Extreme events of 2011: climate change a major factor in some, but not all

By: Dr. Jeff Masters , 1:54 PM GMT on July 11, 2012

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The science of quantifying how climate change changes the odds of extreme weather events like droughts and floods took a major step forward Tuesday with the publication of NOAA's annual summary of the past year's weather. The 2011 State of the Climate report contains a separate peer-reviewed article published in the July issue of the Bulletin of the American Meteorological Society titled, Explaining Extreme Events of 2011 From a Climate Perspective. In the paper, a group of scientists led by Peter Stott of the Met Office Centre in the United Kingdom looked at how climate change may have changed the odds of occurrence of some of 2011's notable weather extremes. These kinds of attribution studies require huge amounts of computer time and take many months to do, but the scientists plan to start making this a regular part of the annual NOAA State of the Climate report. Some of their findings for 2011:

- Determining the causes of extreme events remains difficult. While scientists cannot trace specific events to climate change with absolute certainty, new and continued research help scientists understand how the probability of extreme events change in response to global warming.

- La Niña-related heat waves, like that experienced in Texas in 2011, are now 20 times more likely to occur during La Niña years today than La Niña years fifty years ago.

- The UK experienced a very warm November 2011 and a very cold December 2010. In analyzing these two very different events, UK scientists uncovered interesting changes in the odds. Cold Decembers are now half as likely to occur now versus fifty years ago, whereas warm Novembers are now 62 times more likely.

- The devastating 2011 floods in Thailand caused an estimated $45 billion in damage, making it the world's most expensive river flooding disaster in history. The study found, however, that the amount of rain that fell in the catchment area was not very unusual, and that other factors such as human-caused changes to the flood plain and the movement of more people into flood-prone areas were more important in causing the disaster. "Climate change cannot be shown to have played any role in this event," the study concluded, but warned that climate models predict an increase in the probability of extreme precipitation events in the future in the region.

- The deadly drought in East Africa, which killed tens of thousands of people in 2011, was made more likely by warming waters in the Indian Ocean and Western Pacific. While the scientists did not specifically tie the warming of these waters to human-caused global warming, they noted that climate models predict continued warming of these waters in the coming decades, and this will likely "contribute to more frequent East African droughts during the spring and summer."


Figure 1. An SH-60F Sea Hawk helicopter assigned to Helicopter Anti-Submarine Squadron (HS) 14, flies around the Bangkok area with members of the humanitarian assessment survey team and the Royal Thai Armed Forces to assess the damage caused by the 2011 floods. Image credit: Petty Officer 1st Class Jennifer Villalovos.

Weather on steroids
One interesting aspect of the paper was the scientists' use of the baseball player-steroids analogy to help explain how climate change can increase the odds of extreme weather: "One analogy of the effects of climate change on extreme weather is with a baseball player (or to choose another sport, a cricketer) who starts taking steroids and afterwards hits on average 20% more home runs (or sixes) in a season than he did before (Meehl 2012). For any one of his home runs (sixes) during the years the player was taking steroids, you would not know for sure whether it was caused by steroids or not. But you might be able to attribute his increased number to the steroids. And given that steroids have resulted in a 20% increased chance that any particular swing of the player’s bat results in a home run (or a six), you would be able to make an attribution statement that, all other things being equal, steroid use had increased the probability of that particular occurrence by 20%. The job of the attribution assessment is to distinguish the effects of anthropogenic climate change or some other external factor (steroids in the sporting analogy) from natural variability (e.g., in the baseball analogy, the player’s natural ability to hit home runs or the configuration of a particular stadium)."



Video 1. National Center for Atmospheric Research scientist Dr. Jerry Meehl explains how climate change's impact on extreme weather is like how steroids affect a baseball player.

Jeff Masters

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Quoting nofailsafe:


Ruh roh.

