The White House’s global warming claims are now being contradicted by the Obama administration’s own scientists.
President Barack Obama’s administration has repeated the talking point over the year that man-made global warming has increased the incidence of heavy rainfalls across the U.S., but a new study casts doubt on this assertion.
National Oceanic and Atmospheric Administration (NOAA) scientists recently published a report claiming heavy daily precipitation trends “have been intimately linked to internal decadal ocean variability, and less to human-induced climate change.”
“Analysis of model ensemble spread reveals that appreciable 35-yr trends in heavy daily precipitation can occur in the absence of [man-made greenhouse gas] forcing, thereby limiting detection of the weak anthropogenic influence at regional scales,” NOAA scientists wrote.
NOAA’s new study, however, runs up against the Obama administration’s 2014 National Climate Assessment (NCA), which claims global warming is increasing heavy downpours.
While both studies agree heavy rainfall events have increased, the 2014 NCA suggests global warming is mostly to blame. NOAA, on the other hand, claims man-made warming played a minimal role in increasing heavy rains.
“Human-induced climate change has already increased the number and strength of some of these extreme events,” according to the NCA. “Over the last 50 years, much of the U.S. has seen increases in prolonged periods of excessively high temperatures, heavy downpours, and in some regions, severe floods and droughts.”
“Global analyses show that the amount of water vapor in the atmosphere has in fact increased due to human-caused warming,” reads the NCA. “This extra moisture is available to storm systems, resulting in heavier rainfalls. Climate change also alters characteristics of the atmosphere that affect weather patterns and storms.”
Concern about heavy rains and flooding has been growing in recent years. For example, the Midwest experienced heavy flooding over the holidays last year after being hit with torrential rain. There were also a string of tornadoes hitting towns across the country. The media immediately suggested global warming was at least partly to blame.
In October, South Carolina was hit with a “1-in-1,000 year rain event” as Hurricane Joaquin moved past the U.S. and out into the Atlantic Ocean. Again, it was not so subtly hinted in media reports that global warming caused heavy rains to increase, causing the state to experience massive amounts of flooding.
Nevertheless, it’s difficult to tie global warming to any single weather event, no matter how extreme. Cato Institute climate scientists Patrick Michaels and Chip Knappenberger noted the new NOAA study provides much-needed restraint to alarmist government climate reports.
“[B]asically they’re saying that the federal government’s assessment of the impacts of climate change greatly overstates the case for linking dreaded carbon dioxide emissions to extreme precipitation events across the United States,” Michaels and Knappenberger wrote.
“[T]hey think that folks (including the president and the authors of the National Climate Assessment) are far too premature in linking observed changes to date with our reliance on coal, oil, and natural gas as primary fuels for our energy production,” the Cato scientists noted.
“Whether or not at some later date a definitive and sizeable (actionable) anthropogenic signal is identifiable in the patterns and trends in heavy precipitation occurrence across the United States is a question whose answer will have to wait—most likely until much closer to the end of the century or beyond,” they added.