Perils and Pitfalls of Event Attribution
Perils and Pitfalls of Event Attribution
Some of you may have noticed a story that originated in the Green Blog by John Rudolf on the New York Times website (March 9, 2011) about the Russian heat wave in the summer of 2010. The news story reports on a paper to appear in Geophysical Research Letters by Randy Dole and co-authors who conclude that in the historical record there is evidence of similar events of comparable intensity. It follows, they argue, that the Russian heat wave cannot be attributed to climate change – rather it is a very rare event. (Paper at GRL website, NOAA Description of Dole et al. article, Jeff Masters blog and analysis) For a variety of reasons I followed how this story propagated around the blogs and news services for the next 24 hours. It was picked up by many sites including, quickly, by the (according to comment writers on this blog) mysterious Steven Goddard (any more on that story?).
As it happens, I am writing an article for Earthzine with Christine Shearer on how scientists and the media engage each other about extreme events (Shearer blog on WU). When it is ready, I will proudly announce it and provide a link. That article will focus on a sociological analysis of extreme weather and the media. This blog will touch on a couple of the issues we raise in that article, but mostly it will be a scientist's point of view on the discussion of the value of pursuing the attribution of single events to climate change in a context largely described by public discourse.
Event Attribution: A public question that arises after every new extreme event is: can this event be attributed to climate change? At this point in time, I cannot imagine the answer to that question ever being, convincingly, yes. Scientists often rely on the statement: no single event can be attributed to climate change, but this event is not inconsistent with climate change. I have used that answer; perhaps, I repeat the mantra (Pakistan: A Climate Disaster Case Study). On thinking about that answer, it is more than useless. But then thinking about the question, it is, depending on your point of view: a natural question, a naïve question, an ill-posed question, or a leading question.
Why do I say that I cannot imagine the answer to such an event attribution question being convincingly yes?
Dole et al. study attribution, and they do it magnificently. Their strategy is to do a physical, statistical, and process analysis of historical information. If they find like events in the historical data, then that makes it impossible to attribute the event, wholly and solely, to climate change. This implies an odd metric: an event that is “caused” by climate change must be different than any event that has been previously measured. Do we have to have some Day After Tomorrow event where physical principles are suspended and the world moves to a whole new set of behavior?
The probability that looking through all of the observations, all of the history, that you are going to find a “like event” is high. I say “like event,” because there will be some differences no matter what. Of course, it has been hot in Moscow before, so there is some atmospheric pattern that yields “hot in Moscow.” We find like events and then, maybe, the current event is 10 degrees hotter and two weeks longer; it’s a obvious record. But is it climate change?
More likely than a obvious record, there will be another event that is similar, about the same, but not quite. Then it becomes the same question as, was Henry Aaron better than Babe Ruth? Aaron hit more home runs, but there are lots of other differences that experts point to and argue about: length of season, quality of pitching, … . Throw in Barry Bonds and Mark MacGwire; they hit a lot of home runs. Well maybe the physics (or physiology) of Bonds and MacGwire are different? Is climate change weather on steroids?
Suppose you look through the record and find that the current event is 10 degrees warmer and 2 weeks longer. Is it climate change? Do you know whether or not that if you had just one more year of observations, that you would not find out that that next year had a similar hot period. What about similar events in the medieval warm period? The data system was relatively sparse 100 years ago; maybe we just missed the event. So even if we find an event that is more intense, more persistent, then we have the problem - have we really observed the historical extremes? Have we observed all natural variability? This will always challenge the public and political discourse on event attribution - always.
More likely than finding an event that is extraordinarily different, we find an event that’s about the same length of time, but one degree warmer. Is the thermometer good enough? Are the instrument sites good - have they changed? What about the urban heat island? What about regional water management projects? Good scientific investigation and analysis can account for these issues, but in any event they are sources of differences, which as in the Aaron versus Ruth argument, are irreducible. Perhaps an extreme record can be established, but then, would that be climate change?
It is hard to see how playing the game of defining extreme events and then attributing that event to “climate change” can ever be won. It is often possible to isolate with statistical certainty descriptions that the emissions of greenhouse gases have influenced an event, but that represents one of those paths of nuanced explanation. Such nuanced explanation, again, assures there is not a definitive "yes" in the public and political discourse. In fact, it seems like it is a game that necessarily leads to controversy, and controversy is the fuel of talk radio, blogs propagating around the world, and the maintenance of doubt.
But what about that question of attribution? Let’s say you find an event that is rare, that is extreme, but not a new record - does that really say that the event today, right now, is not climate change?
