Casaubon's Book

Weather vs. Climate…Again

A lot of big snowstorms get people who do not grasp the difference between weather and climate all excited. Consider the VA Republican party who claimed in an ad last week that if it snows, we can’t have global warming. But it isn’t just the skeptics and denialists here – among the believers we routinely see people citing weather, such as the lack of snow in Vancouver for the Olympics. I know that people think this helps, but in the great scheme of things, it doesn’t – if people hear people who are trying act against global warming using their weather as an explanation without evidence, those who try to discredit it also feel they can. I know it is tempting, but just don’t do it.

So let’s go over it again – I know most of you know this, but sometimes you can’t repeat something too often. Climate does affect weather in complicated ways. But climate and weather are not the same thing – weather is what you are having today and going to have tomorrow. Climate is what the overall picture for your area is – and that’s what’s shifting. Weather is highly variable, climate mostly isn’t. That’s why shifts in climate are recognizable, while shifts in weather are hard to pin down – they aren’t always obvious. People think “global warming” and believe that means a steady, obvious pattern of getting warmer – and that’s true in a climate sense. But it often doesn’t play out that way – instead, “global warming” (always something of a misnomer) can result in all sorts of aberrant weather extremes.

For example, consider this point, from meteorologist Jeff Masters

Global warming skeptics regularly have a field day whenever a record snow storm pounds the U.S., claiming that such events are inconsistent with a globe that is warming. If the globe is warming, there should, on average, be fewer days when it snows, and thus fewer snow storms. However, it is possible that if climate change is simultaneously causing an increase in ratio of snowstorms with very heavy snow to storms with ordinary amounts of snow, we could actually see an increase in very heavy snowstorms in some portions of the world. There is evidence that this is happening for winter storms in the Northeast U.S.–the mighty Nor’easters like the “Snowmageddon” storm of February 5-6 and “Snowpocalypse” of December 19, 2009. Let’s take a look at the evidence. There are two requirements for a record snow storm:

1) A near-record amount of moisture in the air (or a very slow moving storm).
2) Temperatures cold enough for snow.

It’s not hard at all to get temperatures cold enough for snow in a world experiencing global warming. According to the 2007 Intergovernmental Panel on Climate Change (IPCC) report, the globe warmed 0.74°C (1.3°F) over the past 100 years. There will still be colder than average winters in a world that is experiencing warming, with plenty of opportunities for snow. The more difficult ingredient for producing a record snowstorm is the requirement of near-record levels of moisture. Global warming theory predicts that global precipitation will increase, and that heavy precipitation events–the ones most likely to cause flash flooding–will also increase. This occurs because as the climate warms, evaporation of moisture from the oceans increases, resulting in more water vapor in the air. According to the 2007 Intergovernmental Panel on Climate Change (IPCC) report, water vapor in the global atmosphere has increased by about 5% over the 20th century, and 4% since 1970. This extra moisture in the air will tend to produce heavier snowstorms, assuming it is cold enough to snow. Groisman et al. (2004) found a 14% increase in heavy (top 5%) and 20% increase in very heavy (top 1%) precipitation events in the U.S. over the past 100 years, though mainly in spring and summer. However, the authors did find a significant increase in winter heavy precipitation events have occurred in the Northeast U.S. This was echoed by Changnon et al. (2006), who found, “The temporal distribution of snowstorms exhibited wide fluctuations during 1901-2000, with downward 100-yr trends in the lower Midwest, South, and West Coast. Upward trends occurred in the upper Midwest, East, and Northeast, and the national trend for 1901-2000 was upward, corresponding to trends in strong cyclonic activity.”

The strongest cold-season storms are likely to become stronger and more frequent for the U.S.

The U.S. Global Change Research Program (USGCRP) began as a presidential initiative in 1989 and was mandated by Congress in the Global Change Research Act of 1990 (P.L. 101-606), which called for “a comprehensive and integrated United States research program which will assist the Nation and the world to understand, assess, predict, and respond to human-induced and natural processes of global change.” This program has put out some excellent peer-reviewed science on climate change that, in my view, is as authoritative as the U.N.-sponsored Intergovernmental Panel on Climate Change (IPCC) reports. In 2009, the USGCRP put out its excellent U.S. Climate Impacts Report, summarizing the observed and forecast impacts of climate change on the U.S. The report’s main conclusion about cold season storms was ” Cold-season storm tracks are shifting northward and the strongest storms are likely to become stronger and more frequent”.

