Paper Offers Possible Link Between Climate Change & Extreme Weather

[WeatherRusty]

These graphs have been used before by "skeptics" to make this case.

They look noisy because they include nonrandom variations that the eye naturally interprets as "random" noise.........

http://tamino.wordpr...rend-and-noise/

And who drew the trend lines on those graphics. What statistical methodology do they represent? The trend lines on those graphs begin and end at the far extremes, obviously not a moving average which is the preferred method of analyzing a data time series for underlying trend.

[ORH_wxman]

These graphs have been used before by "skeptics" to make this case.

They look noisy because they include nonrandom variations that the eye naturally interprets as "random" noise.........

http://tamino.wordpr...rend-and-noise/

You can make a case for uncertainty in the temperature estimates which is what tamino is arguing...but there is no arguing that the actual data has shown no significant warming in the past 10 years.

[PhillipS]

These graphs have been used before by "skeptics" to make this case.

They look noisy because they include nonrandom variations that the eye naturally interprets as "random" noise.........

http://tamino.wordpr...rend-and-noise/

Play all of the chartsmanship games you like - the reality is the Earth has warmed, and is conituing to warm.

[WeatherRusty]

Play all of the chartsmanship games you like - the reality is the Earth has warmed, and is conituing to warm.

That's a good one, and quite accurate. LOL

[TerryM]

Just a thought - but isn't the paper that we're supposed to be discussing dealing with Arctic temperatures as opposed to global temperatures?

Arctic amplification (AA) – the observed enhanced warming in high northern latitudes relative to the northern hemisphere

I suppose arguing about global warming might be entertaining, but don't see how it relates to the topic in any way.

I haven't heard anyone claiming that the high northern latitudes are not warming - did I miss something?

[The_Global_Warmer]

\

There is some heat? Then the 2000s were the warmest decade. 2010 was warmest on record, 2011, warmest on record for a La Nina. 2011 Also has the highest OHC-700M on record, 1000M, and 2000M, lowest arctic sea ice volume, back to back years of huge jumps in Greenland ice melt, massive glacial melt and calving in arctic.

The Earth is continuing to warm.

[skierinvermont]

And who drew the trend lines on those graphics. What statistical methodology do they represent? The trend lines on those graphs begin and end at the far extremes, obviously not a moving average which is the preferred method of analyzing a data time series for underlying trend.

I use that source all the time. It uses linear regression, which is the most appropriate method for calculating trend lines.

The only 'problem' with ORH's graph is the use of the selective starting point in 2001. Starting in 1998,1999,2000, and probably several years after 2001 as well would all yield more positive trends. Also I think the graph uses the old Hadcrut3 instead of the more complete hadcrut4.

[WeatherRusty]

I use that source all the time. It uses linear regression, which is the most appropriate method for calculating trend lines.

The only 'problem' with ORH's graph is the use of the selective starting point in 2001. Starting in 1998,1999,2000, and probably several years after 2001 as well would all yield more positive trends. Also I think the graph uses the old Hadcrut3 instead of the more complete hadcrut4.

I defer to you on that point, but why then are almost every time series we see accompanied by 3 to 5 year moving average trend lines?

[turtlehurricane]

I was referring to TH and LEK as the trolls as they are main red taggers who participate here.

and the Earth has warmed in the last decade. I'm not sure how saying that isn't true isn't trolling.

You're the one that's trolling by posting incorrect statements and then calling us out when we correct them.

[TerryM]

For what it's worth.

The paper concerns itself with Arctic warming, and the graph addressing that was posted by Bluewave yesterday

I haven't heard anyone arguing that the data either misrepresents what's depicted, or that it's not relevant to the thread .

I think Turtles comments back on the 4th posting were well thought out and on topic, and it proves that we can at least at times come together and discuss the important, and probably unpredicted effects of a warming Arctic.

My question is whether these effects are expected to be enhanced, or at least to persist, as long as global warming continues, or will Arctic Amplification (AA) be diminished, or reverse when the sea ice melts out, leaving us to expect less extreme, though warmer weather.

