Dr. Jeff Masters' WunderBlog

Opinion polls of climate change

By: JeffMasters, 3:04 PM GMT en Enero 28, 2009

According to a 2007 Newsweek poll, 42% of Americans believe that "there is a lot of disagreement among climate scientists about whether human activities are a major cause" of global warming". I posed the same question to members of the wunderground community on Monday, and even higher 56% of them thought so. However, the results of a poll that appears in this week's edition of the journal EOS, Transactions, American Geophysical Union, reveals that the public is misinformed on this issue. Fully 97% of the climate scientists who regularly publish on climate change agreed with the statement, "human activity is a significant contributing factor in changing mean global temperatures".



Figure 1. Response to the question, "Do you think human activity is a significant contributing factor in changing mean global temperatures?" The general public data come from a 2008 Gallup poll (see http://www.gallup.com/poll/1615/Environment.aspx). Image credit: EOS, Transactions, American Geophysical Union.

The anonymous poll was performed in late 2008 by Peter Doran, University of Illinois at Chicago associate professor of earth and environmental sciences, along with former graduate student Maggie Kendall Zimmerman. Doran and Kendall Zimmerman sought the opinion of the most complete list of earth scientists they could find, contacting more than 10,200 experts at universities and government labs around the world listed in the 2007 edition of the American Geological Institute's Directory of Geoscience Departments. The 2-minute, two-question poll had 3146 responses (30.7% of those polled). Approximately 90% of the scientists who responded were from the U.S., and about 90% held a Ph.D. degree. Of these scientists, 5% were climate scientists who published more than 50% of all their peer-reviewed publications in the past five years on the subject of climate change. The authors noted that the survey included participants with well-documented dissenting opinions on global warming theory. Question #1 was, When compared with pre-1800s levels, do you think that mean global temperatures have generally risen, fallen, or remained relatively constant?" About 90% of all the scientists and 97% of the climate scientists said temperatures had risen. Question #2 was, "Do you think human activity is a significant contributing factor in changing mean global temperatures?" About 82% of all the scientists agreed, and 97% (75 of 77) climate scientists agreed. This contrasts with the results of a recent Gallup poll that suggests only 58% of the general public would answer yes. Interestingly, petroleum geologists and meteorologists were among the biggest doubters in the new EOS poll, with only 47 and 64 percent, respectively, believing in human involvement.

In a press release on the study, author Peter Doran commented, "The petroleum geologist response is not too surprising, but the meteorologists' is very interesting," he said. "Most members of the public think meteorologists know climate, but most of them actually study very short-term phenomenon." He was not surprised, however, by the near-unanimous agreement by climate scientists. "They're the ones who study and publish on climate science. So I guess the take-home message is, the more you know about the field of climate science, the more you're likely to believe in global warming and humankind's contribution to it." Doran and Kendall Zimmerman conclude that "the debate on the authenticity of global warming and the role played by human activity is largely nonexistent among those who understand the nuances and scientific basis of long-term climate processes. The challenge, rather, appears to be how to effectively communicate this fact to policy makers and to a public that continues to mistakenly perceive debate among scientists."

Commentary
The scientists most involved in assessing the current state of the climate are the most likely to have the "pulse of the planet"--a deep understanding of how the climate works and where we are headed. If 97% of these scientists believe in significant human impact on the climate, then it is probably so. Why is there such a disparity, then, between what they believe, and what the public and other scientists, such as petroleum geologists, believe? Dr. Ricky Rood has some excellent commentary on this issue in his latest wunderground Climate Change blog, and I offer these three reasons:

1) There are a few good climate scientists (3%) that believe humans are not significantly impacting the climate. One tends to hear the beliefs of this tiny minority a disproportionate amount. This is primarily because the fossil fuel industry pumps millions of dollars into PR campaigns to make sure you hear these dissenting views. That's not to say that these scientists are paid lackeys of the fossil fuel industry--that is not the case. These scientists' point of view happens to coincide with arguments that would protect the profits of the fossil fuel industry, so naturally the industry spends a lot of money making sure you hear these points of view. The fossil fuel industry PR campaigns also emphasize the contrarian views of a handful of non-publishing scientists working for private think tanks, who provide a distorted, non-objective view of climate change science (e.g., the attempt to hide summertime Arctic sea ice loss by quoting irrelevant statistics about wintertime global sea ice). These efforts have been highly successful in casting doubt on what is an overwhelming (though not unanimous) consensus among climate scientists. The fossil fuel industry PR campaigns are similar to the ones run by the cigarette industry to cast doubt on the harmfulness of smoking. "Doubt is our product," a cigarette executive once observed, "since it is the best means of competing with the 'body of fact' that exists in the minds of the general public. It is also the means of establishing a controversy." I recommend a reading of the 2008 book, "Doubt is Their Product", which discusses the many efforts by industry over the years to cast doubt on established scientific facts in order to protect industry profits.

2) The media contributes to the disproportionate coverage of the dissenting views, since one can make a news story more compelling by dramatizing conflict and giving equal weight to both sides.

3) Many people have a deep-seated belief in the relative insignificance of humans on a planetary scale. Geologists, who take the long view of time over geologic history, are particularly prone to this. Indeed, the planet is vast, and we are but tiny ants crawling upon its surface during a brief moment in geologic time. However, when one works regularly with the data, it becomes apparent that human activities are beginning to substantially impact weather and climate. When presented with facts contrary to ones beliefs, a good scientist will check the facts extra thoroughly to verify their validity, but then abandon those beliefs that don't fit the facts. The facts as accepted by 97% of our top climate scientists are that atmosphere is but a relatively thin, fragile layer of volatile gases beginning to show unmistakable changes due to the geometric explosion in human population over recent centuries. Those effects are only now beginning to be detectable, which is why human-caused global warming is so controversial in the public's eye. I predict that twenty years from now, climate change will be so obvious that the controversy regarding human responsibility will be gone.


Figure 2. The atmosphere viewed edge on from space. Tall thunderstorm clouds can be seen on the right side of the image, silhouetted against an orange layer of lower atmospheric gases (the troposphere) back-lit by the sun, just below the horizon. Above this layer is the clear blue of the stratosphere and the blackness of space. Seen from space, one can appreciate the thinness and potential vulnerability of the layer of gases that make up our atmosphere. Image credit: NASA Space Shuttle Flight 6 on 4 April 1983.

How representative is this poll?
The findings of another, more in-depth poll of scientists done in 2007 pretty much agreed with this week's Doran/Zimmerman poll, but were much more interesting. The 2007 poll, conducted by Fergus Brown, Roger Pielke, Sr., and James Annan, attempted to assess whether "a significant set of climate scientists agree or disagree with the perspective of the role of humans within the climate system as reported by the 2007 Intergovernmental Panel on Climate Change's (IPCC) Fourth Assessment Report". Out of the 1807 scientists in 53 countries who were contacted, 140 responded. Almost all respondents (at least 97%) concluded that the "human addition of CO2 into the atmosphere is an important component of the climate system and has contributed to some extent in recent observed global average warming". Among the other findings:

1) No scientists were willing to admit to the statement that global warming is a fabrication and that human activity is not having any significant effect on climate [0%].

2) The largest group of respondents (45-50%) agreed with the 2007 IPCC report.

