological and human disasters and costs. The moral hazard no longer lies in researching and deploying climate cooling approaches, but now in the failure to explore all feasible approaches to reduce near-term global warming.

Creating a Sustainable World With Temporary Engineered Cooling Solutions

Many of the climate cooling approaches are low-tech and can be responsibly deployed at local to regional scales with few, if any, potential risks and often, many co-benefits.  Similarly, various of the global-scale approaches can be tested and implemented at low intensity using an “apply, evaluate, adjust” sequencing because their effects are readily reversible if unexpected, potentially deleterious consequences arise.

Learning by Doing – Ramping Up Engineered Cooling Solutions and Governance

World governance is a problem. There is none. Or, there is very little, yet it is implied that engineered cooling solutions are against international law. What guidelines there are goals and principles that are interpreted to be affected by engineered cooling solutions. For example, the Center for Biological Diversity (CBD) has goals that conserves biodiversity and resources, and shares the benefits of genetic resources. Specifically, changes in regional weather patterns could affect ecologies. Some interpret these goals as being negatively impacted by engineered cooling solutions. Maybe so, but does CBD consider the risk/risk analysis, or are they simply applying the moral hazard from days gone by?

Still, it may be possible to pilot-test and gradually deploy high-leverage engineered cooling strategies with great prospects like stratospheric aerosol injection (SAI). This is “learning by doing” and it can be done  at a regional scale without global governance and coordination by following the Great Barrier Reef tropospheric aerosols example. SAI could be pilot tested with consent from affected communities and authorities in accordance with an international, voluntary and transparent “coalition of the willing” agreement. this learn by doing strategy starts with outdoor testing, evaluation and modification of the test to reduce or eliminate negative effects and enhance positive effects. The test are increased in size using the same iterative evaluation and modification process. The results is a full scale strategy in much faster time that traditional science certainty first procedures. Basically, what happens is that scientists turn the scientific knowledge over to engineers that then scale the strategy safely and efficiently. this is what engineers have been doing for 2,000 years. they keep us safe. they are trustworthy.

Emergency Implementation of Engineered Cooling Solutions

In some cases, sufficient authority to deploy an emergency cooling mechanism may already be in place. The International Maritime Organization (IMO) could, for example, address the unintended global warming produced by its well-intended maritime fuel sulfur regulations under its existing authority. First, the IMO could immediately adopt an emergency regulation relaxing 2015 and 2020 shipping fuel sulfur content restrictions in the high seas, to resume sulfate aerosol cooling except when within 200miles of land. Second, as a long-term solution, the IMO could support research and implement regulations requiring use of alternative fuels or power sources and the emission of aerosol precursors more benign than sulfates to human and environmental health, so as to replace the prior beneficial global cooling from burning sulfur. These measures alone could produce significant cooling and buy time to further implement more effective solutions using learning by doing.

Similarly, sulfur regulations in fossil fuels over land could be relaxed. this of course carries with it much higher risk of human and other mortalities, but these risks need to be balanced with the risks of not cooling with emergency urgency. the point of no return waits for none.

There are also new regulations for ultrafine particles when burning fossil fuels in vehicles. Particulate emissions standards in Europe and China in 2014 and 2017 and the US in 2024, sought to regulate ultra fine particulates (UFPs) that double to triple in particle count with gasoline direct injection engines. This direct injection technology is coming to dominate the market because of fuel efficiency but because some sulfur remains in fuels this direct injection technology creates a much bigger problem with aerosols. These emissions are so small, less than 0.1 micron where current regulations ( PM 2.5) regulate particles down to 2.5 microns, their mass is almost negligible and our present mass-based regulations on sulfur emissions no longer apply. The new regs are designed to limit the number of particulate particles instead of the mass of particles by using gasoline particle filters (GPFs). These new limits are likely and significantly reducing a new source of global cooling sulfate aerosols and thus revealing masked warming.  Direct injection creates 1 to 2 times more particles less than 0.1 micron and herein lies the challenge: it is the number of particles that matter to both respiratory illness and global cooling. Smaller particles both cool more than larger particles, and penetrate more deeply into the lungs.

Once again, a risk/risk analysis would quite likely reveal that implementing engineered cooling solutions is a great deal compared to not implementing them because of the short time to the point of no return of tipping responses.