Terry

[beneficii]

So you have debunked Dr. Jones and Kevin Trenberth???

Hold on, the Trenberth reference brings back memories of 2009 and how his words were being taken out of context.

[WeatherRusty]

If anyone is interested in why I state that during the period of global warming as opposed to a more stable state the climate system becomes more turbulent and chaotic, we can discuss it calmly without ridicule being sent my way. Or not. There is more than just one way of approaching the issue of if, why and when dynamic processes should be expected to be enhanced during a period of change. Or not. A meteorologist may prefer to diagnose the problem from a classical fluid dynamics point of view. There is another way to address the problem however, which represents a more holistic approach.

From the standpoint of theoretical physics, a system being driven further away from thermodynamic equilibrium such as is the case with the current day Earth....it is warming....the production of entropy is increased. Entropy is a measure of disorder. Nature dislikes disorder and attempts to smooth out difference. Changes in thermal gradients are taking place at scales ranging from the very small to the planet as a whole, with the net effect of warming the whole. The act of change is what is important in this context, the balance point is shifting and on the move.

Not so fast you say? The global temp is changing to slowly to make a big difference in the weather. The equator to pole gradient is becoming less steep. True, but on smaller scales the changes occurring are much more pronounced and are happening quickly. One example is arctic amplification of global warming and the effect this is having on sea ice and the implications this has for down stream weather.

James Lovelock's GAIA hypothesis is based on this premise. Skeptics of AGW should love this. Natural tendency for a system thrown further away from thermodynamic equilibrium is to react with predominantly negative feedbacks in attempting to restore the balance. The system will always attempt to re-correct itself. That doesn't mean a perturbed system returns to where it was before perturbation however, it means the system will seek to establish equilibrium given the new boundary conditions. It does mean a system given a limited perturbation will not run away uncontrolled.

No one has all the answers, but let's not dismiss some of the various ways scientists are attempting to analyze the question.

[TerryM]

Rusty

Hope you don't think I'm being dismissive of your argument - I'm just trying to steer this thread back to the question of how AA is going to effect NH weather. In my case what I'm concerned with are the long term implications - after the polar ice has gone.

At present huge amounts of energy are simply converting ice into water with no sensible heat being produced. When that is no longer true, does the Arctic start heating at a vastly more rapid pace than now, in effect increasing the AA and the patterns the paper addresses? If so is there anything in the Paleo record that verifies this.

I'm in a rush today and haven't had time to look at the links that Bluewave provided, perhaps they'll clear it up for me. I recall lots of evidence of lush, tropical growth in the Arctic, but also seem to remember something about far less chaotic weather at that time. I've really got stuff I have to do, and places I have to be today. Just wanted to get this in to let Rusty know where I was going in my last post.

Terry

[skierinvermont]

I defer to you on that point, but why then are almost every time series we see accompanied by 3 to 5 year moving average trend lines?

It's just another tool for analyzing the data. It's often more easy to visualize the data when a moving average is employed instead of looking at the raw data in which there is much more variance. Also a moving average might allow one to visualize cyclic or exponential trends, in which case a polynomial regression might be more appropriate than a simple linear regression.

[WeatherRusty]

Rusty

Hope you don't think I'm being dismissive of your argument - I'm just trying to steer this thread back to the question of how AA is going to effect NH weather. In my case what I'm concerned with are the long term implications - after the polar ice has gone.

At present huge amounts of energy are simply converting ice into water with no sensible heat being produced. When that is no longer true, does the Arctic start heating at a vastly more rapid pace than now, in effect increasing the AA and the patterns the paper addresses? If so is there anything in the Paleo record that verifies this.

I'm in a rush today and haven't had time to look at the links that Bluewave provided, perhaps they'll clear it up for me. I recall lots of evidence of lush, tropical growth in the Arctic, but also seem to remember something about far less chaotic weather at that time. I've really got stuff I have to do, and places I have to be today. Just wanted to get this in to let Rusty know where I was going in my last post.