3) A significant minority (15-20%) concluded that the IPCC overstated the role of the human role in affecting the climate.

4) A significant minority (15-20%) concluded that the IPCC understated the seriousness of the threat from human additions of CO2. Ten of the 140 respondents (7%) took the most pessimistic view that we are "seriously damaging the climate" and face "devastating consequences".

Here's the full text of the poll, which I've also put up on my latest wunderpoll to vote on, if you're a Weather Underground member:

Which one statement most nearly matches your personal opinion about the physical science basis of global warming, as exemplified by the 2007 Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report, Working Group 1 (WG1)? [If your personal opinion falls between two adjacent statements, please mark both]

1. There is no warming; it is a fabrication based on inaccurate/inappropriate measurement. Human activity is not having any significant effect on Climate. The data on which such assumptions are made is so compromised as to be worthless. The physical science basis of Anthropogenic Global Warming theory is founded on a false hypothesis.

2. Any recent warming is most likely natural. Human input of CO2 has very little to do with it. Solar, naturally varying water vapor, and similar variables can explain most or all of the climate changes. Projections based on Global Climate Models are unreliable because these are based on too many assumptions and unreliable data sets.

3. There are changes in the atmosphere, including added CO2 from human activities, but significant climate effects are likely to be all within natural limits. The 'scares' are exaggerations with a political motive. The undue emphasis on CO2 diverts attention away from other, important research on climate variability and change.

4. There is warming and the human addition of CO2 causes some of it, but the science is too uncertain to be confident about current attributions of the precise role of CO2 with respect to other climate forcings. The IPCC WG1 overestimates the role of CO2 relative to other forcings, including a diverse variety of human climate forcings.

5. The scientific basis for human impacts on climate is well represented by the IPCC WG1 report. The lead scientists know what they are doing. We are warming the planet, with CO2 as the main culprit. At least some of the forecast consequences of this change are based on robust evidence.

6. The IPCC WG1 is compromised by political intervention; I agree with those scientists who say that the IPCC WG1 is underestimating the problem. Action to reduce human emissions of CO2 in order to mitigate against serious consequences is more urgent than the report suggests. This should be done irrespective of other climate and environmental considerations.

7. The IPCC WG1 seriously understates the human influence on climate. I agree with those scientists who say that major mitigation responses are needed immediately to prevent catastrophic serious warming and other impacts projected to result from human emissions of CO2. We are seriously damaging the Earth's climate, and will continue to face devastating consequences for many years.



Figure 3. Results of the 2007 opinion poll by Fergus Brown, Roger Pielke, Sr., and James Annan of climate scientists, organized by question number (one to seven). In the USA, the mean response was 4.8, compared to 5.2 in all other countries, and 5.6 in EU countries.

Commentary
The majority of climate scientists polled believe the 2007 IPCC reports essentially "gets it right", which is in part why I like to refer to the IPCC report as representing "the official word" on climate. This report concluded that there was a greater than 90% chance that most of the observed global warming in the past 50 years was due to emission of greenhouse gases by human activity. However, there are substantial minorities that believe the IPCC underestimates or overestimates the potential impacts, and these voices need to be respected, as well.

Dr. Ricky Rood talks in greater depth on this issue in his latest wunderground Climate Change blog: "There are many thousands of scientists, and while large groups of individuals often share many like-minded values and beliefs, they are never in lockstep on the details of all aspects of their beliefs. It is not expected that in a community of thousands of scientists that there is a uniform chant of doctrine. This is especially true given the very nature of scientific investigation of an enormously complex system."

Other voices on climate scientist polls
Dr. James Annan's blog
Planet Gore
Realclimate.org.

Jeff Masters

Climate Change

Updated: 7:51 PM GMT en Agosto 16, 2011

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Winter Storm Klaus kills 26 in Europe

By: JeffMasters, 8:20 PM GMT en Enero 26, 2009

Powerful Winter Storm Klaus, similar in strength to a Category 1 hurricane, brought high winds that killed at least 26 people in Spain, France, and Italy on Saturday. Wind gusts as high as 124 mph (199 km/hr) occurred along the northern coast of Spain, and Klaus had a central pressure of 967 mb at its peak on the morning of January 24. Sustained winds of 59 mph were measured at Santander, and wind gusts as high as 69 mph hit Barcelona, where a roof collapsed at a sports center, killing four children. Klaus knocked out power to at least 1.7 million people, and likely did hundreds of millions in damage to Spain and France. The storm caused extensive flooding in southern France, and toppled more than half of the trees in the regions of Gironde and Landes, one of Europe's largest forest areas. It was the worst storm to hit the region since Winter Storm Martin hit in December 1999, killing over 100 people in France and Spain.

A few top wind gusts in Spain from Winter Storm Klaus:

El Musel-Gijon (Asturias): 124 mph (199 km/hr)
Malpica (A Coruña): 114 mph (183 km/hr)
Ancares (Lugo): 113 mph (182 km/hr)
Gijon (Asturias): 104 mph (167 km/hr)



Figure 1. QuikScat image of Winter Storm Klaus approaching Spain at 19:08 GMT Friday January 23, 2009. Winds here suggest Klaus had winds similar to a Category 1 hurricane. Image credit: Paul Chang, NOAA.

Future European storm damage due to climate change
How European extratropical storms like Klaus might change in a world undergoing global warming is highly uncertain. A number of studies cited in the 2007 Intergovernmental Panel on Climate Change (IPCC) report showed significant increases in the intensity and number of extratropical cyclones in recent years. However, the report notes that "as with tropical cyclones, detection of long-term changes in cyclones is hampered by incomplete and changing observing systems". Thus, we cannot tell at present if recent observed changes in extratropical storms are an indication of climate change.

The forecast is also murky. The 2007 IPCC report states, "Confidence in future changes in windiness in Europe remains relatively low....Several studies have suggested a decrease in the total number of cyclones in the Mediterranean Sea, but there is no agreement on whether the number of intense cyclones will increase or decrease".

It's of interest to note that Klaus was a relatively minor storm compared to some past storms that have affected South France. Over-wash deposits in a lagoon in the region were found by Sabatier et al. (2008) to point to Category 3 hurricane-strength winter storms hitting the region roughly once every 100 years. The most recent strikes were in 1839 and 1893.

Hurricane Ike relief efforts presentation
The portlight.org disaster relief charity will be presenting a summary of their Hurricane Ike relief efforts and plans for the future on Wednesday, January 28, at 8:20 am, at the Summerville, SC Kiwanis club. The portlight webcam will be running during the presentation, for those interested.

Jeff Masters

Winter Weather

Updated: 7:06 PM GMT en Enero 05, 2012

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La Niña on the way?

