Groundhogs, tornadoes, hurricanes, and the new IPCC report

By: Dr. Jeff Masters , 5:44 PM GMT on February 02, 2007

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Punxsutawney Phil, the fearless groundhog forecaster of Punxsutawney, Pennsylvania, did not see his shadow this morning, signifying that winter will come to an early close. Phil can expect this to be a common occurrence in the coming millennia, according to the newly released Summary of Policy Makers issued today by the United Nations sponsored Intergovernmental Panel on Climate Change (IPCC). In their fourth report since 1990, the IPCC offers its strongest language yet that Earth's climate is warming and humans are largely responsible:

"Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global mean sea level."

"Most of the observed increase in globally averaged temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations. Discernible human influences now extend to other aspects of climate, including ocean warming, continental-average temperatures, temperature extremes, and wind patterns."


Earth has warmed, sea levels have begun to rise at an accelerated rate, and Northern Hemisphere snow cover has decreased substantially over the past 150 years (Figure 1). These facts are not controversial. The big change from the IPCC's last report, in 2001, is the level of confidence on if humans are to blame. In that report, human-emitted (anthropogenic) greenhouse gases were estimated to be likely responsible for Earth's temperature increase (67-90% chance), while the new report says it is very likely (greater than 90% chance).


Figure 1. Observed changes in (a) global average surface temperature; (b) global average sea level rise from tide gauge (blue) and satellite (red) data and (c) Northern Hemisphere snow cover for March-April. All changes are relative to corresponding averages for the period 1961-1990. Smoothed curves represent decadal averaged values while circles show yearly values. The shaded areas are the uncertainty intervals estimated from a comprehensive analysis of known uncertainties (a and b) and from the time series (c). Image credit: FIGURE SPM-3 from the Summary of Policy Makers from the 2007 Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report.

Predicted temperature rise
The 2007 IPCC report predicts temperature rises of 1.1 - 6.4°C (2 - 11.5°F) by 2100. This is a wider range than the 1.4 - 5.8°C increase given in the 2001 report. However, the 2007 report goes on to say that their best estimate for temperature rise is 1.8 - 4°C (3.2 - 7.1°F).

Predicted sea level rise
The 2007 report predicts that sea level rise by 2100 will be .6 - 1.9 feet (18 - 58 cm). An additional 3.9 to 7.8 inches (10 to 20 cm) are possible if the recent surprising melting of polar ice sheets continues. The 2001 IPCC report gave a much wider range for sea level rise: .3 - 2.9 feet (8 - 88 cm).

What does the IPCC say about stronger hurricanes?
The IPCC did a good job with their treatment of how global warming is affecting hurricanes. Here's their carefully worded statement on the observed changes:

There is observational evidence for an increase of intense tropical cyclone activity in the North Atlantic since about 1970, correlated with increases of tropical sea surface temperatures. There are also suggestions of increased intense tropical cyclone activity in some other regions where concerns over data quality are greater. Multi-decadal variability and the quality of the tropical cyclone records prior to routine satellite observations in about 1970 complicate the detection of long-term trends in tropical cyclone activity. There is no clear trend in the annual numbers of tropical cyclones.


Later in the report, there is a table that shows that there has likely (>66% chance) been an increase in strong hurricanes since 1970 in some regions. It isn't mentioned, but the Atlantic is the region where this increase has been most notable. Also in that table is the assertion that it is more likely than not (>50% chance) that there has been a human contribution to this trend. This statement was leaked to the press yesterday, and resulted in speculation that the IPCC concluded that stronger hurricanes like Katrina were due to human-caused global warming. However, there is a footnote on the table, which wasn't part of yesterday's leaked press reports: "Magnitude of anthropogenic contributions not assessed. Attribution for these phenomena based on expert judgment rather than formal attribution studies."

In other words, the link between stronger hurricanes and global warming is a theory (expert judgment) and is not a conclusion of the IPCC. It is reasonable to theorize that some human contribution is responsible for the increase in strong hurricanes in the Atlantic since 1970, since this increase does correlate so well with the observed increase in sea surface temperatures. However, as mentioned in the earlier paragraph, it is difficult to make a strong statement saying that global warming is responsible for stronger hurricanes, due to the high natural variability of these storms and the poor observational record: "multi-decadal variability and the quality of the tropical cyclone records prior to routine satellite observations in about 1970 complicate the detection of long-term trends in tropical cyclone activity." The IPCC table is confusing, and I believe it was a mistake to assign a probability of how likely a human contribution to hurricane intensity has been. There is not enough good science to make a sound judgment, and this section of the table should have been left blank.

