Underground carbon storage could run out much sooner than we thought

For years, underground storage of carbon dioxide looked like a clever climate trick. Capture the gas, lock it in rock layers, and keep burning fossil fuels while claiming progress. The idea seemed safe because early estimates suggested nearly limitless space.

That illusion has collapsed. New research shows the planet’s usable storage capacity is far smaller than imagined. Instead of centuries of security, this cushion could run out within 200 years.

Carbon storage drops sharply

Industry once placed global capacity at around 14,000 gigatonnes. A closer look, however, strips away risky regions – earthquake zones, fragile ecosystems, and crowded cities. What remains is only about 1,460 gigatonnes.

This tenfold drop changes everything. What once seemed endless is now a resource with strict boundaries, one that must be managed carefully. Every choice about how it is used carries long-term consequences.

If reserved for short-term fixes, the world risks burning through it quickly. If protected for carbon removal, it could become a critical lifeline for stabilizing temperatures far into the future.

Risks hidden beneath the surface

Underground storage carries hazards. Injecting carbon can stir up seismic activity, reactivate faults, or open escape paths. Leaks into aquifers could acidify water and release toxic metals.

Offshore storage avoids some human risks but adds cost and geopolitical disputes. Public pushback also limits expansion, with some governments blocking projects altogether.

Opposition often stems from fears of leaks, distrust of industry promises, and concerns that storage will be used to justify continued fossil fuel use.

These challenges mean underground storage cannot expand smoothly or universally; every project faces technical, political, and social barriers that slow progress and shrink real-world potential.

Carbon storage’s uncertain future

Climate plans already assume storage will be vital to reach net zero. But if it mainly serves fossil fuel plants, reserves could vanish by 2200 – and every decade of delay accelerates that timeline.

Deep emission cuts now ease future pressure, while procrastination forces heavier reliance on shrinking storage space. One promising strategy is to prioritize underground capacity for carbon removal rather than fossil fuel capture.

Direct air capture and bioenergy with carbon storage could actively draw carbon out of the atmosphere, offering a cooling effect.

If the full capacity were dedicated to this role, global temperatures could fall by as much as 0.7 °C (1.3 °F), though in practice the impact may be closer to 0.4 °C (0.7 °F) because the climate system doesn’t respond perfectly symmetrically to removal and emission.

Reserves unevenly spread worldwide

Storage is not shared fairly across the globe. The United States, Russia, and Australia hold large, stable reserves. Europe and India lose far more under stricter risk rules.

Meanwhile, some nations in Africa and South America have vast potential but little historic responsibility for emissions. That imbalance raises thorny questions of justice – who gets to use the storage, and on what terms.

Should wealthy nations pay for access to reserves in countries that contributed less to the crisis? Or should those with the largest reserves prioritize their own development needs first? These questions highlight deep inequalities that will shape future climate negotiations.

Storage can only buy time

Some experts argue the true potential is larger, pointing to decades of safe use in oil and gas reservoirs. They note that many depleted fields have held fluids securely for millions of years and could continue to hold injected carbon just as reliably.

Supporters of this view see existing infrastructure and technical expertise as proof that storage can operate at much greater scale than the conservative estimates suggest.

Even so, most researchers caution against treating underground storage as a limitless solution. It was never designed to be the final answer to climate change.

At best, it should function as a bridge – a temporary measure that buys time while renewables expand, low-carbon industries mature, and societies shift away from fossil fuels.

In that sense, storage is less a cure and more a stabilizer, easing the transition without promising permanence. Its real value lies in supporting broader change, not replacing it.

Carbon future depends on choices

The message is clear: underground storage is limited, risky, and unevenly distributed. It can help, but only if used strategically.

That means prioritizing emission cuts, expanding clean energy, and reserving storage for removing carbon already in the air.

Treating it as infinite would squander one of the few tools that could still reverse warming, leaving future generations with fewer options, higher risks, and a far narrower path to a stable climate.

The study is published in the journal Nature.

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