Klotzbach and Gray say hurricane trend fizzling; Meanwhile Fred is fading

So far this year several storms have come to life in the Atlantic, and then fade as wind shear tears them apart. A newly published study by Klotzbach, Gray, and Fogarty suggests we should get used to this.

This visible image of the Eastern Atlantic Ocean on Sept. 4 at 7:45 a.m. EDT shows Tropical Depression Fred winding down and another low pressure area that just came off the West African coast. Credits: NASA/NOAA GOES Project
This visible image of the Eastern Atlantic Ocean on Sept. 4 at 7:45 a.m. EDT shows Tropical Depression Fred winding down and another low pressure area that just came off the West African coast. Credits: NASA/NOAA GOES Project

From NASA Goddard:  The Eastern Atlantic Ocean continues to generate storms, and as satellites are watch Tropical Storm Fred fade over the next couple of days, a new area of low pressure has moved off the coast of western Africa.

A visible image of the Eastern Atlantic Ocean on Sept. 4 at 7:45 a.m. EDT showed Tropical Depression Fred as a tight swirl of low clouds, with clouds and storms only southeast of the center. The GOES image also showed the new low pressure area called System 91L just off the coast of western Africa. The GOES image was created by the NASA/NOAA GOES Project at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

Where is Fred?

At 11 a.m. EDT (1500 UTC), the center of Tropical Depression Fred was located near latitude 22.3 North and longitude 38.3 West. That puts the center of Fred about 1,275 miles (2,050 km) southwest of the Azores islands. Fred was moving toward the west-northwest near 9 mph (15 kph), and is expected to turn toward the northwest by early on September 6. The estimated minimum central pressure is 1006 millibars.

Maximum sustained winds are near 35 mph (55 kph), and is expected to weaken to a remnant low pressure area by September 5 because it is in an area of strong upper-level winds.

Another System Developing Behind Fred

To the southeast of Fred, another area of low pressure in a tropical wave designated System 91L, had moved off the coast of western Africa. At 0600 UTC (2 a.m. EDT) the center of System 91L was located near 10.7 North latitude and 18.1 West longitude, a couple of hundred miles off the west coast of Africa. System 91L is expected to move south of the Cape Verde Islands late on September 4 and 5.

The National Hurricane Center (NHC) noted that the low continues to show signs of organization and has the potential for some development as it moves westward at 15 to 20 mph across the tropical Atlantic during the next few days. NHC gives System 91L a 40 percent chance to develop in the next two days and 60 percent chance in five days.

So, forecasters will watch as Fred fizzles and 91L ramps up over the next several days.

In related news, Via AP’s Seth Borenstein here:

A new but controversial study asks if an end is coming to the busy Atlantic hurricane seasons of recent decades.

The Atlantic looks like it is entering in to a new quieter cycle of storm activity, like in the 1970s and 1980s, two prominent hurricane researchers wrote Monday in the journal Nature Geoscience.

Scientists at Colorado State University, including the professor who pioneered hurricane seasonal prognostication, say they are seeing a localized cooling and salinity level drop in the North Atlantic near Greenland. Those conditions, they theorize, change local weather and ocean patterns and form an on-again, off-again cycle in hurricane activity that they trace back to the late 1800s.

Warmer saltier produces periods of more and stronger storms followed by cooler less salty water triggering a similar period of fewer and weaker hurricanes, the scientists say. The periods last about 25 years, sometimes more, sometimes less. The busy cycle that just ended was one of the shorter ones, perhaps because it was so strong that it ran out of energy, said study lead author Phil Klotzbach.

Klotzbach said since about 2012 there’s been more localized cooling in the key area and less salt, suggesting a new, quieter period. But Klotzbach said it is too soon to be certain that one has begun.

“We’re just asking the question,” he said.


Here is the correspondence in NatGeo

Active Atlantic hurricane era at its end?

P. KlotzbachW. Gray & C. Fogarty

Nature Geoscience (2015) doi:10.1038/ngeo2529

To the Editor — The Atlantic hurricane seasons in 2013and 2014 were quieter than average, and there are indications that hurricane activity in 2015 will also be below normal. Here we investigate whether the active Atlantic hurricane era that began in 1995may have ended. To this end, we assess hurricane variability in the Atlantic since 1878, along with a proxy for the Atlantic multidecadal oscillation (AMO), whose positive phases have been noted to be closely linked to active periods for Atlantic hurricanes. We find that the AMO proxy values are currently at their lowest values since the early 1990s, when Atlantic hurricane activity was well below average.

