“Research into hurricanes in the North Atlantic indirectly suggests that the last 100 years in Australia have been relatively wet. Forget about Greenhouse. Just the normal swings and roundabouts of the climate have the potential to be devastating…
Graham Young writing at his blog Ambit Gambit goes onto suggest that based on a recent paper in Nature entitled ‘Intense hurricane activity over the past 5,000 years controlled by El Nino and the West African monsoon’ governments might consider “spending more taxpayer monies reconstructing paleo-climate, and less modelling future climate scenarios.”
He also comments, “What’s more, in a challenge to vulgar Greenhouse assumptions, there appear to have been more severe hurricanes in the past than the ones we’ve seen recently, even though the sea was colder then.”
The paper in Nature is worth a read: http://ff.org/centers/csspp/library/co2weekly/20070525/20070525_02.pdf
Jennifer Marohasy BSc PhD is a critical thinker with expertise in the scientific method.
“vulgar”? It’s a pretty basic premise to take that a phenomenon driven by heat will increase when the temperature rises.
No-one has ever claimed that there have not been bigger tropical storms in the past. The question is, how often do they occur.
Finally, proxies, it appears, are now acceptable data.
SJT, What about the differential between temperatures in the tropics and poles … as a driver of tropical storms?
You can’t get a tropical cyclone without heat to drive it. There are many factors involved, but no heat, no storm.
Wind shear, moisture content, temperature differential are all important factors in a storm, but SST is what gets it going and fuels it. As the quote below demonstrates, we don’t know enough yet to define precisely what will happen or how, but models seem to indicate SST will be a significant factor.
2005 might have been an aberration, but it certainly broke just about every known record. Last year the strong El Nino reduced the hurricanes for the USA, but the typhoons were still significantly active in the Asia region. Now that the El Nino is gone, it will be interesting to see what happens this year.
http://www.sciencemag.org/cgi/content/full/309/5742/1844
“Numerous studies have addressed the issue of changes in the global frequency and intensity of hurricanes in the warming world. Our basic conceptual understanding of hurricanes suggests that there could be a relationship between hurricane activity and SST. It is well established that SST > 26°C is a requirement for tropical cyclone formation in the current climate (6, 7). There is also a hypothesized relationship between SST and the maximum potential hurricane intensity (8, 9). However, strong interannual variability in hurricane statistics (10-14) and the possible influence of interannual variability associated with El Niño and the North Atlantic Oscillation (11, 12) make it difficult to discern any trend relative to background SST increases with statistical veracity (8). Factors other than SST have been cited for their role in regulating hurricane characteristics, including vertical shear and mid-tropospheric moisture (15). Global modeling results for doubled CO2 scenarios are contradictory (15-20), with simulations showing a lack of consistency in projecting an increase or decrease in the total number of hurricanes, although most simulations project an increase in hurricane intensity.”
Along with warm water, there must be also be an existing low pressure area / trough between two wind systems such as the easterly monsoon and the westerly trade winds. A low vertical wind shear is also important. The absence of these typically means no cyclones in winter or near the South American coastline.
Another driver of cyclones intensity is the temperature differential between the SST and the air temp above the sea (i.e. what causes the hot air to rise in the first place). If both SST and the air temp rise by the same amount (under a uniform global warming scenario), then an argument can be made that the storm won’t be any more intense.
Chris Landsea says that the apparent storm increase (as per IPCC) is due entirely to our increased ability to detect storms that we wouldn’t have even known existed a few decades ago. Further, we now name subtropical storms such as this month’s “Andrea” which were not named previously.
ftp://ftp.aoml.noaa.gov/pub/hrd/landsea/landsea-eos-may012007.pdf
cheers
Arnost
The comment – “Forget about Greenhouse. Just the normal swings and roundabouts of the climate have the potential to be devastating…”
Umm yea – this is exactly the point – you’ve got a whole bunch of climate that we don’t cope well with now. And maybe more variability in the system than the last 120-150 years of data sugegst.
So AGW will change the tails of those distributions and return frequencies. So you can have worse on top of worse if you like.
Given our experience Arnost I find the uniform global warming scenario fanciful.
There’s some quite good reasons why 2006 was a hurricane fizzer.
http://www.nasa.gov/mission_pages/hurricanes/archives/2007/hurricane_dust.html
But yes agree that wind shear is an issue. It’s more than just SSTs.
Great paper and very relevant. But you have to smile how Graham has interpreted it with such anti-AGW gusto.
(1) More paleo data is now good it appears – which ones would Graham like – the ones that suit his argument or the others. Vale Hockey Stick and bristle pine cones? Can we have a list of goodies and baddies pls?
(2) The paper isn’t global. Emmanuel’s analysis is all ocean basins.
(3) Gee we’re not even in the new greenhouse world yet. Let’s not starting counting chickens this early I think or going “phew”.
(4) Check the last sentence in the paper. Golly gee – I wonder how we might do that – ? “A better
understanding of how these climate patterns will vary in the future is therefore required if we are to predict changes in intense hurricane activity accurately.” Might it be a MODEL – Nah !!
