Guest post by Chip Knappenberger (above graphic by Anthony)
The press has been quick to jump on the idea that post-tropical cyclone Sandy (it was not a hurricane at landfall) was worsened by anthropogenic global warming and that “superstorms” are here to stay.
But I must ask the impertinent question: could anthropogenic global warming actually have lessened the impacts of Sandy?
There are basically three pro-global warming talking points involving Sandy: 1) global warming has caused sea levels to rise, thus making the storm surge larger, 2) global warming has led to higher sea surface temperatures and thus stronger hurricanes, and 3) global warming is making extratropical circulation features more conducive to intense and slower moving storm systems.
There is precious little evidence to definitively support any of these points when applied to Sandy, and, in fact, there exists a body of evidence pointing to the opposite conclusion—that anthropogenic global warming may have actually acted to mitigate the intensity of Sandy. Perhaps what lies closest to our current best understanding is that anthropogenic global warming made little contribution one way or the other.
Let’s start with sea level rise. Water levels at New York City’s Battery Park location have been measured and recorded since 1856. The full record shows an overall (relatively steady) rise of about 0.11 inches per year, for a total rise between 1856 and now of just a bit more than 17 inches. How much of this has to do with anthropogenic global warming? Maybe a third, or about 6 inches. Of the rest, about half was caused by a subsidence of the land (geological processes related to the end of the last ice age, see Engelhart et al., 2009 for example), and the remainder to a warming up from the naturally occurring cold period which ended in the mid-19th century. So of the total 17.34 feet of water (above the station datum) recorded at The Battery tide gauge during the height of Sandy, about 0.5 feet of that could probably be linked to anthropogenic global warming. This is not nothing, but the overwhelming majority of the damage done by the storm surge would have happened anyway. For comparison, the influence of the full moon that night was about as large as the influence of anthropogenic global warming.
As to anthropogenic global warming’s impact on the path, frequency, and intensity of hurricanes, there is a mixed bag of potential outcomes which may be detectable far in the future (towards the end of the century) if anthropogenic greenhouse gas emissions continue to rise. The current science suggests that the frequency of hurricanes could decrease, the intensity may increase slightly, and the preferred path may be displaced out to sea (Wang et al., 2010). The net effect on the U.S. is anyone’s guess at this point (but 2 of the 3 argue for fewer hurricane impacts in the U.S.). But what virtually everyone does agree upon is that any influence of anthropogenic global warming on hurricane characteristics is not detectable in today’s climate (see for example, Knutson et al., 2010). So that talking point is basically off the table.
Which brings us to the third global-warming-made-Sandy-worse talking point—the influence of anthropogenic global warming on the extratropical circulation characteristics.
This is where the rubber really meets the road when it comes to Sandy’s behavior. Without the northward, and ultimately westward pull from the upper atmospheric jet stream, Sandy would have progressed harmlessly eastward, away from the Northeast coast, and out to sea. But that is not what happened. Instead, a fairly deep trough (southward excursion) of the jet stream was coincidentally passing through the eastern U.S. just as hurricane Sandy was progressing up (but offshore) the U.S. Eastern Seaboard. This trough had the effect of attracting Sandy, and drawing it northwestward, pumping energy into it, and changing its character from a hurricane to an extra/post tropical storm system (also known as a Nor’easter in this part of the country). In October, this type of behavior is not particularly unusual. The preferred tropical cyclone track maps provided by the National Hurricane Center (Figure 1) indicate a general tendency for tropical cyclones in October to curve back into the northeastern U.S.—just like Sandy did.
In fact, since the beginning of the 20th century, there have been about a dozen or so tropical cyclones that have made landfall in the U.S. north of Cape Hatteras which had a westerly component to their trajectory either immediately before or just after they came ashore. This includes historically damaging storms such as the 1903 New Jersey hurricane, the 1938 Long Island Express hurricane, and 1972’s Hurricane Agnes which is still the flood of record in many parts of the Northeast.
