Jet Stream

The Jet Stream is Misbehaving

gregladen — Wed, 26 Mar 2014 09:13:35 +0000

The Jet Stream is Misbehaving

From meteorologist Paul Douglas:

Published on Mar 14, 2014
Weather seems to be staling. Look into how the speed of the jet stream causes this "stuck in a rut" weather pattern. Meteorologist Paul Douglas also takes a look back as to how this winter compares to years past. Checking out extreme drought conditions, snow cover and cooler temperatures overall. This did not only impact the U.S. but other areas of the world. England experienced their wettest winter yet!

gregladen Wed, 03/26/2014 - 05:13

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Climate Change

Severe weather

Jet Stream

Weather Whiplash

Hot Winter Days

milhayser — Mon, 20 Jan 2014 12:11:48 +0000

Hot Winter Days

The anti-scientific M.O. of some political conservatives was in full swing during the 'polar vortex,' as frigid weather brought south from the Arctic led many commentators to scoff, "look how cold it is, can you believe anyone thinks the Earth is getting warmer?" Coby Beck adds some perspective from climate historian Christopher C. Burt on A Few Things Ill-Considered, writing "cold snaps like this past week’s used to occur every couple of years in the 1800′s," and more like every 5-10 years in the 1900's. Meanwhile the last time it got so cold in the U.S. was twenty years ago. Coby says "what is remarkable is that this level of cold has become remarkable"—because it used to be commonplace. As the planet gets warmer, regional weather, unlike average global temperature, remains highly variable. Coby concludes, "this is just what scientists refer to as 'winter.'" Or what they used to, anyway.

Greg Laden offers a complementary interpretation, saying the polar vortex is the result of a jet stream increasingly unsettled by the warming of the Arctic. Per the theory of "weather whiplash," extreme temperatures might become more common as the energized jet stream contorts Arctic air. While the eastern U.S. was suffering bitter cold, northern Europe enjoyed unseasonal warmth; there's only so much Arctic air to go around. Which means the northern hemisphere can look forward to hot winter days as surely as very cold ones. The polar vortex was entirely consistent with global warming, and those who claimed otherwise wore their disingenuity on their sleeves.

milhayser Mon, 01/20/2014 - 07:11

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Hah! I was sure this post was going to be about someone in the east finally noticing the unheard of weather we've been having in the Southwest U.S. This is the driest year since record-keeping started.

More on weather whiplash and the Polar Vortex

gregladen — Tue, 07 Jan 2014 13:48:31 +0000

More on weather whiplash and the Polar Vortex

Extreme weather events of all kinds seem to be more common now than they were then. By now I mean the last five to ten years, approximately, and by then I mean ... well, before that. This is because of global warming.

The current Colding caused by a wandering Polar Vortex (which I've heard Rush Limbaugh has declared to be a liberal plot ... thanks Obama!) is probably a result of changes in the nature and configuration of the jet streams and related air masses, as discussed here. Warming caused by the release of fossil carbon, mainly as Carbon Dioxide, has affected the Arctic more than most of the rest of the planet, and this has changed the nature of major air mass movement which, in turn, has disrupted the jet streams, which has caused what we call weather whiplash. If you would like to see an example of weather whiplash, you can probably do so by looking outside because it is happening all over the place all the time. Well, it seems that way anyway. Let's just say that it is happening often enough that the lack of weather whiplash may well be newsworthy.

Peter Sinclair of the Yale Climate Forum has a post and a new video that puts a lot of this together. Here's the video:

Hey, if you are local to the Twin Cities, come on over to Stillwater on Monday and we'll talk about it. Unless you are that one guy who wants to put me on trial and execute me because I think global warming is real! You stay home!

__________________________________________

A rollicking adventure through the rift valley and rain forests of Central Africa in search of the elusive diminutive ape known locally as Sungudogo.

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If I missed it somewhere, I apologize but I looked at this post and the other one and I can't seem to see a time and place on this Monday in Stillwater get-together.

http://www.meetup.com/Critical-Thinking-Club/events/158848652/

Tusind tak.

