But what is so disturbing about all this is that there is very little evidence that these claims are true....that the extreme events of late are the result of greenhouse gas increases caused by humans.
Take the recent amazing heat wave in the eastern and central U.S.: canary in the coal mine for global warming? No evidence of this. In fact, an in-depth analysis by Dr. Martin Hoerling of NOAA Earth Systems Research Lab (ESRL), found here, suggest that the heat wave was the result of natural variability and an unusual, but not unprecedented, change in the upper level flow pattern that pushed tropical air northward over the eastern U.S.. A recent discussion of the March warming by UW Professor Michael Wallace, one of the nation's leading climate scientists and a member of the U.S. National Academy of Sciences, found here, reaches a similar conclusion.
Well, what about the extensive tornado outbreaks of 2011 over the southeast U.S. and the early tornadoes of 2012. Unusual extreme weather connected with global warming? There is no reason to believe this is true. Backing for this statement comes from a comprehensive report of the Intergovernmental Panel on Climate Change (IPCC) on extreme weather events, found here. To quote the IPCC report: "There is low confidence in observed trends in small spatial-scale phenomena such as tornadoes and hail."
What about hurricanes? Have we seen an upward trend in those? The IPCC conclusions:
"There is low confidence in any observed long-term (i.e., 40 years or more) increases in tropical cyclone activity (i.e., intensity, frequency, duration), after accounting for past changes in observing capabilities."
What about extreme temperatures, heavy precipitation, and drought? To aid us in evaluating the trends in these extreme climate events, the National Weather Service has developed a Climate Extremes Index that you can access and plot online.
I tried it out and here is the information for these parameters for 1910-2010:
An important issue that is rarely discussed is that changes in extremes...either natural or from human-forced global warming will not be spatially uniform. So even a strong global warming signal will result in some places getting more extreme weather, while others will get less extreme weather. An obvious example is temperature....if temperatures warm there will be a tendency for more extreme highs and more heat waves. But that also implies that the cold waves will be weaker and less extreme. Ever wonder what is the biggest weather killer in the Northwest U.S.? Not hurricanes or tornadoes, not heat waves or droughts, not windstorms and floods. I am convinced from that statistics I have collected that roadway icing kills and injures more people around here than anything else. And warming should help reduce those deaths and injuries.
And consider that most of the climate models suggest the jet stream will move north under global warming. Big storms and floods are associated with the jet stream. So some folks (on the north side of the current jet stream location) may experience more extreme storminess, but those on the south side could well experience less. There will certainly be losers due to changed extremes under global warming, but there will be a lot of winners as well. Never seem to hear about that.
It is somewhat embarrassing for me to admit this, but part of the problem is that a small minority of my colleagues--people who should know better-- are feeding the extreme-weather/climate hype in the mistaken belief that by doing so they can encourage people to do the right thing--lessen their carbon footprint. Here is an example.
Three final points:
(1) Even if there are changes in the frequency of extremes, that does not necessarily mean human influences are behind them. For example, the earth has been warming for roughly 100-150 years as the planet exited the "Little Ice Age". Much of this warming has undoubtedly been natural, with human-forced warming only really significant during the past 30 years or so. Glaciers have been melting back over the past century and thus some of this loss is undoubtedly due to natural causes.
(2) If we haven't seen trends in extremes that does not mean that we won't see them in the future when the impact of anthropogenic greenhouse warming increases substantially. The earth is only starting to warm up due to mankind's influence on greenhouse gases. The big action...including changes in extremes...is AHEAD of us. Activist types have made a huge mistake in thinking they need to point to observed changes in extremes to make their case for dealing with GW. They are particularly making a mistake when they make claims that have no scientific basis. Global warming skeptics and deniers have made the huge mistake of assuming that a lack of clear changes in the atmosphere during the past decades says something about what will happen in the future, since most of the GW impacts have not yet occurred . Ironically, the activist types are providing the deniers with a potent weapon, since it is pretty easy to disprove many of the activist claims of human-induced global warming enhancing past and current extreme weather.