The Limits of Engineered Cooling Solutions

Even though engineered cooling solutions are the only way we can avoid natural feedback emissions that dwarf humankind’s from the irreversible point of no return of tipping elements, it would not be good luck to assume that we could continue these solutions forever, or even for much more than decades. Our oceans are probably the biggest reason, as increasing acidification is not mitigated by most engineered cooling strategies and ocean systems collapses would likely be of the most serious kind.

Delay in action to deploy engineered cooling solutions, like when we delayed action on reducing emissions, creates a world where even engineers cannot change our future.  As an example, engineered cooling via reflective aerosols does nothing to reduce ocean acidity as the excess CO2 that caused the increased acidity remains. Our oceans are already on the brink of profound acidification that can create extinction level effects with primary productivity. There is great risks in allowing ocean acidity to not only continue, but to increase as it will with aerosol cooling.

Aerosol cooling, and many other types of engineered cooling solutions, also do not do well with high levels of CO2 in that, greater CO2 concentrations in our atmosphere tend to limit the formation of lower clouds allowing more sunlight to strike the Earth’s surface and be changed into heat. therefor the efficiency of many engineered solutions becomes less and less  with greater atmospheric CO2 concentrations.

Conclusion

The road to climate stability and a sustainable planet will ultimately require a complete transformation of global industrial civilization’s economies, systems, and practices, but if we do not first cool, and do so in time frames relative to tipping processes, so as to eliminate untenable futures from tipping responses, all other actions to create a sustainable human culture will be for naught.

The following is a table to what are plausible, thirteen of the most promising cooling strategies from Baiman 2024 – Description of direct climate cooling (DCC) methods.

Baiman 2024 – Description of direct climate cooling (DCC) methods.

Supporting Literature

References

Solar Radiation management (SRM)… Stratospheric sulfate injection and marine cloud brightening sunlight reflection, longwave radiation enhancement  via cirrus cloud thinning.
Solar Radiation Modification (SRM): NOAA – Climate.gov State of the Science factsheet
http://climate.gov/news-features/understanding-climate/solar-radiation-modification-noaa-state-science-factsheet

International Marine Organization’s (IMO) new sulfur limits in ship fuels…  An Open Letter to the IMO Supporting the Utilization of Ship Fuels that Cool the Atmosphere While Preserving Air Quality Benefits – In 2020, International Maritime Organization regulations became effective that sharply limited the sulfur content of shipping fuel to protect human health from dangerous sulfur oxide emissions. However, multiple research studies suggest that these restrictions have also significantly increased global warming by reducing these global-cooling sulfur oxide emissions at a time when warming is accelerating and threatening the 1.5 C warming target significantly ahead of projections. This open letter asks the International Maritime Organization to urgently sponsor research and pilot testing and emergency regulations to reduce this harmful and unexpected global warming impact by, (a) relaxing sulfur restrictions over the “high seas” where the sulfur oxide emissions have less effect on humans, and (b) requiring that shipping fuels that do not contain sulfur include alternative substances that generate global-cooling emissions that are not harmful to humans or nature.
Baiman et al., An Open Letter to the IMO Supporting the Utilization of Ship Fuels that Cool the Atmosphere While Preserving Air Quality Benefit, December 7, 2023.
https://docs.google.com/document/d/1mVlr5MKBrFUUq8Hm4ZmeCPcfKK8myuel/edit?usp=sharing&ouid=116465941111195452408&rtpof=true&sd=true
Global cooling sulfates...

MIT Portal – “Sulfate aerosols produced when humans burn coal and other fossil fuels have produced a substantial cooling effect, up to nearly 1°C. But global warming far outweighs that effect; so far, human activities have warmed the planet by almost 1.5°C.”
How much global warming has been hidden by the cooling effect from sulfur produced by burning coal and oil?, MIT Climate Portal, January 8, 2025.
https://climate.mit.edu/ask-mit/how-much-global-warming-has-been-hidden-cooling-effect-sulfur-produced-burning-coal-and-oil

Below is a sampling of critical literature about Earth systems tipping processes, systems at risk, effects of tipping, and responses that have been activated.

HPAC Published Papers and Conference Posters

A Credible International Approach to Limiting Climate Change Impacts Requires Supplementing Emissions Reduction and GHG Removal with Near-Term Climate MacCracken and Baiman. December 2024. American Geophysical Union Conference Poster Presentation.

