T HE HISTORY of America’s shale industry is brief and dramatic. In just a decade the country has seen the spread of innovative techniques to extract oil and gas locked inside shale rock; the lifting of a decades-long ban on crude exports; a price crash that seemed to decimate the industry—and now a price recovery. Next year the shale boom will account for the biggest surge in one country’s oil output since the International Energy Agency began keeping track. America is now the world’s top oil producer, surpassing Saudi Arabia and Russia.

America’s strides are all the more striking because they coincide with wobbles elsewhere. Output from many giant petro-states looks shaky at best. Exports from Iran are plummeting and due to sink further when American sanctions take effect next month. Venezuela’s production is in freefall. Supplies are vulnerable in Libya and Iraq. Even before the fallout over the disappearance of Jamal Khashoggi, a journalist last seen entering the Saudi Arabian consulate in Istanbul raised questions about the kingdom (see article), many analysts doubted its ability to boost production quickly. Saudi oil exports are already near their peak of the past five years.

The upshot is that the world increasingly relies on American shale. In June America produced 13% of global crude oil, nearly twice the proportion of June 2008; that share will probably rise. This shift is extraordinary, to be sure, but the power it hands to America can also be exaggerated. “The United States is the dominant energy player,” Larry Kudlow, Mr Trump’s economic adviser, boasted this week, able “to cover any shortfalls”. In fact, shale is also bumping against its limits.

In the short term, these limits include bottlenecks in the pipeline infrastructure needed to get oil to market. Companies in the Permian Basin, which spans west Texas and south-eastern New Mexico, are producing more oil than they can pipe out (see article). New pipelines due late next year should help.

Other problems are harder to resolve. Extracting oil from shale has become more efficient since 2014: the median break-even price for producing a barrel is $46. But costs are rising. Executives complain about a long-term labour shortage. Productivity gains in some regions are slowing as wells are drilled closer together. To blast more oil out of rock, companies are now using eye-popping amounts of water and sand. For a single well, hydraulic fracturing (fracking) can involve a total of nearly 65m litres of water, the volume of 25 Olympic swimming pools. That creates logistical and environmental demands. Pumping water back into shale formations is cheaper than carting it away, but that can cause small earthquakes. Colorado is considering new limits on fracking. Other states may decide to follow suit.