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Posted at 11:00 AM ET, 08/16/2010

TWC's Stu Ostro talks weather-climate links

By Andrew Freedman

* Sticky, stormy: Full Forecast | Cool off with a joke *

Extreme weather has dominated world headlines recently, with a record-smashing heat wave in Russia as well as deadly flooding in Pakistan that may rank as that country's worst natural disaster. Here at home, we've endured a sizzling summer, and NOAA announced last week that 2010 is still on track to be the warmest year on record (although La Nina may knock it back a rank or two).

The relationship between global climate change and these extreme events is complex in that climate change did not specifically cause them to occur, but likely did influence them, perhaps in significant ways. An article in Sunday's New York Times clearly laid that out, and (as I have previously noted), Jeff Masters of Weather Underground has provided uniquely in-depth coverage of possible links between climate change and extreme weather

Stu Ostro, senior meteorologist for The Weather Channel, is a rare breed of meteorologist who is increasingly focused on the intersection between climate and weather. A former climate change skeptic, he has compiled a lengthy presentation showing changes in weather patterns that he believes may be related to climate change.

In an email interview during the weekend, Ostro shared his thoughts on climate change and extreme events, and what has convinced him that climate change is now manifesting itself in daily weather patterns.

Andrew Freedman: As a meteorologist, you've been noticing changes in certain weather patterns and the frequency/characteristics of extreme weather events in recent years. What are some of the changes that you've seen, and how do you think they may be related to global climate change?


Stu Ostro
Stu Ostro: I have been closely looking at weather charts since I started college in 1976, when I first gained routine access to them (that was long before the Internet!). By coincidence, that's the year after which globally-averaged temperatures commenced a significant warming trend. Fast forward to the most recent decade. I was noticing that something had changed: the 500 millibar heights seemed to be getting higher. In other words, the pressure a few miles up was rising, at a level which is important to meteorologists and whose charts we routinely analyze. It was like an irresistible force was exerting pressure (no pun intended) on the atmosphere.
My epiphany came a few years ago, when I started looking at the data going back to the 1970s and found that the long-term trend of average annual pressures at that and other levels aloft was indeed significantly upward, especially in the Northern Hemisphere, during the same time that average temperatures had risen significantly. At the same time, what meteorologists call the "1000-500 millibar thicknesses" had demonstrated a similar trend. The depth of that layer of the atmosphere was increasing, and that's directly related to the mean temperature of the layer.
And what also seemed to be happening was that not only was the average pressure aloft rising, that was manifesting itself via particularly strong and/or persistent individual (day-to-day, week-to-week) ridges of high pressure aloft. They in turn are associated with intense heat waves in the summer and unusually warm stretches at other times of year. Furthermore, in tandem with those strong ridges there have been a lot of notable "cutoff lows" (low pressure systems aloft that have been cut off from the main jet stream), and they are often associated with precipitation extremes as well as topsy-turvy temperature patterns.

AF: What do you tell people who ask questions such as, "is this heat wave because of global warming," or "is this flood because of global warming?" The issue of attributing extreme events to climate change is very complex, and I know you've worked to more clearly communicate what is and isn't known.

Ostro: Yes, the system is indeed very complex, and not every weather event can or should be attributed to climate change. But that doesn't mean that no weather events can be linked to it. This was my second epiphany. On December 4, 2006 I went over to the dark side, sending an email to some of my colleagues at TWC which included, "I can no longer accept the mantra of 'individual weather events can't be connected to global warming,' much less be the vocal proponent thereof as I used to [be]."
If I'm asked about a particular event, I objectively look at the data and the pattern and the impacts, and evaluate the degree to which I'm willing to connect that event to the large-scale warming.

AF: Whenever I write about how climate change may already be altering weather patterns, and the changing the nature of extreme events, I get a lot of push back from people who accuse me of mistaking weather for climate, or opportunistically crying "global warming" every time the weather does something strange. Have you had that reaction from people, and how do you respond to such criticism?