(5) Who says climate variability isn’t important – we have whole research insitutes and programs dedicated to the issue. http://iri.columbia.edu/
(6) One of the prime tools that will be used to investigate these findings will be (gasp) a climate MODEL. Does Graham think models are only ever run for the future.
(7) El Nino/La Nina radically influences the tracking patterns of tropical cyclones in the Pacific – so perhaps the same happens in the Atlantic. They may still be out there but in different locations??
(8) As for worst drought in 1000 years – yep probably not but just remember that El Nino-Southern Oscillation only explains about 50% of Australian variation. For example this current drought possibly receding has many non El Nino years.
But nevertheless the AGW hurricane/tropical cyclone/typhoon story is not clear – and the paper makes an important contribution. Thanks to Graham for drawing it to our attention.
Luke, a typical smear from you. “Anti-global warming gusto”? I don’t think I’ve ever once said that CO2 won’t warm the globe. The issue is not whether it does, but to what degree, and how predictable that is, given present knowledge, and whether we ought to try and stop it or just adapt.
The Hockey Stick is junk because it rests on insufficient evidence, uses deficient mathematical algorithms and contradicts what we know from other more reliable sources, such as direct observation.
I’m on the lookout for fraudsters, of which you are a minor sub-species. In the current debate there are more of them on the alarmist side of the argument, than the other – that’s one of the side-effects of the much touted oxymoron the “scientific consensus”.
The interesting thing for me in this paper was the El Nino reconstruction. I pay close attention to these debates, but I’ve never heard it cited in the Australian context. Why not? Even if it only explains 50%, the graph suggests big trouble.
Maybe there are problems with the reconstruction, as there are with the Hockey Stick reconstruction. I don’t have a problem with that. Unlike you, I haven’t closed my mind before hearing the evidence, which is why I’m critical of the global warming propaganda.
The fact is that the El Nino reconstruction raises a question, and trying to divert the conversation to your favourite topics is no answer to it.
And SJT, anyone who asserts that sea surface temperature alone will create hurricanes obviously has a hazy understanding of even lower secondary school science (at least what was taught at that level 30 years ago). It’s temperature differentials that drive hurricanes, and all other extreme weather events.
The fact that a lot of “scientists” don’t seem to understand this suggests that they are either swots, who just regurgitated without understanding as much as they needed to so that they could pass exams, or that they are biologists who never needed to understand in the first place (sorry Jennifer).
But Graham – we have to let Steve McIntyre ream out the paleo data used in the paper. I’m sure he’ll find something wrong with it. He does in every paper that has ever been written.
So have you reviewed the other paleo evidence of El Nino activity or just settled for one paper. SJT and I are simply amused that you’re happy to take the paleo data so uncritically when it suits.
BTW Hockey Stick still seems to be there in the 4AR !
Finally I did said the paper makes a useful contribution. I’m happy to take it at face value.
How tropical cyclones form.
http://www.aoml.noaa.gov/hrd/tcfaq/A15.html
Back on changes in drought frequency and causes non El Nino.
Climate research bodes badly for drought:
Scientists say new research proves the Indian Ocean has significantly warmed and there will be less rain across southern Australia.
The CSIRO research has found a rise of 2 degrees Celsius in the Indian Ocean over the past 40 years.
It confirms long-held beliefs of general warming but for the first time in exact detail.
The researchers say the temperature change cannot be explained by natural variability and is linked to the heating up of the atmosphere.
Chief researcher Dr Gael Alory says the rising temperature of ocean currents means fewer storms along the Australian coast.
“There will be less rainfall on the continent,” he said.
“The rainfall will move more south to just the ocean and that means less rainfall.”
He says Western Australia’s south-west will be hardest hit by the change in climate.
The research was carried out by following the trade routes of ships and measuring temperatures down to 800 metres
http://www.abc.net.au/news/newsitems/200705/s1937008.htm
http://csiro.au/news/ClimateChangeSignalDetected.html
http://www.agu.org/pubs/crossref/2007/2006GL028044.shtml
Sharon Beder, New Scientist 2nd Nov 1991. The Fallible Engineer.
“We know (or should know) that our models are limited in their ability to represent real systems, and we use (or should use) them accordingly. The trouble is that we are so inordinately proud of them that we do not present their limitations to the community, and leave the community with the impression that the models are precise and comprehensive”.
“Structural engineering is the art of modelling materials we do not wholly understand into shapes we cannot precisely analyse so as to withstand forces we cannot properly assess in such a way that the public at large has no reason to suspect the extent of our ignorance”.
From Wikipedia
“All tropical cyclones are areas of low atmospheric pressure near the Earth’s surface. The pressures recorded at the centers of tropical cyclones are among the lowest that occur on Earth’s surface at sea level.[1] Tropical cyclones are characterized and driven by the release of large amounts of latent heat of condensation as moist air is carried upwards and its water vapor condenses. This heat is distributed vertically, around the center of the storm. Thus, at any given altitude (except close to the surface where water temperature dictates air temperature) the environment inside the cyclone is warmer than its outer surroundings.”
SST provides the heat for the moist air to be created over the sea. Without that heat, you don’t get the tropical cyclone. There are many other factors involved, but it is the one that gets the engine going.