Indeed. If that verifies, rain of that magnitude during a morning commute will cause problems, I guarantee that.
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Quoting 1900hurricane:
The 02Z run of the HRRR puts Harris County under the gauntlet:

Link



Ruh roh.
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INVERTED TROUGH APPROACHING THE FLORIDA STRAITS LATE SATURDAY...
PREFERENCE: 12Z ECMWF/00Z CANADIAN/00Z GFS COMPROMISE WITH
AVERAGE CONFIDENCE

THE GUIDANCE AGREES REGARDING THIS SYSTEMS RETROGRESSION. THE
ONLY PIECES OF GUIDANCE NOT WEAKER THAN THE 18Z GEFS/12Z ECMWF
ENSEMBLE MEANS ARE THE 12Z ECMWF/00Z CANADIAN WITH THE 00Z GFS AN
INTERMEDIATE SOLUTION. THE 00Z NAM/00Z UKMET ARE THE WEAKEST. A
12Z ECMWF/00Z CANADIAN/00Z GFS COMPROMISE WILL BE PREFERRED HERE
WITH ONLY AVERAGE CONFIDENCE AS THE GUIDANCE SOMETIMES SHOWS DAY
TO DAY CHANGES WITH UPPER LEVEL SYSTEMS/TUTT CELLS RETROGRADING
THROUGH THE SUBTROPICS.

WEAK SHORTWAVE MOVING NORTHWEST THROUGH THE GULF OF MEXICO...
PREFERENCE: NON-NAM COMPROMISE WITH AVERAGE CONFIDENCE

THE 00Z NAM IS THE DEEPEST WITH THIS SYSTEM /BRIEFLY MATCHED BY
THE 00Z UKMET DURING THE FIRST 24 HOURS OF THE FORECAST/...AND
INDUCES A NOTICEABLE SURFACE LOW WITH IT WHICH DRIFTS TOWARDS THE
CENTRAL GULF COAST NOT SEEN ON THE OTHER DETERMINISTIC GUIDANCE.
ONLY FIVE OF THE 90 12Z GLOBAL ENSEMBLE MEMBERS SHOW THIS TYPE OF
SOLUTION...AND WITHIN THE 21Z SREF ABOUT EIGHT MEMBERS SHOW THIS
SYSTEMS EXISTENCE...WITH THE ETA MEMBERS SHOWING THEIR
CHARACTERISTIC SOUTHERN TRACK WHILE THE WRF MEMBERS STEER IT
TOWARDS THE GULF COAST. WHILE THERE WAS A SOMEWHAT IMPRESSIVE
CONVECTIVE BLOW UP WITH THIS SYSTEM WEDNESDAY MORNING...AND THE
UPPER LEVEL ENVIRONMENT OVER THE AREA DOES NOT LOOK PARTICULARLY
HOSTILE...THERE IS NOT ENOUGH SUPPORT AMONGST THE GLOBAL
DETERMINISTIC AND ENSEMBLE GUIDANCE FOR THE NAMS STRONGER
DEPICTION AT THIS TIME.
THE PREFERENCE IS FOR A NON-NAM SOLUTION
HERE WITH AVERAGE CONFIDENCE.

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Looks like it's not too far away from a TD,maybe by morning.
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Quoting redwagon:

Indulge a 2006 noob, what is this L over FL everybody is talking about? Is is currently theoretical?

Link
Scroll back in time by clicking the -3hr button a few times in the upper-left. The "low" we've been talking about is a mid-level low....shown by green-ish and orange-ish shadings on that 850 mb CIMSS product. It was better defined over south Florida a few hours ago than it is now. I'll have to admit that Kori is on to something when he says the mid-level low was weakening...as the amount of 850 mb CIMSS vorticity over Florida has reduced.

But we've still got the surface tropical wave following behind about to enter the picture. And the upper winds are favorable...Kori also said upper winds are favorable...so I am still wary of this area...
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Quoting HurricaneHunterJoe:


12Z EURO has a little bit wind in eastern gulf 18-20 kts at 850mb. When does the 00Z come out?

In an hour or two. I'm not exactly sure, I'm usually sleeping at this point. :P It's in the very near future though.
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East Pacific Tropical Weather Outlook


000
ABPZ20 KNHC 120532
TWOEP

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
1100 PM PDT WED JUL 11 2012

FOR THE EASTERN NORTH PACIFIC...EAST OF 140 DEGREES WEST LONGITUDE..

THE NATIONAL HURRICANE CENTER IS ISSUING ADVISORIES ON HURRICANE
EMILIA...LOCATED ABOUT 810 MILES SOUTHWEST OF THE SOUTHERN TIP OF
BAJA CALIFORNIA.