By: JeffMasters, 2:53 PM GMT en Enero 23, 2009

A La Niña event may be developing in the Eastern Pacific Ocean, as equatorial sea surface temperatures cooled to 0.73°C below average in December, and have cooled further to -1.1°C below average this week. A La Niña event is defined as occurring when the 3-month running mean temperature anomaly in the equatorial Eastern Pacific cools below -0.5°C for five consecutive months. The 3-month running mean as of January 1 was -0.4°C, so we are still officially experiencing neutral conditions. Approximately 50% of the El Niño forecast models predict that a full-fledged La Niña event will develop between January and May of 2009. Our last La Niña event ended just eight months ago, in May 2008. It is uncommon to have separate La Niña events develop two years in a row. This has only occurred twice since 1950, so I give it a 50/50 chance that a full-fledged La Niña event will develop in 2009. One argument against a La Niña event developing is the current burst of west-to east winds that has developed in the Western Pacific. These westerly winds have developed as a result of a series of cold air outbreaks associated with troughs of low pressure, plus a periodic flare-up of thunderstorm activity called the Madden-Julian Oscillation. This burst of westerly winds has triggered formation of a 200 meter-deep, long-period, eastward-propagating ocean wave known as an equatorial Kelvin Wave. This wave has been marching eastwards over the past few weeks, pushing warmer Western Pacific water into the Eastern Pacific. As the Kelvin wave continues to propagate eastwards towards South America over the next few weeks, it should keep La Niña conditions from amplifying through the rest of January.

Despite the unusually late start to La Niña conditions this winter, the cooler water developing in the Eastern Pacific is capable of having a significant impact on regional weather patterns. We can expect during January-March 2009 above-average precipitation over Indonesia and below-average precipitation over the central and eastern equatorial Pacific. For the contiguous United States, potential impacts include above-average precipitation in the Ohio and Tennessee Valleys and below-average precipitation across the South, particularly in the southwestern and southeastern states. Other potential impacts include below-average temperatures in the Pacific Northwest and above-average temperatures across much of the southern United States.


Figure 1. Latest three-month forecast of precipitation issued by NOAA's Climate Prediction Center.

Volunteers needed for disaster relief fund-raising
The portlight.org disaster relief charity is in the process of wrapping up its Hurricane Ike relief efforts, and is looking ahead to the future. According the new wunderground featured blog, Portlight Disaster Relief, "Our goals are to expand our network of supporters, continue to create a sense of ownership and community and create a financial reserve. Achieving these goals is critical to us being able to serve future hurricane victims in a strategic, pro-active and efficient manner." To this end, Portlight is sponsoring a fund-raising effort this March and April in 40 cities--a Spring Relief Walk. Volunteers in twenty cities have already committed to the effort, and more volunteers are needed! Check out the Portlight Disaster Relief blog for more information.

My next post will be Monday.

Jeff Masters

Climate Change

Updated: 7:51 PM GMT en Agosto 16, 2011

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2008: Ninth warmest year on record

By: JeffMasters, 2:05 AM GMT en Enero 21, 2009

The temperature statistics are in, and the year 2008 ranks as the ninth warmest year for the globe on record, making it the coolest year since 2000, according to an analysis compiled by NASA. NOAA's National Climatic Data Center rated 2008 the eighth warmest on record, and the British Climate Research Unit rated it tenth warmest. NASA noted that given the uncertainty in the measurements, a range of 7th to 10th warmest was reasonable. Global temperature records extend back to 1880. December 2008 was also the eighth warmest December for the globe on record.

The average global temperature the past five years (and the last ten years) is the highest on record. The top ten warmest years since 1880 have all occurred in the past twelve years. So, despite the impressive cold blast in the Eastern U.S. this winter, the global climate is warming. The relatively cool temperatures of 2008 probably represent a normal year-to-year fluctuation in the weather. Cool weather is to be expected globally during a strong La Niña event in the Eastern Pacific Ocean, which was present during the first part of 2008 (see the cool blue colors over the Equatorial Pacific in Figure 1). It is no surprise that the last year it was cooler, 2000, was also the last time we had a La Niña event. With La Niña conditions beginning to develop again this year, I'd be surprised if 2009 turns out to be a record warm year. Dr. James Hansen of NASA is predicting a new global record temperature either this year or in 2010, though.


Figure 1. Global temperature anomalies in 2008 compared to the 1950-1980 baseline period. Below-average temperatures are shown in blue, average temperatures are white, and above-average temperatures are red. (Gray indicates no data.) Most of the world was either near normal or warmer than normal. Eastern Europe, Russia, the Arctic, and the Antarctic Peninsula were exceptionally warm (1.5 to 3.5 degrees Celsius above average). The temperature in the United States in 2008 was not much different than the 1951-1980 mean, which makes 2008 cooler than all of the previous years this decade. Large areas of the central and eastern Pacific Ocean were cooler than the long-term average, linked to a La Niña episode that began in 2007. The graph shows the long-term trend in surface temperatures since 1880. The annual average temperatures are shown in light orange, and the jaggedness of the line indicates how much the average global surface temperature varies from year to year. Because climate is so variable from year to year, it can be easier to spot long-term trends through multi-year averages. The dark red line shows the five-year running average, which is an average of five years of annual temperatures centered on a given year. Even this five-year average shows that climate has ups and downs, but the long-term increase in global average surface temperatures is obvious. The gray barbells indicate the range of uncertainty. Not surprisingly, the uncertainty is larger for older measurements than for more recent ones. Image credit: NASA.

A cool and snowy December in the U.S.
For the contiguous U.S., December was the 35th coolest December, ranking it in the coldest 30% of all Decembers observed since records began in 1895. December 2008 had near-average precipitation, ranking 43rd wettest. It was the 8th wettest December on record in the East North Central U.S., and 9th wettest for the Central U.S. Only the South experienced below average precipitation during the month. For the year 2008, temperatures in the U.S. were not much different than the 1951-1980 mean, which makes 2008 the coolest year since 1997. U.S. records set in December 2008 (courtesy of http://extremeweatherguide.com/updates.asp):

Spokane, WA: All-time 24-hour snowfall, 19.4", 12/17-12/18
Spokane, WA: All-time single storm snowfall: 23.3", 12/17-12/18
Sandpoint, ID: All-time 24-hour snowfall, 27.0"
Jackson, WY: All-time 24-hour snowfall, 27.0"
Fargo, ND: Snowiest month on record: 33.5"
Spokane, WA: Snowiest month on record: 61.5"
Green Bay, WI: Snowiest month on record: 45.6"
Madison, WI: Snowiest month on record: 40.4"
Wausau, WI: Snowiest month on record: 37.6"
Idaho: All-time 24-hour state snowfall record set at Dollar Hide, 46.5", 12/26-12/27 (not confirmed)

At the end of 2008, 20% of the contiguous United States was in moderate-to-exceptional drought. This is a decline from the 28% of the U.S. that was under similar drought conditions at the end of 2007. The average precipitation for the U.S. in 2008 was 30.48 inches, which is 1.34 inches above average. 2008 was the wettest year on record for New Hampshire and Missouri, second wettest for Massachusetts, and third wettest for Connecticut, Illinois, and Iowa. Also, 2008 was the fourth wettest year for Indiana, fifth wettest for Maine, Michigan, and Vermont, seventh wettest for New York, and eighth wettest for Kansas and Rhode Island.

Next post
Check out Ricky Rood's latest blog, called Cold in the East: A rant. There is a lot of misinformation circulating in the media right now about climate change, and Ricky and I will be doing our best to try to explain what is fact and what is crap in the coming weeks. I posted one such discussion last week, when I showed that the recent claims that sea ice is back to 1979 levels were a clever bit of cherry picking of the data that hides the critical summertime loss of Arctic sea ice. I'll have a new blog post on Friday.