The report’s more detailed analysis: “Large-scale storm systems are the dominant weather phenomenon during the cold season in the United States. Although the analysis of these storms is complicated by a relatively short length of most observational records and by the highly variable nature of strong storms, some clear patterns have emerged (Kunkel et al., 2008).

Storm tracks have shifted northward over the last 50 years as evidenced by a decrease in the frequency of storms in mid-latitude areas of the Northern Hemisphere, while high-latitude activity has increased. There is also evidence of an increase in the intensity of storms in both the mid- and high-latitude areas of the Northern Hemisphere, with greater confidence in the increases occurring in high latitudes (Kunkel et al., 2008). The northward shift is projected to continue, and strong cold season storms are likely to become stronger and more frequent, with greater wind speeds and more extreme wave heights”. The study also noted that we should expect an increase in lake-effect snowstorms over the next few decades. Lake-effect snow is produced by the strong flow of cold air across large areas of relatively warmer ice-free water. The report says, “As the climate has warmed, ice coverage on the Great Lakes has fallen. The maximum seasonal coverage of Great Lakes ice decreased at a rate of 8.4 percent per decade from 1973 through 2008, amounting to a roughly 30 percent decrease in ice coverage. This has created conditions conducive to greater evaporation of moisture and thus heavier snowstorms. Among recent extreme lake-effect snow events was a February 2007 10-day storm total of over 10 feet of snow in western New York state. Climate models suggest that lake-effect snowfalls are likely to increase over the next few decades. In the longer term, lake-effect snows are likely to decrease as temperatures continue to rise, with the precipitation then falling as rain”.
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Obviously, it is almost impossible to attribute any one day’s weather, no matter how extreme, to climate change – what we know is that extreme weather events are more likely with climate change. But that doesn’t mean that your day to day weather is evidence for or against. So please, please, please stop saying that you can tell global warming by the weather!

Sharon

Comments

  1. #1 curiousalexa
    February 10, 2010

    Is it correct or incorrect to say that global climate *change* (not just warming) can cause more variable weather patterns?

    I’ve been hearing a lot of complaints here in the far Northeast about this winter’s lack of snow, after the last two winters of heavy snow. I’ve also been told that the last two winters were more “normal”, i.e. like the winters of ages gone by, and this dry stuff where DC steals all our snow (!) is just wrong.

  2. #2 Dunc
    February 10, 2010

    A lot of big snowstorms get people who do not grasp the difference between weather and climate all excited.

    Also people who can’t grasp the difference between “local” and “global”. The world is a big place, and the microscopically tiny bit of it you see outside your window is unlikely to be representative.

  3. #3 Greenpa
    February 10, 2010

    CurousAlexa- have you ever watched the Schlieren lines in a pot of water, as you heat it rapidly to a boil?

    A real question. I did, as a kid, so all this is a little easier to grasp. And I played with it a little, out of curiosity; turning the heat up, down, and watching the water in the pot move at a slow simmer.

    All weather, cold and hot, is caused by heat and its inequalities. It’s fairly easy to comprehend if you think of the world as a pot on “low simmer”. The up and down currents are rather stable, established; they do the same things over and over.

    Then- nudge the heat up, just a tad.

    All the established patterns are upset. You’ll get new ‘hot’ points on the bottom, setting up new upwellings. In order to balance out- the cold patterns have move also. Some of the cold currents will be warmer than before; but because of the basic disturbance, it’s just as likely some of them may spend a few more moments at the surfaces, and be colder than before.

    And the whole thing is moving faster.

    Does that help see it?

  4. #4 Greenpa
    February 10, 2010

    dear Sharon Quixote- if you are willing to undertake to convert and enlighten those who are unable and utterly unwilling to grasp that climate and weather are not the same, I have a similar project I think you should undertake.

    And I’m willing to help fund it! Just go to the nearest ocean shore there, and I’ll send you a bucket. Start bailing, and you will be able to prevent sea levels from rising.

    What a fantastic benefit to the world!

    :-)

  5. #5 Greenpa
    February 10, 2010

    Curious Al- oh, yeah; and the simmering pot thing is much easier to visualize if instead of the normal ring of heat we use on our stoves, you’ve got a 3 quart pot, full, sitting above the single flame of a bunsen burner. Even more vivid if you put the bunsen burner over on one side of the pot.