The last one was tropical storm Danielle, over twenty years ago. This is the longest interval in the record (since 1900) between westward-component storms north of Hatteras. So much for the influence of global warming!
So, given this fairly typical behavior—why would anyone even consider that anthropogenic global warming played a role in Sandy?
For two reasons: 1) any bad weather these days is immediately linked to global warming by someone with an agenda, and 2) there was a paper published last spring (Francis and Vavrus, 2012) in which the authors concluded that the decline of Arctic sea ice (tied to anthropogenic global warming) was causing the Arctic to warm up faster than the lower latitudes, reducing the natural north-south temperature gradient which is where the jet stream (and extratropical storms) gain energy. According to Francis and Vavrus, a less energetic jet stream contracts and becomes more meandering, with relatively deeper troughs and higher ridges which produce slower moving storm systems and more extreme weather.
Since Sandy was strengthened and pulled ashore by a deep trough/ridge system in the jet stream, folks are quick to assume that the Francis and Vavrus mechanism tying in anthropogenic global warming must be involved.
Not so fast!
This is like claiming to have made a new discovery that, when flipping a coin, heads are now more likely to occur than tails. And wouldn’t you know, the next time the coin is flipped, it came up heads—to which you proclaim, “See, I told you so.” And since heads are associated with a bad outcome, the press flock to your explanation. But what is completely overlooked, is that other researchers have examined every coin flip for the past 60 years and found that heads and tails occur with equal likelihood. So the current heads outcome is simply part of the natural 50-50 occurrence of heads or tails.
In this case, the other researchers are a pair of atmospheric scientists from Cornell University which have examined the forward speed of all nor’easters along the East Coast from 1951 through 2006 (Bernhardt and DeGaetano, 2012). And what they found, in their own words, was “There was no clear trend in [nor’easter forward] speed during the time period, although considerable season-to-season variability was present.” In other words, while there is a lot of storm-to-storm and season-to-season variability, there is no overall trend towards slower moving nor’easters (Figure 2)—so much for the Francis and Vavrus hypothesis.
And, there has been a lot of other research on changes in the patterns and characteristics of the Northern Hemisphere jet stream during the period of anthropogenic global warming which did not find that same thing that Francis and Vavrus found (we detailed many of these findings in our March 8, 2012 Current Wisdom). At least one of those papers suggested that the methodology employed by Francis and Vavrus “can generate false, or mask actual, variability patterns including trends” (Strong and Davis, 2007). Others concluded that global warming contracted, the jet stream, flattened it over the eastern U.S., and sped it up a bit—characteristics, which, along with a decreased temperature gradient, if applied to Sandy, would have combined to produce a less intense post tropical storm system than if global warming had not been occurring.
So rather than anthropogenic global warming making Sandy worse, it could have actually lessened its intensity and impacts.
The truth is, is that it is impossible to know how, or even if, global warming played any role at all in the lifecycle of Sandy. The science is all over the map, and the signal-to-noise ratio is so low that no matter what is occurring its impact in any direction is undetectable.
But it is sexier and has much more press appeal to proclaim that the destruction wrought by “superstorm” Sandy is the product of our unrestrained fossil fuel consumption, rather than the equally plausible opposite—that anthropogenic climate changes may have combined to lessen Sandy’s intensity.
References:
Bernhardt, J.E., and A.T. DeGaetano, 2012. Meteorological factors affecting the speed of movement and related impacts of extratropical cyclones along the U.S. east coast. Natural Hazards, 61, 1463-1472, doi:10.1007/s11069-011-0078-0
Engelhart, S.E., et al., 2009. Spatial variability of late Holocene and 20th century sea-level rise along the Atlantic coast of the Unites States. Geology, 37, 1115-1118.
Francis, J., and S. Vavrus, 2012. Evidence linking arctic amplification to extreme weather in mid-latitudes. Geophysical Research Letters, 39, L06801, doi:10.1029/2012GL051000.