Terry

If we go back 34 million years and earlier, neither of the Earth's polar regions were permanently glaciated. The Earth was a much warmer place, with very warm conditions extending into the high latitudes. Solar evolutionary theory indicates the Sun to have been no more than about 99.95% as bright as today measured in all wavelengths of light. Yet the world was so much warmer. How can that be?

The Earth's effective temperature can be determined as the product of just a few easily determined parameters. The radiative energy received at Earth's average distance from the Sun minus the effect of Earth's albedo.

From Wikipedia:

Temperature of the Earth

Similarly we can calculate the effective temperature of the Earth T_E by equating the energy received from the Sun and the energy radiated by the Earth, under the black-body approximation. The amount of energy, E_S, emitted by the Sun is given by:

At Earth, this energy is passing through a sphere with a radius of a₀, the distance between the Earth and the Sun, and the energy passing through each square metre of the sphere is given by

The Earth has a radius of r_E, and therefore has a cross-section of . The amount of solar energy absorbed by the Earth is thus given by:

The amount of energy emitted must equal the amount of energy absorbed, and so:

T_E can then be found:

where T_S is the temperature of the Sun, r_S the radius of the Sun, and a₀ is the distance between the Earth and the Sun. This gives an effective temperature of 6°C on the surface of the Earth, assuming that it perfectly absorbs all emission falling on it and has no atmosphere.

The Earth has an albedo of 0.3, meaning that 30% of the solar radiation that hits the planet gets scattered back into space without absorption. The effect of albedo on temperature can be approximated by assuming that the energy absorbed is multiplied by 0.7, but that the planet still radiates as a black body (the latter by definition of effective temperature, which is what we are calculating). This approximation reduces the temperature by a factor of 0.7^1/4, giving 255 K (−18 °C).^[3][4]

However, long-wave radiation from the surface of the earth is partially reflected (or absorbed and re-radiated back down) in the atmosphere, instead of being radiated away, by greenhouse gases, namely water vapor, carbon dioxide and methane.^[5][6] Since the emissivity with greenhouse effect (weighted more in the longer wavelengths where the Earth radiates) is reduced more than the absorptivity (weighted more in the shorter wavelengths of the Sun's radiation) is reduced, the equilibrium temperature is higher than the simple black-body calculation estimates. As a result, the Earth's actual average surface temperature is about 288 K (14 °C), which is higher than the 255 K effective temperature, and even higher than the 279 K temperature that a black body would have.

-------------------------------------

50 million years ago Earth's temperature was several degrees K warmer than today. The Sun could not have been responsible for that being the case. The energy received from the Sun back then was less than today, unless somehow the Earth's orbit has moved further away from the Sun....

The difference then becomes a function of changes on the Earth itself. Everything else remaining equal, a lack of polar ice caps results in a lowered albedo and a supported warmer black body temperature. Back in those times atmospheric CO2 concentration was in the range between 500-600ppm which would represent the long term concentration necessary to prevent the formation of polar ice caps. Only when CO2 fell below those levels did permanent glaciation become a part of Earth climate.

As can be seen in the above Wiki, the difference between the effective Stefan-Boltzmann temperature and the actual surface temp is 33K. The 33K difference is due to the greenhouse effect. Before 34 million years ago, a stronger greenhouse effect would have prevented glaciation which would have reduced Earth's albedo causing the world to be a much more warm place. We are driving the system back in the direction toward that of climate conditions experienced millions of years ago, and providing the radiative forcing to do so in over just a few centuries rather than over millions of years. Or 10,000 years as in the case of the PETM

[LocoAko]

http://www.climatecentral.org/news/new-study-questions-arctic-warming-extreme-weather-links-16375

A new study calls into question the widely-publicized hypothesis that rapid warming of the Arctic climate, including the precipitous loss of summer sea ice cover, is altering weather patterns throughout the Northern Hemisphere. Specifically, the study, which will be published in a forthcoming issue of Geophysical Research Letters, challenges the findings of previous studies that showed a slowdown in the speed and changes in the shape of the jet stream.

