Ocean temperature increase and hurricanes

[SkepticLance]

Just finished reading an editorial in New Scientist, in which the author suggests that towns like Galviston on the hurricane prone sea coast, should be abandoned rather than rebuilt. This struck me as rather a weird suggestion, since I think we can build protections that would keep up with any reasonably predictable increased sea level and hurricane risk.

 

This led me to the question as to whether hurricane risk is actually increasing that much. While hurricanes have been a little more frequent and a little more severe in the last decade or so, there is no way to tell for sure whether this is due to anthopogenic global warming, or just a natural cycle.

 

It seems to me that the degree of warming is simply too small. We have had an average warming of the ocean of 0.06 Celsius over the past 40 years.

http://findarticles.com/p/articles/mi_hb6376/is_/ai_n28880042

And it appears that a sea water temperature increase of 1 Celsius contributes to a 5% increase in hurricane wind speed.

 

A lot of global warming articles refer to global temperature increases of up to 5 Celsius in the next century or two, and say this will drive more terrible hurricanes. But that is air temperature, which does not affect hurricanes. It is increase in ocean temperature that is critical, and 0.06C is just too trivial to have much impact.

 

Are the hurricane increase proponents just a bunch of theoretical catastrophe lovers, or is there something I have missed?

[iNow]

Just finished reading an editorial in New Scientist, in which the author suggests that towns like Galviston on the hurricane prone sea coast, should be abandoned rather than rebuilt.

I happen to agree. Same thing in New Orleans, Louisianna. It's a waste of money to rebuild them as they will just be demolished again in a few short years.

 

 

Are the hurricane increase proponents just a bunch of theoretical catastrophe lovers, or is there something I have missed?

Yes, I believe you've focused too much on hurricane activity alone (which is getting more intense) and forgotten how sea levels are rising as glacial and arctic ice melts. This rise in sea level poses another challenge to maintaining societies in below sea level coastal regions like Galveston.

[SkepticLance]

iNow

What is your prediction as to sea level rise over, say, 100 years? Current rise is 3 mm per year. Even if that doubled as a 100 year average, that would only be 0.6 metres (2 feet) which the Dutch have shown can be coped with using dykes.

[iNow]

My prediction is that all indicators suggest a rise. I leave the scope of that rise up to the experts. Basically, I'm not sure. It's going up, of that much I'm certain. By how much is debatable, but my point stands. With the combination of increasingly intense hurricanes and increasing sea levels, humans should wrap their heads around those odds and move inland when possible.

[JohnB]

Another question is whether any increase is only regional.

 

The only really severe cyclone (as we call them) recently was Larry in 2006.

 

Aside from that you need to go back to 1974 for the Brisbane floods and Cyclone Tracy in Darwin and 1971 when Althea smashed Townsville. Judging by cities being hit, cyclone activity is down for North Eastern Australia. 32 years between Cat5s is definitely not an increase in either frequency or force.

 

If you watch the first bit of this, you'll hear the cyclone warning siren. I grew up with that siren, it was tested every December but we don't hear it anymore, we don't need it.

 

Cyclones still come but they lack the power of previous ones. Here is a list of Queensland cyclones dating back to 1864, have a read and you'll see what I mean. If there is an increase in size and frequency, it isn't in the Western Pacific region.

[iNow]

Another question is whether any increase is only regional.

Of course hurricane activity is regional. You don't see hurricanes very far inland. You don't see many hurricanes in Idaho (or, Alice Springs for the Aussie).

 

 

To your point about the western pacific, the effects of La Nina and changing ocean currents (hence, changing water temperatures) appear to be the dominant reason for the decrease in cyclonic activity there. It's not so much that hurricane changes are regional as much as there are more than one factor to consider.

Edited December 7, 2008 by iNow

[SkepticLance]

I don't feel that my original question has been answered.

Bearing in mind that ocean temperatures have risen, on average, only 0.06 Celsius in 40 years, and warmer ocean temperature is the driver of hurricanes, how can such a small effect drive more, or more intense hurricanes?

 

Apparently it takes 1 Celsius higher ocean temperature, compared to a smaller hurricane, to create a hurricane with 5% greater wind speed. What would 0.06 C do?

 

I am not convinced that this change is sufficient to have a measurable effect on hurricane frequency or intensity. Changes in measurements of those parameters are, so far, within statistically normal variation. Is there a real change, and if so, how does it happen?

