Steve Sherwood is a climate scientist at Yale University in New Haven, Connecticut, who was not involved in the study. He said the findings are uncontroversial, but the new data set is a boon.
"People haven't really been talking enough about what higher humidity is going to mean in the future," he said, "and part of the reason they haven't been talking about it is that we haven't had very good data."
"They've put out a data set that people can actually use to look at long-term changes," he added.
Global Warming Evidence
Santer of the U.S. Department of Energy led research published recently in the journal Proceedings of the National Academy of Sciences that linked human activity to an increase in atmospheric water vapor. (Gillett was a co-author of that paper.)
Gillett, co-author on the new Nature study, also contributed to a July paper in the journal Nature that linked human activity to changes in rainfall patterns over the past century.
This body of work should silence criticism that the only evidence of global warming comes from surface and ocean temperature records, Santer said. Human influence is prevalent throughout the climate system, he added.
The combined studies should also help scientists more accurately predict Earth's response to increasing levels of greenhouse gases, Gillett said.
For example, he said the models used for the July Nature study underestimated the change in rainfall due to global warming, but that the models do a "reasonably good" job of capturing the humidity changes.
"These results will help to pin down which parts of the hydrological cycle the models can simulate well and which not so well ... and help improve the models," he said.
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