Jeff Masters

Climate Change Climate Summaries

Updated: 7:52 PM GMT en Agosto 16, 2011

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Inauguration weather

By: JeffMasters, 1:11 PM GMT en Enero 19, 2009

Barack Obama won't have the weather as the first concern of his presidency, unlike some of his predecessors. The weather for Tuesday's swearing in ceremony promises to be precipitation-free, with a mix of sun and clouds. With temperatures in the low 30s and a moderate north wind of 10-15 mph, he'll have to bundle up, though. As the afternoon progresses, clouds will dominate for the parade, but the weather at the inauguration promises to be a non-story, unlike some previous occasions:

Most Dramatic and Tragic - 1841:
President William Henry Harrison was sworn into office on a cloudy, windy day, with temperatures in the mid to upper 40s. His speech lasted one hour and 40 minutes, and he rode a horse to and from the Capitol, without wearing a hat or overcoat. Pneumonia developed from a lingering cold he caught on that day and he died just one month later.

Almost as bad - 1853:
President Franklin Pierce was sworn into office during a snowstorm, with temperatures near freezing. Shortly after Pierce took his oath of office, as he began his inaugural address, heavier snow began falling, dispersing much of the crowd and ruining plans for the parade. Abigail Fillmore, First Lady to the outgoing President Millard Fillmore, caught a cold as she sat on the cold, wet, exposed platform during the swearing-in ceremony. The cold developed into pneumonia and she died at the end of the month.

Worst Weather Day - 1909:
President William H. Taft's ceremony was forced indoors due to a storm that dropped 10 inches of snow over the Capital city. The snow and winds began the day before, toppling trees and telephone poles. Trains were stalled, and city streets clogged, bringing all activity to a standstill. Sanitation workers shoveled sand and snow through the night. It took 6,000 men and 500 wagons to clear 58,000 tons of snow and slush from the parade route. Despite the freezing temperatures, howling wind, snow, and sleet, a large crowd gathered in front of the Capitol to view the inauguration, but the weather forced the ceremony indoors. Just after the swearing-in, the snow tapered off.


Figure 1. Inauguration day, 1909. Workers shovel away heavy snow from in front of President Taft's reviewing stand (left). President Taft and wife returning to the White House after the ceremony (right).

The material for this post was taken from an excellent Presidential Inaugural Weather web page put together by the National Weather Service forecast office in Washington D.C. The page has loads more information, for those interested.

Good luck, Mr. Obama!

I'll have a new post on Wednesday.
Jeff Masters

Climate Change

Updated: 7:52 PM GMT en Agosto 16, 2011

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Ice and fire: extremes grip North America

By: JeffMasters, 7:16 PM GMT en Enero 16, 2009

The lowest temperature ever recorded in the state of Maine occurred this morning, according to preliminary data from the National Weather Service. The temperature at Big Black River in northern Maine on the Canadian border bottomed out at -50F, besting the old record of -48°F. Here's the scoop from NWS:

At 0730 am EST this morning a USGS gage at Big Black River recorded a low temperature of -50F. This exceeds the current statewide record low temperature of -48F set on January 19th...1925 at Van Buren. This report is considered unofficial until a review of the equipment and data by the state climate extremes committee as to the validity of this report. If the committee ascertains that this is indeed a valid report...a separate public information statement will be issued at that time.


Figure 1. Temperature trace from the Big Black River, Maine USGS river gauge station, ending January 16, 2009. A record minimum of -50°F (-45.3°C) occurred. Image credit: USGS.

Figure 2. Minimum temperatures this morning for Maine. Image credit: National Weather Service, Caribou, Maine.


All-time state records are difficult to break. The last time a state record low was set was January 5, 1999, when Congerville, Illinois recorded -36°F. Only one state record high temperature has been set in the past the decade--the 120°F temperature measured in Usta, South Dakota on July 15, 2006.

This week's North American cold spell has been a notable one, with daily minimum temperature records falling in seventeen states, Sunday through Friday. A record low for the month of January was set Friday morning in Caribou, Maine, which recorded -37°F. This is the second coldest temperature ever recorded in Caribou, next to the -41°F recorded on February 1, 1962. Mason City, Iowa had it's lowest January temperature on record Friday morning, -31°F, and Cedar Rapids, Iowa, had its all-time lowest temperature for any month Thursday morning, a frigid -29°F. Bismark, North Dakota had its second coldest temperature ever, -44°F, on Thursday morning. This was only 1° from the all time low of -45° on January 13, 1916 and again on February 16, 1936. Bismark is also on pace for their snowiest season on record (61.2" so far).

Record heat in Alaska and California
The temperature swings this week in Alaska have been astounding. At Nenana, in central Alaska, the high was -42°F on Monday, with a low of -52°F. On Thursday morning, the temperature shot up 106°F from Monday, topping out at a positively tropical 54°F--the warmest January temperature ever measured in Nenana. Several other Alaska stations also set record highs for the month of January this week. Record highs for the month of January were also set at four California airports:

San Jose 75°F January 12
Sacramento 70°F January 12
San Francisco 72°F January 13
Red Bluff 78°F January 13, 15, 16

More record highs than lows have been set at the 381 major airports across the U.S. so far this week, through Friday. You can look up all the records at the National Climatic Data Center's excellent U.S. Records web site. Records for this week:

Jan 16
------
9 maximum high temperature records (CA, OR, WA, WY)
20 minimum low temperature records (GA, IA, IL, IN, MI, ME, MN, NH, PA, VT, WI)

Jan 15
------
11 maximum high temperature records (CA, WA, NV)
11 minimum low temperature records (IA, ND, IN, ME, NE, NY, SD)

Jan 14
-------
14 maximum high temperature records (AK, CA, OR, NV)
8 minimum low temperature records (IA, MI, MN, ND, TX)

Jan 13:
-------
13 maximum high temperature records (CA, OR, AK, FL)
9 minimum low temperature records (IA, MI, MN, ND)

Jan 12:
-------
9 maximum high temperature records (CA, OR, WA)
2 minimum low temperature records (AK, ND)

Jan 11:
-------
7 maximum high temperature records (CA, OR, WA)
1 minimum low temperature record (CA)

What's causing all this wild weather?
As usual, a sharp kink in the jet stream is responsible for the wild weather we're having. A ridge of high pressure over Alaska is forcing the jet to bow northwards into northern Alaska, allowing warm air from the Hawaii area to stream northwards over the region. Whenever the jet contorts into such a pattern, there must be a return flow of cold air from the pole that develops. That is occurring over the eastern half of the U.S., bringing us our Arctic air blast. The -17°F at my house in Michigan yesterday morning was the coldest it's been since 1994, brrr!

Jeff Masters

Climate Change

Updated: 7:53 PM GMT en Agosto 16, 2011

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Averaging together antarctic and arctic sea ice hides an important truth

By: JeffMasters, 2:37 PM GMT en Enero 15, 2009

Since my last post designating arctic sea ice loss as the top climate story of 2008, I've heard a lot comments like this one: "Jeff, you just can't seem to understand the that man-made global warming is a fable and complete hoax. In all that blathering about the falsified IPCC reports and the study of the arctic ice sheet, you somehow neglected to mention that the ice recovered not only what it lost last year, but is now larger than the previous known record measured in 1978".