Analyses of Atlantic multidecadal variability. a, Three-year-averaged ACE (green line) and three-year-averaged standardized normalized AMO (blueline) from 1880–2014 with predicted value for 2015 (red squares). The 2015 AMO value is the January–June-averaged value. The year listed is the third year being averaged (for example, 1880is the 1878–1880 average). Correlation between the two time series is 0.61.
Analyses of Atlantic multidecadal variability. a, Three-year-averaged ACE (green line) and three-year-averaged standardized normalized AMO (blueline) from 1880–2014 with predicted value for 2015 (red squares). The 2015 AMO value is the January–June-averaged value. The year listed is the third year being averaged (for example, 1880is the 1878–1880 average). Correlation between the two time series is 0.61.

The Atlantic entered an active hurricane period in 19951–2. From 1995to 2012, accumulated cyclone energy (ACE)3 in the Atlantic basin averaged 140 × 104knot2 compared with 68 × 104knot2 from 1970to 1994, a statistically significant increase at the 5% level. High ACE is also observed from 1878–1899 (108 × 104knot2) and 1926–1969 (101 × 104knot2) compared with low values from 1900–1925 (65 × 104knot2) and 1970–1994 (68 × 104knot2) (Fig.1a). A limited observational network may have led to an underestimate in ACE during the earlier part of the record. The AMO, an indicator of sea surface temperature (SST) variations in the North Atlantic, has been argued to arise from natural climate variations in the thermohaline circulation1,2,4.

Alternatively, it could be primarily driven by alterations in levels of sulfate aerosols5. We argue that the weight of the evidence points towards natural oceanic variability being the principal driver of the AMO1,4,6. The AMO phase was classified as being positive from 1878–1899, 1926–1969and 1995–2012, and negative from 1900–1925and 1970–19942. Positive AMO phases are characterized by above-average far North and tropical Atlantic SSTs, below-average tropical Atlantic sea level pressures (SLPs), and reduced levels of tropical Atlantic vertical wind shear. All three of these conditions are known to create a more favourable environment for Atlantic hurricane formation and intensification1.Following an active 2012 Atlantic hurricane season, most predictions indicated another active season in 20137. A strong temporary weakening of the AMO was observed during 20138, which may have been one of the reasons for the season being quieter than expected. Activity during the 2014 hurricane season was also below normal. The combined ACE of 103 × 104knot2 registered in 2013–2014was the lowest value that had been recorded since the ACE of 71 × 104knot2 in 1993–1994.

And following this marked reduction in activity over the past two years, a below-average season is now expected for 20159. Random resampling of three-year periods of positive AMO phase gives a 1% chance of an ACE of 155 × 104knot2 or lower during the positive AMO phase. It is therefore unlikely, if 2015 turns out to be as quiet as predicted, that we are in a positive AMO phase. Borderline weak El Niño conditions in 2014and strong ElNiño conditions predicted for this year’s hurricane season may, however, also have contributed to observed below-average hurricane activity in 2014and predicted below-average hurricane activity in 2015. A proxy using a combination of North Atlantic SSTs from 50–60°N, 50–10°W and SLPs from 0–50°N, 70–10°W has been utilized to monitor the strength of the AMO in real time10. When the AMO is positive, SSTs in the far North Atlantic tend to be warmer, while SLPs throughout the tropics and subtropics tend to be lower2. This index has decreased since 2012 (Fig.1a): SST anomalies in the tropical and far North Atlantic have become cooler and SLP anomalies throughout most of the Atlantic have increased. The decrease in far North Atlantic SSTs in the past three years has been associated with a weaker thermohaline circulation6. Annual mean SSTs in the North Atlantic have cooled in 2013and 2014 compared with values averaged from 1995to 2012 (Fig.1b). During the most recent 25 positive AMO years (1963–1969and 1995–2012), 204.5major hurricane days (MHD) were observed in the Atlantic, compared with 63.25 during the most recent 25 negative AMO years (1970–1994), a ratio of 3.2to 1. Marked differences are also observed in tropical cyclone tracks in the deep tropics between the positive versus negative AMO phase (Fig.1c). For example, in the Caribbean (south of 20°N, west of 60°W), 16.25MHD occurred during the most recent….


h/t to Leif Svalgaard and Dennis Wingo

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September 8, 2015 8:32 am

There is no evidence of a long term trend in hurricane activity in the sample period 1945-2014

September 8, 2015 8:33 am

What happened to Grace?

