Climate Engineering Explained: Can Geoengineering Really Cool the Planet?

What is Climate Engineering?

Climate engineering, also known as geoengineering, represents humanity's most ambitious technological response to the climate crisis. This controversial field encompasses deliberate, large-scale interventions in Earth's climate system intended to counteract human-caused global warming. As global temperatures continue to rise despite international agreements, scientists and policymakers are increasingly examining whether these radical technologies could provide a necessary emergency brake for our overheating planet. The debate centers on two primary approaches: Solar Radiation Management (SRM), which aims to reflect sunlight away from Earth, and Carbon Dioxide Removal (CDR), which seeks to extract greenhouse gases directly from the atmosphere.

The Solar Radiation Management Controversy

Solar Radiation Management represents the more immediate and contentious branch of climate engineering. These technologies aim to cool the planet quickly by increasing Earth's reflectivity. The most discussed SRM method is stratospheric aerosol injection (SAI), which involves releasing reflective particles into the upper atmosphere to mimic the cooling effects of volcanic eruptions. A 2025 NOAA study published in Geophysical Research Letters revealed an unexpected finding: stratospheric aerosols could create a 'diffusion-brightening' effect, making marine clouds up to 10% more reflective than previously estimated. This discovery suggests SAI might be more effective than initially modeled, but also highlights our incomplete understanding of these complex atmospheric interactions.

Marine Cloud Brightening and Other Approaches

Another SRM technique, marine cloud brightening (MCB), involves spraying seawater droplets into low-lying marine clouds to increase their reflectivity. While theoretically promising, MCB faces significant technical challenges and uncertain regional impacts. According to the Royal Society's 2025 policy briefing, SRM technologies could potentially reduce global temperatures and associated impacts like sea-level rise and extreme weather events. However, these approaches only mask rather than fix the root causes of climate change and would require continuous deployment for decades or centuries. If deployment stopped suddenly, temperatures would rebound rapidly within 1-2 decades, creating what scientists call 'termination shock.'

Carbon Capture and Direct Air Capture Technologies

In contrast to SRM's symptomatic approach, Carbon Dioxide Removal addresses the fundamental cause of climate change. Direct Air Capture (DAC) technology has seen significant advancement in 2025, transitioning from theoretical promise to pragmatic development. Current global DAC capacity remains modest at over 10,000 tonnes per year (as of 2023), but more than 130 new facilities are planned worldwide. A comprehensive review published in ScienceDirect analyzed 1,171 DAC-related research papers from 2015-2025, revealing that while DAC has transformative potential for achieving negative emissions, it faces substantial challenges including massive energy consumption (5-9 GJ per tonne of CO2 for absorption methods) and supply chain concerns.

The Scaling Challenge

The University of Waterloo Climate Institute's May 2025 report emphasizes that DAC represents an emerging industry with significant potential, but scalability remains a major hurdle. Countries like Canada and Kenya are emerging as global DAC leaders due to favorable policies, clean energy resources, and geological storage capabilities. However, the U.S. faces policy uncertainty despite state-level initiatives in California, New York, and Washington. The economic viability of large-scale DAC deployment depends on stable policy frameworks, corporate carbon credit demand, and continued technological innovation to reduce energy requirements.

Ethical and Governance Challenges

The controversy surrounding climate engineering extends far beyond technical feasibility. UNESCO's first report on climate engineering ethics, released ahead of COP28, warns of significant ethical risks associated with these technologies. Key concerns include the potential for these approaches to undermine existing climate policies, divert funding from essential emission reduction efforts, and exacerbate global inequalities. The report highlights what experts call the 'moral hazard'—the risk that governments might reduce their urgency for emissions cuts if they believe technological fixes are available.

Governance represents another critical challenge. As noted in the UN Environmental Programme workshops held in 2025, there is currently no comprehensive international framework for regulating climate engineering. The 2010 Convention on Biological Diversity establishes a de facto ban on most geoengineering activities except for small-scale scientific research with proper oversight. However, this framework lacks enforcement mechanisms and fails to address the complex geopolitical implications of technologies that could be deployed unilaterally by individual nations or even non-state actors.

Expert Perspectives and Future Outlook

Scientists remain deeply divided on climate engineering's role in climate policy. Andrea Hinwood, UNEP's chief scientist, stated in 2025 that the organization is exploring these technologies due to growing concerns about insufficient global emission cuts, while emphasizing they are speculative and don't address climate change's root causes. Critics argue that discussions focus too narrowly on engineering aspects without adequate consideration of social, environmental, and governance risks.

The Carnegie Endowment report from November 2025 highlights an emerging bipartisan backlash against geoengineering in the United States, with both carbon removal and solar radiation management facing political resistance from unlikely coalitions of right-wing populists and environmental traditionalists. This political landscape suggests that technical feasibility alone will not determine whether these technologies are deployed.

Frequently Asked Questions

What is the difference between solar radiation management and carbon capture?

Solar Radiation Management (SRM) reflects sunlight to cool Earth quickly but doesn't address the root cause of climate change. Carbon Dioxide Removal (CDR), including Direct Air Capture, removes greenhouse gases from the atmosphere but works more slowly and requires massive energy inputs.

Can geoengineering replace emissions reductions?

No credible scientific organization suggests geoengineering can replace emissions reductions. The Royal Society, UNESCO, and other expert bodies emphasize these technologies should only be considered as supplementary tools alongside aggressive greenhouse gas reductions, not as replacements for decarbonization.

What are the biggest risks of climate engineering?

The primary risks include: unpredictable environmental consequences, exacerbation of global inequalities, diversion of resources from emissions reduction, potential for unilateral deployment without international consensus, and the 'termination shock' if SRM deployment is suddenly stopped.

Is there international regulation for geoengineering?

Currently, there is no comprehensive international regulatory framework. The 2010 Convention on Biological Diversity provides some guidance, but enforcement mechanisms are limited. UNESCO and other organizations are calling for stronger global governance structures.

When might these technologies be deployed at scale?

Direct Air Capture is expected to reach commercial scale around 2027, while Solar Radiation Management remains largely theoretical with no immediate plans for large-scale deployment due to significant scientific uncertainties and governance challenges.

Conclusion: A Controversial Tool in the Climate Arsenal

Climate engineering represents humanity's most technologically ambitious response to the climate crisis, but it remains deeply controversial. While Solar Radiation Management could potentially provide rapid cooling effects and Carbon Dioxide Removal addresses the fundamental problem of excess atmospheric CO2, both approaches face significant technical, ethical, and governance challenges. The 2025 research landscape reveals growing scientific understanding alongside increasing recognition of these technologies' limitations and risks. As climate impacts intensify, the debate over whether geoengineering represents a necessary emergency measure or a dangerous distraction will likely intensify. What remains clear is that no technological intervention can substitute for the fundamental need to reduce greenhouse gas emissions through the transition to renewable energy and sustainable economic systems.

Sources

UNEP Solar Geoengineering Workshops 2025, NOAA Stratospheric Aerosol Injection Study 2025, Direct Air Capture Progress Report 2025, UNESCO Climate Engineering Ethics Report, Carnegie Endowment Geoengineering Backlash Report 2025