In a very basic, old fashioned way, weather and climate are different descriptions of the same thing. They depend on how we, somewhat arbitrarily, define how we want to organize the observations. Crudely, we average weather to make climate. Since we work from the premise that climate change will be slow, for the most part the same type of weather events will make up the old (natural) climate and the new (changed) climate. Over time, the frequency of events will change, what were rare events in the old climate, might just be less rare events in the new climate. I pose, however, that even in a world that is on average four degrees warmer than today, there will be a seventy two degree, sunny day in the spring in Washington D.C. Do we then march through the days 50 years from now and say, “old climate,” “new climate?” The idea of isolating a single event on a single day or a persistent event and asking if it is caused by climate change – does that make sense? Is it even meaningful given the definition of climate? How did we arrive at the question of climate change being a causative of a weather event?
I want to restate the previous paragraph in a different way. Let’s assume that climate is averaged weather. Then climate is defined by a mean, a standard deviation, and a set of more sophisticated parameters that describe statistical distributions. What we have come to call the natural climate is defined by certain values of the mean and measures of deviations from the mean. The future, changed, warmer climate will have different values of the mean and the measures of deviations. With the presumption that the warming of the climate is incremental, then the majority of the events in the warmer climate will be like the events in the “natural” climate. Therefore, just because a like event existed in the "natural" climate does not mean that the current event is not part of the "changed" climate. There are NOT two climates - a natural one and a changed one - with our job being to determine if we have flipped from one to another. When we say that there will be more extreme events in the changed climate, it does not necessarily mean there will be a relentless unwavering string of records. There will, perhaps, be more events that have been previously rare. But, it is not climate change causing weather events.
As you study climate change, it becomes clear that talking about independent isolated events is not especially productive when trying to address attribution questions. Climate is an average, or perhaps better, an accumulation of weather events. As such it is important to consider how a large number of events act in concert, in correlation, in cohesion.
One other point that I want to make: The practice of isolating a single event and attributing that event to climate change, is one of the most effective ways of opening up scientific investigation to effective scientific criticism. (see Pielke, Sr. et al. 2007) A single-event attribution claim is an open and appropriate invitation to those with knowledge of or interest in local information to investigate the attribution claim. Almost inevitably this leads to identification of more sources of uncertainty, which like the Aaron versus Ruth argument, are irreducible. This necessarily contributes to controversy, and controversy is the fuel of talk radio, blogs propagating around the world, and the maintenance of doubt.
This entire process of event attribution is one place where scientific investigation of the climate interfaces with the media. Therefore, it is also a place where, by definition, scientific investigation interfaces with the political argument. My analysis above suggests that, as framed by the public discourse, the pursuit of the path of event attribution and the explicit or implicit linkage of that attribution to climate change is scientifically questionable. This stands in contrast to the scientific pursuit of extreme events in historical context and the evaluation of whether their frequency of occurrence is changing. Politically or in terms of informing the public, the primary product of the pursuit of event attribution is to build and maintain doubt. The exception to doubt maintenance would be if a definitive, metaphorical smoking gun was discovered. But what is the probability of such a smoking gun being discovered in this process? A different perspective is needed on the role of extreme events in climate and the attribution of such events to global warming. As climate scientists, we have to think about what these studies mean to the body of our field’s communication of climate change.
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Maybe try googling "thesis" and the spelling of it.
LOL
"Steve-o"
Out for now; Play nice everyone.
Really now! Have you ever worked in a nuclear power plant or on the reactor vessel,primary cooling water pumps,boron injection pumps,inside a steam generator, on the control rod drive mechanisms,the missile shield,the secondary steam loop, tandem compound steam turbine or hydrogen cooled generator or emergency diesel generators? How do you know how bad it will get?
Like I said I don't want one atom of it in my lungs. Do you?
"The Atmospheric Avenger" ..?
He should of went with "The Toxic Avenger" I thought,,but its already taken.
Solar doesn't shine all the time only half the day and it gets covered with clouds a lot of the time. Wind doesn't blow all the time,with hydro you need lots of rain,geothermal moves around a lot and can dissipate.
Gulfstream kinetic energy isn't even listed which flows 24/7/365 for millennium unlike any of the on the graph you posted. How big of a box would it be on that graph anyways?
GULFSTREAM KINETIC energy can prevent this in the future! GET THEM NOW! before it is to LATE AGAIN!
Low radioactivity heads for N. America
Low concentrations of radioactive particles are heading eastwards from Japan's disaster-hit nuclear power plant and are expected to reach North America in days, a Swedish official said Thursday. Lars-Erik De Geer, research director at the Swedish Defence Research Institute, a government agency, was citing data from a network of international monitoring stations established to detect signs of any nuclear weapons tests.