In doing so, the study provides additional insight into a nascent area of research regarding how Arctic warming will affect weather patterns in the midlatitudes, notably the U.S. and Europe. As with other emerging scientific issues, consensus on the connections between Arctic warming and midlatitude weather is unlikely anytime soon, but each study can be viewed as providing more clues for future studies.

Much of the current focus centers around the jet stream, which is a channel of fast-flowing air at high altitudes that helps steer weather systems from west to east across the Northern Hemisphere, and it is powered by the huge difference in air temperatures between the equator and the poles.

Researchers such as Jennifer Francis of Rutgers University and Steven Vavrus of the University of Wisconsin have published studies showing the temperature gradient between the equator and the North pole has shrunk causing changes to the jet stream. The main reason behind this is that the Arctic has warmed at twice the rate of the rest of the Northern Hemisphere, a phenomenon known as Arctic amplification. One of the main causes for the increased warming in the Arctic is melting sea ice, which has declined precipitously since 1981 and hit a record minimum last year.

The research shows that the weaker gradient slows the speed of the jet stream in particular seasons and causes it to meander more than usual and make unusual turns like a tourist wandering through Times Square. Francis’ work has also tied rapid Arctic warming, also known as “Arctic amplification,” to an increase in blocked or stuck weather patterns that have been associated with deadly extreme weather events such as the Russian heat wave of 2010, heat and drought in the U.S. in 2012, and even Hurricane Sandy.

The new study, by Elizabeth Barnes of Colorado State University, calls this research into question by showing that what Francis, Vavrus, and others have shown may just be an artifact of their research methods.

In examining trends in the waviness and speed of the jet stream, as well as the number and location of atmospheric blocking events, the study found that the evidence does not support many of the conclusions made in previous studies. Specifically, the study found no significant change in the waviness of the jet stream has been observed based on 30 years of data.

The study concluded that previous research might have construed changes in the height of different layers of the atmosphere for changes in the waviness of the jet stream. The height of specific atmospheric layers are tracked because they correspond to different weather indicators. As the atmosphere warms and air expands, the height of a given layer, measured using its pressure level, also rises. In recent years, the average height of air pressure surfaces has been increasing in the high latitudes, which is consistent with the warming climate.

“This work highlights that observed trends in midlatitude weather patterns are complex and likely not simply understood in terms of Arctic Amplification alone,” the study said. For example, the study found no statistically significant increase in atmospheric blocking events over the North Atlantic, which “suggests that Arctic Amplification over the past 30 years has not had a quantifiable impact on slow-moving weather patterns over North America or the North Atlantic.”

In an email message to Climate Central, Francis said the new study does not significantly contradict her research tying Arctic warming to extreme weather patterns well outside of the Arctic.

“The mechanisms linking Arctic amplification with large-scale circulation patterns are clearly not simple and we still have much to learn. These new results provide additional insight into those linkages,” she said.

However, Francis found fault with parts of the new study. She said that the 30 years of data that Barnes used in her research might hide some of the effects of Arctic amplification, since much of the warming and sea ice loss has taken place in just the past 15 years.

“Because Arctic amplification has emerged from the noise of natural variability only in the last 15 year or so, it is not surprising that its influence would not drive 30-year trends in a statistically significant way,” she said.

Demonstrating the heightened interest in this area of emerging research, on September 12, the National Academy of Sciences is scheduled to hold a workshop in College Park, Md., on new scientific findings related to ties between Arctic warming and midlatitude weather patterns.

For those interested, here is the paper: http://barnes.atmos.colostate.edu/FILES/MANUSCRIPTS/Barnes_2013_GRL_wfigs_wsupp.pdf

Disclaimer: I haven't had time to read the paper yet, so I'm in no way vouching for its scientific validity. I just know in multiple threads that Arctic Amplification and its relationship to mid-latitude blocking and extreme weather events has been discussed ad nauseum around here so I thought I'd share. (On a related note, can this become the official thread for the subject? Discussed is scattered....)

[Jonger]

This would be the time to test this hypothesis, the arctic has been much colder than the last 5+ years.

 

.

