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.
r
And here is
Faceted Search of Blogs at climateknowledge.org
Reader Comments
Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 — Blog Index
So who is Michael going to be talking to now.
Nobody.
Guess that's the way of his side.
You can't listen to the other side of the argument you win.
Congrats Michael.
Now go away if you have everybody ignored.
Better yet go to your own blog and just ban people from there.
Why are you still using the list of selected earthquakes from the USGS (from here)? If you're going to go to all the trouble to figure this out for yourself, don't you want the complete list? You can find the complete list on this page. See the two links below the Frequency of Occurrence of Earthquakes chart.
"Darmok, and Jalad... at Tanagra."
- Dathon (meant as a metaphor to fight a common enemy)
"Picard and Dathon... at El-Adrel."
- New Captain of the Tamarians (referring to Dathon and Picard's experience at El-Adrel)
"Shaka, when the walls fell."
- Dathon and Picard (repeated often by both) (meant as a metaphor to failure)
"Temba, his arms wide!"
- Dathon (meant as a metaphor for giving and receiving)
"That's how you communicate, isn't it? By citing example... by metaphor! Uzani's army... with fists open..."
"Sokath, his eyes uncovered!" (meant as a metaphor to comprehension)
I try to learn from all.
If MichaelSTL can't see any of those posts and has also ignored Cyclonebuster, who the heck is he talking to?
See this picture it proves nuclear is the way to go! How many more times are we going to go through this before we wise up? Ya'll with me now?
And now the black smoke of radiation contamination due to the core meltdown! And you still say nukes are good? I worked at Turkey Point for many years fella. I know when the press is sugar coating things!
So because of an EARTHQUAKE we aren't going to use Nuclear power anymore. HAHAHA
Sorry that morning it happened people at my work said the same thing that the crazy enviromentalists would cry about more nuclear power.
Sorry but it works and just because of an Earthquake people don't want to.
Let me ask you this.
Without the Earthquake would this of happened in Japan that day?
No Mother Nature works in mysterious ways.
You are correct windmills are also a joke when compared to the Gulf Stream kinetic energy.
There is no way they can power us 24/7/365 like Gulf Stream Kinetic energy can! Ya'll with me yet?
Earthquakes are just part of the danger? What about tsunamis caused by landslides, meteor impacts,war and even a greater chance of terrorism occuring???
Well all of that will happen regardless of what kind of energy we are using I have no idea where you are going here.
Of course all that may happen and some has happened now.
Which one is more harmful to the environment when it does happen?
I believe a little leak isn't as bad to the people as say a tsunami just ask Japan or Indonesia or ask Haiti how bad that Nuclear plant hurt them.
Any leak is unwanted don't be mislead by the media sugar coating the event.
Weekend Gulf oil spill traced to Houston firm
(CNN) -- Testing on oil samples recovered from the Gulf of Mexico near Grand Isle, Louisiana, show the material came from a defunct well owned by a Houston company, according to a spokeswoman for the Department of Wildlife and Fisheries.
An oily substance began washing up in Grand Isle on Sunday, the U.S. Coast Guard said. The Coast Guard initially said it believed the material might be coming from dredging operations, but tests later showed it came from a well owned by Anglo-Suisse Offshore Partners, according Olivia Watkins, a spokeswoman for the state wildlife department.
The company said in a statement Wednesday afternoon that it did not believe it was the source of the spill, but had nevertheless dispatched its cleanup contractor to oversee efforts to remove the oil, which the Coast Guard said had impacted an estimated one-half mile of shoreline.
The company said it had reported a spill of less than five gallons of oil from the suspect well on Friday, but said it was surprised at the suggestion that its well could be responsible for a slick as large as that which had been reported because the well has not been leaking and has not produced oil since 2005.
The spill comes as Grand Isle and the rest of the Gulf prepares to mark the one-year anniversary of the April 20, 2010 explosion aboard the Deepwater Horizon oil rig. Eleven workers died and the resulting spill released an estimated 205 million gallons of oil into the Gulf.
Link
5 gallons. LOL! Go ahead sugar coat it!
Visit msnbc.com for breaking news, world news, and news about the economy">
Gulf Stream Kinetic energy stops this Dr. Michio Kaku!