Ostro: I've given talks at workshops and conferences where the previous speaker(s) made it a point to highlight the difference between climate and weather, and I've made it a point to highlight the connections. I'm doing everything I can to get people to break out of the paradigm that climate and weather are separate entities. Aside from the two being intimately and inexorably linked, like the brain and the heart, or a book and its chapters, with weather and climate there's a continuum of scales of time and space.

AF: What is the quintessential example of a recent extreme event that you think was especially consistent with climate observations and projections? In other words, what event really stands out in your mind when you think about a climate change-related extreme event?

Ostro: The obvious one is the Russia heat wave, which has been extraordinary in its intensity and duration, and associated with an exceptionally persistent and strong ridge of high pressure aloft - the same signal as, but even stronger than, the one which was present during the peak of the 2003 Europe heat wave. And this time the heat and ridge were related to a persistent downstream trough just west of Pakistan from about July 20 through the first few days of August, which in turn was associated with the exceptional rainfall and flooding there. At times that trough evolved into a cutoff low, like what I described earlier.

AF: How would you characterize the views within the meteorological community, and specifically the TV meteorology community, toward possible links between climate change and extreme events? Do TV meteorologists tend to downplay potential links, in your opinion? It seems to me that much more work is being done within the climate change community to look for relationships between long-term climate change and shorter-term extreme weather events, despite the fact that short-term weather is in the meteorologists' domain.

Ostro: There have been surveys done which document that a lot of skepticism exists amongst TV weathercasters/meteorologists, and the operational forecasting community in general, about anthropogenic global warming (AGW), both the seriousness of the warming and the amount of the human role. That's been my anecdotal observation as well. Such doubt also undoubtedly exists about linking extreme events to climate change, regardless of cause, but I don't know whether it's more or less than about AGW in general.

AF: You've been documenting extreme weather events for some time now, and have accumulated a ton of data on how the warming climate may already have altered certain atmospheric characteristics. What do you hope to do with this data, and what has the reaction been among people who have seen your presentation?

Ostro: There has been an extreme, and extremely interesting, split in the reaction. Of course hard-core "skeptics" have reacted with cynicism (more so to my blogs than my presentations). I've been called a lot of names, and lately the critics have gotten quite creative, in one case a blogger dubbing me "Mr. Ostroass."
But interestingly, quite a few meteorologists who had previously been highly skeptical about anything to do with global warming have had an enthusiastically positive response. Some of that may be because I'm "speaking their language," i.e. communicating to them by way of weather events and data and charts to which they can relate. I've also received feedback that they've appreciated that I haven't "talked down to them" like they have perceived some climate scientists to have done.
Speaking of climate scientists, I experienced that attitude myself from a well-known one upon seeing an early version of my documentation back in 2005, but I did not let that discourage me. Since then, I have received a lot of encouragement from some top climate scientists, though others have still had a rather chilly reaction. My sense is that for them, they won't take what I've done seriously until it has been subjected to the rigor of a formal analysis followed by the peer review process and then publication in the traditional scientific literature. With the help of collaborators, that's what I hope to do.

The views expressed here are the author's (and interview subject's) alone and do not represent any position of the Washington Post, its news staff or the Capital Weather Gang.

By Andrew Freedman  | August 16, 2010; 11:00 AM ET
Categories:  Climate Change, Extreme Heat, Freedman, International Weather  
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Comments

So my big question is this: had we heeded Dr. Hanson's advice twenty two years ago in 1988 and kept emissions as low as his most optimistic scenario, then the Russian heat wave would not have occurred? Is that what we are saying by linking the Russian heat wave to climate change? Could we have also perhaps prevented the record cold Bolivian weather and the subsequent fish kill?

Posted by: MattRogers | August 16, 2010 11:19 AM | Report abuse

The events in Bolivia could be made more plausible if the rest of the globe was not seeing warm temperatures. Many parts of the globe have seen record breaking heat- and the first 7 months of 2010 have been the warmest on record.

The events in Bolivia are a small amount of variability that would NOT deny the existence of climate change.

