Is the Atlantic hurricane season getting longer?

By: Dr. Jeff Masters , 6:34 PM GMT on December 16, 2008

Share this Blog
3
+

It seems like there have been an unusual number of early and late season tropical storms and hurricanes in the Atlantic in recent years. In 2008, we had four named storms in July, and the second most powerful November hurricane on record. Both 2007 and 2005 had rare December storms, and 2003 featured Tropical Storm Anna, the first April tropical storm ever recorded. This year, Hurricane Tomas made 2010 the fourth straight year with a November hurricane, something that has never occurred in the Atlantic since accurate records began in 1851. Is hurricane season getting longer? Dr. Jim Kossin of the University of Wisconsin published a 2008 paper in Geophysical Research Letters, "Is the North Atlantic hurricane season getting longer?" He concluded that yes, there is a "apparent tendency toward more common early- and late-season storms that correlates with warming Sea Surface Temperature but the uncertainty in these relationships is high".


Figure 1. Observed sea surface temperature (SST) trends during the official North Atlantic hurricane season (June-November) for the period 1950-2007. Units are °C per century. The dashed rectangle denotes the tropical storm formation region south of 30° North latitude and east of 75° West longitude. Data are from the NOAA Extended Reconstructed Sea Surface Temperature V3 product [Smith et al., 2008]. Image credit: Kossin, J., 2008, "Is the North Atlantic hurricane season getting longer?", Geophysical Research Letters, Vol. 35, L23705, doi:10.1029/2008GL036012, 2008.

Methods
Dr. Kossin utilized the "best track" database of Atlantic tropical cyclone activity going back to 1851. However, since lack of satellite and aircraft reconnaissance data before 1950 makes the early part of this record suspect, he limited his analysis to the period from 1950 onward. The era of best data--the satellite era beginning in 1980--was also looked at separately, to ensure the highest possible data quality. The area studied was only a portion of the Atlantic--the tropical storm formation region south of 30° North latitude and east of 75° West longitude. This region has shown considerable warming of the Sea Surface Temperatures (SSTs) since 1950, in excess of 1°F (0.6°C) (Figure 1). A statistical method called "quantile regression" was employed. The method looked at how certain thresholds that mark the beginning and end of hurricane season have changed over the years. For example, the date where 5% of all tropical storms form earlier than that date, was called the 0.05 quantile, and the date where 5% of all tropical storms form later than that date, was called the 0.95 quantile. Kossin was able to show that the date of the 0.05 quantile got steadily earlier and the date of the 0.95 quantile steadily got later since 1950. Hurricane season for both the period 1950-present and 1980-present got longer by 5 to 10 days per decade.


Figure 2. Trends in tropical storm formation dates, in the region south of 30° North latitude and east of 75° West longitude, at the 0.05.0.95 quantiles. Trends are based on the periods (left) 1950-2007, and (right) 1980-2007. The dates (month/year) associated with the 0.05, 0.25, 0.50, 0.75, and 0.95 quantiles for each period are shown on the top axis (these threshold dates are based on the full sample for each period). Shading denotes the 90% confidence interval. Image credit: Kossin, J., 2008, "Is the North Atlantic hurricane season getting longer?", Geophysical Research Letters, Vol. 35, L23705, doi:10.1029/2008GL036012, 2008.

Relationship with Sea Surface Temperature
The broadening of the Atlantic hurricane season found was strongly dependent upon Sea Surface Temperatures. Both the onset and end of hurricane season shifted by 20 days per degree C of warming of the SST. With global warming projected to increase tropical Atlantic SSTs 1-2°C by the end of the century, can we then expect a 40-80 day increase in the length of hurricane season? Dr. Kossin doesn't explore this possibility, and doesn't blame the observed increase in the length of the season on human-caused global warming of the oceans. There is reason to believe that future warming of the Atlantic SSTs won't necessarily broaden the area over which tropical storms will form, though. Papers by Henderson-Sellers et al. (1998) and Knutson et al. (2008) theorize that as SSTs warm, the lowest temperature at which tropical storms can form will also increase. The current minimum temperature of 26.5°C (80°F) may increase to 28.5°C for a 2°C warming of Atlantic SSTs. Johnson and Xie (2010) have found observational evidence that the lowest temperature at which tropical storms can form has indeed been increasing at about 0.1°C per decade in the Atlantic, in line with climate model predictions.