Ya'll with me now?
Annual maximum ice extent reached
Arctic sea ice extent appeared to reach its maximum extent for the year on March 7, marking the beginning of the melt season. This year's maximum tied for the lowest in the satellite record. NSIDC will release a detailed analysis of the 2010 to 2011 winter sea ice conditions during the second week of April.Overview of conditions
On March 7, 2011, Arctic sea ice likely reached its maximum extent for the year, at 14.64 million square kilometers (5.65 million square miles). The maximum extent was 1.2 million square kilometers (463,000 square miles) below the 1979 to 2000 average of 15.86 million square kilometers (6.12 million square miles), and equal (within 0.1%) to 2006 for the lowest maximum extent in the satellite record. Conditions in context
As of March 22, ice extent has declined for five straight days. However there is still a chance that the ice extent could expand again. Sea ice extent in February and March tends to be quite variable, because ice near the edge is thin and often quite dispersed. The thin ice is highly sensitive to weather, moving or melting quickly in response to changing winds and temperatures, and it often oscillates near the maximum extent for several days or weeks, as it has done this year.
Since the start of the satellite record in 1979, the maximum Arctic sea ice extent has occurred as early as February 18 and as late as March 31, with an average date of March 6.
igure 2. The graph above shows daily Arctic sea ice extent as of March 22, 2011, along with daily ice extents for 2006, which had the previous lowest maximum extent, and 2007, the year with the lowest minimum extent in September. Light blue indicates 2011, green shows 2007, light green shows 2006, and dark gray shows the 1979 to 2000 average. The gray area around the average line shows the two standard deviation range of the data. Sea Ice Index data.
Link
After Gas Pains, Consumers Hit With Skyrocketing Grocery Bill
The price at the pump is painful, but the agony doesn't end there.
Faced with soaring shipping costs, food suppliers and manufacturers are raising prices.
Now, a trip to the local supermarket can be as shocking as a stop at the gas station. According to the U.S. Labor Department, food prices climbed 3.9 percent last month. It's the biggest spike since November 1974.
For more than 50 years, Superior Bakery in Cranston, R.I., has supplied area supermarkets with bread, but the rising cost of supplies has forced owner Robert Cicerone to tighten his belt.
"The gas prices have hurt us immensely,” he said. “It hits your traffic margin, your cash flow. Everything that comes in the door has a surcharge," said Cicerone.
Kevin Gomes shops in the produce area at Pacifica Farmers Market in Pacifica, Calif, Wednesday, March 16, 2011. Wholesale prices jumped last month by the most in nearly two years due to higher energy costs and the steepest rise in food prices in 36 years.
Kevin Gomes shops in the produce area at Pacifica Farmers Market in Pacifica, Calif, Wednesday, March 16, 2011. Wholesale prices jumped last month by the most in nearly two years due to higher energy costs and the steepest rise in food prices in 36 years.
Cicerone said he’s paying up to $1,500 a week more to fill up his 12 trucks was gas then he was 10 months ago.
The cost of sugar and flour has also increased, forcing this family business to implement a 6 percent price increase. Among other places, they deliver down the road to Ruggieri's Market, a nearly 100-year-old, family-run grocery store.
The store’s president, Peter Ruggieri, said it’s hard to pass the price increases on to customers.
"The consumer thinks it's the store at store level, that we're just price gouging,” he said. “But in reality, once again, we're working on a smaller percentage to try and keep the product moving, keeping it fresh. We don't like to see the high prices."
Continuing turmoil in the Middle East has raised fears that oil prices will continue to rise, increasing the burden on suppliers, manufacturers, supermarkets and ultimately beleaguered consumers.
“It trickles down everywhere,” said Lou Pelosi, a customer at the store. “ It goes down to the big guy right down to the small guy. It'll hurt us sooner or later and everybody cuts back that little bit.”
Laurence Kotlikoff, an economics professor at Boston University said it’s an across the board struggle, with each piece intrinsically linked to the next.
Boston University Economics Prof. Laurence Kotlikoff says it's an across the board struggle, each piece intrinsically linked to the next.
Energy sources are a key driver and Kotlikoff says an eye to the future will tell us much about price fluctuations today.