Posted by: sleepership | August 16, 2010 11:26 AM | Report abuse

But couldn't the argument that climate change breeds more extremes also support the cold extrema? And perhaps the record high ice in Antarctica perhaps driven by extreme patterns? http://nsidc.org/data/seaice_index/images/s_plot_hires.png

Posted by: MattRogers | August 16, 2010 11:31 AM | Report abuse

Mr Ostro has done well so far considering the complex nature of weather and how it can be influenced by the slight overall warming provided by manmade CO2.

He is ready for the next step which is to study models (I have to dig up the link for huge list of model studies) and read Willis Eschenbach's paper on his thermostat hypothesis. Then he will realize that these events are an indication of negative feedback. In short, global increases in concentrated convection, rainfall, rainfall extremes, heat waves from high amplitude block patterns, all cause "global cooling". These are unequivocal model results. The only remaining questions are whether the hypothesized worldwide increases in extremes are in fact real (they may not be), and to quantify them so that we can determine the approximate amount of negative feedback.

Posted by: eric654 | August 16, 2010 11:37 AM | Report abuse

To my first sentence I should add "plus natural, typically cyclic, warming from various factors like PDO"

Posted by: eric654 | August 16, 2010 11:38 AM | Report abuse

Matt - Given CO2's atmospheric lifetime, even a complete cutoff of CO2 emissions in 1988 would not have helped alleviate climate change for several decades at least. Plus, you can't say definitively that climate change "caused" the Russian heat wave. Same with the cold weather in Bolivia (not an all-time record, btw). Perhaps Stu would differ with me?

As you know: studies have found that as the world warms, we can expect more warm extremes vs. cold extremes, but that cold extremes won't cease to occur.

The record high sea ice in Antarctica may have more to do with ozone hole-related circulation shifts than anything else, and it certainly does nothing to diminish the significance of sea/land ice loss in the Far North, where climate models and theory have long found would experience more rapid warming anyway.

Have you viewed Stu's presentation? As a meteorologist, you would probably find it quite interesting.

Posted by: afreedma | August 16, 2010 12:37 PM | Report abuse

I've generated a chart of difference in the the summer average (JJA) 500mb height between the periods 1995-2009 and 1979-1994:
chart

The result is consistent with Stu's general impression that 500mb heights are getting higher (more yellow to red), though not everywhere, over the northern hemisphere.

Of particular interest is that the maximum increases are occurring over the climatological favored regions for blocking - north Atlantic, north central Europe to Russia, and central Pacific.

Blocking is an incredibly complicated process involving, for example, up and downstream cyclogenesis, which in turn is dependent upon fronts, winds, etc. If all this is tied to climate change, there's a lot going on which requires explanation, offering a significant challenge to researchers.

Posted by: SteveT-CapitalWeatherGang | August 16, 2010 1:06 PM | Report abuse

Steve, nice work, thanks.

That's a pretty short period; it will be hard to separate out decadal cycles from trends. But the bullseye over Moscow is certainly interesting in the present context, as is the huge trough in central Asia!

Posted by: mtobis | August 16, 2010 2:01 PM | Report abuse

I'll save a link to this article when we have the weather is not climate debate next winter during a snow storm.

Lets get real- Heat waves have always existed. Severe storms have always existed. The big difference is with 24/7 news coverage extreme weather events get much more publicity. The weather channel and CNN fighting for who can call themselves hurricane central is just an example.

Posted by: Tom8 | August 16, 2010 2:31 PM | Report abuse

But the IPCC keeps telling us that weather is not climate and the two shouldn't be compared.
You doomers sure get desperate sometimes.
TOO TOO funny.
History will laugh too.
Pollution, Population and Birth Control, NOT Climate Control!!!!!!!!!!

Posted by: paulmerrifield | August 16, 2010 3:08 PM | Report abuse

Stop this insanity NOW!
I want reporters and news editors arrested for leading this false war of climate variation.

