Of Tropical Cyclones and Global Warming

[valkhorn]

I've heard the argument many times that because landfalling hurricanes have diminished, or that because tropical activity is in a slump, that it means the Earth is cooling, or that global warming does not exist.

 

Well, let's take a look at the proposed data:

(Forgive me if this is an unreliable source, replace it with reliable data if you want):

 

 

Landfalls:

 

 

So, if we were to JUST look at the above data, then it seems that tropical activity is either stable or diminishing, right? After all, it has been purported from the side that argues FOR global warming that stronger storms mean that the world is getting warmer.

 

Well, yes and no.

 

If we look at the global oceanic heat content, we see the following:

 

 

 

So what's going on?

 

Well, let's take a look at the ingredients needed to form a tropical cyclone:

 

• Warm water at the surface
• Atmospheric instability
• High humidity in the troposphere
• Enough Coriolis force to create low pressure
• A preexisting disturbance like a batch of thunderstorms or a tropical wave
• Low vertical wind shear

Only one of these is directly associated with ocean heat content. Warm oceans can exist where there is little to no atmospheric instability, or where there is dry air, or little coriolis force (deserts near the equator), or with high wind shear (like what is typically found in higher latitudes), or these conditions may not be favorable where there is high ocean heat content in a given year.

 

So, it's very possible that the earth IS getting warmer, and tropical activity overall could be stable or diminished in some years.

 

It would be INCORRECT to associate an inactive tropical season with global cooling.

 

However, if a tropical season is more active than usual, then the conditions giving rise to the season were improved, and a high ocean heat content due to global warming would be a given. Therefore...

 

While global warming doesn't guarantee an active season, it does make it more likely that storms have a higher potential, and seasons have a higher potential number of storms, and a longer potential length - if other conditions not directly related to global warming are favorable.

 

Feel free to correct me in my conclusion, but I had given this argument a lot of thought. I hear the 'inactive hurricane season' argument being trotted out against global warming, and I know there has to be more to the story than meets the eye.

[ORH_wxman]

Global warming is expected to lead to fewer TCs in general, and a 1-3% increase in max intensity. Essentially, TCs tell us nothing about global warming.

[tacoman25]

Sometimes there are just short term trends that deviate from "norms". I've lost count of how many times people have tried to tie a short term weather/climate trend into something bigger than it probably is, depending on their bias.

[f2tornado]

Global warming is expected to lead to fewer TCs in general, and a 1-3% increase in max intensity. Essentially, TCs tell us nothing about global warming.

 

Yes. I've read a couple of journal articles on the subject suggesting this result. Here is one: http://www.nature.com/ngeo/journal/v3/n3/abs/ngeo779.html Less but slightly stronger is not unreasonable from a basic energy redistribution perspective. I am certain some climate change deniers bring up the lack of tropical systems because people like Al Gore keep telling us tropical cyclones are gonna increase in number and get worse. We even had people suggesting Sandy was a prelude of things to come then a brand new paper comes out suggesting such storms would become even more rare in a warming environment. http://www.redorbit.com/news/science/1112937758/climate-change-steer-hurricanes-away-from-east-coast-090313/

[ORH_wxman]

 

Yes. I've read a couple of journal articles on the subject suggesting this result. Here is one: http://www.nature.com/ngeo/journal/v3/n3/abs/ngeo779.html Less but slightly stronger is not unreasonable from a basic energy redistribution perspective. I am certain some climate change deniers bring up the lack of tropical systems because people like Al Gore keep telling us tropical cyclones are gonna increase in number and get worse. We even had people suggesting Sandy was a prelude of things to come then a brand new paper comes out suggesting such storms would become even more rare in a warming environment. http://www.redorbit.com/news/science/1112937758/climate-change-steer-hurricanes-away-from-east-coast-090313/

 

As I said in another thread, attribution remains of the flimsiest areas of climate science yet it probably gets more media press than any other aspect of climate change.

Especially when it comes to big and scary storms like Sandy or Katrina. It certainly doesn't do the science itself any favors. Even when papers come out that try and attribute certain types of extreme events to AGW, they often have caveats such as "may see an increase" or "in the future, but no discernable trend has existed to date" and the media will just run with it and give a scary headline to the study and gloss over the uncertainty and caveats.

Miscommunication remains a big barrier. Especially when it comes to attribution.

[Jonger]

I don't need to post peer-review literature or quote prominent scientists when I say that we WERE told that high TS activity was the new norm.

 

It was quite a media frenzy between main stream news to Dr. Jeff Masters blog. There is definitely backpedaling underway.

 

This entire ordeal extends to tornado activity as well. Using weather to bolster climate change has been rampant over the last 5-10 years.

[f2tornado]

 

This entire ordeal extends to tornado activity as well. Using weather to bolster climate change has been rampant over the last 5-10 years.