Knutson, T. R., et al., 2010. Tropical cyclones and climate change. Nature Geoscience, 3, 157-163, doi: 10.1038/ngeo779
Strong, C., and R. Davis, 2007. Winter jet stream trends over the Northern Hemisphere. Quarterly Journal of the Royal Meteorological Society, 133, 2109-2115, doi:10.1002/qj.171
Wang, C., et al., 2011: Impact of the Atlantic warm pool on United States landfalling hurricanes. Geophysical Research Letters, 38, L19702, doi:10.1029/2011GL049265.
Global Science Report is a weekly feature from the Center for the Study of Science, where we highlight one or two important new items in the scientific literature or the popular media. For broader and more technical perspectives, consult our monthly “Current Wisdom.”
Related articles
- IPCC – “Sandy Was Not Caused By Anthropogenic Global Warming” (toryaardvark.com)
- NOAA Climate Investigator – No link between Sandy and Global Warming (iceagenow.info)
- Tisdale: Where’s The Anthropogenic Global Warming Signal in the NODC Ocean Heat Content Data (0-700Meters)? (wattsupwiththat.com)
- There will probably be fewer Sandy-like storms in the future (chron.com)
- Climatologist says Sandy not caused by global warming. (wsfa.com)
- Gore blames ‘global warming’… (washingtontimes.com)
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More importantly, as population density increase, most weather events will have a greater impact. More run off due to more cement being poured, more roads and building sites, all these factors increase the impact because all of these events change the environment.
Sorry for repost.
Glaciers have been static or melting since around 1750 according to Manley and glaciers in substantial retreat by 1850 which have been adding to sea level rise. But are things worse now than in the past?
The overwhelming impression I get from reading tens of thousand of mostly European (but primarily British) observations from the last 1000 years is that we live in a benign time and storms were often far worse in the past (which makes Sandy no less horrifying) .
Determining hybrid storms that ‘Sandy’ is said to be is a skilled job best left to those such as Anthony Watts or Judith Curry but can I refer you to the storm of 1717 which affected much of northern Europe and was centred on the north sea?
“It is clear that the ingredients of the severe storm of 24/25 December 1717 as many of the other historic storms here analysed, were a developing meditionality which injected warm very humid air from the south…at a time when very cold arctic air was advancing behind a cold front from the Iceland region.”
11 000 people were said to have died and 15000 houses destroyed at a time when the population was a fraction of today.
From the book “Historic storms of the North sea, British Isles and Northwest Europe” by Hubert Lamb which records the details of hundreds of storms. Many more reports lie undiscovered in such places as the archives of the Met Office which I regularly use for research
The storm surge of this and other storms was prodigious and seem to exceed by far the events of the modern era.
It might be very well worth reading up old books such as the one cited to see if there is any similarity with the ‘hybrid’ storm that Sandy is being called.. It may tell us that the future is like the past or quite unlike it, but it is worth doing
tonyb
It’s a real shame that all these great deconstructions of Sandy are going to waste and the bulk of the public will never read/hear them.
Al Gore will surely use Sandy as the cherry on top of his dirty weather sundae. I wonder if now’s the time to tempt him to a debate? Surely he can’t lose 😉
For comparison, the influence of the full moon that night was about as large as the influence of anthropogenic global warming.
Actually, the influence of the full moon that night was considerably greater than the influence of anthropogenic global warming. Storm surges tend to run proportional to the prevailing tide, not on top of the prevailing tide, so that hurricanes that make landfall at high spring tide are much more damaging than ones that make landfall at low neap tide or for that matter low spring tide (which is even lower). A large storm is going to be driving water ashore across multiple parts of the tidal cycle, so that spring versus neap is a big deal.