Posted by: paulmerrifield | August 16, 2010 3:09 PM | Report abuse

Matt - Interesting study out today on Antarctic sea ice projections. Wired Science writetup: http://www.wired.com/wiredscience/2010/08/antarctic-ice-future/

Posted by: afreedma | August 16, 2010 4:06 PM | Report abuse

does 305 months of weather = climate?

for the 305th month in a row, the most recent monthly global temp was above the 20th century average...

from
http://www.ncdc.noaa.gov/sotc/?report=global&year=2010&month=7&submitted=Get+Report

# The combined global land and ocean average surface temperature for July 2010 was the second warmest on record, behind 1998, at 16.5°C (61.6F), which is 0.66°C (1.19°F) above the 20th century average of 15.8°C (60.4°F).

# The July worldwide land surface temperature was 1.03°C (1.85°F) above the 20th century average of 14.3°C (57.8°F)—the warmest July on record.

# The worldwide ocean surface temperature was 0.54°C (0.97°F) above the 20th century average of 16.4°C (61.5°F) and the fifth warmest July on record. The warmth was most pronounced in the Atlantic Ocean.

# La Niña conditions developed during July 2010, as sea surface temperatures (SST) continued to drop across the central and eastern equatorial Pacific Ocean. According to NOAA's Climate Prediction Center, La Niña is expected to strengthen and last through the Northern Hemisphere winter 2010-2011.

# For the year-to-date, the global combined land and ocean surface temperature of 14.5°C (58.1°F) was the warmest January-July period on record. This value is 0.68°C (1.22°F) above the 20th century average.

(the july report doesn't say anything about consecutive warm months, but the report for june notes that it had been 304 months since the monthly temp was below the 20th century "average".)

eric, you're right: this streak has just got to end sometime...maybe august will be the month? ;-)

Posted by: walter-in-fallschurch | August 16, 2010 5:15 PM | Report abuse

Thanks Andrew for the link to the study. I fully expect Antarctica to start fading around the time the Arctic begins recovering (or has it already?). I also look forward going through Stu's lengthy presentation. I have a great deal of respect for Mr. Ostro!

Will you be addressing the new statistician paper on the Hockey Stick anytime soon? Their assessment 'rediscovers' the pesky Medieval Warm Period (MWP). It's the third peer-reviewed paper from the bottom: http://www.imstat.org/aoas/next_issue.html

Posted by: MattRogers | August 16, 2010 5:26 PM | Report abuse

Walter not August although at least it is cooling off a bit. Northern Greenland seems to have cooled off nicely
http://weather.unisys.com/upper_air/ua_nhem_850.html

I have another technically correct contradiction to your claim of 305 months below the 20th century average. The global average temperature in July was about 1C below the 20th century average. In December the global average temperature will be about 3C above the 20th century average. That's because there is a 4C swing in global average temperature between aphelion and perihelion. Of course that swing doesn't matter so they subtract it from the GISS, UAH, CRU, etc. But it also means the global average temperature doesn't matter either, only local temperatures. Because really, only how hot you are matters or maybe how hot Greenland is (not hot at all right now).

Posted by: eric654 | August 16, 2010 6:32 PM | Report abuse

The oil spills, hurricanes, floods, mudslides, and the global heat wave (which have been the cause of many fires, toxic smoke, and deaths) have many searching for answers. The internet is buzzing with articles and excellent blogs. But could it be simply the biblical sequence of God's wrath being poured out upon the earth which is relevant to current events in today's world. What if we are dealing with the wrath of God? Please understand the wrath of God is letting man slip deeper and deeper into the consequences of his own sin. Please visit my website at http://www.revelation-truth.org . Rev. Daniel W. Blair author of the book Final Warning

Posted by: daniel24 | August 16, 2010 6:39 PM | Report abuse

Steve, probably interannual cycles such as ENSO would still influence 15-year average heights. For the heck of it, I changed your year limits to make 30-year average height differences:

another chart

That means of course going back to the pre-satellite era for which one has to take upper-air analyses with a grain of salt. Over Europe, parts of Asia, North America, and I believe the Gulf of Alaska, rawinsonde coverage was adequate, but the bullseyes over the central Pacific and the Arctic should be discounted. Anyway, the pattern becomes more spread out now, with the biggest warming in Eurasia with smaller warming over North America (light blue is still positive, as the zero line is in the dark blues).

P.S. Welcome to the gang, mt.

