Gee, the AGW meme seems to permeate everything these days. Here’s a place where I least expected it to show up, the venerable Astronomy Picture of the Day, one of the oldest running daily features on the Internet. The first blunder is obvious; the graphic of hurricane tracks for September 4th 2012 has nothing to do with astronomy or NASA, it isn’t even remote imaging, but rather a terrestrial data plot. WUWT?
They must be running out of actual astronomy content. The caption however, is the second blunder, worse than the first. Here’s the caption, complete with links:
Hurricane Paths on Planet Earth
Image Credit & Copyright: John Nelson, IDV Solutions Explanation: Should you be worried about hurricanes? To find out, it is useful to know where hurricanes have gone in the past. The above Earth map shows the path of every hurricane reported since 1851, Although striking, a growing incompleteness exists in the data the further one looks back in time. The above map graphically indicates that hurricanes — sometimes called cyclones or typhoons depending on where they form — usually occur over water, which makes sense since evaporating warm water gives them energy. The map also shows that hurricanes never cross — or even occur very near — the Earth’s equator, since the Coriolis effect goes to zero there, and hurricanes need the Coriolis force to circulate. The Coriolis force also causes hurricane paths to arc away from the equator. Although incompleteness fogs long term trends and the prevalence of hurricanes remains a topic of research, evidence is accumulating that hurricanes are, on the average, more common and more powerful in the North Atlantic Ocean over the past 20 years.
You’d think NASA could get more up to date facts to support their claim, or even use a trusted source, such as an actual paper, rather than the highly biased National Public Radio. The interview is telling for NPR’s advocacy:
Mr. WEBSTER: At all the other ocean basins, their hurricane number has sort of stayed around much the same or decreased slightly in the last 10, 15 years.
HARRIS: So there has been no increase in the total number of hurricanes, but there have been more strong hurricanes and fewer weak ones in the past decade.
Mr. WEBSTER: In all of the basins, including the Atlantic Ocean, the number of Category 4 and Category 5 hurricanes since 1995 have doubled compared to the 1970s and the early ’80s.
HARRIS: Webster says there’s a plausible reason for this. Hurricanes draw heat out of the oceans as they build, and the sea surface temperature in the tropics has warmed by 1 degree since 1972. That may sound like a very small number, but it represents a huge amount of energy.
Mr. WEBSTER: And the interesting thing about when the sea surface temperature gets warmer, it’s like the octane level of the fuel becomes higher and higher because, as you get warmer, you start to evaporate more and more moisture.
HARRIS: Because of this, some scientists have predicted that the biggest hurricanes will become even bigger, with faster and more ferocious maximum winds.
Mr. WEBSTER: We’re not seeing that, at least in the satellite observations that we have.
HARRIS: Still, Webster says that he is seeing a global increase in big storms. It’s not just a regional trend. So he suspects there’s a global cause, and that would be global warming heating up the surface of the world’s oceans. But Roger Pielke Jr. at the University of Colorado is worried about making that link.
Yes, “global increase in big storms”, even though just moments before, Dr. Webster says he’s not seeing any evidence of bigger storms.
To their credit, they do give Pielke Jr. some time, and he’s right to be concerned.
The quote of the week in this week’s Climate and Energy News Roundup from SEPP is fitting for this NASA blunder:
In God we trust; all others bring data! – Motto of the Apollo Space Team
Indeed, and we shall. From Dr. Ryan Maue’s Tropical web page:
Figure: Historical North Atlantic tropical storm and major hurricane frequency since 1970 from the HURDAT best-track dataset. Since 1970, there have been 465 tropical storms including 102 major hurricanes (22%). Since 1995, the ratio is slightly higher (26%) or 64 major hurricanes out of a total of 250 storms. Data File
Figure: Historical North Atlantic tropical storm Accumulated Cyclone Energy (ACE) since 1970 from the HURDAT best-track dataset. It is clear from the ACE metric that the active-era since 1995 in the Atlantic is well described with a marked step increase. This is partially due to a preponderance of long-lived Cape Verde origin major hurricanes that have higher intensity and longer duration which means more ACE. ACE is the convolution or sum of the reported wind speed squared (in knots) over the lifetime of the storm. Data File
So yes, there is a slightly higher ratio of storms since 1995, but as the accumlated Cyclone Energy shows, since 2005, the “more powerful storms” meme has evaporated, much like Al Gore’s influence.
The increase in the number of storms is easy to explain, with much of the increase due to better reporting and newer technology. There’s keen interest i the North Atlantic due to U.S. interests, and the U.S. has the best hurricane tracking program in the world.
Dr. Patrick Michaels points out last Friday in this excellent essay on hurricanes:
It’s been 2,535 days since the last Category 3 storm, Wilma in 2005, hit the beach. That’s the longest period—by far—in the record that goes back to 1900.
Quite a drought. He adds:
Aren’t there more whoppers—the powerful Category 4 and 5 monsters that will mow down pretty much anything in their path? As is the case with much severe weather, we simply see more than we did prior to satellites and (in the case of hurricanes) long-range aircraft reconnaissance. As the National Hurricane Center’s Chris Landsea (with whom I have published on tropical cyclones) has shown, if you assume the technology before satellites, the number of big storms that would be detected now is simply unchanged from the past.
There’s a pretty good example of this spinning in the remote Atlantic right now, which is Hurricane Kirk, far away from shipping channels, land, and nosy airplanes. Kirk is compact enough that it would likely have been completely missed fifty years ago. If it spins up into a Category 4 (which is currently not forecast), that would be another biggie that would have gotten away, back in the day.
There’s another reason that the increase in frequency is more apparent than real: “shorties”. That’s what Landsea calls the ephemeral tropical whirls of little consequence that are now named as storms more because of our detection technology than anything else. There’s also probably an overlay of institutional risk aversion in play, as it is now recognized that seemingly harmless thunderstorm clusters over the ocean can spawn decent floods when they hit land.
There is another driver for an increase in Atlantic hurricane frequency that isn’t operating elsewhere. In 1995, a sudden shift in the distribution of North Atlantic temperatures increased hurricane frequency. Landsea predicted—at the time—that the Atlantic would soon fire up from its hurricane doldrums of the previous two decades, which it did. This type of shift has occurred repeatedly in the last century, both before and during (modest) global warming from greenhouse gases.
The influence of technology on storm reporting is something I’ve talked about in great detail before:
h/t to WUWT reader Mike Leckie for pointing out NASA’s APOTD blunder.