(3) The media has to do more homework on the claims of GW/extreme weather connections. All too often they simply quote and replay the baseless claims of advocacy groups, or juxtapose stories on extreme weather events and the potential for extremes under global warming...leaving their readers to reach their own, and often incorrect, conclusions. And as a side issue, when is the media going to provide information about some of the nonsense than denier groups are pushing (that global warming is ridiculous because the concentrations of CO2 are so small, that we can't forecast climate if we can't predict weather next week, etc....)
I believe the science is fairly clear...the impacts of global warming due to human-enhanced greenhouse gases will be be very significant, that the effects will increase gradually at first, but then accelerate later in the century. There will be substantial impacts on extremes, but the magnitudes and spatial distributions will be complex, and we don't necessarily have a good handle on it at present.
Good post Cliff. I find that I agree with your view of things almost dead-on, you're just much better at articulating it though.
ReplyDeleteI saw an analogy a couple weeks ago that I felt was apt in discussing the connection between Global Warming and extreme weather events.
It was a comparison to a baseball player using performance enhancing drugs. It is almost certain such a player will hit more home runs, but it is nearly impossible to associate any single home run with the use of PEDs. Likewise it is almost certain there will be more extreme events as the effects of global warming become more intense, but it is almost impossible to associate any single storm or event with GW.
It isn't a very scientific analogy, obviously there will be holes in the logic. Such as the IPCC's findings about hurricanes or smaller spatial-scale phenomena that you mentioned. But I felt it was a closer metaphor than most.
Then again...
ReplyDeleteThree sunny, warm Seattle weekends in a row - definite proof that the end is nigh! =}
I wish you had gone about this a different way. Your final paragraph is perfectly sensible, and your overall point on the hazards of trying to attribute particular events to global warming is well taken.
ReplyDeleteHowever, the idea that we have not or cannot observe changes in the present is not correct. Consider this figure, from the same IPCC report you quote: http://ipcc.ch/publications_and_data/ar4/wg1/en/faq-3-3-figure-1.html . It shows trends in the occurrence of extreme hot and cold events, all of which are statistically significant. Alternately, this table nicely summarizes observed trends in extremes: http://ipcc.ch/publications_and_data/ar4/wg1/en/ch3s3-8-5.html#table-3-8 . It agrees with you that trends in local scale phenomena have not been observed, but that trends in a wide variety of other extremes have likely already been detected.
Lastly, I think that the suggestions that this may all be recovery from the previous ice age and that the changes may be a good thing for people in Seattle at certain times of the year undermines the veracity of global warming and the need for adaptation/mitigation respectively.
Good common sense in your post, yet again.
ReplyDeleteIt's frustrating when scientific debates become as polarized as political debates, and everyone involved is expected to support every argument made on "their side", no matter how unlikely.
And the press often strives to whip both sides into a frenzy, rather than maintaining perspective.
Interesting and well said. I think there are certainly human-centered change, but to the extent that we cause the changes we are seeing now. The science says (generally) that we have been lucky creatures in Earth history, having been gifted a fairly stable climate. This old rock will just shake us off when she's tired of us and start over. So get out your BBQ and lawn chairs, relax and enjoy the sunshine.
ReplyDeleteGreat post but it misses the most important question: When will we see our next multi-day streak over 70 degrees? }B^)
ReplyDeleteCliff, You have a point yet you overstate there is no evidence as one of the papers you refer to says,'Our current estimate of the impact of GHG forcing is that it likely contributed on the order of 5% to 10% of the magnitude of the heat wave during 12-23 March. And the probability of heatwaves is growing as GHG-induced warming continues to progress. But there is always the randomness.'
ReplyDeleteSo yes it is not all GHG, and there is is a growing trend to indicate it will play a stronger role with each passing year. Why make it silly to to encourage people to acknowledge the problem and start working toward a solution rather than resist change?
And the comments show the same trend I lamented in my comment.