Well, I can understand this point of view, given complexity of the climate change issue, and the large amount of conflicting information one sees in the media. Let's look at the facts about global sea ice. You can look at the data yourself at the excellent University of Illinois Cryosphere Today web site. Reliable sea ice records go back to 1979, when satellite measurements began. Antarctic sea ice reached its greatest extent on record during the winter of 2007. Summertime ice coverage also increased in 2007-2008 compared to 2006 levels (Figure 1). However, as one can see from Figure 1, there is high variability in antarctic sea ice from winter to summer, and antarctic sea ice can best be described as having stayed constant since 1979 (as stated in the 2007 report of the Intergovernmental Panel on Climate Change (IPCC). The IPCC did find that there had been a significant decline in arctic sea ice, in all seasons, between 1979-2006. Despite this decline, there have been three periods during the past two years when the sum of the arctic and antarctic sea ice was the same or even higher than it was at the start of the satellite era (1979). An article published January 1 on Daily Tech noted that "global sea ice levels now equal those seen 29 years ago". This was pretty close to the truth on December 31, 2008, despite the fact that arctic ice was 1 million km^2 below 1979 levels, since antarctic ice was 0.5 million km^2 above 1979 levels. Although arctic sea ice extent has steadily declined since 1979, especially in summer, this decline is not as great during the winter months. One can find periods in winter when summing together antarctic and arctic sea ice area makes it appear that arctic sea ice loss is no big deal.

However, this is the wrong way to look at the issue. We don't care much about global sea ice in winter. We care about arctic sea ice in the summer. Sharp declines in summertime arctic ice are likely to cause significant and damaging alterations to Earth's climate. Cleverly quoting irrelevant facts about global wintertime sea ice data to hide the summertime loss of arctic sea ice is a tremendous disservice. It's like hiding the potential impact of a major hurricane in a one-week forecast by saying, "the average peak wind speed for the next seven days will be 17 mph", and neglecting to mention that the wind will be calm six of those days, but 120 mph on the other day. The loss of arctic sea ice the past two summers, is, in my view, the most important human-caused climate change event yet--even more significant and dangerous than the opening of the antarctic ozone hole in the 1980s. It's great that we're not seeing loss of sea ice in Antarctica. But, both the Antarctic and the Arctic can be thought of as important internal organs in our living Earth. The fact that the Antarctic has not undergone significant warming and sea ice loss in no way diminishes the urgency with which climate scientists view the diseased state of our Arctic. Fully 88 presentations on arctic sea ice were made last month at the world's largest scientific climate change conference, the American Geophysical Union (AGU) meeting in San Francisco. None of these scientists averaged together the arctic and antarctic sea ice together to show that the overall state of Earth's cryosphere was a healthy one. There was widespread concern for the health of the Arctic among all the scientists I spoke with, and none of the speakers at the talks I attended expressed the idea that the recent melting of arctic sea ice was predominantly natural, with human-caused climate change an insignificant factor. One view (Stroeve et al., 2007) is that human-emitted greenhouse gases are responsible for 47-57% of the arctic sea ice loss since 1979. Heat-absorbing black soot from fires and pollution settling on the white ice is thought to also be a significant contributor.


Figure 1. Antarctic sea ice area as observed via satellite since 1978. The maximum area in winter has ranged between 14-16 million square kilometers, about the same amount of ocean that the Arctic ice covers in winter. However, the antarctic sea ice almost entirely melts away in summer, something the Arctic sea ice does not do (yet). Antarctica is a huge continent that rises thousands of feet above the ocean. It holds about 90% of the world's fresh water, locked up in its massive ice cap. The presence of such a titanic block of ice at the bottom of the world completely dominates the weather and climate of the region, and the year-to-year fluctuations of sea ice don't have a lot of impact on temperatures there. Image credit: University of Illinois Cryosphere Today.

What is the current state of Antarctic climate?
At the December 2008 AGU meeting, scientists gave Antarctica a mixed bill of health. Isabella Velicogna of UC Irvine reported that satellite gravitational variation measurements of Antarctica's ice cap showed significant loss of ice between 2002-2008, but that the large natural variations in melting with the seasons made it difficult to be confident of the results. A somewhat different result was reported by J. Zwally of NASA. Using data from a higher-resolution satellite-borne laser altimeter, he found that there was no major loss of Antarctica's ice sheet between 2003-2007. Regardless of which data set is correct, Antarctica is in better shape than the Arctic because Antarctica has stayed relatively cool in recent decades (Figure 2). For example, the surface temperature at the South Pole cooled 0.05° C between 1980 and 1999 (Kwok and Comiso, 2002). The majority of Antarctica has shown no statistically significant warming over the past 50 years (Turner et al., 2005), and cooling has just been dominant between 1982-2004. In the period 2004-2007, much of the Antarctic warmed (Figure 3), but it is too early to say if this is the beginning of a warming trend. Check out the January 22 issue of Nature when new results about whether or not Antarctica is warming will be published.


Figure 2. Antarctic surface temperatures as observed via AHVRR satellite measurements between 1982 and 2004. Much of Antarctica cooled during this period. Image credit: IPCC The Physical Science Basis, Figure 3.32.


Figure 3. Antarctic surface temperatures as observed via AHVRR satellite measurements between 1981 and 2007. Note that the cooling trend observed from 1982-2004 reversed, thanks to warming from 2004-2007. Image credit: NASA

Why did Antarctica cool between 1982 and 2004 if there was global warming going on?
The weather of the Antarctic is dominated by a strong band of westerly winds that blow around the pole. This circumpolar vortex extends from the surface to the stratosphere, and can attain very high wind speeds, thanks to the absence of large land masses to slow it down. This vortex tends to isolate Antarctica from the rest of the globe, keeping global warming from influencing Antarctica's weather, and allowing the surface to cool. The Antarctic Peninsula, which sticks out from Antarctica towards South America, frequently lies outside the vortex. This has allowed the peninsula to warm significantly, compared to the rest of Antarctica (Figures 2 and 3). The antarctic circumpolar vortex has strengthened in the past 25-30 years, forming an even stronger barrier than usual. Tree ring records (Jones and Widman, 2004) suggest that the circumpolar vortex has shown similar strengthening in the past, so the current cooling trend in Antarctica may be natural.

Another possibility, favored by climate modelers, is that the strengthening of the circumpolar vortex and recent cooling in Antarctica are primarily due to a combination of the recent increase in greenhouse gases and the opening of the Antarctic ozone hole. The ozone hole opened up at about the same time as the recent cooling began. Ozone absorbs UV radiation which heats the atmosphere around it, so the absence of ozone has led to cooling in the stratosphere over Antarctica. This cooling has been about 10° C in October-November since 1985 (Thompson and Solomon, 2002). This has acted to intensify the circumpolar vortex, leading to surface cooling. If the climate modelers are right, the circumpolar vortex will weaken as the ozone hole diminishes in coming decades. This will allow the Antarctic to begin warming with the rest of the globe, in a decade or two.

References and resources
Intergovernmental Panel on Climate Change (IPCC), 2007, The Physical Science Basis.

Jones, J.M., and M. Widman, "Atmospheric science: Early peak in Antarctic oscillation index," Nature 432, 290-291 (18 November 2004) | doi:10.1038/432290b; Published online 17 November 2004.