Stressing that the levels were not dangerous for people, he predicted the particles would continue across the Atlantic and eventually also reach Europe.
"It is not something you see normally," he said by phone from Stockholm. But, "it is not high from any danger point of view."
He said he was convinced it would eventually be detected over the whole northern hemisphere.
"It is only a question of very, very low activities so it is nothing for people to worry about," De Geer said.
U.S. boosts radiation-sniffing system
"In the past when they had nuclear weapons tests in China ... then there were similar clouds all the time without anybody caring about it at all," he said.
Before he spoke, the U.S. Nuclear Regulatory Commission advised any Americans living near Japan's crippled Fukushima nuclear plant to move at least 50 miles away but it played down the risks of contamination to the United States.
"All the available information continues to indicate Hawaii, Alaska, the U.S. Territories and the U.S. West Coast are not expected to experience any harmful levels of radioactivity," it said in a statement on Wednesday.
De Geer was commenting on data from the Comprehensive Test Ban Treaty Organisation (CTBTO), a Vienna-based independent body for monitoring possible breaches of the test ban.
He said he believed the radioactive particles would "eventually also come here."
Story: Brain scan overdose offers glimpse of radiation threat
The CTBTO has more than 60 stations around the world which can pick up very low levels of radioactive particles such as cesium and iodine isotopes.
It continuously provides data to its member states, including Sweden, but does not make the details public.
The New York Times said a CTBTO forecast of the possible movement of the radioactive plume showed it churning across the Pacific, and touching the Aleutian Islands on Thursday before hitting southern California late on Friday.
Story: Demand for potassium iodide spikes; nukepills.com is there
It said health and nuclear experts emphasized that radiation would be diluted as it travelled and at worst would have extremely minor health consequences in the United States.
In a similar way, radiation from the Chernobyl disaster in 1986 spread around the globe and reached the west coast of the United States in 10 days, its levels measurable but minuscule, the newspaper said. The CTBTO projection gave no information about actual radiation levels but only showed how a radioactive plume would probably move and disperse, it said.
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SQUIRT GUNS ON A FOREST FIRE! SUICIDE MISSION.
U.S. military families in Japan offered flights out amid nuclear crisis
Thousands of family members of U.S. service personnel in Japan were offered flights out of the country Thursday as radiation continued to seep from a stricken nuclear plant. The Pentagon said all families at bases on Japan's main island, Honshu, would be given the chance to leave.
President Barack Obama planned to make a statement about Japan at 3:30 p.m. EDT, the White House said.
For the U.S. military, which has more than 55,000 troops in and around Japan, as well as more than 43,000 dependents and thousands more civilian defense employees, the potential scale of the voluntary departure could be enormous.
"Don't panic," Captain Eric Gardner, the commanding officer of Naval Air Facility Atsugi, about 150 miles from the Fukushima nuclear plant, said in a video-message for base personnel.
Gardner said the military would able to take about 10,000 people a day out of the country initially.
"Within the next 24 hours, there will be Air Force cargo, Air Force passenger planes landing here at Atsugi (air base), and taking first women and children out of here, most likely over to Korea for one or two days and then for further transfer to some other place," Gardner said.
The second phase of the plan would involve chartered commercial aircraft to fly out families.
Even as the U.S. military ramps up a massive relief effort, it is also creating new restrictions meant to safeguard troops from the effects of radiation -- including by declaring a 50-mile no-go zone for troops around the Fukushima plant.
Atsugi was one of two U.S. naval bases that told personnel and families to limit time outdoors and to shut off external ventilation after detecting higher-than-normal levels of radiation.
Advertise | AdChoicesThe Pentagon also said some U.S. air crews started preventatively taking potassium iodide tablets on missions that were within 70 miles of the plant as a way to guard against effects of radiation.
How much radiation is dangerous?
Radiation is measured using the unit sievert, which quantifies the amount of radiation absorbed by human tissues. One sievert is 1,000 millisieverts (mSv).
In the U.S., the average person is exposed to about 6.2 millisieverts a year, mostly from background radiation and medical tests.
Some facts about radiation exposure:
%u2022A person would need to be exposed to at least 100 mSv a year to have an increase in cancer risk. Exposure to 1,000 mSv during a year would probably cause a fatal cancer many years later in five out of every 100 people.
%u2022Total body CT scan: about 10 mSv.
%u2022Mammogram: about 0.7 mSv.
%u2022CT colonography: about 5 to 8 mSv.
%u2022CT heart scan: about 12 mSv.
%u2022Typical chest X-ray: about 0.02 mSv
%u2022Dental X-ray: 0.01 mSv.
