New research presented by a Canadian-led study has found that no more than 6 percent and possibly as little as 1.5 percent of world groundwater is renewable in a human lifetime, yet over a third of the world population relies on groundwater for their drinking water.
The researchers were able to determine what percentage of groundwater had been replenished since the 1960s by measuring samples for radioactive hydrogen that was introduced in trace amounts in all surface water during Cold War nuclear weapons testing.
The small renewable percentage of the nearly 22.6 million cubic kilometers of underground water is still high enough to sustain much of the global population, but the problem is that renewable groundwater sources are not evenly distributed. Places like California and Egypt regularly draw on non-renewable groundwater that will someday run out.
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