Kwok, R., and J.C. Comiso, "Spatial patterns of variability in Antarctic surface temperature: Connections to the Southern Hemisphere Annular Mode and the Southern Oscillation", GEOPHYSICAL RESEARCH LETTERS, VOL. 29, NO. 14, 10.1029/2002GL015415, 2002.

Thompson, D.W.J., and S. Solomon, "Interpretation of Recent Southern Hemisphere Climate Change", Science 3 May 2002: Vol. 296. no. 5569, pp. 895 - 899 DOI: 10.1126/science.1069270.

Stroeve, J., M.M. Holland, W. Meier, T. Scambos, and M. Serreze, Arctic sea ice decline:Faster than forecast", GRL 34 L09501, doi:1029/2007GL029703, 2007.

Turner, J. et al., 2005, "Antarctic climate change during the last 50 years", International Journal of Climatology, Volume 25, Issue 3, pp 279-294.

Arctic sea ice

"Antarctic cooling, global warming?" RealClimate.org post, 3 December 2004.

Volunteers needed for disaster relief fund-raising
The portlight.org disaster relief charity is in the process of wrapping up its Hurricane Ike relief efforts, and is looking ahead to the future. According the new wunderground featured blog, Portlight Disaster Relief, "Our goals are to expand our network of supporters, continue to create a sense of ownership and community and create a financial reserve. Achieving these goals is critical to us being able to serve future hurricane victims in a strategic, pro-active and efficient manner." To this end, Portlight is sponsoring a fund-raising effort this March and April in 40 cities--a Spring Relief Walk. Volunteers in twenty cities have already committed to the effort, and more volunteers are needed! Check out the Portlight Disaster Relief blog for more information.

Coming Monday: Inauguration Weather. Wednesday: is the globe cooling? A report on temperatures for 2008, merely the 9th warmest year on record.

Jeff Masters

Climate Change Sea Ice

Updated: 7:53 PM GMT en Agosto 16, 2011

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Top climate story of 2008: Arctic sea ice loss

By: JeffMasters, 4:03 PM GMT en Enero 12, 2009

The top climate story of 2008, as it was in 2007, was the extraordinary summertime sea ice retreat in the Arctic. For the second consecutive year, we experienced the opening of the fabled Northwest Passage through the Canadian Arctic waters. Explorers have been attempting to sail the Northwest Passage since 1497, and 2007 and 2008 are the only known years the passage has been ice-free. In addition, 2008 saw the simultaneous opening of the Northeast Passage along the coast of Russia. This meant that for the first time in recorded history, the Arctic ice cap was an island--one could completely circumnavigate the Arctic Ocean in ice-free waters. Although the summer ice extent in 2008 finished 9% higher than 2007's record minimum, it was still an extraordinary 34% below average, according to the National Snow and Ice Data Center. Furthermore, the ice was thinner at the September 2008 minimum compared to 2007, so the total ice volume (thickness times area) was probably at its lowest point in recorded history in 2008.


Figure 1. Daily arctic sea ice extent for September 12, 2008. The date of the 2008 minimum (white) is overlaid on September 16, 2007--last year's minimum extent (dark gray). Light gray shading indicates the region where ice occurred in both 2007 and 008. Image credit: National Snow and Ice Data Center.

The Arctic "perfect storm" of summer weather in 2007 did not repeat in 2008
The summer of 2007 saw a "perfect storm" of weather conditions favorable for ice loss. Unusually strong high pressure over the Arctic led to clear skies and plenty of sunshine. Arctic winds, which usually blow in a circular fashion around the Pole, instead blew from the south, injecting large amounts of warm air into the Arctic. How unusual were these conditions? Well, at last month's meeting of the American Geophysical Union, the world's largest scientific conference on climate change, J.E. Kay of the National Center for Atmospheric Research showed that Arctic surface pressure in the summer of 2007 was the fourth highest since 1948. Cloud cover at Barrow, Alaska was the sixth lowest. This suggests that once every 10-20 years a "perfect storm" of weather conditions highly favorable for ice loss invades the Arctic. The last two times such conditions existed was 1977 and 1987.

The 2008 melting season began in March with slightly greater ice extent than had been measured in previous years, thanks to a relatively cold winter during 2007-2008. However, since so much ice had melted during the summer of 2007, most of the March 2008 ice was thin first-year ice, which extended all the way to the North Pole. The total ice volume in the Arctic in March 2008 was lower than what the record-breaking year of 2007 had seen. This led to speculation that a new record minimum would be set in 2008, and Santa's Workshop would plunge into the ocean as ice melted at the North Pole. However, the "perfect storm" of summertime weather conditions did not materialize in 2008. From May through July, cooler temperatures and winds less favorable to ice loss occurred. When very warm temperatures moved into the Arctic in August, the ice loss rate accelerated to levels higher than in 2007. However, with sunlight waning, ice loss was not able to reach the levels seen in 2007. Arctic temperatures in the summer of 2008 were up to 4°C cooler along the Siberian coast than in 2007 (Figure 2).


Figure 2. Difference in surface temperature (°C) between the summer of 2008 and the summer of 2007. Blues and purples indicate areas where is was cooler in 2008. The biggest change was over the Bering Sea between Alaska and Russia, where exceptionally sunny weather with southerly winds in 2007 caused record-breaking warmth. Image credit: NOAA/ESRL.

The future of arctic sea ice
Climate models have done a poor job predicting the recent record loss of arctic sea ice (Figure 3). None of the models used to formulate the official word on climate, the 2007 United Nations IPCC report, foresaw the shocking drop of 2007-2008. At the December 2008 AGU meeting, Wieslaw Maslowski of the Navy Postgraduate School hypothesized that the reason for this was the models' improper handling of ocean currents and how they transport heat. He blamed 60% of the melting during the past decade on heat brought in by ocean currents, and projected that summertime arctic sea ice would completely disappear by 2016. Dr. Jim Overland of NOAA's Pacific Marine Environmental Laboratory was more conservative, projecting a 2030 demise of arctic sea ice. He thought we would be "hanging around where we are for a while", and thought it would take two more unusual summers like the "perfect storm" of 2007 to push the system to an ice-free state. He further noted that while summertime air temperatures have been near record levels the past few years in the Arctic, there has been one period of comparable warmth, in the 1930s and 1940s. The year 1941 still ranks as the warmest year in the Arctic, though 2007 was virtually tied with it. However, the warmth of the 1930s and 1940s was different than the current warming, and was caused by the Siberian High moving unusually far east over Europe, driving warm, southerly winds over Greenland. The warmth in the past decade, in contrast, is associated with a warming of the entire planet, and is not due to an unusual pressure pattern driving warm air into the region. This means that the current warming is accompanied by much warmer ocean waters, which have helped caused much of the arctic sea ice loss the past two years by melting the ice from beneath.


Figure 3. Arctic sea ice extent from observations (thick orange line) and 13 model forecasts used to formulate the 2007 IPCC report (light lines). The thick black line is the multi-model ensemble mean, with the standard deviation plotted as a dashed black line. Image has been updated to include the observed 2007 and 2008 measurements. Image credit: Arctic sea ice decline: Faster than forecast by Stroeve et al., 2007.