ReplyDeleteNamely, the 2:30am comment wishes you hadn't mentioned that warming is not necessarily bad for Seattle and mentioned that some component of warming might be recovery from the "little ice age" - mentioning caveats undermines the perceived need for mitigation.
Also, Matt's comment seems to say that even if the March heat wave is 10 to 20 times the expected effect of global warming, one can't look elsewhere for the primary cause of the heat wave - that somehow abets "resisting change".
If people are seeking a one-sided discussion of science policy, rather than the give and take of the scientific evidence, perhaps they should read a different blog.
This idea that there is no evidence in favor of anthropogenic detection or attribution of extreme events is actually an outdated one. in the past several years there has been several studies/climate scientist disputing it.
ReplyDeletewe can start with rahmsdorf and coumou on the recurrence rate of extremes like the russian 2010 heatwaves,as well as their perspective piece in nature.
Hansen et al on the nearly 200 fold increase in >3 sigma heat extremes,
Jennifer francis on the arctic amplification affecting jet stream patterns,
Kerry Emanuel work on increase hurricane 'destructiveness' partly due to increase SST temperatures,
Seung-Ki min et al
on Human contribution to more-intense precipitation extremes
in this short article on dot earth you can see some differing views on exactly this issue.
also please don't miss kevin trenberth opinion on the issue along with its attendant references.
Unknown....many of the studies you quote are very weak or problematic. And please understand that I do expect some significant changes in extremes in some locations later in the century....what I am saying is that too many people are citing current events as signs of global warming...most of those claims are clearly bogus...cliff
ReplyDeleteBad timing of this post. A NE blizzard and Midwest instability in the NW.
ReplyDeleteIm just messing with ya. Good post. But tonight is great...warm and humid. Even though the thunderstorms aren't close to my location, spectacular lightning display in eastern washington tonight to the SE. Very Midwest style. I see a flash every ten seconds.
Cliff, surely you're aware that Hoerling himself found evidence for global warming signal in the 2008 Midwest floods and in the increasing Mediterranean droughts.
ReplyDeleteAdditionally the analysis of his you linked to is preliminary and not yet peer reviewed. Yet you seem to dismiss other peer-reviewed literature on this topic.
There is a semantic -- if that's the right word --problem here which a couple of commenters mentioned. If global warming increased the severity of an event by 10%, did it "cause" the event? Probably not in most people's minds, but I think most people would accept that it is a "contributing factor." Your post doesn't seem to allow for that nuance.
Lastly, it would be great if you would take on of the articles posted above -- several by prominent climatologists -- and explain why it is clearly bogus.
cliff,
ReplyDeleteyou are missing the point of the studies i cited. It is not to make a overwhelming case that current extreme events are wholly (or even largely) due to anthropogenic effects , but to point out that several distinguished climate scientist, with publish peer reviewed articles to back them up, are saying that they have methods that can attribute AGW effects on the *current* weather events (not "in some locations later in the century"), and they would like a open debate in the scientific literature with others who disagree such as Dr. Martin Hoerling.
so while there are clearly exaggerated claims by some (e.g. AGW effects on tornadoes) there is clearly a legitimate debate to be had by informed scientists' on AGW effects on current weather events that should not be ignored.
Unknown,
ReplyDeleteThere are a few scientists who have made the claim that anthropogenic global warming is indicated by a recent extreme events. I have read most of these papers and I believe (as many of my colleagues do) that they are flawed. But the point is that there is no consensus in the community that recent extreme events are indicative of AGW and thus the media and advocacy groups are well advised not to push this point. And consider that the main consensus body of the field....the IPCC...is very cool on such claims...cliff
Just to clarify - my point is not "If global warming increased the severity of an event by 10%, did it cause the event?". Rather, it is if global warming is likely a 5-10% effect, how can we be sure it even contributed in a particular event?
ReplyDeleteI'm not a climatologist, but seeing global warming blamed for individual events in which it MIGHT have been a minor factor, IHMO, opens AGW to criticism needlessly.
