As global temperatures continue to rise at an alarming rate, some scientists and policymakers are considering drastic measures to cool the planet through climate engineering. Also known as geoengineering, these proposed techniques aim to deliberately alter Earth's climate system on a large scale to counteract global warming. While potentially offering a way to rapidly lower temperatures, climate engineering carries significant risks and uncertainties that have made it highly controversial.
The two main approaches to climate engineering are solar radiation management (SRM) and carbon dioxide removal (CDR). SRM techniques seek to reflect a small percentage of incoming sunlight back into space, mimicking the cooling effect of volcanic eruptions. Proposed methods include injecting reflective aerosols like sulfur dioxide into the stratosphere or using ships to spray saltwater into the air to brighten marine clouds. CDR approaches aim to remove carbon dioxide from the atmosphere through both technological means like direct air capture machines and natural solutions like large-scale tree planting.
Several companies are actively developing carbon removal technologies. Carbon Engineering in Canada is building large-scale direct air capture plants that can remove CO₂ from ambient air. Climeworks in Switzerland has deployed smaller direct air capture units and is scaling up operations. Project Vesta is exploring using crushed olivine rock to accelerate natural weathering processes that absorb CO₂. However, current carbon removal efforts are removing only about 2 billion metric tons of CO₂ annually, compared to the over 37 billion metric tons emitted each year from fossil fuels and industry.
Solar geoengineering research remains largely confined to computer modeling and small-scale experiments. No outdoor tests have yet been conducted, though some researchers have proposed limited experiments. The Stratospheric Controlled Perturbation Experiment (SCoPEx) led by Harvard scientists aims to release small amounts of calcium carbonate dust in the stratosphere to study potential effects. However, this project has faced opposition and delays due to controversy over even small-scale testing.
Proponents argue that climate engineering research is urgently needed given the slow pace of emissions reductions and increasing risks of climate tipping points. They contend that having climate engineering capabilities could enhance global security by providing options to rapidly address climate emergencies. Critics counter that pursuing climate engineering could undermine emissions reduction efforts and introduce new risks. There are major concerns about potential negative impacts on weather patterns, agriculture, and geopolitical stability.
The relatively low cost of some climate engineering approaches, particularly SRM, means that a single country or small group of countries could potentially alter the global climate unilaterally. This raises alarms about the lack of international governance frameworks. Climate models suggest that while moderate climate engineering could have widespread benefits compared to unchecked warming, the impacts would not be uniform across regions. Changes in temperature and precipitation patterns could affect food production, water availability, and extreme weather events differently in various parts of the world.
As climate impacts worsen, the debate around climate engineering is likely to intensify. Many experts argue that some level of carbon removal will be necessary to meet climate goals, even with aggressive emissions cuts. But solar geoengineering remains far more controversial. Moving forward, policymakers face complex decisions in whether and how to pursue climate engineering research and potential deployment. Developing robust governance frameworks and international cooperation will be critical to managing the risks and avoiding unilateral action that could spark conflict. Ultimately, climate engineering may prove to be an important tool in addressing global warming, but one that must be approached with great caution given the high stakes involved.