References
Henderson-Sellers, A., et al., 1998, "Tropical Cyclones and Global Climate Change: A Post-IPCC Assessment", Bull. Am. Meteorol. Soc. 79, 19–38.

Johnson, N.C., and S.P. Xie, 2010, "Changes in the sea surface temperature threshold for tropical convection", Nature Geoscience doi:10.1038/ngeo1008

Knutson, T.R., J.J. Sirutis, S.T. Garner, G.A. Vecchi, and I.M. Held, 2008, Simulated reduction in Atlantic hurricane frequency under twenty-first-century warming conditions", Nature Geoscience 1, 359 - 364 (2008), doi:10.1038/ngeo202

Kossin, J., 2008, "Is the North Atlantic hurricane season getting longer?", Geophysical Research Letters, Vol. 35, L23705, doi:10.1029/2008GL036012, 2008.

Jeff Masters

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 207 - 157

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8Blog Index

No Orca yet - probably hasn't had time to turn the computer on!

Still hanging Christmas lights - and still sweating while we are doing it. Don't know whether I prefer the warm temps or the ability to stay cool for a while.

Our daughter in Maine finally got power back last night. We were threatening to fly up and get the baby, poor guy doesn't know what to do with only cold water.
Member Since: Posts: Comments:
Snowing Las Vegas, NV.
Also snowing 6-10" just east of San Diego, CA.
Member Since: Posts: Comments:
sooo ahhh Orca... what you bring back? Tequila, Orcas....... a good tan?
Member Since: Posts: Comments:
I asked this on the last page, but since it's not busy at all tonight and there's a new page, I'll ask again. Anyone know the final death toll from Ike in US? Thanks again
Member Since: January 1, 2008 Posts: 0 Comments: 3785
203. HadesGodWyvern (Mod)
198. hurristat 1:18 AM GMT on December 18, 2008

Quoting HadesGodWyvern:

Cindy or Cinda??


It's Cinda

Member Since: May 24, 2006 Posts: 51 Comments: 46173
202. HadesGodWyvern (Mod)
Darwin Tropical Cyclone Warning Center
Tropical Cyclone Advice Number FOUR
TROPICAL LOW (02U)
11:00 AM ACST December 18 2008
=====================================

At 9:30 AM Australia CST, a Tropical Low [1002 hPa] located at 13.8S 128.3E, or 135 kms west-northwest of Port Keats and 190kms east northeast of Kalumburu at 10 minute sustained winds of 25-30 knots with gusts of 45 knots. The low is reported as moving southeast at 6 knots.

There is the possibility of a tropical cyclone developing in the Joseph Bonaparte Gulf later on Friday. GALES are not expected in coastal areas within the next 24 hours, however gales could develop later.

Tropical Cyclone Watch
=====================
A Cyclone WATCH is now current for coastal and island communities from Cockatoo Island in Western Australia to Port Keats in the Northern Territory.
Member Since: May 24, 2006 Posts: 51 Comments: 46173
201. GatorWX
1:26 AM GMT on December 18, 2008
Moonlight, haven't seen you in a long time, where have you been hiding?
Member Since: January 1, 2008 Posts: 0 Comments: 3785
200. GatorWX
1:24 AM GMT on December 18, 2008
Evening everyone. I asked this question the other night. I am curious if anyone knows the final death toll from Ike in the US. Wiki hasn't updated it, and I can't find a site under search engines. If anyone knows, please let me know. Wiki says 202 still missing, and I doubt this is, but I don't really know. Seems they would either count them as dead or have located their whereabouts. Thanks a lot!
Member Since: January 1, 2008 Posts: 0 Comments: 3785
199. BahaHurican
1:20 AM GMT on December 18, 2008
I'm very interested in seeing the final on Fay. I have a feeling she's going to beat out several prior storms for fickleness and long-term unpredictability.
Member Since: October 25, 2005 Posts: 19 Comments: 22583
198. hurristat
1:18 AM GMT on December 18, 2008
Quoting HadesGodWyvern:
Mauritius Meteorological Services
Tropical Cyclone Warning Number NINE
TEMPETE TROPICAL MODEREE CINDA 04-20082009
04:00 AM Reunion December 18 2008
======================================

At 0:00 AM UTC, Moderate Tropical Storm Cinda (994 hPa) located at 11.3S 66.9E has 10 minute sustained winds of 35 knots with gust of 50 knots. The storm is reported as moving south at 4 knots.