Mumbles McGuirck
Reply to  Slywolfe
September 8, 2015 9:59 am

Grace has been downgraded to a depression and may be a remanent low within 24 hours. Fred is dead. Antony seems to get his tropical updates via NASA press release, hence the delay, 😉

Reply to  Mumbles McGuirck
September 8, 2015 7:27 pm

I’m not dead yet!

Reply to  Mumbles McGuirck
September 9, 2015 12:58 pm


Michael Spurrier
September 8, 2015 8:34 am

http://www.bbc.co.uk/news/science-environment-34181468 – another attempt to make the public more aware of “severe weather”…….

Billy Liar
Reply to  Michael Spurrier
September 8, 2015 9:52 am

It’s about time the UKMO gave up psychology and put more effort into accurate forecasting.

Gerry, England
Reply to  Billy Liar
September 9, 2015 5:30 am

They can’t do that without admitting that their models that are based on ever increasing warmth are wrong and then they have to work out how to deal with the increasing occurrence of meridional jetstream flow as opposed to zonal.

Louis LeBlanc
September 8, 2015 8:34 am

It doesn’t take a Ph.D. in climate science to deduce from the chart that there is no correlation between atmospheric CO2 and hurricane activity.

Brian R
Reply to  Louis LeBlanc
September 8, 2015 11:45 am

Actually it does. Because with post-modern climate science statistics and data manipulation, everything can be correlated to atmospheric CO2.

Patrick Hrushowy
September 8, 2015 8:38 am

Doesn’t all this point to periodic fluctuations in weather (natural variation)?

george e. smith
Reply to  Patrick Hrushowy
September 8, 2015 10:11 am

No ! ” periodic fluctuations ” implies a systematic (cyclic) variation.
” Natural ” variation is often quite random, rather than periodic.
You should not say ” periodic ” if you mean ” occasionally ” rather than ” has a cyclic period “.

ferd berple
Reply to  george e. smith
September 8, 2015 11:27 am

” Natural ” variation is often quite random, rather than periodic.
random or periodic?

Reply to  george e. smith
September 8, 2015 12:45 pm

Good picture, Fred.
I wish more people had a clue about limit cycles and strange attractors, self oscillators, and quasiperiod oscillations in chaotic systems:
(which is not at all unlikely to be the “genera” of the cycles visible in comparatively short analyses of the climate) as special cases of the more general:
although both of these are likely to be chaotic so the simplified descriptions in these pages are likely not stable or long term descriptions of climate. This stuff is subtle and is observed in much simpler open optical systems than the sun-driven climate is likely to be:
(where pretty much all of the kinds of oscillation and route between stable oscillation and full chaos are observed for a particular, but fairly generic, driven optical system).
Here is a much better representation of the kind of attractor likely present in the very high dimensional space that probably describes the climate:comment image

Reply to  george e. smith
September 8, 2015 2:42 pm

Randomly period. Or periodically random.

Reply to  george e. smith
September 9, 2015 5:37 am

rgbatduke September 8, 2015 at 12:45 pm
Good picture, Fred.
I wish more people had a clue about limit cycles and strange attractors, self oscillators, and quasiperiod oscillations in chaotic systems:

Yeah, it’s fun stuff, so much so I wrote my thesis on it!
Unfortunately your last link didn’t come through for me.
There are some nice examples of limit cycles etc. in reaction kinetics, e.g. the Belousov-Zhabotinski reaction, cool flames.
Also in prey-predator interactions, a nice example of which is the longterm study of moose and wolves on Isle Royale which unfortunately looks like it’s about to end due to the wolves dying out.

Reply to  Patrick Hrushowy
September 8, 2015 11:25 am

Weather is dead; we now have “climate events.”
Yeah, I know it’s an oxymoron, but PhD scientists say “climate events.” Years of extra school to learn how to be stoopid.

September 8, 2015 8:50 am

a below-average season is now expected for 20159.