  6. #6 curiousalexa
    February 10, 2010

    But you didn’t answer my question!

    You did decide what dinner will be though – pasta! In a large pot of water. Irresponsibly heated up without a lid. And probably off to one side of the gas burner. [g]

  7. #7 Greenpa
    February 10, 2010

    “But you didn’t answer my question!”

    LOL!!! bloody heck. I’m cracking up here- at myself and my concepts of communication.

    That would be “it is correct”.

    :-) erratic weather is one of the standard expectations.

    So, in regard to MY question, “did that help”, the answer would be “no”. Yes?

    oh, my.

  8. #8 Gary
    February 10, 2010

    I try to always use the term global climate change instead of global warming.

    But if you say global warming, what is temperature? A measure of energy in the air. As the energy level goes up (temp rise) there is more energy for storms. All kinds of storms. I see no problem with the wild weather we are having now and global climate change. More energy in the atmosphere equals more “weather”.

  9. #9 Mystyk
    February 10, 2010

    “…among the believers we routinely see people citing weather, such as the lack of snow in Vancouver for the Olympics.”

    You forget that when most “believers” mention something such as this, they make pains to put it in context. This is great evidence for the Arctic Oscillation when you also mention that across entire sections of Canada and Russia there have been unseasonably warm winters, while just a touch south of those areas (such as much of the East Coast) it has simultaneously unseasonably cold. Explaining this regional climate system is a necessary part of explaining how the global climate system functions, and also helps explain why the snow in Washington D.C. doesn’t disprove Anthropogenic Global Warming.

  10. #10 Alan
    February 10, 2010

    The term “climate disruption” is even better and more compelling than “climate change”. After all, as we’re frequently informed by signs on the tip jars at coffee bars, “Change is good”. And, to way too many idiots, “global warming” just suggests that there will be more days suitable for zooming around on their jet skis (pardon me, “personal water craft”).

    But nobody really thinks disruption is good.

  11. #11 Edward Bryant
    February 10, 2010

    A good friend refers to it as “global climate weirding”.

  12. #12 Nomen Nescio
    February 10, 2010

    Consider the VA Republican party who claimed in an ad last week that if it snows, we can’t have global warming.

    last payday i got my paycheck as usual, and it didn’t bounce. i guess that must mean we’re not in a recession after all.

    (you’d think republicans would be receptive to an analogy with economics, wouldn’t you? but i’ve had no luck with this one so far.)

  13. #13 ChicagoMike
    February 11, 2010

    It’s also helpful to point out that globally, this has been the warmest winter in the record of satellite temperature measurements:

    http://climateprogress.org/2010/02/08/climate-science-extreme-weather-moisture-precipitation-warmest-winter-satellite-record-deniers-jeff-masters/

    And of course the 2000’s were the hottest decade in the instrumental temperature record with 2009 among the 5 hottest years.

  14. #14 Rod Rose
    February 11, 2010

    Consider the Columbia Journalism Review story which remarked that TV weather forecasters generally dispute the concept of “global warming” — I, too, prefer the term “climate change” — because they have been trained in meteorology, not climatology. This is unfortunate because TV weathermen are considered by the general public to be scientists and, therefore, credible sources about the reality of climate change.

    I’m waiting for Apophis, myself.

  15. #15 yogi-one
    February 11, 2010

    I think you just remind people that big snowstorms are in line with AGW predictions, just the same as big hurricanes are. The storms are being amplified by the availability of of warm water (in the case of snowstorms its warm water vapor in the atmosphere, in the case of hurricanes its actual warmer sea water). Most people can connect the dots from more water to bigger precipatation events, and work backward in their minds to see how overall warming climate creates more available precipitation.

    Most people, even those claiming not to “believe” in AGW, understand that GHGs create a greenhouse effect. The public gets at least that much, at this stage of the game.

    I usually get some cred with my lesser-informed friends by making sure of two points before I explain the above: 1. climate is measured over centuries or milleniums, or even geologic timescales, and weather is today’s forecast; and 2. please, let’s keep politics out of the discussion, and only talk about what the scientists have been reporting. If they can’t do that, I end the conversation by saying I am not interested in politics, and they should read the science before further discussing with me.

    So, you first establish some scientific realities that also make common sense to people, and second, draw a clear distinction between science and politics, and refuse to discuss the latter. The minute they start spouting off about Al Gore or Glenn Beck, remind them that’s politics, and not part of the conversation you’re willing to have.

