Every time a hurricane plows into the southeastern United States, or a
tropical storm devastates some other area of the globe, there is a
question about the involvement of climate change. While the media may
have gotten into a habit of simply repeating that it’s not possible to
connect climate change with any given storm, that’s not really true,
because climate change is affecting every aspect of weather. No storm,
or drought, or flood, that’s happening now, has been altered to some
degree by the human-caused warming of the planet.
But this week a pair of new scientific papers look at two aspects of
just how climate change is affecting hurricanes and other tropical
storms. One demonstrates that the likelihood of the largest, most
damaging storms is increasing because of climate change. The other shows
that climate change is also driving these storms into new areas and,
strangely enough, may eventually drive them to extinction.
Both papers are published this week in the Proceedings of the National Academies of Science. The
first comes
from a team at NOAA and the University of Wisconsin—Madison. Looking
back over decades of storm data, they found increasing strength among
tropical cyclones, and increasing probability of major storms. In
particular, there is a “positive trend” toward storms that reach levels 3
to 5 on the Saffir-Simpson hurricane scale. Though … it’s really hard
to call this trend positive. These are, after all, the storms that are
most likely to bring death and destruction to coastal areas, like those
that recently devastated Puerto Rico.
The NOAA paper isn’t really making predictions about where storms are
going in the near term. It’s just reviewing the information back to the
1970s to confirm what might have already seemed obvious — storms are
getting worse. It’s just that now they’re getting worse … with a 95%
probability level. Both the possibility of a storm developing, and the
possibility that a storm will reach higher intensities has increased.
The
second paper, this time from a NOAA team paired with the University Corporation for Atmospheric Research in Boulder,
Colorado, doesn’t look so much at the intensity of storms, but where
those storms are occurring. The authors of this paper show that, even
more than the growing intensity, the changes over the last forty years
are visible in the tracks that tropical storms have taken and in the
places where they form. For example, people living around the southern
Indian Ocean could be forgiven for thinking that tropical storms are on
the decline—because they absolutely have declined in that area. On the
other hand, Americans looking at storms in the Atlantic are definitely
right in thinking that storm frequency has increased. Overall, storms
are up around the world, but they’re not up evenly. Not
everything in the pattern of storm development can be mapped directly to
warming oceans, but human-caused warming appears to be the driving
factor.
One thing that the location team did that the intensity team did not
was to take the model into the future, and that’s where an unusual
effect appears. As the oceans continue to warm throughout the remainder
of the 21st century, the warming oceans continue to push the development
of storms away from the equator. And by the final decades of the
century, the number of tropical cyclones begins to decrease … because
these storms have been pushed right out of the tropics. There may be
storms, they just won’t be tropical storms.
Which probably won’t be a lot of comfort to anyone in their path.
Read more at: Hurricanes are getting more frequent, more violent, and changing locations due to climate change