Cold, Hard Facts

milhayser — Fri, 27 Dec 2013 09:29:11 +0000

Cold, Hard Facts

Coldness can manifest where you least expect it: on a planet rapidly warmed by the combustion of fossil fuel, or in the heart of a star 250 times as massive as our own. On Greg Laden's Blog, Greg explains that an apparent "recovery" of Arctic sea ice from its historic low in 2012 does not invalidate the long-term trend. Greg also explains this year's legacy of extreme weather, such as snow in Cairo, writing that when there is less difference in temperature between equatorial and polar regions, "the jet streams get all wiggly and cause northerly air to reach far to the south in some places and southerly air to reach farther north in other places." Meanwhile, on Starts With a Bang, Ethan Siegel explores the different fates awaiting stars of different sizes. When a star like our own runs out of fuel and begins to collapse, it blows off its outer layers and leaves behind a neutron star or small black hole. Bigger stars, however, start producing antimatter, which lowers the pressure in the star and generates gamma rays that heat up the core even further. These stars end in a pair-instability supernova, which "not only destroys the outer layers of the star, but the core as well, leaving absolutely nothing behind!" But in the biggest stars in the universe, gamma rays cause photodisintegration, which cools down the interior of the star and allows all its mass to collapse into a black hole. The earliest of these massive black holes probably seeded the centers of galaxies, which now contain millions of solar masses.

milhayser Fri, 12/27/2013 - 04:29

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Linking Weather Extremes to Global Warming

gregladen — Tue, 04 Jun 2013 08:32:26 +0000

Linking Weather Extremes to Global Warming

Global Warming is the increase in the Earth's temperature owing to the greenhouse effects of the release of CO2 and other gasses into the atmosphere, mainly by humans burning fossil fuel, but also by the release of Methane from oil wells and melting of Arctic permafrost, natural gas from leaky pipes, and so on. This increase in temperature occurs in both the atmosphere and the oceans, as well as the land surface itself. During some periods of time most of the increase seems to happen in the atmosphere, while during other times it seems to occur more in the oceans. (As an aside: when you use passive geothermal technology to heat and cool your home, the heat in the ground around your house is actually from the sun warming the Earth's surface.)

"Weather" as we generally think of it consists partly of storms, perturbations in the atmosphere, and we would expect more of at least some kinds of storms, or more severe ones, if the atmosphere has more energy, which it does because of global warming. But "weather" is also temperature, and we recognize that severe heat waves and cold waves, long periods of heavy flooding rains, and droughts are very important, and it is hard to miss the fact that these phenomena have been occurring with increasing frequency in recent years.

We know that global warming changes the way air currents in the atmosphere work, and we know that atmospheric air currents can determine both the distribution and severity of storms and the occurrence of long periods of extreme heat or cold and wet or dry. One of the ways this seems to happen is what is known as "high amplitude waves" in the jet stream. One of the Northern Hemisphere Jet Streams, which emerges as the boundary between temperate air masses and polar air masses, is a fast moving high altitude stream of air. There is a large difference in temperature of the Troposphere north and south of any Jet Stream, and it can be thought of as the boundary between cooler and warmer conditions. Often, the northern Jet Stream encircles the planet as a more or less circular stream of fast moving air, moving in a straight line around the globe. However, under certain conditions the Jet Stream can be wavy, curving north then south then north and so on around the planet. These waves can themselves be either stationary (not moving around the planet) or they can move from west to east. A "high amplitude" Jet Stream is a wavy jet stream, and the waves can be very dramatic. When the jet stream is wavy and the waves themselves are relatively stationary, the curves are said to be "blocking" ... meaning that they are keeping masses of either cold (to the north) or warm (to the south) air in place. Also, the turning points of the waves set up large rotating systems of circulation that can control the formation of storms.

So, a major heat wave in a given region can be caused by the northern Jet Stream being both wavy (high amplitude) with a big wave curving north across the region, bringing very warm air with it, at the same time the Jet Stream's waves are relatively stationary, causing that lobe of southerly warm air to stay in place for many days. Conversely, a lobe of cool air from the north can be spread across a region and kept in place for a while.

Here is a cross section of the Jet Streams in the Norther Hemisphere showing their relationship with major circulating air masses:

Cross section of the atmosphere of the Northern Hemisphere. The Jet Streams form at the highly energetic boundary between major circulating cells, near the top of the Troposphere.

Here is a cartoon of the Earth showing jet streams moving around the planet:

The Jet Streams moving around the planet. Not indicated is the Intertropical Convergence Zone (ITCA) around the equator which is both not a Jet Stream and the Mother of All Jet Streams. This post mainly concerns the "Polar Jet." Note that the wind in the Jet Streams moves from west to east, and the Jet Streams can be either pretty straight or pretty curvy. Curvy = "high amplitude." This figure and the one above are from NOAA.

Here is a depiction of the Jet Stream being very curvy. The waves in the Jet Stream are called Rossby waves.

The Jet Stream in a particularly wavy state.

(See also this animation on Wikicommons, which will open in a new window.)