Finally, the IPCC projection for how climate change will affect hurricanes in the future is pretty non-controversial, since they don't attach any numbers saying how large these effects will be:

Based on a range of models, it is likely that future tropical cyclones (typhoons and hurricanes) will become more intense, with larger peak wind speeds and more heavy precipitation associated with ongoing increases of tropical SSTs. There is less confidence in projections of a global decrease in numbers of tropical cyclones. The apparent increase in the proportion of very intense storms since 1970 in some regions is much larger than simulated by current models for that period.


Overall, the IPCC statements on hurricanes are very similar to those adopted by the World Meteorological Organization (WMO) in December, as I discussed in an earlier blog. The WMO report concluded, "Though there is evidence both for and against the existence of a detectable anthropogenic signal in the tropical cyclone climate record to date, no firm conclusion can be made on this point."

What does the IPCC say about stronger tornadoes?
In the wake of today's devastating tornadoes that swept through Central Florida, killing at least 19 people, it is important to ask how climate change might be affecting tornadoes. Well, we don't have good enough long-term observational records of tornadoes to tell, and climate models don't shed any light on the issue, either. Here's the relevant statement in the 2007 IPCC report:

There is insufficient evidence to determine whether trends exist in small scale phenomena such as tornadoes, hail, lighting, and dust storms.

I'll have much more on the IPCC report next week, as will Dr. Ricky Rood of the University of Michigan, who will be writing in our new featured Climate Change blog. Who knows, if we want to collect a quick $10,000, we can "thoughtfully explore the limitations of climate model outputs", as explained in an article posted by the UK Guardian today.


Jeff Masters

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141. HIEXPRESS
12:01 AM EST on February 04, 2007
No tornadoes for us S of Deland this time. The last one was 2003, only F0, (Still EF0). EF3/150 in Lady Lake was spot on. WV from 1998 Florida Tornadoes:
WV
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140. Skyepony (Mod)
4:51 AM GMT on February 04, 2007
PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE MELBOURNE FL
615 PM EST SAT FEB 3 2007

...THE LATEST FIELD REPORT FROM BOTH THE LAKE COUNTY AND VOLUSIA
COUNTY SURVEY TEAMS REGARDING YESTERDAYS KILLER TORNADO EVENT...

...DAMAGE SURVEYS NOW INDICATE THAT AT LEAST THREE TORNADOES ARE
RESPONSIBLE FOR THE DEATH AND DESTRUCTION...

A PRELIMINARY STORM SURVEY CONTINUES IN BOTH LAKE AND VOLUSIA
COUNTIES WHERE EXPERT NATIONAL WEATHER SERVICE SURVEY TEAMS ARE
ASSESSING THE DEVASTATION. THE LATEST REPORT FROM THE LAKE COUNTY
TEAM IS THAT THE TORNADO WHICH RIPPED THROUGH THE VILLAGES AND LADY
LAKE WAS HIGH END EF-3 WITH WINDS OF 155 TO 160 MPH. THE FIRST OF
THREE TORNADOES INITIALLY TOUCHED DOWN IN SUMTER COUNTY NEAR
WILDWOOD AND THE VILLAGES AND THEN CROSSED OVER INTO LAKE COUNTY TO
STRIKE LADY LAKE WHERE THE FIRST EVENT FATALITIES OCCURRED.
CURRENTLY...THERE ARE 7 KNOWN FATALITIES IN THE LADY LAKE AREA.

THE VILLAGES/LADY LAKE TORNADO...TORNADO NUMBER 1...HAS BEEN
CLASSIFIED AS AN EF-3 TORNADO WHICH CAUSED DAMAGE TO STRUCTURES
WHERE MOST WALLS COLLAPSED EXCEPT FOR THEIR INTERIOR ROOMS...AS WELL
AS LARGE TREES BECAME DEBARKED WITH ONLY THE STUBS OF THE LARGEST
BRANCHES REMAINING. MOBILE HOMES WERE COMPLETELY DESTROYED. THIS
TORNADO WAS ONE-QUARTER MILE WIDE DURING ITS MOST FIERCE MOMENTS.
THE TORNADO LIFTED EAST OF LADY LAKE WITH AN APPROXIMATE PATH LENGTH
OF ABOUT 15 MILES. THE TORNADO STRUCK LADY LAKE AT 320 AM.
AGAIN...7 KNOWN FATALITIES ARE ASSOCIATED WITH THIS TORNADO.