A WELL-DEFINED LOW PRESSURE SYSTEM LOCATED ABOUT 450 MILES
SOUTH-SOUTHWEST OF MANZANILLO MEXICO CONTINUES TO SHOW SIGNS OF
ORGANIZATION. THUNDERSTORM ACTIVITY HAS INCREASED NEAR THE CENTER
OF CIRCULATION OVER THE PAST SEVERAL HOURS...AND IF THIS
DEVELOPMENT TREND CONTINUES...THEN A TROPICAL DEPRESSION COULD FORM
WITHIN THE NEXT 6 TO 12 HOURS. THIS SYSTEM HAS A HIGH CHANCE...
NEAR 100 PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE NEXT
48 HOURS AS IT MOVES WEST-NORTHWESTWARD AT ABOUT 10 MPH.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER STEWART
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12Z EURO has a little bit wind in eastern gulf 18-20 kts at 850mb. When does the 00Z come out?
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Quoting NCHurricane2009:

Your not the only one with that opinion...I've got that same assessment too. Earlier...Kori was not so gung-ho about it (he cited that the vorticity was weakening). I think that with the favorable upper ridge overhead...combined with the Bahamas upper low and Gulf upper low as enhanced outflow channels...even a subtle low pressure vorticity can spin up quickly.


LOL...that's a heck of an acroynm...what does it stand for?

Indulge a 2006 noob, what is this L over FL everybody is talking about? Is is currently theoretical?
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Quoting NCHurricane2009:

Your not the only one with that opinion...I've got that same assessment too. Earlier...Kori was not so gung-ho about it (he cited that the vorticity was weakening). I think that with the favorable upper ridge overhead...combined with the Bahamas upper low and Gulf upper low as enhanced outflow channels...even a subtle low pressure vorticity can spin up quickly.


LOL...that's a heck of an acroynm...what does it stand for?

High Resolution Rapid Refresh (it runs one an hour).
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Quoting KoritheMan:


The mid-level vorticity has weakened, for one thing. In addition, wind reports from the Gulf, western Atlantic, and the Florida peninsula, suggest nothing remotely resembling a cyclonic circulation. The only thing this system has going for it is the very favorable diffluent upper pattern forecast by the GFS.
,IF it goes west over the next 12-18hrs,we could see development with the quite favorable UL conditions over the eastern 1/2 of the gom,the aoi has been drifting northerly over the last 12-18hrs.If it goes west better than 50% chance of invest in next 48hrs IMO
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Quoting stillwaiting:
Possible we could get a invest sometime over the next 48hrs IF the vorticity over central florida moves west into the gom IMO.

Your not the only one with that opinion...I've got that same assessment too. Earlier...Kori was not so gung-ho about it (he cited that the vorticity was weakening). I think that with the favorable upper ridge overhead...combined with the Bahamas upper low and Gulf upper low as enhanced outflow channels...even a subtle low pressure vorticity can spin up quickly.

Quoting 1900hurricane:
The 02Z run of the HRRR puts Harris County under the gauntlet:

Link


LOL...that's a heck of an acroynm...what does it stand for?
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00Z and 01Z HRRR runs do about the same thing. Things could get interesting...



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Possible we could get a invest sometime over the next 48hrs IF the vorticity over central florida moves west into the gom IMO.
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The 02Z run of the HRRR puts Harris County under the gauntlet:

Link

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Quoting VAbeachhurricanes:


LOL, I was sorta... but its been a topic of discussion for the past week. Go meet some girls! They really arent that hard to talk to I promise.

I've done that...as comment 1247 said...but I don't know which way to go with who......
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Quoting AllBoardedUp:
Grother, that was too funny.



Besides being Guru Grothar, he is also the King of Comedy!!
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Quoting ProgressivePulse:
Backs off for a couple days then BAMM. That is some serious heat. 216GFS


The heat is literally off the scale. And oddly, for once TX isn't at the nexus of it.
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I suspect storms may fire along the current line of weak echos north of Houston in an hour or two.

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(click to enlarge)

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Quoting NCHurricane2009:

If you are referring to comment 1247...you need to up the age a bit...just past my teenage years...LOL


LOL, I was sorta... but its been a topic of discussion for the past week. Go meet some girls! They really arent that hard to talk to I promise.
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1257. Skyepony (Mod)
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Quoting nigel20:
Emilia



Thats not Daniel magically reinvigorated?
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1255. geepy86
the heat is just relentless
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1254. KEEPEROFTHEGATE (Mod)
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Waiting for storms to flare up again here in the HGX CWA like last night. They caused a few problems this morning:





Moisture axis is a little further north tonight. Maybe that means I'll get in on some of the action this go around?