The impact on the jet stream
The unprecedented melting of arctic sea ice the past two summers has undoubtedly had a significant impact on the early winter weather over the Northern Hemisphere. Several modeling studies presented at the December AGU meeting showed that sea ice melt on this scale is capable of injecting enough heat into the atmosphere to result in a major shift in the jet stream. Dr. Overland remarked that the early cold winter over North America this winter, and the exceptionally cold and snowy early winter in China last winter, were likely related to arctic sea ice loss. The sea ice loss induced a strong poleward flow of warm air over eastern Siberia, and a return flow of cold air from the Pole developed to compensate. Thus regions on either side of eastern Siberia--China and North America--have gotten unusually cold and snowy winters as a result.

The impact on sea level rise
The loss of arctic sea ice will have little impact on sea level rise over the next few decades. Since the ice is already floating in the ocean, melting it does not change sea level much--just like when ice melting in a glass of water will not change the level of liquid in the glass. In the case of sea ice, there is a slight sea level rise, since the fresh melt water is less dense than the salty ocean water it displaces. If all the world's sea ice melted, it would raise global sea level by only 4 mm. This is a tiny figure compared to the 20 feet of sea level rise that would occur from complete melting of the Greenland ice sheet--which is on land.

The impact on melting of the Greenland Ice Sheet
The big concern with arctic sea ice melt is the warmer temperatures it will bring to the Arctic, which will bring about an accelerated melting of the Greenland Ice Sheet. As the sea ice melts, the resulting warmer average temperatures will increase the amount of dark, sunlight-absorbing water at the pole, leading to further increases in temperature and more melting of sea ice, in a positive feedback loop. As temperatures warm, partial melting of the Greenland Ice Sheet will raise global sea levels. While no one is expecting 20 feet of sea level rise from the total melting of the Greenland Ice Sheet for many centuries, even one meter (3.3 feet) of sea level rise due to the partial melting of the Greenland Ice Sheet can cause a lot of trouble. The official word on climate, the 2007 IPCC report, predicted only a 0.6-1.9 foot sea level rise by 2100, due to melting of the Greenland ice sheet and other factors. These estimates did not include detailed models of ice flow dynamics of glaciers, on the grounds that understanding of the relevant processes was too limited for reliable model estimates. The IPCC estimates were also made before the shocking and unexpected loss of arctic sea ice of the past two summers. In light of these factors, a large number of climate scientists now believe the IPCC estimates of sea level rise this century are much too low. The most recent major paper on sea level rise, published this month by Grinsted et al., concluded that there was a "low probability" that sea level rise would be in the range forecast by the IPCC, and predicted a 0.9 - 1.3 meter (3 - 4.3 feet) rise by 2100. Pfeffer et al. last month concluded that a "most likely" range of sea level rise by 2100 is 2.6 - 6.6 feet (0.8 - 2.0 meters). Their estimates came from a detailed analysis of the processes the IPCC said were understood too poorly to model--the ice flow dynamics of glaciers in Greenland and Antarctica. The authors caution that "substantial uncertainties" exist in their estimates, and that the cost of building higher levees to protect against sea level rise is not trivial. Other recent estimates of sea level rise include 1.6 - 4.6 feet (0.5 - 1.4 meters) by Rahmstorf (2007).

What would 3 feet of sea level rise mean?
Rising sea levels will lead to permanent and intermittent flooding in low-lying coastal areas across the world. A global sea level rise of .9 meters (3 feet) would affect 100 million people worldwide, mostly in Asia. The impact of hurricane storm surges will significantly increase as a result of sea level rise. Given a 3 foot rise in sea level, Hurricane Ike's storm surge would have overwhelmed the levees in Port Arthur, Texas, flooding the city and its important oil refineries. Galveston's sea wall would have been overtopped and possibly destroyed, allowing destruction of large portions of Galveston. Levees in New Orleans would have been overtopped, resulting in widespread flooding there, as well. I'll have a full analysis of who's at risk, and what the risks are, in a series of forthcoming blog posts this year.

What can we do?
One reasonable suggestion, presented by Trish Quinn of NOAA at the December 2008 AGU meeting, would be to limit the amount of crop residue burning that goes on in Eastern Europe and Asia each year. These fires generate large amounts of black soot that blows into the Arctic. These black particles on the white ice leads to a significant amount of warming during the summer months, when the black particles absorb sunlight.

For more information
The wunderground sea level rise page has detailed background info on sea level rise.
The wunderground Northwest Passage page is also a good reference.
realclimate.org has a nice post summarizing the recent sea level research.

I'll have a new blog post Wednesday or Thursday.

Jeff Masters

Climate Change Sea Ice

Updated: 7:53 PM GMT en Agosto 16, 2011

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The global tropical cyclone season of 2008: below average

By: JeffMasters, 5:25 PM GMT en Enero 08, 2009

It was a below average year for global tropical cyclone activity, and the destructive power of these storms was close to the lowest levels observed since since reliable records began in the early 1980s. However, the the total number of global deaths from tropical cyclones was the highest since 1991, thanks to the estimated 140,000 people killed in Myanmar from Tropical Cyclone Nargis. The total number of storms world-wide was 90, slightly lower that the average from the past 25 years of 92 (Figure 1). The global number of hurricanes, intense hurricanes (Category 3 and higher), and Category 4 and stronger storms were all below average. Only one Category 5 storm was recorded in 2008--Super Typhoon Jangmi, which attained winds of 165 mph at 06 GMT on September 27, as it approached the north coast of Taiwan. The last time so few Category 5 storms were recorded globally was in 1974, when there were none. The 2008 hurricane season was much above average in the Atlantic, but the Atlantic only accounts for about 13% of all global tropical cyclone activity.


Figure 1. Statistics for the global tropical cyclone season of 2008. The three numbers in each box represent the actual number observed in 2008, followed by the averages from the period 1983-2007 (in parentheses), followed by the record (in red). Averages and records were computed using the December 23, 2008 release of NOAA's new International Best Track Archive for Climate Stewardship.

A notable feature of the 2008 tropical cyclone season was the low Accumulated Cyclone Energy (ACE) for the season. ACE is a measure of the total destructive power of a hurricane season, based on the number of days strong winds are observed. ACE for an individual storm is computed by squaring the maximum sustained winds of the storm at each 6-hourly advisory, and summing up over the entire lifetime of the storm. The ACE value for 2008's storms was close to the low values on record seen in 2000-2001 and the early 1980s (Figure 2). Part of the reason for the low ACE values in 2008 (and in 2007) was due to the presence of a La Niña event in the Eastern Pacific. During such events, the formation region for Western Pacific typhoons moves northwestward, closer to China. Thus, storms that form in the Western Pacific spend less time over water before they encounter land, resulting in less time to intensify. They also accumulate a lower ACE due to their shorter duration. Since the Western Pacific is responsible for 35% of the world's major tropical cyclones, the global ACE value is strongly tied to year-to-year variations in the El Niño/La Niña cycle. The last major La Niña event (2000-2001) is clearly evident in Figure 2 as a minimum in global and Northern Hemisphere ACE.


Figure 2. Global (green) and Northern Hemisphere (blue) Accumulated Cyclone Energy (ACE) 24 month running sum through December 31, 2008. Note that the year indicated represents the value of ACE through the previous 24-months. Image credit: Ryan Maue, Florida State University.