Gale Force Winds
===================
20 NM radius from the center

Near Gale-Force Winds
====================
30 NM radius from the center extending up to 70 NM in southern semi-circle

Dvorak Intensity: T3.0

Forecast and Intensity
=========================
12 HRS: 12.0S 66.6E - 40 knots (Temp%uFFFD Tropicale Modere%uFFFD
24 HRS: 13.4S 65.7E - 35 knots (Temp%uFFFD Tropicale Modere%uFFFD

Additional Information
======================
System has reached moderate tropical storm stage during the night and given the name "Cinda" by Mauritius Meteorological Services at 0000z. Stronger winds extend further in the souther semi-circle, due to the gradient effect with the subtropical high pressures. The potential for intensification of this system appears limited. Environmental conditions are still expected to deteriorate starting today.


Cindy or Cinda??
Member Since: October 15, 2008 Posts: 11 Comments: 2312
197. hurristat
1:16 AM GMT on December 18, 2008
Quoting StSimonsIslandGAGuy:
World population growth is not a simple exponential curve, as average world birth rates have been falling since the 1970s. But the population will still rise considerably through mid century. This is the latest census bureau (updated Dec 2008)


they're getting farther apart...
Member Since: October 15, 2008 Posts: 11 Comments: 2312
196. SarasotaToo
12:58 AM GMT on December 18, 2008
StSimons, that's fascinating...Do you know what's factored into that drop in percentage increase?
Member Since: July 27, 2008 Posts: 0 Comments: 33
195. KEEPEROFTHEGATE (Mod)
12:57 AM GMT on December 18, 2008
Quoting Orcasystems:
Bad news..I am back :(

Complete Blog Refresh
Mirror Site
was the vacation good orca bet yer all tanned up for the holidays

o welcome home
Member Since: July 15, 2006 Posts: 175 Comments: 54858
193. moonlightcowboy
12:42 AM GMT on December 18, 2008
Quoting StSimonsIslandGAGuy:
World population growth is not a simple exponential curve, as average world birth rates have been falling since the 1970s. But the population will still rise considerably through mid century. This is the latest census bureau (updated Dec 2008)



Good evening, all! Yup, Simon. I've done some reading in the past about "sustainability." I'm curious, according to the graph (as I see it) why do you think it's supposed to take about 20 years to go from eight to nine billion - especially, since it's only supposed to take about 10 years to go from seven to eight billion? Seems with that many more people having babies that it would take nearly as much as 20 years to grow exponentially again.
Member Since: July 9, 2006 Posts: 184 Comments: 29610
192. HadesGodWyvern (Mod)
12:39 AM GMT on December 18, 2008
Mauritius Meteorological Services
Tropical Cyclone Warning Number NINE
TEMPETE TROPICAL MODEREE CINDA 04-20082009
04:00 AM Reunion December 18 2008
======================================

At 0:00 AM UTC, Moderate Tropical Storm Cinda (994 hPa) located at 11.3S 66.9E has 10 minute sustained winds of 35 knots with gust of 50 knots. The storm is reported as moving south at 4 knots.

Gale Force Winds
===================
20 NM radius from the center

Near Gale-Force Winds
====================
30 NM radius from the center extending up to 70 NM in southern semi-circle

Dvorak Intensity: T3.0

Forecast and Intensity
=========================
12 HRS: 12.0S 66.6E - 40 knots (Temp%uFFFD Tropicale Modere%uFFFD
24 HRS: 13.4S 65.7E - 35 knots (Temp%uFFFD Tropicale Modere%uFFFD