Research published in the Proceedings of the National Academies of Science last February, in a paper titled "Quasiresonant amplification of planetary waves and recent Northern Hemisphere weather extremes," links global warming to the setup of high amplitude waves in the Jet Stream, as well as relatively stationary, blocking, waves that cause extreme warm or cold conditions to persist for weeks rather than just a few days. According to lead author Vladimir Petoukhov, “An important part of the global air motion in the mid-latitudes of the Earth normally takes the form of waves wandering around the planet, oscillating between the tropical and the Arctic regions. So when they swing up, these waves suck warm air from the tropics to Europe, Russia, or the US, and when they swing down, they do the same thing with cold air from the Arctic...What we found is that during several recent extreme weather events these planetary waves almost freeze in their tracks for weeks. So instead of bringing in cool air after having brought warm air in before, the heat just stays."

So how does global warming cause the northern Jet Stream to become wavy, with those waves being relatively stationary? It's complicated. One way to think about it is to observe waves elsewhere in day to day life. On the highway, if there is enough traffic, waves of cars form, as clusters of several cars moving together with relatively few cars to be found in the gaps between these clusters. Change the number of cars, or the speed limit, or other factors, and you may see the size and distribution of these clusters (waves) of cars change as well. If you run the water from your sink faucet at just the right rate, you can see waves moving up and down on the stream of water. If you adjust the flow of water the size and behavior of these "standing waves" changes. In a baseball or football field, when people do "the wave" their hand motions collectively form a wave of silliness that moves around the park, and the width and speed of that wave is a function of how quickly individuals react to their fellow sports fan's waving activity. Waves form in a medium (of cars, water molecules, people, etc.) following a number of physical principles that determine the size, shape, speed, and stability of the waves.

The authors of this paper use math that is far beyond the scope of a mere blog post to link together all the relevant atmospheric factors and the shape of the northern Jet Stream. They found that when the effects of Global Warming are added in, the Jet Stream becomes less linear, and the deep meanders (sometimes called Rossby waves) that are set up tend to occur with a certain frequency (6, 7, or 8 major waves encircling the planet) and that these waves tend to not move for many days once they get going. They tested their mathematical model using actual weather data over a period of 32 years and found a good fit between atmospheric conditions, predicted wave patterns, and actual observed wave patterns.

The northern Jet Stream originates as a function of the gradient of heat from the Equatorial regions to the Polar regions. If air temperature was very high at the equator and very low at the poles, the Jet Stream would look one way. If air temperatures were (and this is impossible) the same at the Equator and the poles, there would probably be no Jet Stream at all. At various different plausible gradients of temperature from Equator to the poles, various different possible configurations of Jet Streams emerge.

One of the major effects of global warming has been the warming of the Arctic. This happens for at least two reasons. First, the atmosphere and oceans are simply warmer, so everything gets warmer. In addition, these warmer conditions cause the melting of Arctic ice to be much more extreme each summer, so that there is more exposed water in the Arctic Ocean, for a longer period of time. This means that less sunlight is reflected directly back into space (because there is less shiny ice) and the surface of the ice-free northern sea absorbs sunlight and converts it into heat. For these reasons, the Arctic region is warming at a higher rate than other regions farther to the south in the Northern Hemisphere. This, in turn, makes for a reduced gradient in the atmospheric temperature from tropical to temperate to polar regions.

Changing the gradient of the atmospheric temperature in a north-south axis is like adjusting the rate of water flowing from your faucet, or changing the number of cars on the highway, or replacing all the usual sports fans at the stadium with stoned people with arthritis. The nature of the waves changes.

This video shows how Donald Trump and Bill O'Reilly are like global warming.

In the case of the atmosphere of Earth's Northern Hemisphere, global warming has changed the dynamic of the northern Jet Stream, and this has resulted in changes in weather extremes. This would apply to heat waves, cold snaps, and the distribution of precipitation. The phenomenon that is increasingly being called "Weather Whiplash" ... more extremes in all directions, heat vs cold and wet vs. dry, is largely caused by this effect, it would seem.

This study is somewhat limited because it covers only a 32 year period, but the findings of the study are in accord with expectations based on what we know about how the Earth's climate system works, and the modeling matches empirical reality quite well.

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See also: Killer Heat Waves and Floods Linked to Climate Change by Stephen Leahy and Slowing Rossby Waves Leading to Extreme Weather? by Stuart Staniford.

