Warming temperatures and changes in ocean circulation and salinity are driving the breakup of ice sheets in Antarctica, but a new study suggests that intense storms may help push the system over the edge.
A research team led by U.S. and Korean scientists deployed three moorings with hydrophones attached seaward of the Nansen Ice Shelf in Antarctica’s Ross Sea in December of 2015, and were able to record hundreds of short-duration, broadband signals indicating the fracturing of the ice shelf.
The “icequakes” primarily took place between January and March of 2016, with the front of the ice sheet calving into two giant icebergs on April 7. The day the icebergs drifted away from the shelf coincided with the largest low-pressure storm system the region had recorded in the previous seven months, the researchers say.
Results of the study are being published this week in Frontiers in Earth Science.
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Journal Reference:
R. P. Dziak, W. S. Lee, J. H. Haxel, H. Matsumoto, G. Tepp, T.-K. Lau, L. Roche, S. Yun, C.-K. Lee, J. Lee, S.-T. Yoon. Hydroacoustic, Meteorologic and Seismic Observations of the 2016 Nansen Ice Shelf Calving Event and Iceberg Formation. Frontiers in Earth Science, 2019; 7 DOI: 10.3389/feart.2019.00183
Politics versus science in attributing extreme weather events to manmade global warming.
If you follow me on twitter, you may have noticed that I was scheduled to testify before the House Oversight and Reform Committee on Jun 12 [link]. The subject of the Hearing is Contending with Natural Disasters in the Wake of Climate Change.
Late on Jun 10, I received an email telling me that the Hearing is postponed (as yet unscheduled). Apparently the Committee finds it more urgent to have a Hearing related to holding the Attorney General and Secretary of Commerce in contempt of Congress [link]. Interesting to ponder that Congressional procedural issues are deemed to be more important than Climate Change.
So I spent all last week working on my testimony (which is why there have been no new blog posts). I hope the Hearing will eventually happen (Michael Mann is also scheduled to testify).
Hurricanes and climate change constitute a major portion of my testimony. You may recall my recent series on Hurricanes & climate change [link]. Specifically with regards to detection and attribution, my bottom line conclusion was:
“In summary, the trend signal in hurricane activity has not yet had time to rise above the background variability of natural processes. Manmade climate change may have caused changes in hurricane activity that are not yet detectable due to the small magnitude of these changes compared to estimated natural variability, or due to observational limitations. But at this point, there is no convincing evidence that manmade global warming has caused a change in hurricane activity.”
CFAN predicts an active North Atlantic hurricane season season.
The Atlantic hurricane has begun. We are off to an early start with one wimpy subtropical storm that lasted less than a day, and a small system that is trying to spin up in the Bay of Campeche.
Other forecast providers have begun issuing forecasts:
NOAA predicts a near normal season with 4-8 hurricanes.
Tropical Storm Risk predicts slightly below normal activity, with 6 hurricanes and ACE of 88.
With the devastating Dayton, Ohio tornadoes fresh on our minds, it is useful to examine exactly why (modest) global warming has produced fewer – not more – of such events.
The simple answer is that tornado formation requires unusually cool air.
Very few thunderstorms produce tornadoes. In the hot and humid tropics, they are virtually unheard of. The reason why is that (unlike hurricanes) tornadoes require strong wind shear, which means wind speed increasing and changing direction with height in the lower atmosphere.
These conditions exist only when a cool air mass collides with a warm air mass. And the perfect conditions for this have existed this year as winter has refused to lose its grip on the western United States. So far for the month of May 2019, the average temperature across the U.S. is close to 2 degrees Fahrenheit below normal.
Although many meteorologists and climatologists confirm that there is no data suggesting global warming is causing more frequent and intense tornado and hurricane activity, there is a small but influential alarmist group who claim otherwise. And it’s no surprise who the click-baiting media parrot at maximum volume.
Landfalling hurricanes downward trend
At the 5:45 mark, Joe presents a chart depicting the frequency of US landfalling hurricanes since 1900:
Dr. Philip Klotzbach of Colorado State University writes on Twitter:
Seasonal #hurricane forecast from @ColoradoStateU predicts slightly below-average season: 13 named storms, 5 hurricanes & 2 major (Cat 3+, >=111 mph) hurricanes. Primary reason for slightly below-avg forecast is anticipated continuation of weak #ElNino.
We anticipate that the 2019 Atlantic basin hurricane season will have slightly belownormal activity. The current weak El Niño event appears likely to persist and perhaps even strengthen this summer/fall. Sea surface temperatures averaged across the tropical Atlantic are slightly below normal, and the far North Atlantic is anomalously cool.
Our Atlantic Multi-decadal Oscillation index is below its long-term average. We anticipate a slightly below-average probability for major hurricanes making landfall along the continental United States coastline and in the Caribbean. As is the case with all hurricane seasons, coastal residents are reminded that it only takes one hurricane making landfall to make it an active season for them. They should prepare the same for every season, regardless of how much activity is predicted.