Additional Information
======================
System has reached moderate tropical storm stage during the night and given the name "Cinda" by Mauritius Meteorological Services at 0000z. Stronger winds extend further in the souther semi-circle, due to the gradient effect with the subtropical high pressures. The potential for intensification of this system appears limited. Environmental conditions are still expected to deteriorate starting today.
Member Since: May 24, 2006 Posts: 51 Comments: 46173
189. KoritheMan
12:36 AM GMT on December 18, 2008
For those who may not know, the NHC finally released their report on Hanna today. Take a look at it.
Member Since: March 7, 2007 Posts: 597 Comments: 21112
187. BahaHurican
12:24 AM GMT on December 18, 2008
184. hurristat 7:09 PM EST on December 17, 2008

My bigger concern about the GW issue is not what the cause is so much as what the impacts are likely to be. I agree we should consider causes; if we can mitigate against the effects by shutting down the cycle I can see the value of that. OTOH, it seems that anything we do now will still leave us with quite a few years when we will have to cope with a least some of the consequences. That's why I found the comments about overpopulation, developed vs. developing, and land / water use so interesting. If arid areas are going to spread or shift in scope, for example, what are the potential impacts on food production in that part of the world?

Somebody mentioned earlier the role of TCs in moving water into the SE US, and I know they perform similar functions along the SE African coast (and prolly to a lesser extent to NW Australia). How might shifting temperatures affect traditional storm tracks, storm rates, etc? We've seen a short-term shift on the basis of La Nina / El Nino vacillations, so we know something similar, but longer lasting isn't out of the range of possibility.

I'm also thinking about the Grey/Kolbach Dec forecast, which the good doc repeatedly reminds us has little skill. Nevertheless, it does indicate that hurricane predictors can / do shift based on climate-based patterns, so that things we used to read before as indicators may no longer be so reliable.

Just a few thoughts.
Member Since: October 25, 2005 Posts: 19 Comments: 22583
186. Stormchaser2007
12:19 AM GMT on December 18, 2008
Quoting stormdude77:


I'm in ''lurking'' mode...I also find find STL's post to be quite informative and accurate.



Yeah I do too...dont really think that there annoying. Sometimes the stuff he posts is interesting.
Member Since: June 9, 2007 Posts: 4 Comments: 15946
185. BahaHurican
12:13 AM GMT on December 18, 2008
stat,

What I like best about the blog is when we can slam each other with the data LOL. I get a real education out of it.

I guess that's why I was annoyed with the two reports about GW I saw this past week, where each reporter sounded more like one of our local summer bloggers in defense of his / her position than like well-trained, scientific journalists. Just about the only thing missing from one of them was the "but he started it first". . . lol. What's the world coming to the the bloggers are the sound voice of reason and the reporters are "he-saying and she-saying"???
Member Since: October 25, 2005 Posts: 19 Comments: 22583
184. hurristat
12:09 AM GMT on December 18, 2008
Quoting BahaHurican:
I'm not sure if this is a correct statement. Countries like Singapore and Bangladesh aren't overpopulated because they are poor; they're overpopulated because they have large population densities. If u mean problems we associate w/ overpopulation, perhaps it would make more sense. Nevertheless, the most densely populated places (Macao, Hong Kong, Singapore etc according to Wikipedia) are all highly reliant on outside sources of food and water, and I wonder how similar population densities along the entire coastlines of the world would impact supplies of water and arable land. I can't see it as merely a matter of economics; there is a footprint issue too.


The density is largely the issue; another is reproduction rates... Singapore is in no way, shape, or form poor. (no offense) But I get your point.

The reliance on outside sources is a different topic, but the relationship between density and arable land is related to overpopulation.
Member Since: October 15, 2008 Posts: 11 Comments: 2312
183. hurristat
12:04 AM GMT on December 18, 2008
Quoting stormdude77:


I'm in ''lurking'' mode...I also find find STL's post to be quite informative and accurate.


I may disagree with him, but when I do, I can prove my point with more data... just because you don't agree with someone doesn't mean their argument is invalid.
Member Since: October 15, 2008 Posts: 11 Comments: 2312
182. BahaHurican
11:59 PM GMT on December 17, 2008
Quoting chilliam:
You'll find that overpopulation is a problem coming from poor economic conditions. The problem is *not* overpopulation, but rather awful economies. Solutions should address the root problem, economics.