More about Climate Change HERE

Petoukhov, V., Rahmstorf, S., Petri, S., & Schellnhuber, H. (2013). Quasiresonant amplification of planetary waves and recent Northern Hemisphere weather extremes Proceedings of the National Academy of Sciences, 110 (14), 5336-5341 DOI: 10.1073/pnas.1222000110

gregladen Tue, 06/04/2013 - 04:32

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How about all the Stratospheric Aerosol Geo-Engineering that goes on? Shall we link this to weather? http://tinyurl.com/m3q5dut

"Injecting sulphate aerosols into the stratosphere belongs to the most discussed GE approaches because
it is assumed to be of high effectiveness and low costs
[Shepherd et al.,2009;Lenton and Vaughan2009,Crutzen,2006;Wigley,2006].
However, safety is judged to be low and more studies on the impact of stratospheric aerosols are needed in order to evaluate possible side effects. Possible side effects are impacts on the hydrological cycle, stratospheric ozone and cirrus clouds. Recent studies have addressed the question of possible effects on ozone and the hydrological cycle [Tilmes et al., 2008; Heckendorn et al., 2009; Robock et al.,
2008; Trenberth and Dai , 2007]. Tilmes et al., [2008] analyzed the sensitivity of ozone depletion to proposed GE schemes and found that the recovery of the Antarctic ozone hole would be prolonged by some decades if large burdens of SO2 are brought into the stratosphere on a continuous basis. Also, the hydrological cycle will likely be affected by stratospheric aerosols.
Robock et al., [2008] used a global climate model to investigate the regional climate responses to stratospheric sulphate injections and found modified Asian and African monsoons which reduce the precipitation regionally and thus endanger the food supply. Reduced precipitation over land was also found by Trenberth and Dai, [2007] who evaluated observational data after the eruption of Mt. Pinatubo in 1991. "

Fascinating. What impact will the recent findings of Ice2sea re :expected warming similarity to warming(surface) of past 150 yrs as well as sea level rise similarity? I am also confused by the apparent beneficial aspect of the atmospheric rise in Co2 concentrations as described in Earth and Sky 5/31/2013 "Greening of the Deserts" .Won,t the additional WV increase due to warming eventually overcome sulftates effects as the WV concentrations spread Globally thru mixing? How are the Sulfates reaching such high altitudes? Volcanoes emit to 20,000 ft.altitudes but how are powerplants doing this?

The Ice2Sea results have been somewhat misinterpreted (as expected) by the press. The overall Ice2Sea project is very important and they are doing excellent work, but the melting models are primarily based on the physics of ice melting and don't address very well (though they try to some extent) the mechanics of glacial wastage. The people who study Ice that I've spoken to feel that mechanical deterioration of major continental glaciers, esp. Greenland and the Western Antarctic will likely cause rapid and stepwise melting. Think of the Ice2Sea results as being very very conservative.

This has nothing to do with the "Greening of the Deserts" research. This is a fertilization effect expected with increased CO2 and often pointed to by climate change denialists who want us all to relax about messing up the earth's climate system. These effects are expected to be minimal. Unfortunately, CO2 is a limiting factor with limits, and excessive heat in arid lands will dominate and has dominated vegetative change there. Also, ground level ozone is likely to counteract this fertilization effect.

You would have to explain what WV is (West Virginia? Weight-Volume Ratio) in order for the latter part of your comment to make sense. If you know.

Well, I guess from your answer this is just all "over my head" Thank you for responding so quickly. I thought that "WV" was used describe "water vapor". Was my use of the initials improper? What is the correct shorthand for water vapor then.Wouldn,t the Co2 fertilization effect be expected to impact plant growth in moist areas long before Desert areas ?The question on sulfate distribution, altitude? Ice2sea temp forecasts? Further thoughts?

Ah, water vapor!

The CO2 fertilizer effect anywhere is negligible.
The other effects you are talking about are pretty much unrelated to the jet stream, discussed here, and are also not really related to the overall problem of global warming.

Negligible?That is a surprisingly short answer.I was stunned by the implications of that report. I see now that I was actually responding to another poster re; aerosols/ altitude. What about the question of WV, and temps as players in relation to storm frequency/energy? Specifically the temp forecasts of Ice2sea? 32 yrs of data seems short for such strong assumptions.Don't you agree?

I think you should separate your thoughts into separate paragraphs and I'll promise to do the same.

How about separate posts? Coffee wearing off, Ron,I completely misunderstood your post till I followed your link! I read recently of Chinas non scrubbing power plants being blamed for the aerosols and causing some cooling. What a dangerous sounding plan! Very Glad the authors seem to agree. Our current Climate State seems fairly Benign .At least when compared with the mortality rate of the LIA due to crop failures/ cold/and reduced growing seasons starving the human population and contributing greatly to disease.I hope nothing is done to return us to that lovely Climate State!

Greg, Why is the Co2 fertilizer Effect Negligible? I read the Greening of the Deserts and was stunned at the implications given the added WV due to Warming.

Greg, The Ice2sea report predicts warming fairly similar to the rise since 1850 out to early 22nd century. Any chance no dramatic change in frequency/energy of storms with the predicted warming rate looking fairly gradual?