"There's always a calculation with those kinds of exhaustible resources as to when to sell it and so the future can affect the present in terms of the price so people can say 'look, I think prices in the future are going to be higher, demand's going to be higher, I'm not going to pump as much.' That makes prices today go up," said Kotlikoff.
And with prices rising, the cost of business means trickle-down economics is in full effect from the pump to the produce.
Link
Some of us have lives.
So we can't be on here 24/7.
Not saying you are but some are on way to much.
Where's proof that they are sugar coating it?
But in the case of temperatures and man made global warming they aren't sugar coating anything?
Plus why would the Liberal Media sugar coat it when they are in the pockets of Obama COUGH NCB COUGH?
Seems to me like they would be better off being on the extreme side.
WHO CARES?!?!?!?!
LEAVE!!!!!
I know you can't see this but others can.
SHHHHH.
They don't like to know that.
Climate Change Likely Caused Polar Bear to Evolve Quickly
Climactic changes might currently be threatening the survival of polar bears (Ursus maritimus), but similar shifts appear to have played an important part in bringing the species into existence in the not too distant past.
Researchers announced today that they have sequenced the mitochondrial genome of an ancient polar bear. The genetic traces they found in the bear's 110,000- to 130,000-year-old jawbone reveal that the species likely split from brown bears (U. arctos) just 150,000 years ago, at a time when specializing in arctic living quickly became an advantage rather than a liability.
The species' rapid evolution sheds new light on one of the emblematic species of climate change. Although the breed has become a popular flagship species for the issue, scientists knew little about how past climate affected the bear's evolutionary success.
Link
Well, looks like climate change created a new bear,
just like the end of the last glaciation removed
the mega fauna from Northern Hemisphere.
Just listened to a NPR story on Curt Stager on how
we may have helped that extinction. And that Lake
Champlain does not ice over anymore. Really, these
Paleoclimategeologistpeerreviewed Dr's need to get out of the classroom a little more frequently.
Link
And they claim he was a climate warming sceptic.
Link
Really?
I do appreciate all the modern technology that allows
me to poke holes in all these issues.
It is liberating.
Arctic sea ice ties for smallest area this winter
(Reuters) - Even at its biggest, Arctic sea ice extent this winter was among the smallest ever seen, apparently tying with 2006 for the least amount of ice covering the region around the North Pole, U.S. researchers reported.
Sea ice on the Arctic Ocean usually starts growing in September and hits its maximum area in February or March; this year, the maximum appeared to occur on March 7, when ice stretched over 5.65 million square miles (14.64 million square km), according to the National Snow and Ice Data Center.
That area of ice-covered water is 471,000 square miles (1.2 million square km) below the average maximum ice extent observed by satellites from 1979 to 2000, the center said in a statement.
As of Tuesday, the extent of the ice had shrunk for five straight days, but there is a chance it could expand again, the center said.
"Sea ice extent in February and March tends to be quite variable, because ice near the edge is thin and often quite dispersed," the statement read.
This thin ice is sensitive to weather, which can make it move or melt quickly, and it often stays around the maximum for days or weeks, as it has done this year.
Arctic sea ice extent -- the area the ice covers in summer and winter -- is one measure scientists use to track changes in global climate.
The center plans to release a detailed analysis of winter sea ice conditions during the second week of April.
Link
This costs tens of trillions while Gulf Stream Kinetic Energy costs tens of Billions. Ya'll with me yet?
Well...I'm not MichaelSTL but I'll take it...
According to data gleaned from the following two links:
http://www.skepticalscience.com/Various-estimates -of-Greenland-ice-loss.html
http://en.wikipedia.org/wiki/Greenland_ice_sheet
Pretty wide spread of estimates and significant uncertainties in the long-term, with most having short observation times of 5-10 years, as can be seen in the graph below:
The most recent estimates (the last five years or so) give estimates of about 110 to 290 Gt (Gigatons) per year, or given the total ice sheet mass of about 3 million Gt, between 0.004-0.01% mass loss per year.
I would say long-term acceleration is also somewhat uncertain since it relies on very short observation intervals as well--especially the GRACE gravity estimate--but here is a graph from the Skeptical Science link:
Acceleration results are given in the graph; the corresponding percentages are about 0.0007 ± 0.00003%/yr for the mass balance method, and 0.0006 ± 0.0003%/yr for the gravity method.