Climate change and the 2008 global tropical cyclone season
The 2008 global tropical cyclone season shows that these storms are subject to large natural variations. Given this high natural variability and the short record of good data we have (just 25 years or so), it will be very difficult at present to prove that climate change is affecting global tropical cyclone activity. The situation is different in the Atlantic, where we have a longer reliable data record, and the storms seem to be more sensitive to changes in Sea Surface Temperature. I'll be putting together a full review of the scientific progress on understanding the link between climate change and Atlantic and global hurricane activity over the coming few months.


Figure 3. Satellite image of 2008's strongest tropical cyclone at maximum intensity: Super Typhoon Jangmi. Jangmi was rated a Category 5 storm with 165 mph winds at 06 GMT Sep 27, 2008, making it the only Category 5 storm of 2008. The storm eventually weakened to a low-end Category Four before striking Taiwan. It left two people dead and caused at least $800 million (2008 USD) in damages. Image credit: NOAA/SSD.

Jeff Masters

Updated: 9:59 PM GMT en Enero 08, 2009

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Top weather story of 2008: Cyclone Nargis

By: JeffMasters, 5:04 PM GMT en Enero 05, 2009

The top weather story of 2008 has to be the catastrophic impact of Cyclone Nargis on the nation of Myanmar (formerly Burma). Nargis (the Urdu word for 'daffodil') hit the low-lying, densely populated Irrawaddy Delta region of Myanmar on May 2, 2008. Nargis' Category 4 winds of 135 mph brought a storm surge of up to 4 meters (13 feet) to the coast, inundating regions up to 40 km inland. At least 140,000 people perished, according to official estimates by the U.N. and the government of Myanmar. This makes Nargis the ninth deadliest cyclone in world history. The storm made 800,000 people homeless, destroying 450,000 homes. Approximately 2.4 million people were significantly affected by the cyclone, and total damage has been estimated at $4 billion.

Recovery from the cyclone will take years. The loss of livestock, buffalo for plowing, fishing nets, and boats was near total in many regions of the coast. Fallen trees still block many transportation routes, and the much of the rich farmland used to grow crops has been made salty by the inland penetration of Nargis' storm surge. About 30% of the villages in the devastated region still have a high proportion of their homes using plastic or canvas sheeting for roofs or walls, and undernutrition and lack of clean water are still problematic. However, international aid has made a big difference, and much of the affected area has benefited from the aid.

A once-in-500-year event for Myanmar?
Tropical cyclones are uncommon in Myanmar, which has had only six Category 1 or stronger storms since 1970, and eleven since 1948. Nargis is the third strongest cyclone on record to hit Myanmar, and the deadliest and most damaging. The previous highest death toll from a tropical cyclone in Myanmar was 187, during the Category 1 storm that hit on May 7, 1975. Nargis is the first major tropical cyclone to hit Myanmar since Category 3 Cyclone Mala hit on April 28, 2006. Mala hit a less populated area less prone to storm surge, and killed 22 people and damaged 6000 buildings. It is remarkable that no other tropical cyclone over the past 300 years has hit the Irrawaddy Delta and caused major loss of life. An unusually strong and far-southward extending trough of low pressure turned Nargis to the east much farther south than is the norm for the North Indian Ocean. In the pre-1970 years, there is only one hurricane-force storm recorded to have hit Burma, a Category 1 cyclone in 1936 that killed 36 people. A significant cyclone hitting the Irrawaddy Delta causing thousands of deaths would very likely have been recorded, had this happened any time in the past 300 years. Such events were recorded in both India and Bangladesh during that period. Nargis appears to have been the only major tropical cyclone to hit the Irrawaddy River Delta in recorded history, and may be a once-in-500-year event.


Figure 1. Visible satellite image of Nargis shortly before landfall. Image credit:NASA.

Nargis' storm surge
Nargis took the worst possible path, tracking right along the low-lying, heavily populated Irrawaddy River Delta. Moreover, the storm hit at high tide, greatly increasing the impact of the storm surge. Tidal range in the Irrawaddy River Delta is about five feet between low tide and high tide, and the death toll would have been much, much lower had the storm hit at low tide. Further amplifying the storm surge's height was the fact that Nargis was moving rather slowly--about 11 mph. Slow moving tropical cyclones can drive a much higher storm surge into narrow estuaries that connect to the ocean, since there is more time for the surge to penetrate inland. Nargis' track, forward speed, and high tide timing created a "perfect storm" able to cause an unprecedented storm surge in the Irrawaddy River Delta. The only saving grace was the relatively small size of the cyclone.

Human factors helped make the storm surge worse. About 80% of the mangrove forest along Myanmar's coast has been destroyed, to make room for rice paddies and shrimp farms. Mangroves--tall, gnarly, salt-tolerant trees--act to blunt and slow down the progress of the storm surge and reduce the wave action of the ocean. Had more mangroves been left to survive, the impact of the storm surge would have been lessened. How much so, no one can say, for there are few observations of the storm surge to verify models of this. Keep in mind that the mangroves are far more effective in protecting against a sudden, powerful wave like the 2004 tsunami, compared to the slower, hours-long inundation of a storm surge.


Figure 2. Topography of Myanmar, with track of Cyclone Nargis superimposed. Image credit: NASA.

Failure of the Myanmar government
Nargis was remarkable not only for its death toll, but for the failure of Myanmar's dictatorship to provide adequate warnings before the storm. The Indian Meteorological Department (IMD), which is responsible for tropical cyclones warnings in the North Indian Ocean, classified Nargis as a "severe cyclonic storm" three days prior to landfall, and warned of landfall in Myanmar of Nargis as a Category 1 or 2 storm. However, the official state-controlled New Light of Myanmar newspaper carried this forecast the day before landfall: "the severe tropical cyclone NARGIS...is forecast to cross the coast during the next 36 hours...Under the influence of this storm, rain or thundershowers will be widespread...frequent squalls with rough seas will be experienced off and along the Myanmar coast. Surface wind speed in squalls may reach [50] mph." This forecast was buried on page 15 of the miscellaneous section of the newspaper. No mention of hurricane-force winds or of Nargis' storm surge was made. However, the IMD does not make forecasts of storm surge, which is something that needs to be corrected in the future, according to an excellent assessment of Cyclone Nargis published in Nature by Dr. Peter Webster of Georgia Tech. Dr. Webster also advocates that a relatively small investment by the developed world in improved warning systems and shelters for the region can dramatically lower death tolls and the money needed for aid responses for future storms. Sounds like a great investment to me!

Finally, Nargis was also remarkable for the initial refusal of Myanmar's government to allow foreign aid into the country after the storm. Over a week passed before significant aid was allowed in, which greatly exacerbated the suffering of the storm victims and undoubtedly led to a higher death toll.

Nargis links
Post-Nargis Joint Assessment (July 2008).
Post-Nargis Periodic Review I (December 2008).
Nature paper by Dr. Peter Webster of Georgia Tech (July 2008).

My next blog post will be Wednesday or Thursday, when I'll continue to report on the major weather and climate events of 2008.

Jeff Masters

Updated: 6:30 PM GMT en Enero 06, 2009

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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.

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