I'm not sure if this is a correct statement. Countries like Singapore and Bangladesh aren't overpopulated because they are poor; they're overpopulated because they have large population densities. If u mean problems we associate w/ overpopulation, perhaps it would make more sense. Nevertheless, the most densely populated places (Macao, Hong Kong, Singapore etc according to Wikipedia) are all highly reliant on outside sources of food and water, and I wonder how similar population densities along the entire coastlines of the world would impact supplies of water and arable land. I can't see it as merely a matter of economics; there is a footprint issue too.
Member Since: October 25, 2005 Posts: 19 Comments: 22583
181. stormdude77
11:47 PM GMT on December 17, 2008
Quoting Stormchaser2007:
Does anyone even read STL's posts?


I'm in ''lurking'' mode...I also find find STL's post to be quite informative and accurate.
180. BahaHurican
11:46 PM GMT on December 17, 2008
Quoting chilliam:


And I'm not? Or is that you trying to retort with a glib comment so everyone ignores the actual facts in my argument?

Show some respect ... as you said yourself a few minutes ago: "But, that still does not give you the right to disrespect so many honorable people."
Chill, I think he's trying to say that your argument ignores the massive growth in other parts of the world, which therefore tends to support the idea that there IS overpopulation and overconsumption.

It's called rebuttal, not disrespect.

He makes a good point too, since some of the areas where populations have been on the rise are also areas with potential water shortages.
Member Since: October 25, 2005 Posts: 19 Comments: 22583
179. BahaHurican
11:42 PM GMT on December 17, 2008
Quoting Stormchaser2007:
Does anyone even read STL's posts?
I do. As others have said, I'm willing to read posts that attempt to present information in a scientific and reasonably balanced manner.

Hey, I even read the FOX News one, and I have found FOX to be remarkably biased towards whatever their current bias of the week is in their reporting . . . .
Member Since: October 25, 2005 Posts: 19 Comments: 22583
178. BahaHurican
11:37 PM GMT on December 17, 2008
Can we not try to polarize this issue along religious lines? Neither the political liberals or conservatives have a hold on God, Allah etc, and neither group has the "mandate" on conservation. All Christians are not a part of the Religious Right, and a whole lot of the "Religous Right" are not Christians. These are the kinds of non-issue baggage that are keeping us from developing clarity about really important issues like keeping the world in as good a shape as possible.

Can't we be good husbands of the "vineyard" of the earth? If we destroy our home, we don't have a guarantee of being granted another one.
Member Since: October 25, 2005 Posts: 19 Comments: 22583
177. Orcasystems
11:35 PM GMT on December 17, 2008
Bad news..I am back :(

Complete Blog Refresh
Mirror Site
Member Since: October 1, 2007 Posts: 81 Comments: 26511
176. BahaHurican
11:31 PM GMT on December 17, 2008
Quoting weathermanwannabe:
Hey All; I see Dr. M, and his colleagues, are still looking at GW issues and the impact on hurricane season........I am not qualified to discuss the issue, and it will take years to "nail" it down with evidence one way or the other...However, and for a change of topic, I had a conversation with a respected FSU met professor a few weeks ago and he felt that we/they were all missing the boat with the GW debate in terms of immediate urgency of issues; he basically said that the issue of growing shortages of "fresh water" for the growing earth population is the most pressing issue facing us right now......(He told me, "forget about GW being a real factor in your lifetime, your kids "may" have to worry about that, but everyone is talkng about GW and not stressing enough right now how this water issue will be affecting us in the very near future)...............Just some food for thought...........WW
People started talking about the water issue about 20 years ago as a serious shortterm problem. I think we're getting to the point where some "futuristic" style movies about criminals attempting to steal / control water supplies and wars being fought over water rights are likely to seem more factual than fictional. It's already been an issue here in the Bahamas simply because of our geography (small islands existing on minute, fragile limestone rock water lenses and captured rainfall). However, I can see water-rich countries having a stronger position as clean water supplies dwindle and climate patterns inevitably shift.
Member Since: October 25, 2005 Posts: 19 Comments: 22583
175. atmoaggie
11:30 PM GMT on December 17, 2008
That being said, just because data wasn't collected the way is is being collected now, we can't assume that the data is completely invalid. For example, the fact that we have better coverage of the EATL via satellite today doesn't mean that there was no ship's data available from the area 100 years ago.