The second thing that supports your assertion (and the coupled assertion that AGW was smaller than the influence of the full moon as far as storm surge height is concerned) is that weather systems are driven by temperature differentials, not temperature absolutes. It isn’t warm oceans per se, it is the contrast between warm oceans and low shear in the upper atmosphere where temperatures are cold that establishes the stable outflow required for a really powerful hurricane or other tropical storm. Sandy was the result of a rare confluence of warm tropical weather (producing a hurricane of indifferent strength but relatively large in size) and the contrasting cold ridge that both steered it and fed it even as the “tropical” characteristic of the storm was falling apart.
There is direct evidence that the level of peak “superstorm” violence in NA tropical storms is, if anything, decreasing across the current sustained flat peak temperatures that have held since the late 90’s. It has been seven years and counting since the last major hurricane came ashore in the United States:
http://www.weather.com/news/weather-hurricanes/major-hurricane-drought-us-20120814
Wilma in 2005 was the last category 3 or greater hurricane to come ashore in the US. Sandy wasn’t even a tropical storm as it came ashore; it was an extratropical nor’easter of unusual size. We are almost certainly not going to see a category three storm come ashore in 2012, as hurricane season is almost over — the north atlantic is visibly starting to cool. We are supposed to see the formation of another nor’easter this week, though — an extratropical storm still fuelled by warm water over the gulf but driven up to the level of a “storm” of substantial size by the inflow of cold air coming down from Canada. This storm may or may not end up being “super” as it dumps still more rain and storm surge on infrastructure not yet recovered from Sandy, but it illustrates very nicely that it isn’t the heat content of the ocean per se — the air and water temperatures are already well down from summer peaks — it is the juxtaposition of hot and cold reservoirs.
Historically this is equally apparent from records — many of the most violent storms are not associated with high temperatures per se, and many of the most violent storms we know of (and hurricane season itself) occur when the weather is cooling, not when it is warming — both tornadoes and hurricanes are favored when cold is juxtaposed with hot, the former when a cold front overruns warm air, the latter when low shear permits the establishment of an upflow “chimney” to the colder upper troposphere and stratosphere — the eye — so that cool air can flow in over the ocean, warming and picking up moisture, be lifted (violently) up in the eye, and then outflow in the colder UT while dropping both the heat and the water out of the air as precipitation, driven by self-organized-critical pressure differential created at the eye by the uplifting air;
rgb
Okay, agreed then: anthropogenic global warming is a reality.
“The truth is, is that it is impossible to know how, or even if, global warming played any role at all in the lifecycle of Sandy.”
It is all speculation. No scientist worth his salt would conclude one way or the other. Sandy was not an unprecedented storm. If Sandy had turned East instead of West, we wouldn’t even be talking about it. So unless someone can show how global warming is able to steer a hurricane toward land, there is nothing unusual here. All this amounts to is a bunch of political propagandists stirring up emotional hysteria. The temptation is just too great for them to allow a natural crisis to go to waste.
It is also necessary to distinguish between Global Warming, which can, in principle, be measured, and Anthropogenic Global Warming, which cannot be measured directly and must be inferred based on various assumptions regarding how much of a contribution to the observed warming humans really have had.
Since we have seen that natural effects can totally negate the human contributions of increasing CO2, (no net global warming has been recorded for over a decade) such effects would have been at least as important as CO2 related ones in contributing to the last warming spurt from the mid 1970s to the early 2000s.
There are facts, and then there is conjecture.
The fact is that hurricanes and post-tropical storms have been impacting the east coast for all of recorded time, and for a long time before Europeans discovered America. Because of this fact, it is logical (and prudent) to assume that hurricanes and post-tropical storms will continue to impact the east coast from time to time, at various locations, and with varying degrees of chaos and damage.
For that reason, it is imprudent to assume that just because a major storm has not impacted a certain area for a long time, that area is safe to build on or inhabit. Perhaps imprudent is not strong enough; it is actually irresponsible, perhaps even foolish.
