A couple of days ago NYT’s Andrew Revkin took exception to the use of the word “collapse” in headlines surrounding the paper suggesting that Antarctic ice sheets were in “imminent unstoppable collapse” there’s lots of hype surrounding this, and even the governor of California fell victim to it with a ridiculous claim of needing to move LAX airport.
Today we have a paper from
MIT University of Wisconsin and NOAA that claims tropical storm intensity is shifting poleward by about 30-40 miles per decade. What struck me was this juxtaposition of the two press releases in the Eurekalert feed. It is almost as if they aren’t talking about the same paper. And, MIT had nothing to do with the paper’s publication, yet they are writing a press release about it. Here is a screencap of the Eurekalert feed:
One seems hyped with inflammatory and scary language, the other does not. What was also interesting is that both PR’s were presented by women with “Allen” as last names. I present both press releases in full below, and you can determine for yourselves if one is hyped or not.
Tropical cyclone ‘maximum intensity’ is shifting toward poles
Researchers find that the average latitude where tropical cyclones achieve maximum intensity has been shifting poleward since 1980
Over the past 30 years, the location where tropical cyclones reach maximum intensity has been shifting toward the poles in both the northern and southern hemispheres at a rate of about 35 miles, or one-half a degree of latitude, per decade according to a new study, The Poleward Migration of the Location of Tropical Cyclone Maximum Intensity, published tomorrow in Nature.
As tropical cyclones move into higher latitudes, some regions closer to the equator may experience reduced risk, while coastal populations and infrastructure poleward of the tropics may experience increased risk. With their devastating winds and flooding, tropical cyclones can especially endanger coastal cities not adequately prepared for them. Additionally, regions in the tropics that depend on cyclones’ rainfall to help replenish water resources may be at risk for lower water availability as the storms migrate away from them.
The amount of poleward migration varies by region. The greatest migration is found in the northern and southern Pacific and South Indian Oceans, but there is no evidence that the peak intensity of Atlantic hurricanes has migrated poleward in the past 30 years.
By using the locations where tropical cyclones reach their maximum intensity, the scientists have high confidence in their results.
“Historical intensity estimates can be very inconsistent over time, but the location where a tropical cyclone reaches its maximum intensity is a more reliable value and less likely to be influenced by data discrepancies or uncertainties,” said Jim Kossin, the paper’s lead author, who is a scientist with NOAA’s National Climatic Data Center currently stationed at the NOAA Cooperative Institute for Meteorological Satellite Studies at the University of Wisconsin–Madison.
Consistent with this poleward shift, many other studies are showing an expansion of the tropics over the same period since 1980.
“The rate at which tropical cyclones are moving toward the poles is consistent with the observed rates of tropical expansion,” explains Kossin. “The expansion of the tropics appears to be influencing the environmental factors that control tropical cyclone formation and intensification, which is apparently driving their migration toward the poles.”
The expansion of the tropics has been observed independently from the poleward migration of tropical cyclones, but both phenomena show similar variability and trends, strengthening the idea that the two phenomena are linked. Scientists have attributed the expansion of the tropics in part to human-caused increases of greenhouse gases, stratospheric ozone depletion, and increases in atmospheric pollution.
However, determining whether the poleward shift of tropical cyclone maximum intensity can be linked to human activity will require more and longer-term investigations.
“Now that we see this clear trend, it is crucial that we understand what has caused it – so we can understand what is likely to occur in the years and decades to come,” says Gabriel Vecchi, scientist at NOAA’s Geophysical Fluid Dynamics Laboratory and coauthor of the study.
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Study: Dangerous storms peaking further north, south than in past
New analysis of cyclones shows migration away from tropics and toward the poles in recent decades
Powerful, destructive tropical cyclones are now reaching their peak intensity farther from the equator and closer to the poles, according to a new study co-authored by an MIT scientist.
The results of the study, published today in the journal Nature, show that over the last 30 years, tropical cyclones — also known as hurricanes or typhoons — are moving poleward at a rate of about 33 miles per decade in the Northern Hemisphere and 38 miles per decade in the Southern Hemisphere.
“The absolute value of the latitudes at which these storms reach their maximum intensity seems to be increasing over time, in most places,” says Kerry Emanuel, an MIT professor and co-author of the new paper. “The trend is statistically significant at a pretty high level.”
And while the scientists who conducted the study are still investigating the atmospheric mechanisms behind this change, the trend seems consistent with a warming climate.
“It may mean the thermodynamically favorable conditions for these storms are migrating poleward,” adds Emanuel, the Cecil and Ida Green Professor of Earth and Planetary Sciences at MIT.
The implications are serious, since the movement of peak intensity means regions further north and south of the equator, which have not previously had to face many landfalls by violent cyclones, may now have greater exposure to these extreme weather events. That, in turn, could lead to “potentially profound consequences to life and property,” the paper states. “Any related changes to positions where storms make landfall will have obvious effects on coastal residents and infrastructure.”
Moving with the trade winds?
The paper, “The Poleward Migration of the Location of Tropical Cyclone Maximum Intensity,” was co-written by Emanuel, James P. Kossin of the University of Wisconsin, and Gabriel A. Vecchi of the National Oceanic and Atmospheric Administration (NOAA).
To conduct the study, the scientists used international data from 1982 to 2012, collected by NOAA’s National Climactic Data Center. They used the location of peak intensity of cyclones as a benchmark because it is a more consistent metric than statistics such as storm duration: The duration can be harder to estimate because of difficulties in establishing precisely when a storm should first be considered a tropical cyclone.
While there are regional differences in the poleward movement of cyclones, the fact that every ocean basin other than the northern Indian Ocean has experienced this change leads the researchers to suggest, in the paper, that this “migration away from the tropics is a global phenomenon.”
However, Emanuel notes, the global mechanisms underlying the trend are a matter for further research.
“We think, but have not yet been able to establish, that this is connected to independently observed poleward expansion of the Hadley circulation,” Emanuel says, referring to a large-scale pattern of global winds, which in recent years has also moved further poleward. The paper notes the potential impact of vertical wind shear, which inhibits cyclone formation; data suggests a decrease in wind shear in the tropics and an increase at higher latitudes.
Emanuel notes that researchers in the field are continuing to examine the links between storm migration and global warming. Over the past three decades, the incidence of cyclones in the tropics has actually diminished — because while tropical cyclones may become more intense in a warmer climate, it is actually more difficult to generate them.
Ocean temperatures between 82 and 86 degrees Fahrenheit seem to be “ideal for the genesis of tropical cyclones,” Emanuel says, “and as that belt migrates poleward, which surely it must as the whole ocean warms, the tropical cyclone genesis regions might just move with it. But we have more work to do to nail it down.”
Written by Peter Dizikes, MIT News Office
MIT Department of Earth, Atmospheric and Planetary Sciences
MIT announces new initiative on environment
Bigger storms ahead