[iNow]

http://www.usgcrp.gov/usgcrp/links/hurricanes.htm

 

http://www.scienceforums.net/forum/showthread.php?p=419479#post419479

[Sayonara]

I don't feel that my original question has been answered.

Just before your hurricane question you seemed to query why the towns should be moved when they could be more robustly defended. A possible explanation is that the cost of adequate defences could exceed the cost of occasional rebuilding, making it simply not viable as an alternative. I wonder how we would go about getting figures on that.

[SkepticLance]

Swansont

I may not have been clear enough in my query. Sorry. My main concern is to ask why such a small change in sea temperature is supposed to have caused an increase in hurricane frequency/intensity.

 

iNow

Can I ask you a favour? If you answer a query with a reference, could you please post a quote from that reference showing the relevent bit. Some references are very long, and I really don't want to have to read all of them to find a statement to answer my query. I am sure that other people will appreciate this also.

[swansont]

Swansont

I may not have been clear enough in my query. Sorry. My main concern is to ask why such a small change in sea temperature is supposed to have caused an increase in hurricane frequency/intensity.

 

Excuse me? I have not previously posted in this thread. (This is one reason many prefer people to use the quote function.)

[SkepticLance]

Swansont

Temporary cerebral short circuit.

I meant to address Sayonara. My apologies.

[foodchain]

Another question is whether any increase is only regional.

 

The only really severe cyclone (as we call them) recently was Larry in 2006.

 

Aside from that you need to go back to 1974 for the Brisbane floods and Cyclone Tracy in Darwin and 1971 when Althea smashed Townsville. Judging by cities being hit, cyclone activity is down for North Eastern Australia. 32 years between Cat5s is definitely not an increase in either frequency or force.

 

If you watch the first bit of this, you'll hear the cyclone warning siren. I grew up with that siren, it was tested every December but we don't hear it anymore, we don't need it.

 

Cyclones still come but they lack the power of previous ones. Here is a list of Queensland cyclones dating back to 1864, have a read and you'll see what I mean. If there is an increase in size and frequency, it isn't in the Western Pacific region.

 

If you can accept that environmental change can occur then I think questions like global warming are perfectly acceptable. Saying that I would just like to point out that CO2 in terms of ppm increase is observed globally, not just regionally. It may be something in an effect that whatever change we are inflicting is not enough to completely stop for instance any particular weather pattern yet, like a jet stream.

 

Its not that weather itself has to become completely different. Just a few degree change over a relatively short period of time geologically speaking is enough to cause severe havoc. Europe, or France in particular experienced a rather intense heatwave years ago which killed a lot of people, and of course with all the ice melting what is to blame, as in what melts ice? So what will our behavior lead to, should not be undercut so easily as to say hurricane activity is only regional in regards to ocean temperatures.

 

I just don't understand how you can try to corner global warming into some purely regional effect alone, when clearly its not the case.

[SkepticLance]

To foodchain

In my own opinion, one of the really bad but frequent myths surrounding global warming issues is the belief that localised short term heat waves or cold snaps can be blamed on global warming.

 

The highest air temperature due to climatic effect ever recorded was in the desert of Libya in the year 1911, when it came close to 60 Celsius. This was the second coldest year of the 20th Century!

[foodchain]

To foodchain

In my own opinion, one of the really bad but frequent myths surrounding global warming issues is the belief that localised short term heat waves or cold snaps can be blamed on global warming.

 

The highest air temperature due to climatic effect ever recorded was in the desert of Libya in the year 1911, when it came close to 60 Celsius. This was the second coldest year of the 20th Century!

 

Yes, but I think along those lines also what can account for all the CO2. Would it be difficult to say disconnect any modern atmospheric or oceanic behavior in regards to this and how? I think a simple point with the hurricanes is that global warming could be false because not all hurricane behavior is linear? Or that because regionally, global warming could play out differently means global warming is false? I would expect normal and random behavior to occur in light of global warming, such as being in hilly terrain during sunset, the winds in such a situation I imagine would be extremely difficult to predict. I don't however though think global warming should not be viewed in conjunction with modern weather phenomena, maybe it will get more intense and worse in others, or maybe just one short term impact of GW is just more stronger hurricanes withing a shorter period of time. I think its just because I get hung up on how people can deny anything anymore, not so much question such.