    I am referring to interacting with acquaintances and friends in a casual way, not taking on paid professionals whose career is to deliver disinformation to the public.

    There’s huge difference between a friend who is open to learning something new, and a professional denialist, who knows the truth but has decided to try to profit from lying to the public about it.

  16. #16 Trevor M
    February 12, 2010

    Gee willikers. If those attempting to study AGW had been held up to the same close scrutiny and peer review as people working in the sciences, there WOULDN’T BE any of these problems. As everyone can now see by the examples set by the CRU and the UN group, AGW is a field of study that seems to rest on one pillar of science and two pillars of TRUTHINESS — and a fourth pillar of sketchy politics.

    The sooner the religious overtones and indignation and political labeling used by AGW proponents goes away, the sooner some respectability can be earned by those trying to elevate AGW study to a science.

  17. #17 Greenpa
    February 12, 2010

    trevor m: “The sooner the religious overtones and indignation and political labeling used by AGW proponents goes away, the sooner some respectability can be earned by those trying to elevate AGW study to a science.”

    Oh, what malarky. I think you’re as guilty as those you cite, of cherry picking the comments of nincompoops to make your “point”

    I know quite a few global warming researchers, having presented papers at 3 international conferences. Probably a higher percentage of them are good, sound, scientists than the average at fancy universities.

    The recent noise about the emails was just that- noise. Via hacking, the rest of the world was allowed to see what academics usually hide meticulously – some of them are morons. Just like the rest of humanity.

    Climate science is inherently difficult. Considering that they are working on the edge of possible science, they do a very good job.

  18. #18 Jan
    February 13, 2010

    I agree with Dunc “The world is a big place, and the microscopically tiny bit of it you see outside your window is unlikely to be representative.”

    In the Netherlands we now have the coldest winter ever. However the last 8 summers are getting warmer. We’ll see what happens.

  19. #19 Lora
    February 13, 2010

    Oh hell, even the microscopically tiny bit of weather I see out the window DOES show climate change indicative of warming.

    Robins in January in New England. They have a hard time competing with the cardinals at my bird feeder. Last frost dates for gardening arriving earlier and earlier, I can set tomatoes out in April if I want–which used to be a sure recipe for doom. First frost dates happening later and later, we’ve kept the growing season for summer squash, garden cress and other frost-sensitive crops going right up till Halloween, no cold frame required. I have apricots in my orchard, from old varieties that were never thought to do well in the late frosts of New England springs–bought on a gamble, and it paid off, they fruit with no problem. Last year I lost a bunch of seedlings I was hardening off in the cold frame, not to the usual late frosts but instead to unexpectedly warm days that overheated the cold frame and cooked the plants.

    Maple syrup season has to stop early because the buds sprout sooner than they used to. The 4 week transition from freezing/40F weather to real tree-flowering spring is no longer 4 weeks, and if you try to stick to the old-time 6 week season that the ag colleges recorded as normal in the 1930s-1940s, you’ll get a lot of weird-tasting “buddy” sap for your efforts.

    Frost heaving used to be a major problem around here: You’d get perennials or bushes or something on sale at the end of the season from the garden centers, plant them, and in late winter/early spring the accursed things would pop right up to the surface of the soil from frost heaving, ripping the small feeder roots and killing the plant. Building codes required really deep foundations because of frost heaving, and your best bet was dry-laid blocks or stone, because poured concrete would crack in a few years. Everyone knew this, that if you didn’t get a giant rootball and dig a 3′ hole with a bunch of gravel in it for a 10 inch potted plant, you could expect your landscaping to erupt in February/March. That is now a rarer problem limited to frost pockets, and you can get away with planting in November if you want: the plants will be fine even with a 1″ layer of decorative mulch. Poured concrete foundations now last a lot longer, the basement repair companies don’t make so much money anymore.

    Even the fishing patterns are effed: If you schedule a fishing trip to catch migratory fish like salmon and bluefish, you better be really careful about when to go, or you’ll miss them. I am old enough to remember salmon fishing in late March/early April in PA and NY, bluefish not till summer beach season. I’ve caught blues in early May this far north! Are the freakin’ FISH now acting under the amazing charisma of Al Gore? Really?

  20. #20 golu
    February 20, 2010

    very useful

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