It follows that, if you are going to build anything in an area known to be occasionally and randomly impacted by powerful and dangerous storms, such construction should be capable of surviving such a storm. Things such as roadways, railroad tracks, drainage, industrial and residential buildings all need to be designed with the foresight required to prevent tragedy when such a storm impacts them. On the west coast, especially in California, there are laws and rules about building construction that are designed to minimize damage in the event of earthquakes.
It is my understanding that in areas farther south, including Florida and Texas, which are more often impacted by even more severe storms, there is typically less damage because of decades of foresight and planning designed to reduce the human impact of such storms.
It should be obvious where I’m going with this. The areas impacted by post-tropical storm Sandy were not prepared for such a storm, but they should have been. While there wasn’t much that most individuals could do to reduce their personal losses, it is the responsibility of city, county and state planners to devise appropriate building codes, land usage rules, and other bylaws to reduce the impact of a natural disaster, and it appears to me that we are witnessing yet another failure of these local governments to fulfill their respective mandates.
Neither Katrina nor Sandy were excessively extreme storms to occur in their regions, however both impacted areas that had grown lax in their preparedness. It’s very fashionable to blame the vague, misty notions of human impact on the weather (er, climate), doing so is mere conjecture. The FACT is that these areas failed to do enough to prepare for the inevitable storms.
More storms, and even more powerful storms, will impact the east coast, with varying degrees of damage and chaos, no matter what we do to reduce CO2 emissions. Since altering our entire civilization and way of life will not reduce future storms, the logical course of action continues to involve preparedness and survivable design and construction in areas prone to such storms. Whether Sandy had a “measurable” or meaningful connection to any sort of human activity is absolutely meaningless. The fact is that it happened.
If AGW believers truly believed that Sandy represents “the new normal”, they would be vocal proponents of better preparedness and more intelligent design and construction of buildings and neighborhoods. Since their sole urging seems to be more about profit making and increased taxation to force others to use less petroleum, I have to assume that most don’t actually believe what they are so loudly claiming.
Fact is that every single person. who lives on the East coast from Boston down
to Panama, knows he lives in Huracan country with a Huracan season starting
each May….and each American person has plenty of plywood sheets ready in his
basement and a water pump to get the water our of his basement………This is the
NORMALITY for hundreds of years….this is the American way of life….everybody
expects that this seasons huracane willl take away something….(part of life)…
…..why the whining that the huracane now is MANMADE……??
Better ask the stupid and the ignorant: Show me your plywood, show me you
water pump….. or are you full of BS and you are unprepared?
Why should the central government chip in for stupidness of individuals, who do not
pay their insurance……?? JS
I just read of New Jersey’s small earthquake, which struck today in the wee hours. T’was but a tiny one, 2.0, the size said to be triggered by minor things like drilling a well.
But it will be scientifically established by chronically repeated conjecture that the earthquake was triggered by Sandy, from the massive influx into the water table, from the extraordinarily low pressure moving over the land, from whatever sounds passably plausible.
And it is already established fact among the denizens of the alarmist blogs that Sandy was caused by global warming.
Thus this will be a proven example of climate change causing earthquakes!
I’m really sorry. but as global cooling carries on, there might be a few extra storms//…
http://wattsupwiththat.com/2012/10/26/even-nasa-has-gotten-into-the-frankenstorm-meme/#comment-1136432
Great and sophisticated insight. But what about the 2 most basic reasons for weaker storms under rising temperatures ?
1. Historical evidence shows, that storms have been (much) stronger during the little ice age
2. Basic physics: Temperatures increase much faster around the poles, reducing temperature and thus energy potentials along longitudes.
And Pierce Corbin suggests that a new little ice age is imminent and therefore there is more to come…
[snip . . content free . . mod]
Chip Knappenberger : You never addressed your second point, “global warming has led to higher sea surface temperatures and thus stronger hurricanes.”