Now that’s a long-range forecast! 🙂

Reply to  jheinrich
September 8, 2015 5:15 pm

Where is the editing of these articles? Those codes inserted into the writing were very distracting. Doesn’t anyone check or proof read when publishing?

September 8, 2015 8:55 am

Didn’t I just read that the strengthening El Nino had something to do with weaker hurricanes? As El Nino strengthens, it causes strong winds aloft over the Caribbean, which sheers the tops off of the hurricanes.
Well, that’s what I thought I read— here on WUWT, anyway.

Mumbles McGuirck
Reply to  mjmsprt40
September 8, 2015 10:07 am

Yes, but the El Nino functions on a shorter time scale, 1-2 years. The AMO is, well, multi-decadal. There are all sorts of natural climate variations which occur on a range of time scales, some of them we don’t know about because our accurate weather records don’t go back far enough.

Brad Rich
September 8, 2015 9:12 am

The new normal is short-lived hurricanes? Wait a minute. How long does it take to decide that there is a new normal?

Reply to  Brad Rich
September 8, 2015 3:36 pm

About as long as it takes to get a grant proposal written.

September 8, 2015 9:26 am

It would help to see the updated AMO chart with the story.

September 8, 2015 9:29 am

They might have gotten away with this if they predicted it 10 years ago…
…but, as usual, they are behind the eight ball again
Got to check my insurance and panels now……by the time they get around to “predicting” it’s over and starts in the other direction

Dodgy Geezer
September 8, 2015 9:30 am

…So far this year several storms have come to life in the Atlantic, and then fade as wind shear tears them apart….
I’m about to publish a paper showing that climate change is so powerful that it can create huge storms AND THEN rip them apart! Contributions are requested from the usual suspects…

Mike from the cooler side of the Sierra
September 8, 2015 9:41 am

Grace has been trying to die gracefully in the middle of the Topical Atlantic. Let her go.

Robert Ballard
Reply to  Mike from the cooler side of the Sierra
September 8, 2015 10:49 am

Poor Grace must have been too powerful.
“… it was so strong that it ran out of energy,” said study lead author Phil Klotzbach.

Reply to  Robert Ballard
September 8, 2015 2:08 pm

This isn’t a completely crazy concept, BTW. Thunderstorms and Hurricanes are mechanisms where the Earth self-organizes to more efficiently lose heat! In both cases, warm wet conditions on the ground are cooled as the water evaporates (removing the latent heat of evaporation from the ground or sea surface). This heat self-organizes into uplifting moist air that adiabatically cools as it rises (where cooler, drier, denser air is falling somewhere else as it is displaced) but which lifts the heat absorbed on the ground and captured as latent heat up through most of the troposphere quite rapidly (compared to the time required for radiative loss from the ground through the same GHG-laden atmospehre). At some height a) it radiates its heat to infinity as the greenhouse gases are no longer optically thick between the air and 3 K “infinity” above; b) the moisture condenses out, releasing its latent heat to if necessary rise further before it radiates away but with a lot less distance to traverse.
Thunderstorms do this on a localized scale on the order of miles to tens of miles across (although then can be clustered along fronts tens to hundreds of miles long, or even longer). Hurricanes organize this same process so that it happens over patches of ocean hundreds of miles across, with inflowing winds sweeping across the sea surface and cooling it even as the removed heat adds energy to the inflowing air, then spiraling up the “chimney” of the eye, then outflowing at the top as rapidly cooling clouds with very high albedo that drop ice and rain down through the dense moist clouds that lie underneath. They are the largest heat engines on the surface of the Earth, and they dissipate an enormous amount of energy, very (comparatively) quickly.
The Atlantic itself is comparatively cool relative to much of the 90’s and early 2000’s, and has been for the last five or ten years, hence the longest stretch in recorded history without a category three or higher hurricane making landfall (at that level) in the continental US (most that do hit come from the Atlantic). El Nino has increased shear, but even without it there just haven’t been as many major or minor hurricanes for the last few years. We are now a matter of weeks away from a stretch of ten full years without a major hurricane hitting the US, and if we make it the chances are excellent that we’ll go at least another 250 days without one (as there won’t be that long left in hurricane season, and the Atlantic is already visibly cooling down from the temperatures that are “likely” to support a catastrophic hurricane in a low-shear environment). Not that we cannot easily have a major hurricane in the rest of September or early October — it is the prime season for major hurricanes — but there are only a couple of patches of the “very warm” (32+C) water that can easily support them, although there is still a reasonable amount of water that is 26 C or warmer that is “warm enough” to sustain a good sized hurricane. But with high shear and only certain places with the warmer water, the tropical storms that are forming are fairly quickly cooling off the ocean underneath and are literally running out of warm-water-energy “gas”.
Grace has pulled SSTs down to 26C/76F, which is quite cool for running a hurricane and is destined/predicted so far to become a tropical depression that never reforms and that comes no where near the US. 92L is right on the edge of the 30 C boundary, but it is so far north that almost any motion is likely to take it quickly into 26C and cooler water, and just the energy it pulls to fully form and organize may keep it from ever spinning up to more than “barely a hurricane” status. It is on track to arrive at maybe Newfoundland in a few days, possibly as a nasty storm but over 20 C water or cooler that won’t sustain a “hurricane” in all probability shear or not.
The Gulf is still plenty warm enough to support a hurricane, even a major one. So is a comparatively narrow strip of water out due East of Florida, and the near shore and Gulf stream waters all the way up to North Carolina. But it looks like the US East Coast is due for a cold front that should arrive in a few days and push out over the Atlantic, bringing fall temperatures to at least the land side and potentially starting the cooling of even sunlit waters near the shore. It will be interesting to see if we enter October still warm or if fall has properly begun and the Atlantic is actively cooling.