I hope I was helpful.
You're welcome.
But just like every other case.
You'll have their own peers say they are innocent.
Then for some ridiculous reason everybody thinks it is ok.
Eventually that lower ocean heat makes it to the top due to convection currents. Correct?
Calculate how many gigatonnes of cold water flow through the tunnels per year if needed while at the same time producing electrical power?
From a strictly mathematical standpoint...
mass=3000000-melt; where melt=integral(200+20t)
This yields melt=200t-10t² and mass=3000000-200t-10t²
I am going to solve it the lazy way (LOL):
Graphing m=3000000-200t-10t² below:
See here.
Looks like just under 540 years. Setting m=0 and solving for t yield about 537.814 years.
* * *
Now, from a practical standpoint, it's a stretch to assume that the rate of acceleration of melt will be over the next 500 years, especially considering the short periods of observation. Note also that near the end of the 500 year period, ice would have to be melting at over 10,000 gigatons per year to keep up with the graph. Values such those do not seem realistic.
Calculate how many gigatonnes of cold water flow through the tunnels per year if needed while at the same time producing electrical power?
I don't think I can be fairly accused of trying to select "conservative" estimates here as I took the estimates from a Skeptical Science post from February 2011. Perhaps the site is somewhat more conservative than Climate Progress though.
Anyway, my first question is whether the Petermann event is calculated within the 540 cu km value; if it is then it should be noted that an event such as the Petermann one will greatly skew the average for the year. The Petermann event wasn't really that unusual. Of course the value is specified as be "inland ice" so maybe it's not being included.
My next point would be that this is only a one-year observation. Also, as the graph from Skeptical Science notes, there are several estimates that have been done within the past five years, several that have been done concurrently. I'm not sure that simply because a study was concluded/published later it necessarily "refutes" all earlier studies. In particular the study with the lowest estimate alleged that previous measurements were overestimated due to incorrect/insufficient corrections for rebound of crust under melting ice. Unless subsequent studies addressed this I can't really see how the previous study in necessarily "refuted". More than likely, the spread in estimates is likely indicative of the uncertainty and difficulty in measuring the ice melt.
* * *
As far as the perceived censorship: I have no idea by what process the post was removed--I didn't flag or minus it myself--but I can see why Admin might do it. All the post did was complain that there were twenty posts or so that MichaelSTL couldn't see because he had ignored them. He seemed to be suggesting that people that he has ignored don't have a right to comment, which is a bit inflammatory and would just lead to argumentative responses. If he's going to "Ignore" people, he should perhaps actually ignore them.
Japan reactor core may be leaking radioactive material, official says
Tokyo (CNN) -- Authorities in Japan raised the prospect Friday of a likely breach in the all-important containment vessel of the No. 3 reactor at the stricken Fukushima Daiichi nuclear power plant, a potentially ominous development in the race to prevent a large-scale release of radiation.
Contaminated water likely seeped through the containment vessel protecting the reactor's core, said Hidehiko Nishiyama of the Japan Nuclear and Industrial Safety Agency.
Three employees working near the No. 3 reactor Thursday stepped into water that had 10,000 times the amount of radiation typical for a nuclear plant, Nishiyama said. An analysis of the contamination suggests "some sort of leakage" from the reactor core, signaling a possible break of the containment vessel that houses the core, he said.
The workers have been hospitalized and work inside the reactor building has been halted, according to the agency.
Work inside two other reactor buildings also had to stop and workers had to be pulled back Friday after the discovery of high levels of radiation in water at those locations, a Tokyo Electric Power Company official said Saturday. Water is still being pumped into the containment vessels, the utility official said.
Nuclear power experts cautioned against reading too much into the newest development, saying the workers exposed to radioactive water might not suffer injuries any more serious than a sunburn.
Moreover, evidence of radioactivity in the water around the plant is not necessarily surprising given the amount of water sprayed onto and pumped into the reactors, said Ian Hutchinson, professor of nuclear science and engineering at the Massachusetts institute of Technology.
Link
Viewing: 351 - 401
Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 — Blog Index