THE LAKE MACK/DELAND TORNADO...TORNADO NUMBER 2...WAS ALSO HIGH END
EF-3 WITH WINDS OF 160 TO 165 MPH. IT WAS ALSO ONE-QUARTER MILE
WIDE. IT RESULTED IN COMPLETE DESTRUCTION OF MOBILE HOMES...AND
CAUSED LARGE TREES TO BECOME DEBARKED. THE ESTIMATED TORNADO WINDS
NEAR LAKE MACK PEAKED AT 165 MPH WHICH RESULTED IN 10
FATALITIES...AND 150 TO 155 MPH WINDS AT FOREST DRIVE AND STATE ROAD
44 WHICH RESULTED IN 3 MORE FATALITIES. A TOTAL OF 13 KNOWN
FATALITIES OCCURRED WITH THIS DEADLY TORNADO. THE TORNADO CONTINUED
ACROSS THE COUNTY LINE NEAR HONTOON ISLAND...CROSSING INTO VOLUSIA
COUNTY...AND STRIKING DELAND AS A HIGH END EF-2 TORNADO WITH WINDS
OF 130 TO 135 MPH AS REPORTED BY THE VOLUSIA COUNTY TEAM. IT WAS
ONE-EIGHTH MILE WIDE AND LIFTED EAST OF INTERSTATE 4 NEAR THE
VOLUSIA COUNTY FAIRGROUNDS. THE PATH LENGTH WAS APPROXIMATELY 22
MILES. THE TORNADO STRUCK LAKE MACK AT 348 AM AND DELAND AT 402 AM.

THE NEW SMYRNA BEACH/PONCE INLET TORNADO...TORNADO NUMBER THREE...
HAS BEEN INITIALLY RATED AS AN EF-1 TORNADO WITH WINDS OF 100 TO 105
MPH. THE TORNADO UPLIFTED ROOFS ON MANY STRUCTURES...CAUSING A
SIGNIFICANT LOSS OF ROOFING MATERIAL...THE COLLAPSE OF CHIMNEYS...
AND COLLAPSING GARAGE DOORS. ADDITIONAL DAMAGE OCCURRED TO PORCHES
AND CAR PORTS. THIS TORNADO TOUCHED DOWN JUST EAST OF INTERSTATE 95
NORTH OF HIGHWAY 44 IN NEW SMYRNA BEACH AND MOVED THROUGH PONCE
INLET. THE PATH LENGTH IS ABOUT 5 MILES. THE TORNADO STRUCK PONCE
INLET AT 427 AM.

THIS STATEMENT IS ONLY AN INITIAL REPORTING FROM THE SURVEY TEAMS.
IN THE COMING DAYS...CONSIDERABLE EFFORT WILL BE INVESTED TO ENSURE
THAT THIS HISTORICAL EVENT IS ACCURATELY DOCUMENTED.

A WORD ABOUT THE NEW ENHANCED FUJITA (EF) TORNADO SCALE...THE
EF-SCALE WAS DEVELOPED TO BETTER ASSESS WIND SPEEDS ASSOCIATED WITH
A WIDE VARIETY OF STRUCTURAL DAMAGE...FROM SINGLE-WIDE MOBILE HOMES
TO INDUSTRIAL BUILDINGS TO FRAMED ONE OR TWO FAMILY HOMES...AND MANY
MORE. THIS SCALE IS CONSIDERED A DAMAGE SCALE...WHEREAS THE
TRADITIONAL FUJITA SCALE (F-SCALE) WAS MORE OF A WIND SPEED SCALE.

FOR MORE INFORMATION ON THE NEW EF-SCALE...PLEASE SEE THE FOLLOWING
WEBSITE:

HTTP://WWW.SPC.NOAA.GOV/FSCALE

$$

DWS/NWS MELBOURNE FL


Member Since: August 10, 2005 Posts: 300 Comments: 41218
139. hurricane23
11:34 PM EST on February 03, 2007
Tropical cyclone 11P now at 35kts forcasted to intensify to 50kts in the coming days.

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Track Forcast for 11P
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Member Since: May 14, 2006 Posts: 8 Comments: 13849
137. 1900hurricane
8:17 PM CST on February 03, 2007
Dora doesn't look to healthy now...





Member Since: August 2, 2006 Posts: 47 Comments: 11908
135. pottery
7:33 PM AST on February 03, 2007
Hello. Where is everyboddy ????
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134. weatherboykris
8:18 PM GMT on February 03, 2007
Just the subtropical jet.
Member Since: December 9, 2006 Posts: 125 Comments: 11346
130. Inyo
6:56 PM GMT on February 03, 2007
El Nino didnt do what it was 'supposed' to, what makes you think La Nina will either? Everyone will predict 23423424 hurricanes again.
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129. Thunderstorm2
6:05 PM GMT on February 03, 2007
Hi again everyone
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127. marky48
5:58 PM GMT on February 03, 2007
Warm Front novel about global warming in contest and needs votes. Dr. Masters proofed some of it but I can't get past the firewall now.
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126. hurricane23
12:31 PM EST on February 03, 2007
Well atleast it was nothing life threating.Never go outside during severe weather that was not very smart on your behalf.Talk to later Going to have lunch with wife.
Member Since: May 14, 2006 Posts: 8 Comments: 13849
125. Thunderstorm2
5:29 PM GMT on February 03, 2007
i went outside in it and got hurt
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124. hurricane23
12:28 PM EST on February 03, 2007
Glad your doing ok after that tornado outbreak that went on up there.Get yourself a weather radio it might very well save you and familys life next time severe weather threatens your area.I own one of my own.Hope u have great day.




