The (false) belief that climate change causes weather
August 7, 2017 5:06 PM   Subscribe

Weather is local, climate change is global. The former cannot be attributed to the latter. This is what I've always believed because it's what I remember hearing climatologists say. Meanwhile, newspapers and news channels again and again attribute extreme weather to climate change. Either I'm wrong or they're wrong.

I believe in global warming because global warming is a matter of fact, not opinion. Not believing in it would be as delusional as not believing in the fact that droughts, floods, hurricanes, and other forms of extreme weather happen.

But in the past week the New York Times and CNN/MSNBC et al have attributed the following local/regional weather events to global warming: the heat wave in the pacific NW, the heat wave in Europe, the forest fires in France, the forest fires in British Columbia, the "monsoon" in Arizona.

Is this kind of specific causal attribution (of specific local weather events to global climate change) scientifically tenable?
posted by BadgerDoctor to Science & Nature (22 answers total) 2 users marked this as a favorite
 
I think it's more that weather is complicated and multicausal. Climate change makes it more likely for certain patterns to occur (such as a warmer, drier weather pattern in Place X, etc.) but you can't draw a straight line between climate change and any specific weather event.
posted by tivalasvegas at 6:30 PM on August 7 [8 favorites]


While no specific weather event can be said to be definitively caused by climate change, these sorts of extreme events become more likely and regular as climate change progresses.

While I would find it problematic to see a statement like that in a scientific article, I have no problem with attributing these events to climate change in a more public forum. And, as time goes on (and we do nothing about climate change), reports like this about a specific event being caused by climate change become more and more likely to be correct.

If "100 year events" happen every year, it doesn't matter if it was this year's or last year's that was the "regular" one that wouldn't have happened without climate change.
posted by Betelgeuse at 6:32 PM on August 7 [25 favorites]


New York Times today published latest draft of the new U.S.-Global Change Research Program Climate Change Report, produced every four years by 13 federal agencies. Link here. Quote from the Times story: "Among the more significant of the study’s findings is that it is possible to attribute some extreme weather to climate change. The field known as 'attribution science' has advanced rapidly in response to increasing risks from climate change."
posted by nohattip at 6:41 PM on August 7 [13 favorites]


It's now possible to say that a particular weather event was made more likely by climate change (for example, linking a specific drought to climate change). There's a large project called World Weather Attribution with a group of researchers that specializes in this.
posted by pinochiette at 6:42 PM on August 7 [14 favorites]




You know how "Correlation does not prove causation"? And how people use that to bludgeon any scientific study that they don't personally agree with?

This is the same thing. No, climate change doesn't "cause" changes in weather, in the sense that you can't use "It's 92 degrees today in Detroit!" as "proof" of climate change, nor "It's 62 degrees today in Detroit!" as "proof" that climate change doesn't exist. But an entire summer of higher-than-average temperatures across the entire country -- even though that's "just" a bunch of weather added together -- can serve to bolster the evidence that the climate is changing.

Climate causes weather: the climate at McMurdo Station, Antarctica, is different from the climate in Death Valley, and that's why the weather is usually extremely different in those two places.
posted by Etrigan at 8:01 PM on August 7 [4 favorites]


Yeah, you're wrong in principle, and I make no comment on any specific weather event. Climate change can and does change weather patterns, and attribution techniques today are incredibly powerful and subtle. The pop-sci links I would give have already been cited above, let me know if you would like citations to the scholarly literature on the topic.

TLDR: yes this type of stuff is absolutely scientifically tenable, provided you are comfortable with statements of likelihood as opposed to statements of certainty.
posted by SaltySalticid at 8:42 PM on August 7 [6 favorites]


This is a great question. Rising temperatures globally cause extreme weather fluctuations in localized regions. PNW, continental Europe and France are getting headlines because they tend to have very modulated temperature ranges as a result of their various geographies; the fact that the most temperate and populated places on earth are experiencing heatwaves isn't a local weather headline but a global trend headline.

If you view a visualization of the last 200 years or so of trade winds, el nino etc you can see why these places would seem more effected, from a local point of view.

Areas that normally experience more extreme temperature and storm severity ranges are also seeing a higher incidence of devastating storms in the last decade or so. The east coast of the US is a great example (yes basically the whole coast).