Reply to  Robert Ballard
September 9, 2015 3:33 am

Watching the series of serve storms that one year (the Al Gore year) was like watching a pot of water bubbling on the stove. Storms are heat engines, and it is obvious those storms were removing heat from the ocean.
Have their been other periods of such frequent storms following by years of low storm activity?

Mike from the cooler side of the Sierra
September 8, 2015 9:44 am

Tropical Atlantic

Chip Javert
September 8, 2015 10:27 am

Well I don’t know about you guys, but I live on the Atlantic coast of central Florida.
About 10-12 days ago the savage kinda-sorta-almost hurricane Erika ripped thru here with darn near 12-14 MPH winds. Pretty much dusted off all my palm trees.
The damage was incredible – mainly to careers of all the 20-something weather-persons (?) here in Fla who lost an opportunity to go stand outside in a hurricane and report “IT’S RAINING REALLY HARD” and “THE WIND IS BLOWING REALLY HARD”.

Dodgy Geezer
September 8, 2015 10:45 am

…About 10-12 days ago the savage kinda-sorta-almost hurricane Erika ripped thru here with darn near 12-14 MPH winds….
That’s an extremely mild hurricane. Possibly the mildest hurricane I’ve EVER heard of. It sets a record for mild hurricanes.
So you had a record-breaking hurricane a week or so ago? That PROVES global warming…

Reply to  Dodgy Geezer
September 8, 2015 4:04 pm

Unprecedentedly mild! Just like mild winters, a sure sign of the coming apocalypse.

Reply to  billw1984
September 9, 2015 10:32 am

X: Sir, how do you stand on this issue?
Y: I’m extremely neutral.

September 8, 2015 10:54 am

Seth Borenstein said:

Scientists at Colorado State University, including the professor who pioneered hurricane seasonal prognostication,

Later on he mentions Klotzbach, but he never mentions Gray’s name. Either sloppy writing, or editing, or he doesn’t like Gray.
Later on he quotes three other scientists who disagree with Klotzbach and Gray, starting with

“I think they’re pretty much wrong about this,” said MIT meteorology professor Kerry Emanuel, who also specializes in hurricane research. “That paper is not backed by a lot of evidence.”
Emanuel doesn’t believe in the cycle cited by the researchers or the connection to ocean temperature and salinity. He thinks the quiet period of hurricanes of the 1970s and 1980s is connected to sulfur pollution and the busy period that followed is a result of the cleaning of the air.