Completely agree. We didn't necessarily miss whole storms when we had 2 ship obs and those ship obs may be good data. Some of the classifications, such as number of TSs and/or when they happened has some serious questions, though.

Remember earlier this year when we are all calling a system a TS and due to lack of QuikScat data showing a closed system, NHC was slow to call it a TD? Comparing the historical (> than 20 years ago) to now is very much like comparing the proverbial apples to oranges.

"just because data wasn't collected the way is being collected now, we can't assume that the data is completely invalid" This is so true of surface stations. The historical surface ob data as a representative value for an area and/or a component of a mean global telephone number is likely far more valid than the same for today.

Thanks for the civility comment...hope it gets through to everyone.
Member Since: August 16, 2007 Posts: 6 Comments: 12463
174. BahaHurican
11:24 PM GMT on December 17, 2008
Quoting Skyepony:
Death Map I thought was a bit contrived. Only goes back to 1970. Go back 100 years & South FL would look more like South LA. Same might have been said about CA, faultlines can be infrequent. General point about the heat being the worst killer can't really be disputed. I just wouldn't pick me out a "safer" place to live based on it.
I wonder if there is any such place as a "safer" place. Seems there's something that'll getcha just about anywhere. Guess u gotta pick ur poison . . .
Member Since: October 25, 2005 Posts: 19 Comments: 22583
173. BahaHurican
11:21 PM GMT on December 17, 2008
BTW, I agree we should work hard to keep a civil tone; I agree we should keep the discussion focused on issues rather than personalities.

I think some people on both sides of the issue can benefit from eliminating the judgemental name-calling.

I also think links to sources for this topic should be clearly focused.

I don't think we can avoid discussion of this topic, since it impinges so directly on the purpose of this blog (and this website!), but it behooves us to make the conversation worth the while, doesn't it?
Member Since: October 25, 2005 Posts: 19 Comments: 22583
172. BahaHurican
11:14 PM GMT on December 17, 2008
Quoting Skyepony:
P451~ If the data being so iffy & the media's scientist's in disagreeance is so confusing why close your eyes to what is happening? Answer me this.. When before the last few years was the Northwest passage open? Some try & say satalites skew all the data...How about the satalites showing Greenland & permafrost melting way faster then ever thought possible? At this point saying the world hasn't warmed a noticable amount is like saying an ice cube doesn't melt because of heat.

It's frustrating since the data sets will never be 100% right. That doesn't change the fact the physical changes to the earth are happening faster than the worst dooms sayers said. That is more real than data sets.

We need to stop polluting the world now for alot of reasons. Not fight about why & continue burning resourses & unsustainable farming.

Surfmom~ Have a sweet ride, weather couldn't be nicer..


Got ur back on this one. NW passage prolly was last open when Greenland was green enough to earn the name, say, maybe 600 years ago? 1000 years ago? Anyway, my point is we are missing a lot of the data we need to confirm some of the hypotheses out there.

That being said, just because data wasn't collected the way is is being collected now, we can't assume that the data is completely invalid. For example, the fact that we have better coverage of the EATL via satellite today doesn't mean that there was no ship's data available from the area 100 years ago.

We all benefit more from directing our attention to using our data wisely and allowing both enthusiasm and skepticism to be healthy rather than rabid. If more of the so-called scientific reporters and commenters on both sides of this issue would be more objective in their word choice, we might actually get a better understanding of the real science. Nobody benefits from the you-say-I-say.
Member Since: October 25, 2005 Posts: 19 Comments: 22583
171. AstroHurricane001
11:07 PM GMT on December 17, 2008
Re: hurristat:

World overpopulation is very much a short-term problem, and one that is mostly restricted to developing countries. In fact, in some developed countries, we may even see "not enough people" become a problem. Although a global population of around 12 billion by 2100 will further exuberate our economic and environmental crises, we have much bigger problems ahead of us.
Member Since: August 30, 2008 Posts: 8 Comments: 2835
170. hurristat
10:48 PM GMT on December 17, 2008
Quoting OSUWXGUY:
Hi All! Been a while since I was on...

The reason why the minimal threshold for storm formation might increase from 26.5°C to 28.5°C is as follows:

Warming Ocean -> More Deep Convection & Latent Heat Release Aloft -> Warming of the Upper Atmosphere

Currently 26.5°C and higher SSTs generally lead to unstable conditions that foster deep convection. However, if the upper atmosphere warms the ocean would have to warm as well to maintain instability.