Posted by: imback | August 16, 2010 7:02 PM | Report abuse

eric, "my" (noaa's actually) claim is 305 month above the 20th century average. i presume that's what you meant. re perihelion/aphelion: i guess that's why they compare july to july etc...

Posted by: walter-in-fallschurch | August 16, 2010 7:15 PM | Report abuse

Matt- this article is groundbreaking. To have an actual statistician try to reproduce the findings of Mann et al. is very insightful. It is too bad Andrew would not give fair time to any dissenting article, but this is the bias that we all know exists on this website.

Posted by: Tom8 | August 16, 2010 7:57 PM | Report abuse

"The global average temperature in July was about 1C below the 20th century average. In December the global average temperature will be about 3C above the 20th century average. That's because there is a 4C swing in global average temperature between aphelion and perihelion."

Eric: I think you have your temperatures reversed. My understanding was that while the Earth is indeed further from the sun in July, it is actually, on average, warmer than it is in December. That's because the low heat capacity of all that Northern Hemisphere land that is pointed at the sun in July has a larger effect on average temperatures than the Earth's distance. Having said that, I think that Walter's use of anomalies to track large scale anthropogenic climate change is the right way to go.

MattRogers: Do you mean the annual Arctic sea ice recovery which usually starts in September, or are you claiming that 2007 was a minimum for Arctic sea ice and Arctic sea ice will start growing on average?

Posted by: marcusmarcus | August 16, 2010 8:14 PM | Report abuse

imback

The 30 year period is sure to smooth out the changes. The two 15 year periods I specifically selected because they are essentially the periods Stu was basing his impression that 500 mb heights were increasing (and because 1979 - the first year of the first period - was the first time satellite data became available.

I certainly agree that decadal trends and/or differences in the characteristics of El Nino events (occurring in both periods) may have played a role in the differences from the first to second 15 year period. Whatever the reason, the trend of increasing heights is real and must reflect warming of the atmosphere at least between the surface and a few miles up (little difference in 1000 heights, so thickness (temperature) increasing

Anyone out there looking for a thesis topic??

Posted by: SteveT-CapitalWeatherGang | August 16, 2010 8:39 PM | Report abuse

marcusmarcus, you are right. Here's more detail backing up what you said: http://spaceweather.com/glossary/aphelion.html In any event, they adjust that difference out of the anomaly data. Also the temperature anomaly is the most precise way to track changes, so Walter would probably need to say something like "anomaly from 20th century average was greater than zero for 305 consecutive months".

Posted by: eric654 | August 16, 2010 9:33 PM | Report abuse

Walter, I meant above (typo). But the more precise statement would use "positive anomaly" since that can be done by comparing each month to that monthly average without adjustments. If you say "temperature" then you would have to say "adjusted global average temperature".

Posted by: eric654 | August 16, 2010 9:40 PM | Report abuse

Marcusmarcus: That's a very good question for Matt re: sea ice. His implication re: Arctic sea ice recovery struck me as odd, to say the least.

Matt - I saw Watts' post on the statistics paper yday and am looking into it. Question for you though: If the Hockey Stick study were proven completely invalid tomorrow, what would it mean for the larger body of evidence supporting manmade climate change? Many people attack that study as if it were the bedrock of climate change research.

Posted by: afreedma | August 16, 2010 10:27 PM | Report abuse

For a planet that is 4.5 billion years old, we seem to be breaking a lot of "records" in the past 65 television years. Really ? C'mon, this planet is not done evolving, it will always change, with or without man. In Missouri I regularly find fossils of sea life. I don' think this means I need to drive a Prius. Let's stop trying to save the planet...let it do what it's going to do and enjoy the ride until Al Gore creates a perfect environment on MARS. Today's datum is presented as if I am supposed to be scared..another TV media tactic to keep all of us in suspension. Get over it, mankind will not last forever, so stop trying to save geopolitical borders due to drought...let nature happen normally.