I put a hell of a lot more credence in Klotzbach and Gray than in Emanuel. In 2013 http://www.climatecentral.org/news/study-projects-more-frequent-and-stronger-hurricanes-worldwide-16204 reported:

A new study by Kerry Emanuel, a prominent hurricane researcher at MIT, found that contrary to previous findings, tropical cyclones are likely to become both stronger and more frequent in the years to come, especially in the western North Pacific, [true for this year, but it’s likely more El Niño than climate] where storms can devastate the heavily populated coastlines of Asian nations. Emanuel’s research showed the same holds true for the North Atlantic [no in El Niño years!], where about 12 percent of the world’s tropical cyclones spin each year.

James Elsner, an atmospheric scientist at Florida State University who was not involved in this study, downplayed the study’s conclusions given the considerable uncertainties involved with using computer models to simulate complex storms such as hurricanes.
“The results from the new Emanuel are provocative, but in my opinion there is little reason to put much weight on them when considering what might happen to tropical cyclone activity during the next 50 to 80 years,” he said in an email to Climate Central. “This kind of predictive risk analysis can be useful, but it would benefit greatly by being grounded in risk metrics computed from observed data.”

Reply to  Ric Werme
September 9, 2015 4:50 am

Nearly all the global warming hysteria is based on computer models.
It is like a mental disease. Relying on computers while not understanding the basic rule of computers: garbage in/garbage out. If someone puts in ‘scary data’ it will come out ‘super scary predictions’ and since all the stuff being fed into computers are rigged to show scary CO2 stuff, sure enough, that is what the computer spits back out in ‘predictions’.

September 8, 2015 10:56 am

Sea current shows that the wind returns to the east by South America.

September 8, 2015 11:17 am

Ok anyone. How long will it take before some moron declares that climate change is endangering hurricanes?

James Francisco
Reply to  Logoswrench
September 8, 2015 12:26 pm

Think of all the jobs lost repairing the storm damage. FEMA employees with nothing to do. The horror.

September 8, 2015 11:17 am

I’ve learned to not give much credence to people making long-term forecasts.

Reply to  PaulH
September 9, 2015 12:52 am

That’s the most intelligent comment that I’ve seen on this board. Good going, PaulH.

September 8, 2015 11:41 am

Seth Borenstein ? Has that guy still not got a real job ??

September 8, 2015 11:45 am

Long range forecasting is made by fools.

Reply to  climatologist
September 9, 2015 12:54 am

And economists and astrologers and tarot card readers.

September 8, 2015 11:59 am

Perhaps a more accurate headline would have been Klotzbach and Gray say “Atlantic” hurricane trend fizzling.

Jeff L
September 8, 2015 12:00 pm

Interesting that this last ~20 years are characterized as “active” when we haven’t had major (>= cat 3) since Wilma nearly 10 years ago. If right , perhaps the major hurricane hit drought will continue much longer. That would be good news for coastal dwellers for sure.

Reply to  Jeff L
September 8, 2015 3:41 pm

Hurricanes bring much needed rain to many coastal areas. A few years ago South Carolina was officially in a drought condition mostly due to the lack of hurricanes.

September 8, 2015 12:36 pm

UPDATE: I predict NOAA will revise the hurricane classifications soon, dropping classification wind speeds by 50% for each category. This will allow the prognosticators to be more accurate????
Sarc/off, of course.

Reply to  brad
September 9, 2015 6:32 am

Heh. I was wondering when we started naming tropical depressions. Afaik, Fred is the first, and my first thought was, Gee, the hurricane watchers are getting dangerously bored. I think I remember when even tropical storms only had names if they were the remnants of hurricanes.

William Astley
September 8, 2015 1:01 pm

There has been no warming for 18 years. What has changed to explain the sudden drop in Hurricane activity?
The cult of CAGW can explain away a drop in Hurricane activity to normal cycles. I am curious how they will attempt to explain away significant planetary cooling. As will we soon see based on observations, the entire scientific basis of the IPCC reports was incorrect. The planet has started to cool.
The Greenland ice sheet has cooled year by year for the last 3 years and gained 200Gt winter 2014/2015. Curious that the cult of CAGW did not report evidence of cooling and the increase in Greenland Ice sheet mass.
The following is a Hurricane example that supports the assertion that the IPCC’s objective was to create sound bits to push CAGW, rather than to determine what was the scientific reason for the warming in the last 150 years, the reason for cyclic climate change in the paleo record, and the reason for the 18 year end of global warming.

