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:
Here is a cartoon of the Earth showing jet streams moving around the planet:
Here is a depiction of the Jet Stream being very curvy. The waves in the Jet Stream are called Rossby waves.
(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.
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
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.,  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.,  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,  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.
Ocean temps have gone up even more:
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.