As the climate crisis escalates, attention is increasingly focused on geoengineering – large-scale technological interventions into the Earth’s climate system. While these methods promise to cool the planet and capture carbon, present a dangerous reality: geoengineering could devastate biodiversity and disrupt ecosystems, while pushing real climate action into the background.

Biodiversity, the richness of life and the essence of ecosystems, is essential for the health of the planet and human well-being. It supports important functions such as climate regulation and pollination. However, at a time when biodiversity is under enormous pressure from climate change, pollution and habitat destruction, highly speculative geoengineering interventions risk accelerating ecosystem collapse and species extinction. These techniques could fundamentally alter the delicate balance of Earth's vital systems, seriously compromising its ability to protect the biosphere. Moreover, the illusion of a "Plan B" created by geoengineering risks postponing crucial action to reduce greenhouse gas emissions. For these reasons, UN Convention on Biological Diversity (CBD) has been introduced since 2010 de facto a moratorium on the deployment of geoengineering, which has been repeatedly confirmed.

Risks of Solar Radiation Modification (SRM)

Technologies solar radiation modification (SRM) are highly speculative techniques that seek to artificially cool the planet without addressing the root causes of the climate crisis. Proposed techniques include stratospheric aerosol injection (SAI) a marine cloud brightening (MCB)Their deployment could dim the amount of sunlight reaching Earth, likely leading to negative impacts on plant species and increased food insecurity. These technologies would also likely lead to uneven temperature changes, such as excessive cooling in the tropics and warming at the poles, which would stress species that would be unable to adapt.

Other risks of SAI include changes in precipitation, which could slow the global water cycle and cause average precipitation to decrease by up to 2 %, threatening water and food security. Some forms of SAI are also likely to weaken the ozone layer, increasing the amount of harmful UV radiation reaching the Earth. A key risk is also termination shock – sudden and catastrophic increase in global temperatures if large-scale deployment of SRM (e.g. SAI, MCB or marine micro-bubbles) abruptly stopped. Because solar geoengineering does not address the root causes of climate change, it risks worsening the pre-existing ocean acidification crisis.

Threats to ocean ecosystems

Marine carbon dioxide removal (Marine CDR) techniques aim to force the ocean to sequester even more carbon, but if deployed, they would introduce huge new risks to already stressed marine ecosystems.

Technologies ocean alkalinity increase (OAE), whether through minerals or electrochemical processing, would require enormous mining costs comparable to the global iron ore industry, which would degrade terrestrial ecosystems. Direct harm to marine life threatens through the introduction of highly corrosive alkaline materials or water that can burn marine species. Furthermore, electrochemical OAE is a highly energy-intensive process that would require the processing of enormous volumes of seawater, which would be detrimental to marine life.

Ocean fertilization nutrients to promote algae growth risks disrupting the connectivity of marine ecosystems, which would hinder species migration and reproduction. These techniques also risk creating toxic algal blooms that poison marine life and oxygen depletion events that would lead to suffocation.

Other methods such as biomass diving (depositing plant matter on the ocean floor), ignore the fact that deep-sea life is fragile, largely unknown, and provides important ecosystem functions. Sinking biomass could cause physical damage by depositing packages on the ocean floor and subsequent acidification from the bottom up, negatively affecting food webs.

Terrestrial geoengineering and mass disruption

Land geoengineering poses a risk of disrupting ecosystems on a mass scale. Enhanced weathering (EW), which is a terrestrial variant of OAE, would require a huge amount of mining and brings uncertainty about the ecological toxicity of crushed materials spread over agricultural land.

Biochar a bioenergy with carbon capture and storage (BECCS) would have enormous environmental costs. Implementing these technologies on a large scale would require growing biomass plantations on more than twice the land currently cultivated. This would lead to massive biodiversity loss due to habitat and food loss. Furthermore, biochar, using potentially toxic feedstocks including plastics, tires, or municipal waste, would pose unique pollution risks. Toxins absorbed by plants in biochar-treated soil could lead to the accumulation of deadly arsenic, cadmium, lead, and mercury in animals and humans.

The way forward: Prioritizing prevention

The potential damage to biodiversity and ecosystem functions from geoengineering also poses significant risks to human rights. The UN Human Rights Council’s Advisory Committee on Geoengineering has warned that the deployment of geoengineering has the potential to violate the rights of “millions and perhaps billions of people.”

The global response must be guided by the principles of precaution and environmental justice. Geoengineering is neither insurance nor an adjunct to mitigation. Instead of promoting dangerous, highly speculative technologies, policymakers must Prioritize real climate solutionsthat protect and restore biodiversity. This includes a rapid, just and complete phase-out of fossil fuelsGovernments should enforce the CBD's moratorium on geoengineering, ban all outdoor experiments, and reject geoengineering in climate policies and carbon market mechanisms. JRi