Summary-
Proposition 1: Human-Induced Warming is on a Path to Double Well Before 2100
Proposition 2: Destructive Impacts are Already Occurring and Approaching Tipping Points Pose Severe Risks
Proposition 3: Emissions Reductions and CDR, While Essential, Can Only Limit Future Warming
Proposition 4: Only Complementing Emissions Reduction and CDR with Climate Intervention has the Potential to Offset Further Warming and Reduce the Rapidly Increasing  Risks
https://drive.google.com/file/d/1PDHBYTt5MtYTLmMevc7plVxx0orB0DJ1/view?usp=sharing

Addressing the Urgent Need for Direct Climate Cooling: Rationale and Options. Baiman et al. August 2024. Oxford Open Climate Change.

Summary –
Climate change has already caused enormous damage and elevated the risk of catastrophic harm to humans, ecosystems, the global economy, and international security. An increasing number of direct climate cooling (DCC) approaches have the potential to moderate at least some of the projected disruption when applied at scales ranging from local to global. Without deployment of at least some of the cited cooling approaches, the multi-decade average temperature increase will soon exceed the 1.5°C or 2.0°C limits agreed to in the Paris Accord in 2015. The 2023 exceedance of 1.5°C is already a clear indication of urgency. On a global scale, restoring the relatively beneficial climatic conditions of the 20th Century will require a restoration plan to return global warming to well below 1°C. To be effective, such a plan would need to include (i) researching, field testing, and deploying one or more large-scale cooling influence(s) perhaps initially in polar regions and applying local and regional cooling measures that also support adaptation, (ii) accelerating emissions reductions with an early prioritization of short-lived climate-drivers, and (iii) deploying large scale carbon removal to draw down legacy greenhouse gas. Only by applying emergency cooling “tourniquets” to our critically injured Earth will there be a near-term possibility to limit the worst climate disruption while emissions reduction and removal take effect over the long-term. As approaches may be selected and implemented in a wide variety of ways, locations, times, and intensities, no attempt has been made here to determine what mix is optimal. That will depend on modeling, experimentation and learning by doing.
https://academic.oup.com/oocc/article/4/1/kgae014/7731760<

An Open Letter to the IMO Supporting Maritime Transport that Cools the Atmosphere While Preserving Air Quality Benefits. Baiman et al. July 2024. Oxford Open Climate Change.

Summary

We are in a global warming emergency that is being exacerbated by a rapid decline in anthropogenically-caused atmospheric aerosol loading. Recently implemented International Maritime Organization (IMO) regulations on bunker-fuel sulfur oxide (SOx) are an important contributor to these reduced aerosol loadings and high sea surface temperatures. Numerous studies have suggested that these reduced aerosol loadings have and will significantly increase global warming. Higher sea surface temperatures have been implicated in the intensification of extreme flooding worldwide and in the dying of an estimated 19% of coral reefs globally since 2009 . This suggests the need to reconsider and refine the regulations.
https://academic.oup.com/oocc/article/4/1/kgae008/7706251

HPAC Slide Presentations and White Papers

Baiman et al., Addressing the Urgent Need for Direct Climate Cooling: Rationale and Options, Slide Presentation. November 2024.

Summary –
There is a need for COP policy to reach beyond averaged global warming metric and net-zero emissions.
There are great risks of not slowing the pace of global climate change.
There are potential benefits of adding direct cooling technologies to the policy mix.
Potential approaches for direct climate cooling and tables described.
Challenges and opportunities presented.
The necessity for direct climate cooling as a policy complement to emissions reductions and carbon removal discussion.
https://docs.google.com/presentation/d/1EZR1WXEO8uZCg1JJ9gte7sr55mpGAik-/edit?usp=sharing&ouid=116465941111195452408&rtpof=true&sd=true

Baiman, Direct Climate Cooling (DCC) Coordination and Governance, Slide Presentation, October 2024.