As for storms in general becoming more severe, the basic premise, as I understand it, is that a warmer atmosphere will have much more energy in it, which will be available to drive storms.
Luke
as someone who lives in Melbourne, the change in weather patterns appears to be permanent, El Nino or not. The low pressure systems and cold fronts that regularly used to sweep across the South of Australia are now tending to cross further to the south, giving all that lovely water to the fish. The La Nina only seems to be giving us what used to be called average rainfall so far, when what we need to get back to normal is flooding across the catchments.
Ian
the models work, the buildings don’t fall down and the A380 flies. Models aren’t perfect, but they are an essential part of modern engineering, without which we couldn’t have much of what we take for granted these days.
And from 1988, when computers and models were much more primitive.
http://www.realclimate.org/index.php/archives/2007/05/hansens-1988-projections/
Hansen’s projection comes up pretty good. Any economist who could do a projection that could would be given the Nobel Prize.
SJT if you are taking your comments for granted I’d suggest you read the article which discusses why what gets taken for granted can have bridges collapsing, buildings falling down, shuttles making spectacular headlines and even getting engineers sued.
Seems to contain some useful information for other professions.
SJT
Re projections
So we can expect that Stern won’t be getting a Nobel Prize?
Ian
they aren’t perfect, but the success of them is evident, including Hansens’ model, which was much more primitive back then than the models are today.
We know it will get warmer, it has to with the basic greenhouse effect, the only question is, how much more due to feedback effects?
Ian
I would also point out the models from the CSIRO predicted the reduced rainfall for the southern parts of Australia.
Since we’re talking models…
I’ve been reading the tealeaves and there appears to be a convergence in the forces of nature. I know that Luke’s been praying for rain in SEQ, (and you do need it) – so to be a “positive alarmist”, here’s a prediction:
There may be a significant rain event for SEQ in the second week of June.
RMS has a mother of a cold front projected to form out in the SE Indian Ocean out at 7 days.
http://wxmaps.org/pix/aus3.144hr.png
Significantly, at this time there is projected to be no fat high pressure cell over the middle of Australia – and in fact there’s a big low pressure cell south that should force this cold front far higher in the following week or so than some of the ones that brought the rain to SE Australia recently.
http://wxmaps.org/pix/aus2.144hr.png
The RMS long term projection shows LOTS of rain just of the coast in the second week of June.
http://wxmaps.org/pix/prec7.html
NOW, the MJO, has just been predicted to be in phase 4 somewhere around 10-14 July.
http://www.apsru.gov.au/mjo/sitrep.asp
I reckon that if the RMS progs eventuate, the MJO will bring a lot of it onshore. (Phase 3 and certainly phase 4 usually bring higher than normal rains to SEQ in the winter season).
The drought is a long way from being over – but there are good signs out there…
Hope I don’t have much mud on my face after this, and that all you guys in SEQ walk in a lot of it.
(Note, all the links are to live sites so they will change over the course of the next couple of weeks…)
cheers
Arnost
SJT
From the above posts, after you read Beder have a go at Chapter 14 in Steinbeck’s “Log from the Sea of Cortez”
Arnost – always good to see some rain. Rain in Brissy in last few days but no catchment runoff yet depsite some falls in the dam area.
Arnost
IGES has a very good track record around here. Maybe I should go back to desilting the dam in which I’ve just bogged the dozer.
Once again we have gross misreporting in the links to the ABC on-line provided by Luke above and some very sloppy drafting of abstracts.
The Indian Ocean has not warmed by 2C. The tropical surface temperature has increased by up to 2C and the thermocline in the area between 40S and 50S has extended down to 800m depth. This does not mean that the entire 800m of thermocline has undergone a 2C warming. The rest of the Indian Ocean thermocline has apparently undergone some disturbance, including sub-surface cooling (a reduction in depth of thermocline) in the tropics.
The goegraphically challenged may need to be informed that the Indian Ocean actually extends from 20N to almost 70S (90 degrees in total) and a zone representing 11% of that arc has apparently experienced some warming. It should also be noted that at 45 degrees S the distance between 10 degrees of longitude is only 70.7% of 10 degrees at the equator.
So even allowing for the wider expanse of Indian Ocean south of Africa and Australia, it appears that less than 10% of the Indian Ocean has exhibited a deepening of thermocline. This zone of deeper thermocline is 0.5 degrees (about 500km) further south than it has been in the recent past.
This is a lot different to the story as reported.
Oh for heavens sake Motty – it’s the bloody SSTs in critical areas that determine the climate. Read again with eyes wide open and dogma subroutine deactivated. And they’ve been on the SST warming stuff for some time – even buggered up some seasonal forecasting research due to the emergence of Indian Ocean trends.
Wait till you get the start of year national and global temperature reports. It’s gonna be more more.
Another sidestep Luke.
Still on tealeaves. GFS 7 days out – the projections for a significant rain event for SEQ are firming – and a lot of it’s now over land:
http://forecasts.bsch.au.com/apf.html?region=qld&days=7.5
cheers
Arnost