Cliff, just FYI. I posted the 10:01 pm comment, and I didn't mean to post as "unknown" -- but for some reason Google does not show my name or user ID.
ReplyDeleteI mention this because I notice several other unknowns, and some of them probably had the same issue.
-Douglas
Cliff: Since you refused to post my thoroughly polite and respectful comment, and since Unknown and I overlapped on many points, perhaps you can post this. He cannot be contacted from the link on this blog. I would hope that he will contact me. He knows lots and I would like to strike up a conversation.
ReplyDeleteregards, Don
Fixed Carbon,
ReplyDeleteI have published EVERY SINGLE comment I received. Be sure you did not do something that resulted in Blogger's spam filter from putting your comment aside....cliff
Cliff: Yikes. I will try again.
ReplyDeleteThanks, Don
Cliff: You have covered one facet of problems with inferring climate change from extreme weather. For me, the poster child of this “Extreme Silliness” is Senator Inhofe’s igloo built to melt after a February, 2010 snow storm in Washington DC. Nonetheless, as your post suggests, the science of inferring climate from weather is difficult. It is not unlike the symptomology of disease (Is that dizziness that I had this morning a symptom of heart disease?). We have false and true positives. Your post focuses upon false positives. The problem is discriminating falseness. As John M. Wallace, to whom you refer, has written “It is difficult for the public to grasp the significance of global warming because the mildness of its early symptoms belies the gravity of its long-term consequences…attribution of extreme events to human-induced climate change is often viewed as gratuitous and labeled as fear mongering. A more effective communications strategy, in my view, is to use these events to illuminate society's increasing vulnerability to natural disasters in the face of our deteriorating planetary life-support system.”. He wrote similar themes in the LA Times today. At the same time, science is making progress toward discriminating false from true positives in patterns of extreme weather (rather than events in isolation), much as medicine has done with patterns of symptoms of disease (That frequent dizziness that you are having is related to arterial disease.). A recent paper, “A decade of weather extremes” by D. Coumou and S. Rahmstorf in Nature Climate Change, argues that the evidence suggests that “for some types of extreme — notably heat waves, but also precipitation extremes — there is now strong evidence linking specific events or an increase in their numbers to the human influence on climate. For other types of extreme, such as storms, the available evidence is less conclusive, but based on observed trends and basic physical concepts it is nevertheless plausible to expect an increase.”
ReplyDeleteDear Cliff, thanks for this post. Could you please explain what is so unscientific about the survey reported in the NYT? It comes from Yale http://environment.yale.edu/climate/files/Extreme-Weather-Climate-Preparedness.pdf and is quite thorough it seems. Perhaps the public has an opinion about the role of anthropogenic climate change in extreme weather that does not match with the scientific consensus. But does that make the survey unscientific?
ReplyDeleteTo Unknown posting at 4:09pm and citing Kerry Emanuel - Dr.Emanuel himself has since backtracked on the work you cite. The work was heavily criticized by his peers and when he did further analysis he modified his conclusions.
ReplyDeleteVery nice post Cliff.
ReplyDelete@Laurens: Facts are not dictated by public opinion. Global warming occurs whether people believe in it or not. As such, the poll results (which yes, are valuable) need to be framed differently.
In the 1970's a NOAA science manager was predicting increasing weather extremes, based on an ocean temperature data series. A hotter ocean had to have an influence on atmospheric dynamics.
ReplyDeleteNow we know that solar energy is being retained in the atmosphere and that energy has to go somewhere. Part of it is retained in the atmosphere as heat, part as kinetic energy in atmospheric transport, part as increased oceanic evaporation, part in ocean surface temperature increase.
One might expect ocean and atmospheric dynamics to be affected and it would be surprising if they weren't. Since these dynamics are in part deterministic and in part probablistic one should expect increased stochasticity or increased "noise" in these systems.
Thus, although individual weather events cannot be attributed to the overall energy input to the system, a trend in the redistribution of atmospheric heating, cooling and precipitation patterns, and increased severity of weather events can be.