PROBABILITIES FOR AT LEAST ONE MAJOR (CATEGORY 3-4-5) HURRICANE LANDFALL ON EACH OF THE FOLLOWING COASTAL AREAS:
1) Entire continental U.S. coastline – 48% (average for last century is 52%)
2) U.S. East Coast Including Peninsula Florida – 28% (average for last century is 31%)
3) Gulf Coast from the Florida Panhandle westward to Brownsville – 28% (average for last century is 30%)
PROBABILITY FOR AT LEAST ONE MAJOR (CATEGORY 3-4-5) HURRICANE TRACKING INTO THE CARIBBEAN
(10-20°N, 88-60°W) 1) 39% (average for last century is 42%)
Things often calm down after January 1 during El Nino years….but not this year…with the U.S. West Coast from central California to Washington State about to be pummeled by a series of storms. Rain, snow, wind? Plenty for everyone.
A view of the latest infrared satellite imagery shows an amazing line-up of one storm after another stretching way into the Pacific. A traffic jam of storms.
Let’s examine our stormy future, using a series of sea level pressure forecasts from the UW WRF weather forecast models (solid lines are sea level pressure, shading in lower atmosphere temperature).
In the whirlwind that is 2018, there has been a notable lack of high-end twisters.
We’re now days away from this becoming the first year in the modern record with no violent tornadoes touching down in the United States. Violent tornadoes are the strongest on a 0 to 5 scale, or those ranked EF4 or EF5.
It was a quiet year for tornadoes overall, with below normal numbers most months. Unless you’re a storm chaser, this is not bad news. The low tornado count is undoubtedly a big part of the reason the 10 tornado deaths in 2018 is also vying to be a record low.
While we still have several days to go in 2018, and some severe weather is likely across the South to close it out, odds favor the country making it the rest of the way without a violent tornado.
If and when that happens, it will be the first time since the modern record began in 1950.
Sediment cores from Western Lake provide a 7000-yr record of coastal environmental changes and catastrophic hurricane landfalls along the Gulf Coast of the Florida Panhandle. Using Hurricane Opal as a modern analog, we infer that overwash sand layers occurring near the center of the lake were caused by catastrophic hurricanes of category 4 or 5 intensity. Few catastrophic hurricanes struck the Western Lake area during two quiescent periods 3400–5000 and 0–1000 14C yr B.P. The landfall probabilities increased dramatically to ca. 0.5% per yr during an “hyperactive” period from 1000–3400 14C yr B.P., especially in the first millennium A.D. The millennial-scale variability in catastrophic hurricane landfalls along the Gulf Coast is probably controlled by shifts in the position of the jet stream and the Bermuda High.
I’ve updated a plot of Florida major hurricane strikes since 1900 with Hurricane Michael, and the result is that there is still no trend in either intensity or frequency of strikes over the last 118 years:
Les côtes de Flandre n’ont pas toujours été aussi paisibles qu’aujourd’hui, et je n’oublie pas le raz-de-marée du 31 janvier 1953 qui toucha les Pays-Bas et notre littoral, faisant plus de 1800 morts et des dégâts considérables. (photo : à Ostende).
Pêchés dans diverses chroniques et ouvrages (notamment “La Flandre mystérieuse” de Saint Hilaire), j’en ai fait une compilation qui n’a bien entendu aucune prétention scientifique ou historique, mais ces événements avaient laissé une trace dans la mémoire populaire, trace qui a hélas fortement tendance à s’effacer.
J’y ajoute quelques événements survenus en France et aux Pays-Bas, dont on peut raisonnablement penser au vu de leur localisation, qu’ils eurent des conséquences sur nos côtes
Even before Hurricane Florence made landfall somewhere near the border of North and South Carolina, predicted damage from potentially catastrophic flooding from the storm was already being blamed on global warming.
Writing for NBC News, Kristina Dahl contended, “With each new storm, we are forced to question whether this is our new, climate change-fueled reality, and to ask ourselves what we can do to minimize the toll from supercharged storms.”
The theory is that tropical cyclones have slowed down in their speed by about 10 percent over the past 70 years due to a retreat of the jet stream farther north, depriving storms of steering currents and making them stall and keep raining in one location. This is what happened with Hurricane Harvey in Houston last year.
But like most claims regarding global warming, the real effect is small, probably temporary, and most likely due to natural weather patterns …
All around the world the climate druids are at work.
Show me the error bars
Once upon a time a scientist talked about thirty year trends and anachronistic things like “confidence intervals”. Now, thanks to the discovery of Unscience, any noisy, random short data is fair game to be declared undeniable climate change. Periods of flooding also qualify, as do periods of nice weather, though strangely no one mentions those. Where are the headlines? If climate change caused drought on the East Coast of Australia, it’s also causing average rain and good crops in Western Australia.
In terms of scientific data analysis we don’t get that many droughts or six-day-August-heatwaves to analyze. They’re complex phenomena caused by multiple factors and we only have short records. This makes them ideal to be oversold to hapless folk as a “sign” of climate change.
One of the main difficulties with tornado records is that a tornado, or evidence of a tornado must have been observed. Unlike rainfall or temperature, which may be measured by a fixed instrument, tornadoes are short-lived and very unpredictable. If a tornado occurs in a place with few or no people, it is not likely to be documented. Many significant tornadoes may not make it into the historical record since Tornado Alley was very sparsely populated during the 20th century.
Much early work on tornado climatology in the United States was done by John Park Finley in his book Tornadoes, published in 1887. While some of Finley’s safety guidelines have since been refuted as dangerous practices, the book remains a seminal work in tornado research. The University of Oklahoma created a PDF copy of the book and made it accessible at John Finley’s Tornadoes(link is external)
