claim: The increase in atmospheric methane, a greenhouse gas, in the latter part of the 20th century was explained as coming from expansion of grazing and rice cultivation, but the cause was found to be leaking gas pipelines in the Soviet Union which are now being properly managed and maintained.
evidence: The Ordovician saw the highest sea levels of the Paleozoic, and the low relief of the continents led to many shelf deposits being formed under hundreds of metres of water.