Whiplash: Climate change to make Sandy-like paths less likely, study says

Visualization of Hurricane Sandy's winds (NASA)

Visualization of Hurricane Sandy’s winds (NASA)

After Superstorm Sandy hit a road block in the atmosphere’s flow over the Atlantic and took a hard left crashing ashore in New Jersey, a rush of stories emerged speculating climate change may have played a role in the unlikely turn.

Now a new study says, not so fast: climate change will make such a move less common, not more.

“[W]e demonstrate that climate models consistently project a decrease in the frequency and persistence of the westward flow that led to Sandy’s unprecedented track, implying that future atmospheric conditions are less likely than at present to propel storms westward into the coast,” concludes the study “Model projections of atmospheric steering of Sandy-like superstorms”, published Tuesday in the Proceedings of the National Academy of Sciences (PNAS).

Interestingly, this study – for the second time in three weeks – highlights opposing ideas about how global warming will influence the jet stream, the atmosphere’s high altitude steering current.

One the one hand, you have Elizabeth Barnes of Colorado State, lead author of the new PNAS study, whose work challenges the idea that global warming will cause the jet stream to slow down and favor the exceptionally rare but devastating circumstances that brought Sandy ashore.  She finds no strong signal of this dynamic in the historical record and her new modeling study, with co-authors Lorenzo Polvani and Adam Sobel, predicts the opposite in the years ahead.

Related: Arctic warming and our extreme weather: no clear link new study finds

On the other hand, there’s Jennifer Francis of Rutgers University, who stands by her hypothesis the declining Arctic sea ice will cause the jet stream to weaken and meander more – which can focus and enhance extreme weather.

Related: Researcher defends work linking Arctic warming and extreme weather

“You can’t warm the Arctic two to three times faster than the rest of the Northern Hemisphere and not have an impact on the large-scale circulation,” Francis told Climate Wire’s Stephanie Ogburn. “”It is only in the last 15 years or so that we have been able to see this [change in the jet stream] really starting to kick in.”

The competing ideas  are part of the classic give and take in an emerging, high stakes research area.  The New York Times’ Andrew Revkin says the media’s presentation of the conflicting scientific views can lead to  “journalistic whiplash.”

In 2008, Revkin explained:

When science is testing new ideas, the result is often a two-papers-forward-one-paper-back intellectual tussle among competing research teams.

When the work touches on issues that worry the public, affect the economy or polarize politics, the news media and advocates of all stripes dive in. Under nonstop scrutiny, conflicting findings can make news coverage veer from one extreme to another, resulting in a kind of journalistic whiplash for the public.

This has been true for decades in health coverage. But lately the phenomenon has been glaringly apparent on the global warming beat.

Whiplash is certainly at play in the case of the Barnes and Francis work (other scientists are involved too, as Ogburn’s piece discusses).

“[M]any fear that the herky-jerky trajectory is distracting the public from the undisputed basics and blocking change,” Revkin said in 2008.

In my view, though, the whiplash effect can be overcome if we simply present and accept this work for what it is: a set of exploratory hypotheses that are scientifically interesting but not ready for prime time in aiding decisionmakers.

But rather than focusing on the speculative conclusions of emerging single studies, it’s better if we appreciate and act on conclusions about the risk of climate change scientists agree on, for example, per a 2013 consensus statement:

1) Sea levels will rise, increasing the risk of storm surge from hurricanes.

2) Hurricanes are likely to increase in intensity on average in the coming decades.

Not to mention, development along the coast will also increase vulnerability to potentially growing storms and higher seas.

Coastal planners, take notice.

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