Spanish Scientists Propose Draining Aral Sea to Capture CO2

A team of Spanish scientists has put forth an ambitious and unconventional plan to address a significant source of greenhouse gas emissions: the dried-up Aral Sea. Their proposal involves refilling the colossal basin with water, not merely to restore a lost ecosystem, but to actively capture atmospheric carbon dioxide.

The Aral Sea, once the fourth-largest lake in the world, situated between Kazakhstan and Uzbekistan, suffered a catastrophic decline starting in the 1960s. The diversion of its feeder rivers for intensive Soviet cotton agriculture transformed the vast inland sea into a desolate, saline desert. This ecological disaster is well-documented, but a recent Spanish-led study has quantified a less-discussed consequence: the Aral Sea’s dry bed has become a massive emitter of greenhouse gases.

Climate Impact of a Dry Lakebed

The research highlights that the desiccated seabed of the Aral Sea has released an estimated 748 million tons of CO2 since its drying began. This figure is comparable to the annual combined emissions of Spain, France, and Belgium. Historically, arid regions converted to irrigated farmland were often considered carbon sinks. However, the study reveals that when the water source for these irrigation systems is a lake that has itself dried up, the net balance shifts dramatically towards greenhouse gas emission.

Lakes and wetlands naturally act as carbon sinks, trapping atmospheric carbon absorbed by vegetation during photosynthesis, which then settles in the bottom sediments. The critical element is the water column, which physically isolates these carbon-rich sediments from atmospheric oxygen.

The Problem of Oxygen Exposure

When the water disappears, this isolating “cap” is removed. Atmospheric oxygen rapidly penetrates the exposed sediment layers, triggering a biological response. Dormant microorganisms awaken and begin to degrade the organic matter that has accumulated over centuries. This aerobic microbial degradation process is the primary driver behind the massive release of stored carbon dioxide into the atmosphere.

Measurements taken by the Spanish research team support this mechanism. By analyzing sediments across the former seabed, they observed that areas dried more recently still contain significant amounts of organic carbon compared to those exposed in the 1960s, indicating an ongoing release process.

A New Approach to Mitigation

The study’s conclusions are stark: current mitigation strategies in the Aral Sea region, such as planting vegetation on the dry bed, are largely ineffective. These arid ecosystems offer minimal CO2 absorption capacity, failing to provide a real solution to the emissions problem.

The researchers argue that the only viable method to halt this microbial degradation and curb CO2 emissions is to re-establish the physical isolation by covering the area with water once more.

Technical and Financial Viability

Scientists estimate that without intervention, approximately 605 million tons of CO2 remain to be released from the Aral Sea’s bed. Preventing this massive emission requires a monumental, yet technically feasible, undertaking. A significant challenge is the region’s outdated irrigation network, which wastes up to 90% of the water it transports.

Modernizing this infrastructure is estimated to cost €8.5 billion. Such an investment, however, could potentially restore around 50% of the lake’s original 1960 surface area, yielding global climate benefits.

Financing the Ambitious Project

To fund this large-scale hydrological engineering feat, the research authors propose a novel financial mechanism: leveraging the avoided emissions themselves. If the Aral Sea is refilled and its CO2 emissions are halted, the prevented release of 605 million tons of CO2 could be converted into marketable carbon credits. Preliminary calculations suggest this could generate approximately 323 million tons in equivalent credits, valued on the international market between €3.1 billion and €15.8 billion.

This proposal offers a unique perspective, transforming a symbol of environmental devastation into a potential climate mitigation tool, driven by scientific research and innovative financing. The practical implications for global climate efforts could be substantial if the plan moves beyond theory.

Key facts

The practical impact of this proposal lies in its potential to actively remove a significant source of greenhouse gas emissions while simultaneously addressing the legacy of a major ecological disaster. For readers interested in climate technology and environmental solutions, this research offers a novel, albeit complex, pathway toward carbon reduction.

Source: Unos científicos españoles quieren salvar al planeta con un plan alocado: rellenar de agua el mar de Aral para capturar CO2 – Xataka (https://www.xataka.com/ecologia-y-naturaleza/unos-cientificos-espanoles-quieren-salvar-al-planeta-plan-alocado-rellenar-agua-mar-aral-para-capturar-co2)