Posted by: solarstar777 | August 17, 2010 5:53 AM | Report abuse

Marcusmarcus, yes, I put a question mark on my 'has it started already?' comment because 2008 saw more end-of-year ice than 2007 and 2009 saw more end-of-year ice than 2008. Could 2010 follow suit here? So far it looks like we will again stay at least well above the 2007 low.

Andrew, the part of the hockey stick that is most contentious is the removal of the MWP with the purpose of stating we've never been this warm in the human record. This stats paper is refuting that, seemingly.

Posted by: MattRogers | August 17, 2010 6:12 AM | Report abuse

I think the most basic conclusion from the new stats paper is that the methodologies used to remove the MWP, especially in 1998 (fig 1 in the new paper), are not supported in mainstream statistics. The 1998 paper (Mann98) had some really egregious errors like the use of normalization over just the instrumental record period instead of the whole period which when followed by PCA produces hockey sticks (high variance in instrumental record and low variance before).

The Mann 2008 paper (fig 2 in the new paper) has several problems including ("hide the decline" - arbitrary truncation of recent proxy data) and more importantly, that Mann's techniques for extracting the temperature will produce hockey sticks from certain types of noise.

An important thing to remember is that the new work takes all the proxy data at face value. It has been amply shown elsewhere that some of the proxy data should not be use (Bristlecone pines) and some is used incorrectly ("upside down Tiljander"). When those are removed, the Mann 08 results are not statistically significant before 1500 (IOW, can't say anything definitive about the MWP).

In short, the new paper destroys the old hockey stick http://upload.wikimedia.org/wikipedia/en/e/ed/Hockey_stick_chart_ipcc_large.jpg and adds very large uncertainty intervals to the newer hockey stick
http://upload.wikimedia.org/wikipedia/commons/b/bb/1000_Year_Temperature_Comparison.png

Posted by: eric654 | August 17, 2010 7:27 AM | Report abuse

solarstar777, you said,
"Let's stop trying to save the planet...let it do what it's going to do and enjoy the ride..."

jeez...were you a bush-appointed EPA official?

Posted by: walter-in-fallschurch | August 17, 2010 8:12 AM | Report abuse

Andrew- I will jump in with an answer. The hockey stick has been held as demonstration that the climate we are experiencing today is much different than anything that has occurred in the past. It has been used to support that anthropogenic causes are undoubtedly behind the recent spike in temps.

Posted by: Tom8 | August 17, 2010 9:45 AM | Report abuse

matt, marcus, andrew,
any idea where we could find a graph like this but with more years shown?

http://nsidc.org/data/seaice_index/images/daily_images/N_stddev_timeseries.png

also, it would be nice to see one showing the whole year...

Posted by: walter-in-fallschurch | August 17, 2010 9:53 AM | Report abuse

oops, i meant to include eric in that last salutation...

Posted by: walter-in-fallschurch | August 17, 2010 10:03 AM | Report abuse

Walter, I found most recent monthly levels for the entire data set (back to late 1970s) from NSIDC. You can see the inverse behavior of both Poles right now:

http://nsidc.org/data/seaice_index/images/s_plot_hires.png

http://nsidc.org/data/seaice_index/images/n_plot_hires.png

Of course, you are working with much higher numbers in the South (mean of 16 million km vs. 10 in the North).

These sites will update in Sept with the August values and so on...

Posted by: MattRogers | August 17, 2010 10:10 AM | Report abuse

Posted by: eric654 | August 17, 2010 10:19 AM | Report abuse

thanks guys. that graph eric found is more like what i was imagining. it would be nice if it also showed the '79-2000 average line. eyeballing it from the NSIDC graph, it looks like the '79-2000 average minimum is around 7,000,000 sq.km. that value is above any value shown on the eric's graph.

so, matt, when you say you're expecting a "recovery", do you expect it to go back up above that '79-2000 average? i mean, that would be more like a recovery, not just a situation where we avoid setting minimum records.

Posted by: walter-in-fallschurch | August 17, 2010 11:07 AM | Report abuse

Yes, Walter, that will be the big question. It seems like we are at an important moment. When we had the 2007 low, predictions were made (and repeated by politicians like John Kerry) of an ice-free Arctic in 3-5 years. So it would appear that we would need to start testing that 2007 low point if we are to continue this downward trend in the direction of that forecast. I believe it is fantastic that we can track this data via satellite and wish we had it prior to the 1970s.