After some prolonged deliberation, I have decided to withdraw from participating in the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC). I am withdrawing because I have come to view the part of the IPCC to which my expertise is relevant as having become
politicized. In addition, when I have raised my concerns to the IPCC leadership, their response was simply to dismiss my concerns….
Shortly after Dr. Trenberth requested that I draft the Atlantic hurricane section for the AR4’s Observations chapter, Dr. Trenberth participated in a press conference organized by scientists at Harvard on the topic “Experts to warn global warming likely to continue spurring more outbreaks of intense hurricane activity” along with other media interviews on the topic. The result of this media interaction was widespread coverage that directly connected the very busy 2004 Atlantic hurricane season as being caused by anthropogenic greenhouse gas warming occurring today. Listening to and reading transcripts of this press conference and media interviews, it is apparent that Dr. Trenberth was being accurately quoted and summarized in such statements and was not being misrepresented in the media. These media sessions have potential to result in a widespread perception that global warming has made recent hurricane activity much more severe.
Moreover, the evidence is quite strong and supported by the most recent credible studies that any impact in the future from global warming upon hurricane will likely be quite small. The latest results from the Geophysical Fluid Dynamics Laboratory (Knutson and Tuleya, Journal of Climate, 2004) suggest that by around 2080, hurricanes may have winds and rainfall about 5% more intense than today. It has been proposed that even this tiny change may be an exaggeration as to what may happen by the end of the 21st Century (Michaels, Knappenberger, and Landsea, Journal of Climate, 2005, submitted).

Reply to  William Astley
September 8, 2015 2:11 pm

The Greenland ice sheet has cooled year by year for the last 3 years and gained 200Gt winter 2014/2015. Curious that the cult of CAGW did not report evidence of cooling and the increase in Greenland Ice sheet mass.

How do you know this? I’m not doubting you, note well, I’d just like to see references.

Reply to  rgbatduke
September 9, 2015 4:56 am

Where they say:
“Satellite observations over the last decade show that the ice sheet is not in balance. The calving loss is greater than the gain from surface mass balance, and Greenland is losing mass at about 200 Gt/yr.”
My emphasis.

Reply to  rgbatduke
September 9, 2015 11:17 am

“Satellite observations over the last decade show that the ice sheet is not in balance. The calving loss is greater than the gain from surface mass balance, and Greenland is losing mass at about 200 Gt/yr.”

Noted. However, I do have trouble with one assertion of the article. It says near the bottom that the calving ice, as it melts, can cause SLR. This is not really true. The ice that calves is already floating (there is no mechanical support to speak of far from the shore). Floating ice does not substantially raise water levels as it melts.
The effect on SLR is thus a lot more subtle. There is a cycle of water being deposited on top of the actual land and water surface (which is removed, on average, from the), a very, very long process of that water moving downhill and out until it reaches the sea, is pushed out to where it floats, and eventually calves/melts into the ocean. There is a substantial lag between establishing some rate of ice/snow accumulation on the land surface and it being balanced at the ocean. The rate at which water enters the ocean today was more or less determined by snow/ice accumulation rates (integrated over a period back to) centuries ago, differentially lagged by the distance to the coast and the speed of plastic flow in the glaciers.
This makes predicting what happens to SL very difficult indeed. It is more likely determined by the rate at which the floating sea ice calves than by any rate at which snow or ice accumulate. The calving rate itself is a self-limiting process as if it exceeds the rate that ice flows down from the land, at some point the ice will melt back towards shore and then stop, limited by the rate that the glaciers flow into the sea. That rate was likely established hundreds of years ago, during the little ice age, when lots of snow and ice were accumulating, and is probably almost completely insensitive to the rate at which snow and ice are accumulating now.
The complexity is evident in the maps in the article. Almost all of the land surface area of Greenland is actually accumulating ice. The only places that are not are right on the coast. One can think of lots of reasons that the coast could be losing ice faster than the central part accumulates it — local warming of the coastal areas that are melting because of fluctuations in the Gulf Stream or AO/NAO being close to the top of the list. Are these fluctuations “caused” by global warming or are they a natural phenomenon that happen all the time and that can constructively or destructively interfere with the melting of ice/snow boluses that have made it down the hill that reflect deposit rates from centuries ago?
We just saw an article on the possibility that the freshening of the waters off of Greenland (in part caused by this melt) could itself alter the thermohaline flow and chill Greenland, Iceland, and the northern part of Europe. That is, there are internal feedback loops that are at least possible, although we were not in a position to directly observe earlier ones and have to infer their existence from things like the pattern of deposits of the small rocks that are dropped to the ocean floor as the glaciers melt. We don’t really know how the feedback loops work to modulate things like melt or growth; at best we make guesses, and not necessarily well-educated guesses at that.
So making any sort of predictive assertion about what is going to happen to sea level requires at the very least a lot of unproven assumptions. Sure, it could be right. In the short run, calving from coastal ice around Greenland could cause SLR, although there is little evidence that the rate that this is happening has observably changed compared to rates observed in the past without the help of AGW (if any). It is also true that sea levels are rising and not falling or remaining neutral, although again this is something that has almost certainly continued at a fairly steady clip all the way back to the end of the Little Ice Age, and it is likely that the LIA caused sea levels to fall. There is clearly no such thing as an “equilibrium” sea level, given tectonic movements and the ongoing surface rebound from the immense weight of ice over northern lands during the last ice age 12000 years ago.