[Cory]

Has anyone seen a recent paper that claims weather events would be less extreme on a warmer planet (not Loco's Arctic paper)? I saw it somewhere a few days ago and thought I'd bookmarked it to read later, now I can't find the damn thing. As far as I know, the authors aren't on any character assassination lists (yet), so I was interested in the findings. 

[ORH_wxman]

Has anyone seen a recent paper that claims weather events would be less extreme on a warmer planet (not Loco's Arctic paper)? I saw it somewhere a few days ago and thought I'd bookmarked it to read later, now I can't find the damn thing. As far as I know, the authors aren't on any character assassination lists (yet), so I was interested in the findings. 

 

 

I believe it may have been this paper.

 

 

http://www.nature.com/nature/journal/vaop/ncurrent/full/nature12310.html

[Cory]

I believe it may have been this paper.

 

 

http://www.nature.com/nature/journal/vaop/ncurrent/full/nature12310.html

 

That was it. Thanks!

[ORH_wxman]

http://www.washingtonpost.com/blogs/capital-weather-gang/wp/2013/08/21/researcher-defends-work-linking-arctic-warming-and-extreme-weather/

 

 

Here are Jennifer Francis’ comments in full…

Comments on Barnes 2013: Revisiting the evidence linking Arctic amplification to extreme weather in midlatitudes. GRL. by J.A Francis

I am pleased that Dr. Barnes, a respected and talented atmospheric dynamicist, has taken an interest in the topic of linkages between the rapidly changing Arctic and the large-scale circulation. The emerging influence of Arctic amplification (AA) on mid-latitude weather patterns is complex, and her expertise will help resolve some fundamental dynamical questions that are relevant to understanding mechanisms driving these linkages as the Arctic continues to warm faster than elsewhere.

What perplexes me, however, is that her intent in interpreting the new results in Barnes (2013) seems less than objective and is a direct attempt to disprove the work presented in Francis and Vavrus (2012; hereafter FV12). A very different interpretation of the results could be made. While her overarching conclusion is that the connections between AA and mid-latitude extreme weather are unfounded, I see a great deal of support for our results in her new work. For example:

Figure 2 presents time series of wave amplitudes (or extents) measured using two methods: one similar to ours and an alternative based on seasonal latitude differences. In all cases the trends are positive, suggesting an increase in amplitude during fall and summer, albeit only some of the trends are statistically significant. Because AA has emerged from the noise of natural variability only in the last 15 year or so, it is not surprising that its influence would not drive 30-year trends in a statistically significant way. Note that her new method does exhibit significant trends. This supports FV12.

My interpretation of the results in her Figure 3 is that in the ranges of 500 hPa heights that typically occur in mid-latitudes during summer (5.6 to 5.8 km) and autumn (5.5 to 5.7 km), the wave amplitudes are increasing from the early to the later part of the record. This, once again, supports FV12. She claims that because warming is shifting a particular height contour northward, it is incorrect to conclude that wave amplitudes are increasing. In fact, it is this northward shift – in particular the larger shift in high latitudes where warming is greatest – that we hypothesized would be a factor causing the waves to elongate.

Figure 4 presents measures of wave phase speed. While FV12 did not present wave speeds, we speculated that larger amplitude waves should have slower wave speeds. Her measure of phase speed for waves at 500 hPa slows with time, supporting our speculation. She then measures speeds at the 250 hPa level and finds no change in speed. This much higher level is near the tropopause, often above the jet stream, and can be affected by dynamics of the stratosphere. The stratosphere is cooling with increasing greenhouse gases, leading to very different dynamical changes. Why did she choose to analyze this level? My only guess is to deliberately cast doubt on FV12.

The mechanisms linking Arctic amplification with large-scale circulation patterns are clearly not simple and we still have much to learn. These new results provide additional insight into those linkages, but it appears that the interpretation of these results in Barnes (2013) was conducted with a particular intent. I welcome and appreciate Dr. Barnes’ contribution to the community’s efforts to understand the effects of AA on large-scale circulation changes, but perhaps a more balanced approach to interpreting the results could be applied going forward.

 

 

Its interesting about how the trends have only appeared in the past 15 years or so...the same time we've seen the least warming on the globe in the past 35 years.