It all has to do with environment lapse rates...



Okay thank you I was trying to figure that out.
Member Since: October 15, 2008 Posts: 11 Comments: 2312
169. hurristat
10:46 PM GMT on December 17, 2008
MichaelSTL 150.

While I respect your stance, I do think that once countries become developed, the birth rate goes down, sometimes below the death rate. For instance:

Birth Rate (per 1000)- Death Rate (per 1000)= new people (per 1000)

Italy= 8.36-10.61= -2.25 new people (per 1000)
Canada= 10.29-7.61= 2.68
United States= 14.18-8.27= 5.91
Japan= 7.87-9.26= -1.29
Australia= 12.55-6.68= 5.87
New Zealand= 14.09-7.00= 7.09
Denmark= 10.71-10.25= 0.46
Estonia= 10.28-13.35= -3.07
Finland= 10.39-10.00= 0.39
Iceland= 13.50-6.81= 6.69
Ireland= 14.33-7.77= 6.56
Latvia= 9.62-13.63= -4.01
Lithuania= 9.00-11.12= -3.12
Norway= 11.12-9.33= 1.79
Sweden= 10.15-10.24= -0.09
United Kingdom= 10.65-10.05= 0.60
Austria= 8.66-9.91= -1.25
Belgium= 10.22-10.38= -0.16
France= 12.73-8.48= 4.25
Germany= 8.18-10.80= -2.68
Liechtenstein= 9.86-7.42= 2.44
Luxembourg= 11.77-8.43= 3.34
Monaco= 9.09-12.06= -2.97
Netherlands= 10.53-8.71= 1.82
Switzerland= 9.62-8.54= 1.08
Cyprus= 12.56-7.76= 3.80
Russia= 11.03-16.06= -5.03
Hong Kong= 7.37-6.6= 0.77
Malta= 10.33-8.29= 2.04
Singapore= 8.99-4.53= 4.46
Spain= 9.87-9.90= -0.03
Portugal= 10.45-10.62= -0.17
Greece= 9.54-10.42= -0.88
Slovenia= 8.99-10.51= -1.52
South Korea= 9.09-5.73= 3.36
Taiwan= 8.99-6.65= 2.34
Czech Republic= 8.89-10.69= -1.80
These are all the countries that are considered "developed." Notice that most of them are under 7.00, and there are only a handful over 5.00. As you can see, the United States is not done with its process and that number is likely to go down. To show you how low these numbers are, here's Sierra Leone for comparison:

45.08-22.26= 22.82 new people (per 1000)
If all the undeveloped countries could be raised to developing or developed standards, world overpopulation would not be a problem.
Member Since: October 15, 2008 Posts: 11 Comments: 2312
168. OSUWXGUY
9:59 PM GMT on December 17, 2008
Some of the modeling efforts made by Knutson et al. should help shed some light on what is likely to happen, however the data length limitiations will simply not let any conclusive statements be made on whether GW has influenced hurricane activity anytime soon.
167. Seastep
9:58 PM GMT on December 17, 2008
Quoting MichaelSTL:


... global warming will cause (may have already caused) weather patterns to shift...


Or.... weather pattern shifts cause GW. ;)
Member Since: September 9, 2008 Posts: 6 Comments: 3414
166. OSUWXGUY
9:56 PM GMT on December 17, 2008
After reading all the comments I think many good points were made. Figured I'd summarize some of the salient themes that I agree with:

1. The Data Record is too short
2. Pre 1980's storms may have been missed - not sure if they would preferentially be missed at the beginning/end of the season because storms then are likely to be weaker/have shorter duration
3. Warm phase of the AMO switched in the middle of the satellite period - so the increase in season length after 1995 could largely be due to warmer SSTs
4. Shear/Dry air are typically the major limiting factors during the early/late parts of the season in the Atlantic Basin - though higher SSTs do play a role



165. GBlet
9:49 PM GMT on December 17, 2008
Did anyone catch Sci Fi last night? Some scientist believe that the crystal skulls contain the info to stop the damage that we have done to the planet.
Member Since: September 13, 2007 Posts: 0 Comments: 435
164. OSUWXGUY
9:44 PM GMT on December 17, 2008
Hi All! Been a while since I was on...