Greg,Don't mean to be a pest,but I read an article where Hansen describes this ongoing research as "speculative". Would you agree that the rising WV which it is my understanding is 75% surface heat retention and has been increasing along with warming since the LIA may have a large impact here?

How's this for a real "Duh?" What caused the end of the last ice age around 35K years ago? Global warming! Earth wobble, change in orbit around the sun, etc, Who knows. But the last I heard not too many humans were around then throwing up a whole lot of CO2 into the atmosphere. Here's another factoid hard for you Liberals to accept.: Temperatures have remained stagnant over the past 20 years while the planet "polluted" the atmosphere with a massive increase in CO2. Bummer!

This man made blame hysteria is all about politics. But, hey, "drink the Koolaide" and live the Green life if you want to.

George. The last glacial maximum was at 18K years ago, so your timing is a bit off.

There are three major factors that determine climate, all of which vary naturally. Orbital geometry, the effects of which are very subtle and it is hardly a forcing effect but rather an allowing condition for other forcing effects. Configurations of continents, mountains, water bodies. Atmospheric gases.

All of these change naturally.

The biggest change happening over the last century and this one is the change in atmospheric gases. The change we are seeing now his happening at a rate greater then ever known from our paleo record since the origin of life. Humans are causing it.

Temperatures have not remained stagnant over the last 20 years; air temps have gone up. Have a look at this graph.

http://www.skepticalscience.com/pics/McLean2011Failure.png

Ocean temps have gone up even more:

http://www-argo.ucsd.edu/levitus_2009_figure.jpg

That is not how you spell Kool Aid.

socalpa, no, I don't. Here's a good primer on the role of water vapor: http://www.skepticalscience.com/water-vapor-greenhouse-gas.htm

Greg, you have returned! Several of your statements above I disagree with. I will ask questions on those later. Since the lag after warming onset is estimated by most of the Paleo climate guys as about two centuries or more, Isn't it possible much of the warming at least in the Oceans began two centuries before the Co2 concentrations passed 20PPM over background in the 1940s or 1950s?

Greg, my bev of choice is coffee,

As one of the paleo guys I reject your premise. So, no.

Woops, I just reread the Paleo guys lag stuff. 200yrs min of Ocean warming till Surface Temps respond! That means Warming started right about Galileos time in the Oceans! 800 or more yrs till co2 levels respond! Co2 increase sure looks manmade but how does it account for Ocean warming prior to 1930 or so when emissions started climbing? Could this be why the projected Ocean and surface temps are looking more and more Gradual? Isn't this Good News?

Socalpa, you might find this interesting inre the fertilization effect: http://www.climatesciencewatch.org/2013/06/04/the-co2-fertilization-eff…

Paleo guy is a specific person? Who is that?

Anyway, no, that information about ocean warming is not correct. In any event, I'm not sure how a lag is good news. It would simply mean that some of the negative effects of global warming would be delayed so much that we would not notice them until it was too late to do anything about them.

Thanks so much for responding, I will of course follow your link. Please if you would tell me specifically why the rise in the Ocean temps could NOT be from warming before surface temps started rising after the LIA.

At this moment we actually know very little about how heat actually gets into the ocean, at what rate, how and when it may come out of the ocean, etc.

We do know however that the rise of the oceans has doubled over the last ten years compared to the previous ten years; the amount of warming of the atmosphere has been positive over this period (it has gone up) but less than other recent decades; the temperature of the deep ocean has gone up during this period.

The think is, you can't put heat in the ocean one day and expect thermal expansion to take place at any time later. It would be instantaneous (more or less).

Sea Level Rise has doubled over past ten years? Source please. How could the warmth below the suface not be caused by surface to Ocean heat exchange? Does anyone know how long it is estimated to take for surface heat to reach Deep Water? If not, How can the warming lag be eliminated as a factor in recent temp measurements or rise in sea levels?

I just put up a blog post that discusses sea level rise and ocean melt, you can check that out. If the doubling of ice melting that happened over the last ten years is itself a trend, i.e., a doubling every ten years, then we'll have about 5 meters by 2090.

" Source please. How could the warmth below the suface not be caused by surface to Ocean heat exchange? "

I did not realize this was an issue. I didn't say anything about that.

"Does anyone know how long it is estimated to take for surface heat to reach Deep Water?"

As I've said, this is not well understood.

"If not, How can the warming lag be eliminated as a factor in recent temp measurements or rise in sea levels?"

There is not a warming lag. There is warming in the atmosphere and the ocean, and sometimes the atmosphere warms more than the ocean, sometimes the ocean warms more than the atmosphere.

And again, if you warm up water it expands. It does not wait 200 years and then expand.