Code Tech:
Totally correct and completely agree. Let’s extend that a bit further? Why built in known flood plains that are prone to flooding every 15 or 20 years? Why built close to or on unstable subsoils that are prone, occasionally, to subside and or slide? Why built homes and streets etc. on fault lines or even close to them? If government rules are necessary, and some are, let them make sense. Do not built anything around Mt. Baker.
About Sandy & the presidential race on Real Science I commented:
Look, everybody, someone should have spearheaded a major advertising campaign to change public opinion about climate change. It would have worked because 1) the arguments are on are side and most of the public doesn’t know these arguments, and 2) conservatives are fired up about the agw issue and would have donated huge $ to promote the self-financing anti-AGW ad campaign.
Changing opinion on climate change could have made a big difference in this campaign, not just in the presidential race, but in the senate and house races also. A huge number of Dem candidates, including O, would have been hurt if public opinion was moved a notch or two against climate change. And look at Sandy, O appears to have gotten a bump not just because he appeared presidential to some, but also because on the margins it reinforced his climate change message. PACS have spent a $billion or whatever on these campaigns. Why didn’t we spend just a fraction of that to change the foundation of public opinion with regard to climate change? Do it in 2013! I’ll try, but I won’t have the time etc to do it. Someone else do it. Again, just get started with an effective message, and donations will roll in. It will be self-financing!
“There are basically three pro-global warming talking points involving Sandy: 1) global warming has caused sea levels to rise, thus making the storm surge larger, 2) global warming has led to higher sea surface temperatures and thus stronger hurricanes, and 3) global warming is making extratropical circulation features more conducive to intense and slower moving storm systems”.
——————————–
THREE pro-global warming talking points…
Okay, agreed then: the science isn’t settled.
Jeff says:
November 5, 2012 at 9:43 am
Okay, agreed then: anthropogenic global warming is a reality.
And so Jeff demonstrates perfectly the alarmists’ misunderstanding of the sceptical position.
Jeff: If one does accept AGW, there is still the debate over the magnitude, and whether AGW is “catastrophic” and also whether it is the dominant force given the myriad other forcings and feedbacks. Given the IPCC’s gross overestimates of temperature rise I would say those points are worth debating. It’s also worth noting that there has been no significant warming for well over a decade. Clearly other forces are at play. Alternatively you can believe (without evidence other than twisted models) that CO2 is dominant over H2O and the world and all its species are going to Hell.
Manfred
I made just that pont to Nasa. They said that a more limited temperature dfferential between the poles and tropics coud result in fewer storms but could result in bigger storms.
They of course know nothing of the LIA and whilst I have frequently ponted out that observational records confirm the LIA produced more extreme weather they seem to have little interest in the past.
tonyb
Thanks for writing this. The alarmists allow for no positive impacts of global warming, it’s all bad all of the time. I’m not buying it.
Would we be having all this palaver about Sandy if it hit at low tide?
http://www.usatoday.com/story/tech/sciencefair/2012/10/29/sandy-full-moon-tide/1666479/
No government funding for you! Signed the Climate Soup Bully. Good question and great info.
Chip Knappenberger: “… could anthropogenic global warming actually have lessened the impacts of Sandy?”
No. For the simple reason anthropogenic global warming is not occurring.
Water vapor is 810 times more powerful as Greenhouse gas than man-made CO2, making man-made CO2’s impact trivial.
AGW is not Science, it is a Socialists’ creation. AGW is a SCAM by likes of Gore to get rich off of going green, likes of Mann for purpose of job security and funding, and by U.N. to achieve power over the Free for purpose of controlling them.
Is a little sanity creeping in?
When there is a hurricane drought they stay silent. When ONE hits then it’s a sure sign of global warming. Never mind the data, THIS hurricane was caused by global warming. Yaaaawwwwn.
tonyb,
I can’t seem to track it down but I did read about LIA producing terrible hurricanes in the Atlantic.