Random citations by trusted sources. https://earthobservatory.nasa.gov/Features/RisingCost/rising_cost5.php https://earthobservatory.nasa.gov/Features/ClimateStorms/page2.php http://nca2014.globalchange.gov/highlights/report-findings/extreme-weather
posted by love2potato at 8:45 PM on August 7 [1 favorite]


Climate is just the long-term weather trends of a given area. So climate and weather are 2 sides of the same coin. As climate changes, what you are saying is that the (short term, daily) weather averages and trends have changed. So it is technically incorrect to say that climate change causes weather events; however, we use it for convenience.
posted by DoubleLune at 8:45 PM on August 7 [3 favorites]


"I lost my job because of the recession." "I was late to work because of traffic." "My car broke down because it was old." In all kinds of different situations, we seem to have no trouble attributing a specific outcome due to a broad, random event. In fact we seem more eager to do that for negative events than for positive ones -- no one ever says "I got a new job because the economy is so good" or "My commute was short because fewer people were driving today."
posted by miyabo at 9:06 PM on August 7 [9 favorites]


It's not the clear and obvious relationship between global warming and the increasing frequency of extreme weather events that's problematic; it's the actual idea of causality, which has always been something of a slippery fish.

It's reasonable to view a net increase in the heat in a system as identical to - in fact, defined by - the corresponding net increase in that system's internal activity. It's also reasonable to view unusual local manifestations of that internal activity as having been caused by the increase in global system heat.

If a particular instance of extreme weather occurs, and this happens more quickly after some other collection of instances of extreme weather than one would expect from a world unaffected by global warming, then especially if such events keep on happening at anomalously high rates it's not completely unreasonable to claim that this particular instance was caused by global warming.

In much the same sense, it's not completely unreasonable to claim that having been caught in a concertina smash at a red light this morning was caused by heavy traffic. Causality is a notion broad enough to encompass both triggers like the sound of a gunshot and overall conditions like the instability of the mass of snow built up on the mountain and the gravitational potential energy held within it as causal of any given avalanche.

Dogmatic insistence that it is never reasonable to attribute any given extreme weather event to the effects of global warming generally has more of a political motivation than a respectable philosophical or scientific one.
posted by flabdablet at 10:04 PM on August 7 [5 favorites]


This saying (along with Weather isn't Climate and Vice Versa) got traction because deniers were using every major snow fall and/or lower than average temperature (and this relevant XKCD on the moving goal posts of "cold" temperatures) to say "See; today's weather totally disproves global warming/climate change).
posted by Mitheral at 10:17 PM on August 7 [1 favorite]


If anybody tells you THIS hurricane was caused by global warming or THAT drought was caused by it, tell them, "Prove it."

You can't dust for hurricane fingerprints.

If they tell you, "The climate models predict. . ." challenge them further. I haven't yet met a person who truly understands global warming enough to say this particular weather phenomenon is a result of it. It always devolves into, "The best researchers say. . ." or "The climate models say. . ." or "The consensus is. . ." Einstein and Galileo went against the consensus. Look at the troubles they had and the truth they revealed. Nobody I've seen really understands global warming right down to their eyes, ears, and strictly logical reasoning--which is what real scientists are supposed to rely on.

You said it best yourself, "I've always believed. . ." Yes, it is a belief.

Challenge, challenge, challenge. Until you understand it--not believe it--or until THEY understand it.
posted by Lord Fancy Pants at 10:44 PM on August 7 [1 favorite]


The literature on "attribution" is indeed where you should look if you want the scientific perspective on this. Let's say there's a severe drought. The idea with attribution is that you can run a climate model (or a bunch of models) many times with and without the climate-affecting gases and aerosols we've emitted since the dawn of the Industrial Revolution; if a drought of the same or greater magnitude in the same location and general time period is more common with the emissions, we can say that our emissions made that kind of event more likely—sometimes, MUCH more likely. This often gets shortened in media coverage to "GHG emissions [or climate change] caused this event."

It's impossible to say that any one severe event was caused by climate change, in the same way impossible to say whether a smoker's 40-years-of-3-pack-a-day habit caused their lung cancer. Severe events happened before the Industrial Revolution, and lung cancer sometimes strikes non-smokers.

(I'm not a climate modeler myself, but I've worked adjacent to climate modeling and with climate modelers, and my PhD advisor was getting into attribution during the last couple of years of my thesis.)
posted by dondiego87 at 12:22 AM on August 8 [1 favorite]


Einstein and Galileo went against the consensus.

They had evidence. Climate change deniers do not.
posted by His thoughts were red thoughts at 12:25 AM on August 8 [12 favorites]


An honest die will roll a 6 sometimes.

A die weighted towards 6 will roll a 6 more often. For any single 6-roll, an honest die could have rolled 6 in the same instant -- but the weighting causes the excess of 6s, even so.

------

Increasing greenhouse gases in the atmosphere increases the proportion of solar energy that the earth retains as heat, minute by minute. We have lab experiments to explain why and satellite observations to check that it's happening (we can measure the radiation leaving the planet as well as the radiation coming in). So we know that there is more energy added to the terrestrial system than there used to be.