Not so sure about your answer, Greg, Seems to contradict what I just read from the guys studying Vostok Ice Cores.Oceans warm long before surface temps show the rise. Oceans continue to warm after that I would assume. Where can I find more about this aside from your blog.The reason I mentioned the Ocean surface heat exchange is because the Oceans are warmer than expected below 700ms which I read just recently.

Greg, Solar radiance does a heck of a job on Warming Ice Free Oceans directly. If whatever the sun was doing to cause the LIA changed ,wouldn't the seas begin to slowly warm in response? Couldn't that ongoing warming explain most of the 7 in sea level rise of the past century? Co2 passed extra 20PPM late 50s.Would not warming from back then haveto be added to background rise since LIA?

"Where can I find more about this aside from your blog."

Read this entire web site, your questions are answered all over it: http://www.skepticalscience.com/

"The reason I mentioned the Ocean surface heat exchange is because the Oceans are warmer than expected below 700ms which I read just recently."

Actually, I just mentioned that recently.

"Couldn’t that ongoing warming explain most of the 7 in sea level rise of the past century?"

Have a look at this blog post for numbers on the relative contribution of different factors on sea level rise: http://scienceblogs.com/gregladen/2013/06/06/the-science-of-melting-ice…

To all the global warmers . I ask,will you guarantee with your way life that the solutions being proposed will change anything? Because the proposed solutions will change peoples lives and not always for the better. You should be made to give up every asset you have and start from 0. The understanding of this planet and the universe will never be constant or predictable and science will never explain everything. Twenty years from now if scientists have different findings you should be held accountable. Can you even give me a guarantee we will be here 20 years from now ? No you cannot. I know squat about science , but do know science from 20 yrs ago has changed dramatically by past predictions that have failed to come true . The science of today is not the end-all . In the history of this planet we are but a second in time and who's too say how this planet responds to anything or if this may be a first in the history of the planet . Science has studied the history of the planet and still they do not know 100% of the past. In the future ,tomorrow , next year or whatever timeframe you want to use if a scientist comes out with a discovery (been known to happen) that completely changes everything we know, is there a do over? So enough with scaring everyone with science please! We have to adapt , as that is nature and extinction is in the history of this planet and humans may very we'll be a part of this planets history, extinct.

Why are we having such bad weather?

gregladen — Mon, 03 Jun 2013 12:50:38 +0000

Why are we having such bad weather?

I think most people will agree that in North America (and other places) we've been having some bad weather. Some of the weather is not necessarily intrinsically bad ... so what if it is a little cooler or a little warmer than you expect. Aridity? Deserts are nice! Extra rainfall? Great for the plants. But actually that sort of thing has its down side since important systems like agriculture, the water supply, and Spring Break work reasonably well because of expectations that might not be met if the weather is different.

Other weather is intrinsically bad. I'd mention tornadoes but at the moment climate and weather experts are not at all agreed on whether or not we are having more, worse, bigger, or otherwise badder tornadoes and if there are differences in tornadoes this decade compared to earlier decades, why that is the case. But other things can be pointed to. Superstorm Hurricane Sandy was the hurricane that should not have gone where it went, should not have been so strong, perhaps should not have been at all. Droughts. Widespread wildfires caused by droughts. Lots and lots and lots of rain causing widespread flooding. Heat waves and cold waves. As a category of things that can happen, these things are in the "bad weather" category, and it is reasonable to ask why they are happening so much "these days."

It is possible that these changes in weather, or more exactly, these examples of rapidly changing weather that have come to be known as "Weather Whiplash," are caused by global warming which in turn is caused by the unchecked release of large amounts of fossilized carbon into the atmosphere with the burning, by humans, of fossil fuels. But before I get to that argument (short answer: Weather Whiplash is caused by global warming, but hold on just a sec..) I want to point something else out that is very important.

I want to point out the problem of understanding shifting conditions. Let's say you are a storekeeper and every day you make a certain amount of profit. How much you make each day varies a great deal owing to a large number of factors. I knew a guy who worked in a camera shop just off Wall Street. He would sell no cameras for days on end and then suddenly sell a gazillion cameras. That would be on a day that the stock market went way up and traders felt flush, and went and bought the expensive cameras and lenses they had been coveting for weeks. I know people who had businesses on Cape Cod and how much money they made on a given weekend depended on the weather forecast for "The Cape" shown to Boston area audiences on Friday (regardless of the actual weather itself, generally). But underlying all this is another set of factors that do not vary day to day or hour to hour (or week to week or even seasonally). One is the overall long term state of the economy (how much stuff do people buy, based on how free they feel with their cash). Another is the overall demand for your particular goods, which may vary little if you sell food but a lot if you sell some trendy widget.