These trends are ameliorated by the fact that a substantial portion of increased CO2 input to the atmosphere is being asorbed by the oceans. If that weren't the case we might have far fewer skeptics and breath holders regarding global climate change.
In defense of Climate Central, I found their coverage of the March heat wave to be quite nuanced--and far from silly. http://www.climatecentral.org/news/global-warming-increased-odds-of-march-heatwave-experts-say/
ReplyDeleteVery well done! I think global warming is a joke!
ReplyDeleteCaleb,
ReplyDeleteBe sure to read the last paragraph of Cliffs post.
Cliff, leaving aside short-wavelength specific event observations, what's your opinion about the emergent widely distributed statistical bulge/aberration in high versus low temperature extremes? Is this a fingerprint of climate modification consistent with expectations of the role of improved efficiency of heat retention as an effect of C02, natural variation, or a mixture of both?
ReplyDeleteAnd for the record, don't you think that posts just like this one (calling experts, advocates, and science reporters silly) and calling peer reviewed science "bogus" is just the kind of fodder deniers live for? Don't kid yourself that you are above the politics of this thing and can comment on others' words without seeing the damage your own words can do. The most favorite "myth" of the science deniers is that the scientists themselves can't agree and that there is not a clear consensus and that the jury is still out. You are fueling that fire. Just ask commenter Caleb.
ReplyDeleteYour use of the term 'denier' is highly offensive. It was chosen to associate with 'holocaust denier,' and is obviously not appropriate language when discussing science or political policy.
ReplyDeleteThere are many who would like to see abortion termed infanticide. And every mention of Obama should label him a socialist, right? Do you not see what you are doing? There is a difference between 'denying' a proposition based on a massively complex mathematical model, and killing five million Jews. Please allow those of us who don't buy the entire apocalyptic ratbag of global warming to define ourselves - we are as capable of doing so as 'pro-choice' women.
Edith, I suspect Cliff is not familiar with sites such as WUWT and thus possibly does not know how a phrase that would be perfectly adequate in one context may be used in another as fuel for the fires of demagoguery, as you suggest.
ReplyDeleteWith a roster of credible opponents of relatively elementary physics so small as to be nonexistent, climate contrarians are frequently left with no recourse but to twist words offered by those who know better.
For myself, I take Cliff's point to be that our hydrocarbon sewage accumulation problem is bad enough that no hyperbole is required to describe it.
It's Cliff who uses the term "deniers" as part of his argument. Honest skepticism in science is vital and necessary to advance our understanding. Denial is something entirely different--blindness due to other emotional, psychological, political, or economic factors. Denying gravity is far different from denying the Holocaust, for example. Notably, however, the outcome in the case of human-caused global warming may be as serious as genocide, though I wasn't making a connection to the Holocaust by using the term. I think Cliff would agree there--see his last paragraph. Denial is denial. I think denial of scientific consensus when the stakes for real people are this high is perfectly appropriate. I don't see the connection to partisan claims about what constitutes socialism (mostly just character attacks) or abortion (nobody--pro-choice or not--denies the scientific premise that abortion, as the term itself indicates, terminates a pregnancy.) Anyway, you lost me at "ratbag." And @dbostrom, I agree! No hyperbole is required. I'm with you there. The point of contention is whether Cliff is correct that we haven't seen any fingerprints of climate change yet in weather events or whether the legions of climate scientists who are now using models to make precise attributions are indeed finding hard evidence that human-caused climate change is now a factor (one among many and not necessarily the central one or the trigger) in *every* weather event. I'm not a scientist, but as other commenters have noted here there's evidence from highly reputable scientists to contradict what Cliff is claiming (Namely that we cannot prove AWG now in weather events but that we will likey see it later in the century vs. we can determine AGW as one factor now), and I am not ready to call all that peer reviewed science or nuanced reporting about it bogus, silly, or hyperbolic. It's not to say there isn't exaggeration out there. But I think name-calling among peers and earnest reporters is counterproductive to say the least.