 

The tornado correlation is an absolute joke as there is no scientific evidence to suggest they are either increasing in number or getting worse. Al Gore keeps piling on yet even the scientists are telling him to shut up about tornadoes http://www.politico.com/story/2013/06/gore-scientists-wont-let-us-connect-climate-to-tornadoes-92581.html Tornadoes need CAPE and wind shear to spin. In a warming environment the jet stream should weaken through arctic amplification and potentially shift north. This would serve to limit wind shear.

[skierinvermont]

I don't need to post peer-review literature or quote prominent scientists when I say that we WERE told that high TS activity was the new norm.

 

It was quite a media frenzy between main stream news to Dr. Jeff Masters blog. There is definitely backpedaling underway.

 

This entire ordeal extends to tornado activity as well. Using weather to bolster climate change has been rampant over the last 5-10 years.

 

I've been following climate science for the last 8 years and I was never under the impression that high TC activity was expected. The general idea has been 'we don't really know but our best guess is slightly reduced # and slightly increased intensity.'

[f2tornado]

I've been following climate science for the last 8 years and I was never under the impression that high TC activity was expected. The general idea has been 'we don't really know but our best guess is slightly reduced # and slightly increased intensity.'

 

This was the general but far from unanimous consensus in the scientific literature and there remains debate. http://www.usatoday.com/story/weather/2013/07/08/climate-change-global-warming-hurricanes/2498611/  Now, go ask for the opinion of Average Joe on the street and he's likely to say there will be more storms for reasons Jonger pointed out. There is a disconnect between the science, the media, and the public. Some AGW policy advocates are upset there is a lot of outright denial but they are partially to blame for busting out a pile of hyperbole, yeah you Al Gore, that hasn't come to fruition or has been largely debunked. I suspect most people really do have a basic understanding of the CO2 science but are highly skeptical of the various attributions being bantered about by wannabe armchair climate scientists (Al Gore, the Sierra Club, Forecast the Facts, Greenpeace, etc) since a number of the proposed attributions are simply not happening on a noticeable level. The science has been drowned out be sensationalist headlines, instant pseudo-scientific reaction to events, and ghost pepper alarmists.

[Cory]

Feel free to correct me in my conclusion, but I had given this argument a lot of thought. I hear the 'inactive hurricane season' argument being trotted out against global warming, and I know there has to be more to the story than meets the eye.

 

It's pretty much the opposite of every "event=AGW" story that breaks out every time the wind gusts over 60 knots. Neither of those types of statements have anything to do with science (or thinking in general). They're cheap one-ups in mindless political arguments. 

[Snow_Miser]

An inactive hurricane season doesn't mean that GW is false, but it certainly casts some doubt on whether any such GW signal exists in the Hurricane record, especially given the conflicting signals with 2005 being extremely active, and this year not being active at all (so far).

 

There also appears to be a lot of noise in the ACE dataset, so we may not have our answer with regard to what the GW signal is, until a while from now.

 

[PhillipS]

An inactive hurricane season doesn't mean that GW is false, but it certainly casts some doubt on whether any such GW signal exists in the Hurricane record, especially given the conflicting signals with 2005 being extremely active, and this year not being active at all (so far).

 

There also appears to be a lot of noise in the ACE dataset, so we may not have our answer with regard to what the GW signal is, until a while from now.

 

 

Interesting plot - it appears to me that most of the variability has been in the northern hemisphere.   I agree with you that if there is an AGW effect on TCs it's not apparent in the record to date.  About a year ago, someone (ORH?) discussed the idea that increased shear would keep many tropical systems from growing into TCs.  Are there any observations for how the tropical wind shear this year compares with the past?

[Snow_Miser]

Interesting plot - it appears to me that most of the variability has been in the northern hemisphere.   I agree with you that if there is an AGW effect on TCs it's not apparent in the record to date.  About a year ago, someone (ORH?) discussed the idea that increased shear would keep many tropical systems from growing into TCs.  Are there any observations for how the tropical wind shear this year compares with the past?

 

I think one of the reasons for the inactive season this year has been the more stable atmosphere than usual associated with an enhanced presence of the SAL. Not sure if warming impacts the SAL or not though.

[blizzard1024]

 

 

As I said in another thread, attribution remains of the flimsiest areas of climate science yet it probably gets more media press than any other aspect of climate change.

Especially when it comes to big and scary storms like Sandy or Katrina. It certainly doesn't do the science itself any favors. Even when papers come out that try and attribute certain types of extreme events to AGW, they often have caveats such as "may see an increase" or "in the future, but no discernable trend has existed to date" and the media will just run with it and give a scary headline to the study and gloss over the uncertainty and caveats.

Miscommunication remains a big barrier. Especially when it comes to attribution.

amen.