In the absence of good information, how do you know if your business is about to either tank, because people stopped buying your goods, or take off, because people can't get enough of your goods? If your sales shift a great deal in one day, is that enough information? No. If your sales shift for an entire week, does that tell you something? Maybe, probably not. Most likely, you can identify normal pseudo-cycles, ups and downs, that occur in your business and estimate their length. Some factors cause your business to go up and down over scales of weeks, some over scales of days. Perhaps you can estimate that if you get an average amount of business over six months, and that is higher or lower than the previous six months, then you can say that a basic shift has happened.

Weather has cycles and pseudo-cycles just like businesses do, and they run over the course of days, seasons, years, and somewhat longer cycles that have to do with the position and relationships of major high pressure systems that shift around over cycles of five to fifteen years, and a few other thigns.

Now think about what we expect from global warming.

A simple yet usable model is this: More CO2 in the atmosphere = more heat (energy) in the atmosphere = climate change. But the expected climate change is not linear. Models that seem to work together with direct observation show us that more CO2 has resulted in aridity and wildfires in certain areas. But if we go back in time to when there was even more CO2 in the atmosphere, it seems like everything was wetter, so the whole drought and wildfire thing may be something that gets worse and worse through the 21st century, but at some point is replaced by a whole different set of problems. With respect to sea level rise, which I think is one of the biggest problems we face, it is not likely that the continental glaciers will melt steadily. Most likely they will melt, once their melting really gets going, both steadily and in fits and starts, causing the occasional large rise in sea level.

In other ways, the climate system is likely to change rapidly from one state to another. We are seeing the melting of Arctic Sea Ice each year doing this now, going from one system where there was melting and re-freezing at a certain rate, and changing to a completely different system. Along with this we may be seeing a fundamental long term shift in the nature of Arctic air masses from one way of being to another.

It is like making ice cream, or butter, shaking catchup out of a bottle, or going steady. You work on it and work on it and work on it and all you have is cream and ice, or cream in the churn, or catchup stuck in the bottle, or a friend. Then, suddenly, you have ice cream, or butter, catchup spewing out all over the place, and a significant other. There are many things in life that work this way, where there is not a steady change over long periods of time, but rather, a lot of one thing followed by a sudden shift to a whole different kind of other thing.

So, here's the problem. If cycles of normal climate change are in the order of a dozen years, but a particular true shift in the basic pattern of climate takes, say, five years and thereafter everything is different, how do you know it happened? How do you know that the "new normal" is a long term change rather than a temporary shift?

There are two ways to know this. One is to wait and see, but if you were thinking of doing something about it but only taking action after you are sure, this is foolish. The other is to use reason and science and stuff to figure out what is going on and then make your best estimate of the situation.

And this brings us back to Weather Whiplash, the New Normal, and the nature of the climate change we may very well be experiencing now. There is an explanation for Superstorm Hurricane Sandy, for Nemo and some of the other storms we've had over the last year or so, and for the strange spring and early summer we are experiencing now, and please don't forget, the strange winters and summers we've been having for the last few years. This explanation applies mainly to the Northern Hemisphere and has to do with the Arctic and the Polar Jet Stream.

The Earth's climate operates as a mechanism for moving excess heat form equatorial regions towards the poles in air and oceanic currents. In the atmosphere, part of this happens when warm tropical air rises and moves away from the equator, drops, and then flows back towards the equator. Farther from the equator, a separate cycling of air currents is thus set up, where air moves up then south at altitude, then drops along side that first cycle of air. Then, there is a third similar giant rotating donut of air closer to the poles. At those positions where the air is moving up, there tend to form high pressure systems, and where the air flows away from these high pressure ridges or mounds, low pressure systems develop. If you stand back and look at the Earth from a distance you can see bands of wet and bands of dry, and regions where certain kinds of storms (like hurricanes, for example) tend to be confined.

The jet streams form at the boundaries between these large scale systems, at altitude, near the top of the troposphere. The jet streams don't really shape the larger scale systems; rather, they exist because the larger scale systems exist. But once they are in place, the jet streams can determine what happens in those systems.

One of the major jet streams is the Polar Jet Stream that separates temperate regions form more arctic regions. This boundary between two major air masses, defined by that jet stream, can be thought of as analogous to the partition that separates the freezer compartment in the top of a typical refrigerator from the fridge part down below. With this partition in place, the stuff in the freezer stays very cold, and the stuff in the refrigerator stays less cold. If you kept all the cooling coils in place but removed that partition, the difference between the freezer and refrigerator compartments of your Frigidair would be reduced significantly.