%u2022Coast-to-coast airplane flight: about .03 mSv. Airline crews flying the New York-Tokyo polar route are exposed to 9 mSv a year.
Sources: Reuters; New England Journal of Medicine; American Cancer Society; World Nuclear Association and Taiwan's Atomic Energy Council
.Potassium iodide can saturate the thyroid gland and prevent the uptake of radioactive iodine. When given before or shortly after exposure, it can reduce risk of cancer in the long term.
Late Wednesday, the U.S. State Department authorized the voluntary departure, including relocation to safe areas within Japan, of about 600 family members of diplomatic staff in Tokyo, Nagoya and Yokohama.
Diplomatic dependents have not been ordered to leave, but the State Department will bear the expense of their transportation if they choose to go, NBC News reported.
Commercial airlines were scrambling to fly thousands of passengers out of Tokyo Thursday.
On a smaller scale, Temple University in Pennsylvania said it was arranging a charter flight to evacuate 200 of its American students currently in Japan, University President Ann Weaver Hart said, according to a report in The Philadelphia Inquirer. The school will cover the cost of the flight.
The students were due to fly to the U.S. through Hong Kong on Saturday. Most of its non-U.S. staff and students, who are mostly Japanese, had decided to stay, Hart said.
The United States has urged its citizens in Japan to consider leaving and warned U.S. citizens to defer all non-essential travel to any part of the country as unpredictable weather and wind conditions risked spreading radioactive contamination.
Joanne Moore, a spokesperson for the U.S. State Department, told msnbc.com that the government did not know how many Americans were in Japan as they are not required to register with the embassy there.
However, according to the Japanese Bureau of Statistics website, there were 52,683 Americans registered as living in Japan as of Dec. 31, 2008.
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CORRECT! Do you comprehend it?
This is a climate change blog correct? That is what they do. They change climate for the better. Can you comprehend them? I will be glad to tutor you in all the good they can do for us all on Gods Good Earth! Lets keep it that way!
MOSCOW — A St. Petersburg professor faces up to two years in jail over his ties to the banned National Bolshevik Party, RIA-Novosti reported Monday.
They should cast there net farther, they would be surprised at what they would find.
Ice Ensnares Dozens of Vessels in Gulf
Ten icebreakers are leading the ships to open water in convoys, Rosmorrechflot said.
By Irina Titova
The St. Petersburg Times
Published: March 16, 2011 (Issue # 1647)
At least 97 ships were stranded in the ice in the eastern part of the Gulf of Finland while waiting for help from icebreakers Tuesday, the administration of the St. Petersburg seaport reported.
On Monday, there were 138 ships awaiting help, and two days ago, the line consisted of 160 ships. The problem has been particularly serious during the last month.
Ten icebreakers, including the nuclear ship the Vaigach, which came to the rescue from Murmansk, are currently trying to ease the maritime traffic jam.
The icebreakers are leading the ships to open water in convoys, the Federal Agency of Sea and River Transport, or Rosmorrechflot, said.
The severe winter in Western Europe this year has had consequences across the region, including in the Baltics. Meteorologists said in January that the area saw a lot of winds coming from the west that compacted the ice in the eastern part of the Gulf of Finland. Such dense ice was last registered in the area in 1992, Rosmorrechflot said.
The ice is most dense close to St. Petersburg, where in some places it is more than a meter thick. The strength of the pressure exerted by the ice is measured at three points — a serious threat for the exteriors of the vessels.
Most of the ships trapped in the ice are cargo vessels, but some are passenger ferries. The Princess Maria ferry that travels between St. Petersburg and Helsinki reportedly arrived seven hours late in the Finnish capital last week. The vessel’s operators then decided to temporarily postpone its trips through Tuesday, March 15.
Another ferry — the St. Petersburg — that carries passengers between the port of Ust-Luga in the Leningrad Oblast and the city of Baltiisk in the Kaliningrad Region waited for help from icebreakers for six days from March 3 through March 9 — triple its usual journey time of two days. The ferry’s 12 passengers, who included a pregnant woman, were reportedly running out of food.
A tanker and a dry cargo ship collided in the Gulf of Finland on Sunday due to the situation. As a result of the collision, the tanker sustained a three-meter-wide hole and the front part of the cargo ship was damaged. No fuel leaks or injuries were reported, according to the 100 TV local television station.
The captains and crews of some ships in the Gulf of Finland, especially large cargo vessels, turned out to be unprepared for navigation under conditions of thick ice, as well as for traveling in a convoy and under manual operation, Rosmorrechflot said.
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I wonder if they call that a barbecue spring????
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