The oceans and atmosphere (and biology and geology) dissipate energy. For instance, the Hadley cells arise because solar energy (observably, and due to easy geometry) is stronger per square meter near the equator. They give us global wind patterns, like the Tropic of Cancer and the Horse Latitudes. The ocean circulatory gyres respond to varying temperature and depth of the oceans, and the global wind patterns, and the locations of the continents. Currently the gyres make Cornwall's coast warm and California's surf cold.

"Weather" as people experience it is those patterns seen at our scale.

More energy in the system has to increase the flux through the dissipation systems, until it reorganizes them entirely. Looked at at our scale, "increase" and "reorganize" are both changes in the weather.

The responses are increasingly predictable, too, because we've been monitoring this giant alteration for decades now. Meteorological forecast skill has been going up even as we depart from the historical baseline that skill is tested against.
posted by clew at 12:32 AM on August 8 [7 favorites]


Lord Fancy Pants has laid out the standard line of argument currently fashionable among global warming deniers, from which one is expected to draw the inference that there can be no kind of causal relationship between global warming and extreme weather events, which - combined with the fact that there have always been extreme weather events - further implies that global warming is simply not worth being concerned about and that anybody who says it is must be some kind of alarmist.

This line of argument is unsound, because it takes no account of the obvious fact that any system as complex as a weather event will have multiple causes; that is, it will only happen and can only happen when all the necessary preconditions are in place.

As I said earlier, causality is a slippery conceptual fish. If I press the accelerator in my car sufficiently to raise its speed from 100km/h to 120km/h, then crash into another car, was the increase in crash energy and consequent increased lethality caused by my car's increased speed, or was it caused by my having pressed the accelerator?

My having pressed the accelerator was quite clearly the cause of both the car's 20% increase in speed and its 44% increase in kinetic energy. Even so, comments about crashes being made worse because of speed are common currency, even though approach speed and crash energy are simply correlated by the laws of kinematics rather than either being causal of the other.

One of the conditions necessary for a hurricane to happen is the presence of sufficient local heat in the surface waters of some part of an ocean. The atmospheric greenhouse effect traps heat, some of which ends up in the oceans. Anthropogenic emissions of carbon dioxide and methane enhance the atmospheric greenhouse effect, and thereby cause an increase in the amount of heat trapped by the oceans. Some of that extra heat ends up in the surface waters. Therefore, some of the heat causing any given hurricane is directly caused by anthropogenic emissions of carbon dioxide and methane, which also cause global warming.

And by analogy with the car accelerator vs crash energy example, it is quite reasonable to use "global warming", which strictly speaking refers to an effect of anthropogenic emissions of carbon dioxide and methane, as verbal shorthand for the emissions themselves. Arguments about whether global warming can legitimately be described as causal of the severity of any given weather event are analogous to arguments about whether habitual speeding can legitimately be described as causal of the severity of any given crash, and serve mainly to obfuscate the fact that human choices are indeed an important causal factor affecting both.
posted by flabdablet at 1:01 AM on August 8 [13 favorites]


Not believing in it would be as delusional as not believing in the fact that droughts, floods, hurricanes, and other forms of extreme weather happen.

If these are the things you consider to be weather, then you should note that these just happen to be the things singled out by the National Climate Assessment report as increasing as a direct result of climate change.

Think about the counterfactual. How could something be affecting the climate in a big way over an extended period all over the world but not affect the weather? How could the weather remain unchanged in the face of changing levels of energy in the ocean and the atmosphere?

Einstein and Galileo went against the consensus

There were no such people. They sound like made up names to me - something you just happen to believe, rather than something that is actually true. I'm sure you can point to all sort of 'evidence' and 'experts' who say they were real people, but I know better, and I know what THEY are trying to do.
posted by obiwanwasabi at 1:32 AM on August 8 [5 favorites]


I like to think of the analogy of civil unrest for climate, and getting punched in the face as weather (hear me out).

If I go out in the street today (nice and quiet climate) and get punched in the face that is "regular weather". An unusual event that just happened, wrong place wrong time. Regular weather in this example.

If I go out in the street in the middle of a riot (increased energy in the climate) and I am punched in the face then I can't definitively say that the riot caused that. Sometimes people get punched in the face. But the fact that hundreds of other people were getting punched in the face means I can say with pretty good certainty that "I got punched in the face due to the riot". Those who say "ah, but maybe you'd have been punched in the face anyway" are technically correct but obviously missing the larger point.
posted by Gratishades at 2:26 AM on August 8 [10 favorites]


Generally reads more as "willfully" than "obviously".
posted by flabdablet at 8:17 AM on August 8 [3 favorites]


They're not reporting weather, they're selling weather reports. They have to polish it for their audience.
posted by Sunburnt at 11:25 AM on August 8


[Lord Fancy Pants, you need to step away from this thread now. ]
posted by restless_nomad at 9:45 PM on August 8


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