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Quoting VAbeachhurricanes:
God this place is turning into a depressed single teenage boy blog.

If you are referring to comment 1247...you need to up the age a bit...just past my teenage years...LOL
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Backs off for a couple days then BAMM. That is some serious heat. 216GFS

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God this place is turning into a depressed single teenage boy blog.
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Strike....

I mean

out...
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I'm out. Later all.

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Quoting WxGeekVA:
May as well clear this up, it's as good as of a time as any... It's not the same girl from last weekend, but a different one. You could say now she's my ex-ex-girlfriend :P Pretty much long story short, after the last breakup my friend who was my ex had some deep conversations which led to some truths which led to us getting back together. :-)

TL;dr got back with my ex after stuff happened :)

And I'm really happy about it too :-D

Glad things are working for you....

For me...merely at the online phase with someone (and NO she aint on this blog LOL)...but she is mysteriously gettin harder to reach each day. This to forget about a 1st someone who probably never noticed me anyway. Add to that...now I saw a 3rd someone at a dinner party the other day (but I don't know what she thinks about me)...but we talked pretty well...

In short...don't know what to do....sigh......sorry for that but not in the best mood right now...
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Out for now.
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1244. nigel20
Have a good night everyone!

Emilia

98E
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Quoting NCHurricane2009:

Interesting...what are your thoughts on what makes this a low probability event?


The mid-level vorticity has weakened, for one thing. In addition, wind reports from the Gulf, western Atlantic, and the Florida peninsula, suggest nothing remotely resembling a cyclonic circulation. The only thing this system has going for it is the very favorable diffluent upper pattern forecast by the GFS.
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1240. KEEPEROFTHEGATE (Mod)
Quoting Grothar:


I don't speak haiku.

But if I did my response would be:

Her winds are strong and her eye is hallow
but your analysis seems a little shallow.


no more shallow then yourself
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1238. geepy86
Quoting BobWallace:


After I posted my questions I realized that there could very well be people who have not been informed that the theory of evolution does not state that man evolved from ape.

Someone cloistered in a religious community or home-schooled by fundamentalist parents might well have been misinformed about the theory of evolution. Seems like that is what I was told when growing up. In the South. A long time ago.

So I'll change my question a bit. Is it possible that anyone who has been out in the "real" world and spent time on the internet has not heard that the theory of evolution points out common ancestry and not that man evolved from ape?

Do you think that anyone on this site would read me stating "The Theory of Evolution does not claim that man evolved from ape" and go "Wow! First time that I've heard that."?

my take on a theory, it is what it is....
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Another heat wave coming on the GFS.
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Quoting WxGeekVA:
May as well clear this up, it's as good as of a time as any... It's not the same girl from last weekend, but a different one. You could say now she's my ex-ex-girlfriend :P Pretty much long story short, after the last breakup my friend who was my ex had some deep conversations which led to some truths which led to us getting back together. :-)

TL;dr got back with my ex after stuff happened :)

And I'm really happy about it too :-D


Nice. Good luck!
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Quoting KoritheMan:


10% at best.

Interesting...what are your thoughts on what makes this a low probability event?
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1234. Grothar
Quoting MrMixon:
Perhaps Grothar is onto something with the "threat to the southwest" analysis for 98E. We've had some huge fires in the Four Corners states this year. A massive precipitation event would reduce fire danger, but could be messy in post-burn areas. Wikipedia has a whole page for NEW MEXICO HURRICANES. Who knew?





Thanks, MrMixon. I said it before the models came out earlier today. It looks like 98E wants to slide behind the ridge and pull a Northy. I don't know if it will be stronger than Emilia, but it looks like it could be bigger in size right now.
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Quoting nigel20:

Hey sunline. It's was pretty dry and hazy across most of Jamaica today...it seems as if you had similar weather conditions as well.


The same here... SAL was high..

Only a small shower in my area
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Good lord, lol. 144 GFS

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Not sure what the fact that all civilizations have a creation story really means other than that we desperately do not want to be alone and that we have one of the most equally amazing and dangerous powers in existence, imagination.

We see the universe, we are aware of our existence within it, and want it to make sense. That doesn't mean it will oblige.


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

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