[ORH_wxman]

You wonder if it took reaching a certain global temperature level for an extended period of time for it to

emerge as factor?

 

 

Its definitely possible. I am also weary of this also being the period when the NAO/AO went back into its negative phase since the Francis et al study started in 1979. Essentially the early part of their sample is dominated by the +AO regime of the 1980s and early 1990s and the latter part is dominated by the recent negative AO regime.

 

That start period/end period is going to produce a massively positive trend in meridional flow in the upper levels just based on the decadal AO variability. There's certainly an argument to be made about how some of the recent extreme -AO patterns we have seen were enhanced by AGW/warming. But that type of attribution has a long way to go as it is based mostly on the sea ice theory. The original theory with the AO and AGW is that AGW causes the AO to trend more positive as the circumpolar current lifts more poleward with time.

[LocoAko]

http://www.washingtonpost.com/blogs/capital-weather-gang/wp/2013/08/21/researcher-defends-work-linking-arctic-warming-and-extreme-weather/

 

 

Here are Jennifer Francis’ comments in full…

Comments on Barnes 2013: Revisiting the evidence linking Arctic amplification to extreme weather in midlatitudes. GRL. by J.A Francis

I am pleased that Dr. Barnes, a respected and talented atmospheric dynamicist, has taken an interest in the topic of linkages between the rapidly changing Arctic and the large-scale circulation. The emerging influence of Arctic amplification (AA) on mid-latitude weather patterns is complex, and her expertise will help resolve some fundamental dynamical questions that are relevant to understanding mechanisms driving these linkages as the Arctic continues to warm faster than elsewhere.

What perplexes me, however, is that her intent in interpreting the new results in Barnes (2013) seems less than objective and is a direct attempt to disprove the work presented in Francis and Vavrus (2012; hereafter FV12). A very different interpretation of the results could be made. While her overarching conclusion is that the connections between AA and mid-latitude extreme weather are unfounded, I see a great deal of support for our results in her new work. For example:

Figure 2 presents time series of wave amplitudes (or extents) measured using two methods: one similar to ours and an alternative based on seasonal latitude differences. In all cases the trends are positive, suggesting an increase in amplitude during fall and summer, albeit only some of the trends are statistically significant. Because AA has emerged from the noise of natural variability only in the last 15 year or so, it is not surprising that its influence would not drive 30-year trends in a statistically significant way. Note that her new method does exhibit significant trends. This supports FV12.

My interpretation of the results in her Figure 3 is that in the ranges of 500 hPa heights that typically occur in mid-latitudes during summer (5.6 to 5.8 km) and autumn (5.5 to 5.7 km), the wave amplitudes are increasing from the early to the later part of the record. This, once again, supports FV12. She claims that because warming is shifting a particular height contour northward, it is incorrect to conclude that wave amplitudes are increasing. In fact, it is this northward shift – in particular the larger shift in high latitudes where warming is greatest – that we hypothesized would be a factor causing the waves to elongate.

Figure 4 presents measures of wave phase speed. While FV12 did not present wave speeds, we speculated that larger amplitude waves should have slower wave speeds. Her measure of phase speed for waves at 500 hPa slows with time, supporting our speculation. She then measures speeds at the 250 hPa level and finds no change in speed. This much higher level is near the tropopause, often above the jet stream, and can be affected by dynamics of the stratosphere. The stratosphere is cooling with increasing greenhouse gases, leading to very different dynamical changes. Why did she choose to analyze this level? My only guess is to deliberately cast doubt on FV12.

The mechanisms linking Arctic amplification with large-scale circulation patterns are clearly not simple and we still have much to learn. These new results provide additional insight into those linkages, but it appears that the interpretation of these results in Barnes (2013) was conducted with a particular intent. I welcome and appreciate Dr. Barnes’ contribution to the community’s efforts to understand the effects of AA on large-scale circulation changes, but perhaps a more balanced approach to interpreting the results could be applied going forward.

Interesting rebuttal. Thanks for posting. I'm very curious to see where this topic goes in the coming years.