Summary –
Not Deploying DCC is the “Moral Hazard” Now Confronting Humanity.
Waiting for Full Governance will be too Late.
Local and Regional DCC can be Deployed Now.
Globally Scalable DCC Piloting Could Start Now.
Weaponization of SAI is Highly Unlikely.
Immediate Relaxation of IMO Sulfate Regulations Could Exert Significant Global Cooling.
DCC Deployment, Coordination and Governance are Likely to Evolve Together over Time.
https://docs.google.com/presentation/d/1mQed7U89TEjOWi31rTGwaubg0vpk-SzK/edit?usp=sharing&ouid=116465941111195452408&rtpof=true&sd=true

Baiman et al., (13 authors) Understanding the Case for Direct Climate Cooling” White Paper. Presented at the Panel on Climate Justice, Union for Radical Political Economics, American Economics Association/Allied Social Sciences Association/New Orleans, January 8, 2023.
https://online.fliphtml5.com/aacla/jkur/

More References

Reflecting Sunlight: Recommendations for Solar Geoengineering Research and Research Governance, National Academies, 2021.

Summary-
Climate change is creating impacts that are widespread and severe for individuals, communities, economies, and ecosystems around the world. While efforts to reduce emissions and adapt to climate impacts are the first line of defense, researchers are exploring other options to reduce warming. Solar geoengineering strategies are designed to cool Earth either by adding small reflective particles to the upper atmosphere, by increasing reflective cloud cover in the lower atmosphere, or by thinning high-altitude clouds that can absorb heat. While such strategies have the potential to reduce global temperatures, they could also introduce an array of unknown or negative consequences. This report concludes that a strategic investment in research is needed to enhance policymakers’ understanding of climate response options. The United States should develop a transdisciplinary research program, in collaboration with other nations, to advance understanding of solar geoengineering’s technical feasibility and effectiveness, possible impacts on society and the environment, and social dimensions such as public perceptions, political and economic dynamics, and ethical and equity considerations. The program should operate under robust research governance that includes such elements as a research code of conduct, a public registry for research, permitting systems for outdoor experiments, guidance on intellectual property, and inclusive public and stakeholder engagement processes.
https://vimeo.com/530878274

Zarnatske et al., Potential ecological impacts of climate intervention by reflecting sunlight to cool Earth, Proceedings of the national Academies of Sciences, April 5, 2021.
Abstract – As the effects of anthropogenic climate change become more severe, several approaches for deliberate climate intervention to reduce or stabilize Earth’s surface temperature have been proposed. Solar radiation modification (SRM) is one potential approach to partially counteract anthropogenic warming by reflecting a small proportion of the incoming solar radiation to increase Earth’s albedo. While climate science research has focused on the predicted climate effects of SRM, almost no studies have investigated the impacts that SRM would have on ecological systems. The impacts and risks posed by SRM would vary by implementation scenario, anthropogenic climate effects, geographic region, and by ecosystem, community, population, and organism. Complex interactions among Earth’s climate system and living systems would further affect SRM impacts and risks. We focus here on stratospheric aerosol intervention (SAI), a well-studied and relatively feasible SRM scheme that is likely to have a large impact on Earth’s surface temperature. We outline current gaps in knowledge about both helpful and harmful predicted effects of SAI on ecological systems. Desired ecological outcomes might also inform development of future SAI implementation scenarios. In addition to filling these knowledge gaps, increased collaboration between ecologists and climate scientists would identify a common set of SAI research goals and improve the communication about potential SAI impacts and risks with the public. Without this collaboration, forecasts of SAI impacts will overlook potential effects on biodiversity and ecosystem services for humanity.
https://www.pnas.org/doi/10.1073/pnas.1921854118

Planet Earth Cool Kit
A reference for methods to remove methane and CO2 and reflect sunlight
https://cool-planet.earth/cool-methods/


Ocean-Based Cooling Solutions
The Blue Cooling Initiative (BCI) is an urgent and critical response to the accelerating climate crisis, spearheaded by a diverse coalition of scientists, opinion leaders, civil servants, and politicians. The Initiative focuses on advancing ocean-based cooling solutions, with a particular emphasis on Marine Cloud Brightening (MCB). By enhancing cloud reflectivity, MCB aims to increase the amount of sunlight reflected back into space, thereby cooling the planet. https://bluecooling.org/

Healthy Planet Action Coalition

An international group of climate scientists, engineers, entrepreneurs, and policy and advocacy experts

Terms of Use | Privacy Policy |  Contact
We are an international organization located on Planet Earth, third planet from our sun in the Milky Way Galaxy.
Website design and all images and video by Bruce Melton unless otherwise attributed – free use with permission.
V2 Beta Site – See the old site here.