Study: Warming Will Shift Tracks of Future Sandy-Like Tropical Storms Away from U.S. Northeast

“The weather patterns that steered deadly Superstorm Sandy into the East Coast last year may be on the decrease, thanks to rising levels of greenhouse gases in the atmosphere,” states the press release for a study published today in Proceedings of the National Academy of Sciences. The release continues:

While the atmospheric conditions that pushed Sandy into the New Jersey coast in October 2012 will still occur in the North Atlantic, a team of researchers led by Elizabeth Barnes, assistant professor in the Colorado State University Department of Atmospheric Science, has found that those conditions will occur less often, making it less likely that any future superstorms that form will be steered into the United States.

“Using state-of-the-art climate models, we project that there will be a decrease in the frequency and persistence of the westward flow that led to Sandy’s unprecedented track,” Barnes said. “That implies that future atmospheric conditions are less likely than at present to propel tropical storms westward into the coast.”

Two anomalous weather patterns slammed Sandy into the Northeast, according to Barnes. First, the jet stream shifted toward the south. Second, a “wave breaking” and blocking event in the upper atmosphere blocked the normal west-to-east wind, “causing the wind to blow back towards North America rather than out to sea.” When Sandy “met the block and the westward wind flow, it accelerated toward the New Jersey Coast with winds in excess of 80 miles per hour.” In the PNAS study, “the models show a lessening of the frequency of the breaking-and-blocking pattern with a poleward shift of the jet-stream in the future, and that this is found for the Southern Hemisphere as well.”

There may be no greater heresy in this enlightened age than the notion that global warming will avert weather disasters. But there’s evidence it has already begun.

In June, Cato Institute climatologist Chip Knappenberger, in a column on MasterResource.Org, described several “Billion Dollar Weather Events Averted by Global Warming.” Not unlike the Barnes PNAS study, Knappenberger found that wind patterns “consistent with” global warming prevented two tropical storms from developing into full-blown hurricanes and prevented two others from hitting the U.S. East Coast. Here’s an excerpt:

Billion-Dollar Aversions: Some Recent Examples

I have begun to compile a list of averted billion-dollar weather events during the past year “consistent with” anthropogenic global warming. A full list is necessarily much greater because there are certainly many more events that we could never know about because they didn’t rise to the extreme to be recorded.

Hurricane Debby, June 2012. Hurricane Debby never formed. Increased vertical wind shear “consistent with” expectations from global warming prevented the development of tropical storm Debby into hurricane Debby. Damage estimates from tropical storm Debby have been estimated at $250 million with 5 direct and 3 indirect fatalities from the storm. Had global warming not helped to inhibit the growth of the storm system, these totals may well have been higher, exceeding a billion dollars. (For more information of the life of Debby, see here.)

Hurricane Florence, August 2012. Hurricane Florence never formed. Increased wind shear and African dust—both conditions which are “consistent with” anthropogenic global warming, combined to inhibit the formation of the Cape Verde tropical cyclone. As many Cape Verde tropical cyclones develop into major hurricanes and make landfall along the U.S. coastline, in the absence of the inhibiting conditions, major Hurricane Florence may have made a direct hit on Miami, or Charleston, or Washington DC causing many billion dollars in damage and taking countless lives. (For more details of the life of Florence, see here.)

Hurricane Leslie, September 2012. Hurricane Leslie was another Cape Verde tropical cyclone that looked to be headed toward the southeastern U.S. coastline. But the influence of an atmospheric “blocking” pattern—the same type of pattern that acted to intensify Hurricane Sandy and steer it into the northeastern U.S. (and which has been called “consistent with” global warming)—acted to halt the westward progression of the storm systems and inhibit its development. Instead of becoming a disastrous landfalling hurricane, Leslie drifted out at sea, eventually delivering a glancing blow to southeastern Newfoundland. A potential multi-billion dollar disaster averted thanks to factors “consistent with” global warming. (For more details of the life of Leslie, see here.)

Hurricane Nadine, September 2012. Hurricane Nadine was Cape Verde tropical cyclone that never really got going. Instead of a potentially damaging major hurricane making a direct hit along the Southeastern U.S. coast, conditions “consistent with” global warming, such as a large Atlantic Warm Pool (above average sea surface temperatures in the tropical north Atlantic), conspired to steer the storm northward, harmlessly into the central Atlantic instead of allowing it to track across warm waters conducive for tropical cyclone intensification and on course for a potentially calamitous U.S. landfall. Another potential billion-dollar-plus disaster averted. (For more information on the life of Nadine, see here.)

I could continue on this list of potential damaging hurricanes, but you get the idea—every one that didn’t grow to a major hurricane and make landfall along the U.S. coastline was potentially influenced by factors “consistent with” anthropogenic global warming.

There are many times more tropical cyclones that didn’t cause a billion-dollar weather disaster than did. In fact, we are currently in the midst of the longest period since 1900 that the U.S. has gone without a major hurricane making landfall—and this despite human-caused climate change.

Knappenberger goes on to describe other billion-dollar benefits “consistent with” global warming in 2013: reduced crop damage from winter freezes in Florida and California, a forecast East Coast snow blizzard in March that never materialized, a 12-month period notable for its lack of tornado activity, and severe weather forecast for the Midwest (similar to the 2012 derecho) that did not occur.

President Obama and others like to say that global warming is a factor in every weather event. But if so, global warming must be partly responsible for good weather as well as bad, disasters averted as well those that occur — a conclusion supported by both Barnes’s study and Knappenberger’s column.