Member Since: May 14, 2006 Posts: 8 Comments: 13849
123. Thunderstorm2
5:21 PM GMT on February 03, 2007
Its already dropped about 1.25 inches on me already
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122. hurricane23
12:18 PM EST on February 03, 2007
Not a biggie scattered rain showers up there which will likely approach me later.

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121. Thunderstorm2
5:11 PM GMT on February 03, 2007
This iss what im dealing with now Link 23
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120. hurricane23
12:09 PM EST on February 03, 2007
Posted By: clwstmchasr at 11:53 AM EST on February 03, 2007.

Thanks for the update on El Nino. A La Nina season worries us here in Florida. After a quiet 2006 hurricane season '07 is looking to turn active again.

I also live in florida in the miami area and i will say that having la nina conditions present does not mean florida will be at greater risk this season.It all will determine on how the steering currents set up.Having la nina in place will no doupt create a more favorable enviroment for tropical storm formation but we could also end up with a year similar to 1995 when most activity got turned away into the atlantic.In any given season in my opinion south florida is going to have a few threats and we just have to be ready for that possiblity.Overall alot of unanswered questions we still be present for the next couple of months until we get closer to cane season.No worries for now. Adrian

PS!Iam enjoying this summertime warmth across the area with highs 85-87 degress.
Member Since: May 14, 2006 Posts: 8 Comments: 13849
119. hurricane23
11:56 AM EST on February 03, 2007
Cloud cover will definately be on the increase across south florida during the day today.

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Animated florida radar

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Member Since: May 14, 2006 Posts: 8 Comments: 13849
117. hurricane23
11:40 AM EST on February 03, 2007
Incredible visible view of Dora!

Member Since: May 14, 2006 Posts: 8 Comments: 13849
115. ryang
12:34 PM AST on February 03, 2007
Dora's forecast track.

track
Member Since: August 25, 2006 Posts: 329 Comments: 12456
114. hurricane23
11:29 AM EST on February 03, 2007
Good morning,

Its really incredible how fast those cool anomalies are expanding.We could be seeing negative SST anomalies that support La Nina conditions in the next week or two.

Member Since: May 14, 2006 Posts: 8 Comments: 13849
113. ryang
12:31 PM AST on February 03, 2007
Hey TS2.
Member Since: August 25, 2006 Posts: 329 Comments: 12456
112. Thunderstorm2
4:28 PM GMT on February 03, 2007
Hope El Nino left flowers
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111. Thunderstorm2
4:25 PM GMT on February 03, 2007
Hi Ryan
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110. ryang
12:23 PM AST on February 03, 2007
Yes it is gone.
Member Since: August 25, 2006 Posts: 329 Comments: 12456
108. Thunderstorm2
4:21 PM GMT on February 03, 2007
Well El Nino is hanging on by a thread
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107. weatherboykris
4:22 PM GMT on February 03, 2007
It's already gone.We are headed toward La Nina.
Member Since: December 9, 2006 Posts: 125 Comments: 11346
105. MargieKieper
8:41 AM CST on February 03, 2007
"Owl Chick Gets Warm Bed at Zoo:"

Mild weather in early winter fooled a pair of tropical owls into thinking it was mating season and hatching a baby.


Nice pic of the baby owl.
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104. Patrap
7:22 AM CST on February 03, 2007
CIMSS MIMIC "DORA", impressive.. Peak Vmax 115kts.Link
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103. HadesGodWyvern (Mod)
4:41 PM CST on February 03, 2007


135 mph Cat 4 storm
Member Since: May 24, 2006 Posts: 56 Comments: 50409
97. hurricane23
5:13 AM GMT on February 03, 2007
Yes indeed!


Member Since: May 14, 2006 Posts: 8 Comments: 13849
96. hornfan
5:12 AM GMT on February 03, 2007
Good job on your blog weatherboykris.
Member Since: August 26, 2006 Posts: 28 Comments: 7902
95. Skyepony (Mod)
5:07 AM GMT on February 03, 2007
Thanks LowerCal & HGW. So the sun has just come up on Dora.
Member Since: August 10, 2005 Posts: 300 Comments: 41218
94. weatherboykris
4:59 AM GMT on February 03, 2007
My recap is on my blog.On the outbreak of storms.
Member Since: December 9, 2006 Posts: 125 Comments: 11346

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Dr. Masters co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters from 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather

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