Another thing the Polar Jet Stream does is to generate the overall shape of the boundary between temperate and more northerly air masses. The jet stream can be straight, like a big ring around the earth, or it can be all wavy, with major undulations north and south. In the latter case, these undulations can move around the planet or they can sit in place. When they sit in place, they may cause an entire region to be habitually wet, or dry, or more importantly cool or warm, for a long period of time. (This is called "blocking.") The shape and movement pattern of the Polar Jet Stream ultimately determines the overall pattern of weather everywhere in temperate and subarctic regions.

Now, remember that the position and shape, and movement pattern, of the Polar Jet Stream is determined by high pressure ridges and the low pressure systems they set up (more accurately, these things interact). High pressure systems are relative; A warmish region of the earth, warm relative to nearby cooler regions, will set up a high pressure system. So, during the summer, land masses tend to create high pressure relative to nearby oceans, but during the winter, the oceans may create stronger high pressure relative to land.

And at this point we can see how climate change caused by CO2 increases create Weather Whiplash and other effects.

Warming conditions have caused the Arctic sea to have much less sea ice on it for much longer periods of the summer. This, in turn, allows more sunlight to heat the arctic, because less sunlight is reflected away by shiny ice, and more sunlight provides heat to the sunlight absorbing open water. This changes the relationship between high and low pressure areas in the Northern Hemisphere. This, in turn, has caused the Polar Jet Stream to freak out. Sometimes it is very wavy, often it is blocked, and sometimes it is simply weakened to the point that it almost goes away and allows the freezer and refrigerator compartments to meld.

Cool weather in the United States is not really cool wether. It is the more even, less compartmentalized, distribution of heat across the region north to south. Everything is on average warmer (because of warming) but there is not a very stark boundary between the northern colder regions and the more southerly warmer regions. Last April when we were busy getting snowed on every few days in Minnesota, the Arctic was warmer (but still cold) than it normally would be. Last fall, the shape of these weather systems caused Superstorm Hurricane Sandy to be stronger, and to fail to do what these storms normally do: head north by northeast and dissipate. Instead, the storm turned left and blotto'ed New York, Connecticut and New Jersey.

Peter Sinclair of Climate Denial Crock of the Week, famous for his videos, in a post on Weather Whiplash, has produced a video that covers some of this very nicely:

So, lets get back to the original question. Why are we having such bad weather? Because the system that is usually in place, with a strong Polar Jet Stream that tends to be linear during the summer, has changed to a different system where the Arctic Oscillation ... a high-low pressure system pattern ... has shifted to a "negative" configuration because of warming of the Arctic sea. This different system has a number of effects that combine with other effects of global warming to produce strange weather. Those other effects include there being more energy in the atmosphere, and more moisture concentrated in more discrete dense patches, which therefore also means some very dry conditions. Blocking may have caused dry conditions to persist longer over selected areas than otherwise, and at the moment, blocking and added moisture seems to be causing the midsection of the United States to become the world's largest water park. And, between storm fronts, the overall weather of the region is cool, yet the storm systems are very energetic.

Weather Whiplash. It makes sense because everything that is happening conforms to expectations based on what we know about climate and weather. Will this really be the "new normal?" Is a few years in a row of a strange acting Polar Jet Stream and that other stuff the result of a fundamental change in the way our climate system works, or is it just a typical variation that we can expect to happen now and then. Well, if this was a typical variation of the type we normally see on occasion, there would be less incredulity among climatologists, meteorologists, and forecasters. It makes more sense to explain Weather Whiplash as a new state that the climate has shifted to (mostly, expect some more back and forth, I assume) because of the unchecked release of fossil Carbon into the atmosphere by the burning of fossil fuels by humans.

gregladen Mon, 06/03/2013 - 08:50

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So, it seems that we might expect unusual weather, but does the fact that it is cause by a blocking jet stream mean that the specific bad weather we have in a give season will be different every time that season comes around or will patterns develop, so for example, Central Europe will always have a lot of early summer rain?

So we should probably not build the Keystone Pipeline then.

Thanks for that explanation. Skeptical Science has some good info on how Jet-streams work too.

Could the weather not just be a case of the Earth itself slightly going off course due to Earthquakes,Items being tested in the atmosphere etc and not global warming!!!!! After all the seasons have changed and Countries are experiencing weather they have never had before!!! Just a simple suggestion

The global warming theories have made famous political figures and others rich rich rich. They have brainwashed people into thinking that this cold weather is global warming. I cannot believe that people believe this crap. Wake up and stop buying these books. Remember a few months ago when scientists got stuck up in ho ho land on boat? The waters froze instantly. I cannot believe sane people would believe such nonsense. For the hard core beleivers go buy more books and make them richer, No im not a conservative nor a republican, but I have opened my eyes and woke up.

Ron, what books are you yammering about? Books about science? Physics and climatology text books used in school? What books!