The reason why the minimal threshold for storm formation might increase from 26.5°C to 28.5°C is as follows:

Warming Ocean -> More Deep Convection & Latent Heat Release Aloft -> Warming of the Upper Atmosphere

Currently 26.5°C and higher SSTs generally lead to unstable conditions that foster deep convection. However, if the upper atmosphere warms the ocean would have to warm as well to maintain instability.

It all has to do with environment lapse rates...

Quoting streamtracker:
Jeff,


Papers by Henderson-Sellers et al. (1998) and Knutson et al. (2008) theorize that as SSTs warm, the lowest temperature at which tropical storms can form will also increase. The current minimum temperature of 26.5°C (80°F) may increase to 28.5°C for a 2°C warming of Atlantic SSTs.


Why would that be so? Increase in sheer?

Thanks for informative post.
162. hurristat
9:40 PM GMT on December 17, 2008
Quoting conchygirl:
Now you've gone and done it, you will be the newest addition to the Poof list (Ignore). LOL


He was in post 108 or something like that. I have one person on my poof list: 15hurricanes.
Member Since: October 15, 2008 Posts: 11 Comments: 2312
161. AstroHurricane001
9:29 PM GMT on December 17, 2008
Quoting P451:


I don't... and I think it's obvious we're in a period of warming. However I don't know if anyone has a clear answer on how much and for how long?

NW Passage: Was it not navigated in the early 1900s? It's a "fabled" water route and it did not get that way by always being frozen up could it?

We all know the climate has at any given time in the past been much colder and much warmer than it is today.

The bigger questions are how much is it warming, how much of an effect are we having on that warming, and how far does it continue before a cycle of cooling begins?

With the data that we're trying to make a case with I don't think we can have a factual answer. Again, given just the one ocean temperature image in this blog's head, we all know there weren't satellites and buoy's recording ocean temperatures over such large areas with great accuracy going back to 1950 so how can that map be fact? It can't. It's theory.

That's what I question. Not if we're warming but how much.

As to prevention it's simply not possible when you have countries such as India, China, and Russia refusing to curb their emissions in any way. It will also take decades at the very least to develop non-fossil fuels that everyone can afford and transition over to.

So I don't really think there's a viable answer to prevention any time soon.


As it stands now, GW cannot be stopped. We can try to reduce its impact, but not stop it entirely. Although it has been warmer than it is predicted to be, it's about the rate of warming, not just how much it warms by. When a six-degree warming occured in the Permian-Triassic, 90% of all life went extinct. This amount of warming is possible within the next 100 years. The extra fast warming is releasing feedback mechanisms, which is making it accelerate even faster. We've been in a stable climate for the past 10,000 years, and that's all about to change. Although climatic stability is rate in Earth's pre-Holocene period, the sudden reversal of the current stability, as a fellow Wikipedian puts it, "will be seen as nothing short of apocalyptic".
Member Since: August 30, 2008 Posts: 8 Comments: 2835
159. MissNadia
9:07 PM GMT on December 17, 2008
Quoting vortfix:
Here's an editorial commentary from Investor's Business Daily:




The Day After (Inauguration)



INVESTOR'S BUSINESS DAILY

Posted 12/15/2008

Climate Change: The Associated Press warns that the new administration won't have much time to save the planet from a global warming apocalypse. Never mind that the "ticking time bomb" is a

I put this up last night and MichaeSTL called it "Totally Insane" LOL
Member Since: July 27, 2008 Posts: 0 Comments: 3003
158. AstroHurricane001
9:05 PM GMT on December 17, 2008
Well, strong winds are still possible here Sunday night, but probably not as strong as my previous prediction (120 km/h), but UKM is still going crazy. It appears we could have about 48 cm (19 in) by Christmas! GFS is suggesting possibly 80 cm by New Years! Of course, the extra snow could compact. It looks like the end of the year could be crazy weatherwise. Time to make a 12-ft snowman! LOL.
Member Since: August 30, 2008 Posts: 8 Comments: 2835

Viewing: 207 - 157

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8Blog Index

Top of Page

About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.