The hidden complexity of shale gas extraction and its environmental footprint

Health · Published 9 October 2026 Swipe more like this →

In short: Trapped within fine-grained sedimentary rock, shale gas is far harder to extract than conventional gas. While it offers a lower-carbon alternative to coal, the process of hydraulic fracturing introduces unique risks, from potential water contamination to localized seismic activity, making it a centerpiece of modern energy debates.

Shale gas is an unconventional form of natural gas, primarily composed of methane, found within shale rock. Unlike conventional gas found in sandstone or limestone, shale is a fine-grained sedimentary rock with small, relatively unconnected pores. This lack of permeability means the gas does not flow easily, necessitating hydraulic fracturing—or fracking—to release it. This process involves drilling deep, horizontal holes and pumping a mixture of water, sand, and chemicals at high pressure to fracture the rock and allow gas to flow into collection wells.

The scale of these resources is immense. In 2015, the total 'unproved technically recoverable resources' were estimated at 214.6 trillion cubic metres across 46 countries. China holds the largest estimated resources at 31.6 tcm, followed by Argentina (22.7 tcm) and Algeria (20 tcm). Projections from 2016 suggested shale gas could account for 30 per cent of global natural gas production by 2040.

However, the method is not without controversy. A 2016 US Environmental Protection Agency study found that fracking can potentially contaminate drinking water, though a 2012 Royal Society and Royal Academy of Engineering report found a very low risk of such contamination in the UK due to the depth of the operations. Additionally, injecting fluids can activate pre-existing faults, potentially causing small local tremors. While most seismicity in places like Oklahoma has been linked to wastewater disposal rather than the fracking itself, the risk remains a key consideration for geological mapping.

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