Posted by: MattRogers | August 17, 2010 11:25 AM | Report abuse

Steve, mtobus, and imback,

To imback's point about the colors, yes, the ESRL site's default color schemes and scales can be a bit misleading when subtracting sets of years. Here are the same charts, but with white as the near zero color and equal positive/negative scales. Although subtracting anomalies, the net result is the same set of values as on your maps, and the colors give a more intuitive sense of the domination of positive vs. negative.

http://tinyurl.com/500mb-SteveT
http://tinyurl.com/500mb-imback

Yes, mtobis, that positive bulls-eye near Moscow is interesting ...

And Steve, yes, that was a key to my epiphany: that there's been a pronounced trend upward in the 500 mb heights but not the 1000 mb heights. So, the warming of the atmosphere is manifesting itself via rising 1000-500 mb thicknesses, which makes sense, and in turn that's manifesting itself via rising 500 (+/-) mb heights.

Posted by: StuOstro | August 17, 2010 9:36 PM | Report abuse

Matt - John Kerry really predicted the complete disappearance of Arctic sea ice in the summertime by 2010? Seriously? I don't recall that at all.

If you read the scientific literature on sea ice loss in the Arctic, and the causes of it and consequences as well, I don't think you'd find many people who claimed such a quick decline (with credibility, at least). Nor will you find many who think that the fact that '08 and '09 were slightly above 2007 represents a sustainable recovery. We can examine the 2010 numbers at the end of the melt season - still a couple of weeks left.

Posted by: afreedma | August 17, 2010 11:00 PM | Report abuse

Unfortunately, Google has offered me multiple/conflicting John Kerry predictions. Just last month, he revised his threat to 5-10 years out. But last summer he wrote a story threatening 2013.

http://www.politifact.com/truth-o-meter/statements/2009/sep/02/john-kerry/kerry-claims-arctic-will-be-ice-free-2013/

http://blog.washingtonpost.com/capitalweathergang/2008/06/north_pole_ice_could_briefly_d.html

http://www.boston.com/news/nation/washington/articles/2007/12/12/arctic_ice_melt_spurs_a_dire_new_warning/

Haha Andrew...look at this one from the WashPost talking about rapid Antarctic melt! http://www.washingtonpost.com/wp-dyn/content/article/2006/03/02/AR2006030201712.html oops

http://www.boston.com/news/politics/politicalintelligence/2009/07/kerry_panel_loo.html

So the 2013 prediction made in 2009 is the closest I could find...but I can't seem to find his comments from 2007/2008 on it. Nonetheless, if we are to reach this 2013 low, we will need to start testing the 2007 record, right?

Posted by: MattRogers | August 18, 2010 6:51 AM | Report abuse

Hi Matt,
While sea ice is growing around Antarctica, the ice sheet is losing ice (estimates here:
http://www.agu.org/pubs/crossref/2009/2009GL040222.shtml)

Some perspective is needed however. The estimate of loss (246 Gt / year which is about 273 km3 / year) is .0011% per year since Antarctica has 25,000,000 km3 of ice.

Posted by: eric654 | August 18, 2010 9:37 AM | Report abuse

Matt - re: Antarctica, the WashPo article you pointed to was about the ice sheet (i.e. land ice). Not sea ice. There is a very big difference between the two.

The 2013 date may have come from testimony provided to the Senate Foreign Relations Committee from various scholars/national security professionals, who have cited that date as a possible summer melt out point. An article a year or so ago in Foreign Affairs cited this date, for example. I disagree with that assessment, as it seems way too early to me based on recent trends, but it depends on how you define "ice free in summertime."

Posted by: afreedma | August 18, 2010 10:34 AM | Report abuse

Thanks Eric and Andrew. Looks like I did confuse the distinction there re: Antarctic ice sheet vs. sea ice!

Posted by: MattRogers | August 18, 2010 2:15 PM | Report abuse

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