ReplyDeleteEdith,
ReplyDeleteThere IS evidence of impacts due to greenhouse gas changes induced by humans....it is just being overhyped by some and the biggest impacts are in the future. That is my point. I AM NOT saying there are no impacts.
..cliff
Thanks for clarifying, Cliff. I implore you to make that point more clearly. It was lost on me...and seemingly on several other readers. For one thing, you hide the most important paragraph at the end. What we get first is that we shouldn't believe anything we hear about a weather-climate connection. I agree that reporters, advocates, and scientists shouldn't overstep. But we also shouldn't eat our own young by omitting or obscuring the clear statements about the reality of climate change--like the one you just made. A great service scientists can do for public understanding is underscoring that point--that there IS evidence of impacts due to greenhouse gas changes induced by humans--rather than calling each other silly. If we could simply say that over and over again, at the beginning of every communication, and with that kind of concision and clarity, we'd be getting somewhere with lagging concern and mitigation by elected officials. Thanks again. EA
ReplyDelete> Take the recent amazing heat wave
ReplyDelete> in the eastern and central U.S.:
> canary in the coal mine for global
> warming? No evidence of this.
> In fact, an in-depth analysis by
> Dr. Martin Hoerling ...
Cliff, though the context of this post was focused on anthropogenic global warming and you explicitly stated so in the earlier parts of your post, you became inconsistent in the later parts. Thus, did you mean to write, in the above excerpt, "... canary in the coal mine for anthropogenic global warming?"?
Further, are you defending your binary hypothesis, "No evidence of this" by citing ESRL's Hoerling, or do you have your own analysis which you have omitted in this blog post? (if so, here's hoping for a future followup post, the world can't wait to read it!).
Further to the Hoerling citation, you wrote:
> … suggest that the heat wave
> was the result of natural
> variability and an unusual, but
> not unprecedented, change in the
> upper level flow pattern that
> pushed tropical air northward over
> the eastern U.S.
That's a useful citation to commit to this post, but what you omitted, which is pertinent given the context, is this excerpt from Hoerling:
> The weak overall contribution of
> GHG warming to the magnitude of
> the March 2012 heatwave
> notwithstanding, a signal of
> about +1°C warming appreciably
> increased the odds of a record
> March heatwave occurring.
Its noteworthy that Hoerling used the explicit adjective, "weak", to describe ESRL's estimation of contribution of GHG warming to the aformentioned March 2012 heat wave event. Weak is not zero, and there's no metaphorical axiom about a coal mine canary's level of illness that I'm aware of [1]:
[1] http://en.wikipedia.org/wiki/Canary_in_the_coal_mine#Detection_of_toxic_gases
> Well into the 20th century, coal
> miners in the United Kingdom and
> the United States brought
> canaries into coal mines as an
> early-warning signal for toxic
> gases including methane and
> carbon monoxide. The birds, being
> more sensitive, would become sick
> before the miners, who would then
> have a chance to escape or put on
> protective respirators.
Also omitted from your Hoerling citation:
> The event reminds us that there
> is no reason to believe that the
> hottest, "meteorological maddest"
> March observed in a mere century
> of observations is the hottest
> possible. But this isn't to push
> all the blame upon randomness.
> Our current estimate of the
> impact of GHG forcing is that it
> likely contributed on the order
> of 5% to 10% of the magnitude of
> the heat wave during 12-23 March.
Although I'm not an ornithologist, it seems reasonable to imagine some canaries might be particularly sensitive and fall ill to seemingly small or trace amounts of toxic gases, like the greenhouse gas methane, inside coal mines.
In one of your follow ups to a commenter named "Unknown", you wrote:
> Unknown....many of the studies you quote are very weak or problematic.
The Unknown commenter loosely referred to five studies (Hansen et al, Jennifer Francis, Kerry Emanuel, Seung-Ki min et al, Trenberth). Are there any in particular that you're willing to go on record and cite as "weak or problematic" and if so are you prepared to offer a defense of your counterpoints?
Best regards,
-Brendan Lane Larson, Meteorologist