[npts2020]

Barry Commoner in the 1970's (I think in "The Closing Circle") predicted that global warming would increase size, strength, and possibly frequency of hurricanes and other destructive storms. The logic being, that as you put more energy into the atmosphere, the more activity you have. I am not sure what the current state of the science is, but it does make perfect sense to me.

[bascule]

It is increase in ocean temperature that is critical, and 0.06C is just too trivial to have much impact.

 

It's actually heat and the thermal gradient that matters, not temperature.

 

Are the hurricane increase proponents just a bunch of theoretical catastrophe lovers, or is there something I have missed?

 

The effect on vertical wind shear is also of utmost importance. Changes which decrease vertical wind shear increase the strength of hurricanes.

[CaptainPanic]

iNow

What is your prediction as to sea level rise over, say, 100 years? Current rise is 3 mm per year. Even if that doubled as a 100 year average, that would only be 0.6 metres (2 feet) which the Dutch have shown can be coped with using dykes.

 

We sink faster than that

(Estimates are that the Netherlands, on average, sinks 4 mm per year).

 

Sorry, not in the mood for finding a link to back that up.

 

Original question:

Just finished reading an editorial in New Scientist, in which the author suggests that towns like Galviston on the hurricane prone sea coast, should be abandoned rather than rebuilt. This struck me as rather a weird suggestion, since I think we can build protections that would keep up with any reasonably predictable increased sea level and hurricane risk.

 

This led me to the question as to whether hurricane risk is actually increasing that much. While hurricanes have been a little more frequent and a little more severe in the last decade or so, there is no way to tell for sure whether this is due to anthopogenic global warming, or just a natural cycle.

 

It seems to me that the degree of warming is simply too small. We have had an average warming of the ocean of 0.06 Celsius over the past 40 years.

http://findarticles.com/p/articles/mi_hb6376/is_/ai_n28880042

And it appears that a sea water temperature increase of 1 Celsius contributes to a 5% increase in hurricane wind speed.

 

A lot of global warming articles refer to global temperature increases of up to 5 Celsius in the next century or two, and say this will drive more terrible hurricanes. But that is air temperature, which does not affect hurricanes. It is increase in ocean temperature that is critical, and 0.06C is just too trivial to have much impact.

 

Are the hurricane increase proponents just a bunch of theoretical catastrophe lovers, or is there something I have missed?

 

The oceans have not warmed up. The air however has warmed, we know it (it's called global warming). Since there is warmer air over the ocean, it automatically must transfer more heat into the ocean. If the ocean has not heated up, it means that the ocean is able to lose the heat again. The only mechanism to do so is by evaporation. Evaporated water condenses again. And that is the process that drives a hurricane. It makes sense to me, even though I think we'll all agree that reality is more complicated than my 3-4 line description here.

[JohnB]

I just don't understand how you can try to corner global warming into some purely regional effect alone, when clearly its not the case.

I have absolutely no idea where you got that from what I said.

 

CO2 and temps are measured globally, however this does not mean that the climatic response in each region is the same. A rise in global temps may increase hurricane activity in the Atlantic, however I was showing that the Western Pacific does not seem to be exhibiting the same behaviour.

 

Hence, while the global temps may rise, an increase in hurricane activity may be a regional effect.

 

Has hurricane/cyclone activity increased?

Doesn't really look like it. In fact it would appear we are at near record levels of inactivity. The graph would imply that something other than just SSTs were involved.

 

Some articles link African dust levels to hurricane activity, so perhaps we need to look at something a bit more involved than a simple SST rise= more hurricanes.

 

You may want to read Emanuel et al 2007 published in the AMS Journal "Hurricanes and Global Warming: Results from Downscaling IPCC AR4 Simulations" who state;

The findings presented here are largely consistent with those obtained by direct simulation of tropical cyclones by global models as well as by downscaling using regional models embedded in global models. The majority of such exercises to date show a decrease in global genesis rates, as summarized, for example, by Bengtsson et al. (2007). For example, recent global model-based studies (e.g., Bengsson et al. 1996; Sugi et al. 2002; Oouchi et al. 2006; Yoshimura et al. 2006; Bengtsson et al. 2007) all show decreasing frequency of tropical cyclones globally, although some studies show regional increases.