September 8, 2015 2:04 pm

Now there’s an inconvenient truth

Julian Flood
September 8, 2015 11:45 pm

Does a hurricane feed itself on the release of heat from condensation? I’m thinking of the lapse rate change from dry to moist and the way that a lack of CCNs would delay condensation and hence growth. If so, is a hurricane sensitive to the quality and quantity of aerosols it rips off the sea surface? If so, how sensitive?
A few years ago I flew down to Madeira and saw a huge smoothed area of ocean a couple of hundred miles north of the island, thousands of square miles in total, and the surface was resisting a force four wind with very few whitecaps in the smooth. I note that the currents swing round across the Atlantic and would drift pollution from that area into the hurricane track.
One of the papers referenced by the above (5) talks of sulphate aerosol change perhaps being important. Any aerosol change would be, surely. If so then a smooth (pollution, biological response to pollution or however caused) might be enough to make Fred fizzle. Could one gut a hurricane with a big dump of pollution in its path? My sf writer’s fingers are beginning to itch.
rgb, been out with the pint of mixed light oil and surfactant yet? Benjamin Franklin (google Clacton pond) will be proud of you….

Reply to  Julian Flood
September 9, 2015 5:58 am

Releasing latent heat by condensation is a vital aspect of powering a hurricane. It couples into the minimum SST temperature (a rule of thumb) that people look to for conditions to develop tropical storms, and perhaps is most spectacular when a Cat 4 or 5 storm entrains a plume of dry air – the storm will collapse in hours and take days to recover to even Cat 3 status. I like to say wind shear cuts off the storm at its neck, and dry air cuts it off at the knees.
I don’t think lack of CCNs is important once you have clouds or raindrops, as more moisture will condense on them, and raindrops will get blown apart when they get beyond typical raindrop size.
The air in the eye of a hurricane is warm and dry. I wonder what would happen if you could pump that 100 km outside of the eye. You could build a contraption powered by the eyewall’s wind that cuts off the storm at its feet.
Ought to be a good SF short story in there.

September 9, 2015 4:28 am

How long has it been since * Superstorm * Sandy ? The next storm of any size will be unprecedented because CAWG has a very tiny memeory. They also have the uncanny ability to forget every claim they ever made, alter the past, and relocate the present as something it isn’t. As long as any statement agrees that the earth has a fever as being correct and any evidence of any kind that no warming is taking place as being wrong.

Pamela Gray
September 9, 2015 6:47 am

…and in three…two…one. Human influence has created a lack of natural hurricanes.

Reply to  Pamela Gray
September 9, 2015 10:59 am

Yes… and just wait for the new research to show just how bad its going to be with fewer strong hurricanes and the global cooling caused by the global warming. No doubt it will be worse than we thought.

johann wundersamer
September 9, 2015 10:14 am

Yes, ‘Alternatively, it could be primarily driven by alterations in levels of sulfate aerosols(5)’
and yes, there’s always a lot of alternatives for a chain of weakest links.
(5) who ever asks for alternative sulfate aerosols when science is settled.

Coeur de Lion
September 11, 2015 1:50 am

When I was maneuvering my line-of-battleship in the Caribbean coupla centuries ago, my navigator used to say: “June too soon. July stand by. August go you must. September remember. October all over”. Still OK?

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