(Emphasis mine)

[iNow]

Hurricane frequency has not gone up, but hurricane intensity has. If you look only at high intensity storms, those have increased in frequency dramatically.

 

 

Intensity is the revelant bit, not gross number of storms.

 

 

http://www.time.com/time/health/article/0,8599,1839281,00.html

So far, tropical ocean temperatures have risen by about 0.5 degree C since 1970, which could explain the more powerful storms. The

Nature

researchers estimate that every 1 degree C increase in sea-surface temperature would result in a 31% increase in the global frequency of category 4 and 5 storms. Given that computer models indicate that ocean temperatures could rise by up to 2 degrees C by 2100, those are scary calculations. It's especially worrying because the most intense storms do the most damage by far — several minor storms can equal the damage of a single severe hurricane. "The category 1 or 2 storms don't do that much," says Emanuel. "It's the 3 and 4 storms that really do the damage, and we could see more of them."

[SkepticLance]

iNow

Obviously reports of sea water temperature rise vary. I am not sure that Time magazine can be called the ultimate authority, though. I have seen various estimates, ranging from 0.03 C to your 0.5 C from the Time article. Here is another :

http://www.global-greenhouse-warming.com/sea-temperature.html

 

"Sea temperature is rising and the oceans are warming. Over the period 1961 to 2003, global ocean temperature has risen by 0.10°C from the surface to a depth of 700 m."

 

This is closer to my original reference estimate of 0.06C. I find myself seriously doubting the Time magazine estimate.

 

So why the discrepancy? I hate to have to tell you this, iNow, but you are quoting an error. Over the last 40 years, global average air temperature has risen 0.5 C. Even the most basic understanding of the science will tell you that sea temperature ALWAYS rises more slowly than air temperature. I live by the sea and scuba dive summer and winter. I record sea temperature. The maximum air temperature change seasonally is nearly 30 Celsius. The maximum sea temperature change, at least below the top 2 metres, is 7 Celsius.

 

For Time magazine to suggest sea temperatures will rise by 0.5 C while air temperatures rise by exactly the same amount will tell anyone with even small scientific understanding, that Time made a mistake. I would suspect that the author slipped a decimal point, and it should have been 0.05 C.

Edited December 9, 2008 by SkepticLance

[iNow]

Obviously reports of sea water temperature rise vary. I am not sure that Time magazine can be called the ultimate authority, though.

Try reading the article (and the quote I supplied). It was based on data published in the journal Nature.

 

 

This is closer to my original reference estimate of 0.06C. I find myself seriously doubting the Time magazine estimate.

See above.

 

 

For Time magazine to suggest sea temperatures will rise by 0.5 C while air temperatures rise by exactly the same amount will tell anyone with even small scientific understanding, that Time made a mistake. I would suspect that the author slipped a decimal point, and it should have been 0.05 C.

Bye bye, Lance.

[swansont]

So why the discrepancy?

 

One is a global average, while the other is a tropical measurement?

[iNow]

This is another one of those math word problems that Lance has such trouble with. He equates an "if/then" statement with a prediction, hence his tangential attempt at rebuttal.

 

The quote again:

 

The

Nature

researchers estimate that every 1 degree C increase in sea-surface temperature would result in a 31% increase in the global frequency of category 4 and 5 storms. Given that computer models indicate that ocean temperatures could rise by up to 2 degrees C by 2100, those are scary calculations. It's especially worrying because the most intense storms do the most damage by far — several minor storms can equal the damage of a single severe hurricane. "The category 1 or 2 storms don't do that much," says Emanuel. "It's the 3 and 4 storms that really do the damage, and we could see more of them."

 

 

A quote which was shared in support of my comments to John regarding the important measurement being hurricane intensity, and the increasing frequency of stronger hurricanes (category 4 & 5), not overall frequency or hurricanes of all categories.

[SkepticLance]

iNow

The Time magazine error was the 0.5 C increase in sea temperature. Let's not get off track here.

 

The air temperature in 40 years increased 0.5 C. Sea temperature ALWAYS lags way behind air temperature. It is called thermal lag. It is physically impossible for the air to warm 0.5 C and have the sea warm the same degree in 40 years.

 

I have read three other references. They gave ocean warming at 0.03 C, 0.06C and 0.1 C - and the discrepancy is explained by the different time periods being discussed. 0.5 C is ridiculous, and if you think about it for a while you will agree.