Heat Waves (4) A Climate Case Study:
Heat Waves (4) A Climate Case Study:
In the last article I wrote that the extreme events of 2011 were providing us with the opportunity to think about climate and how to cope with a warming world. The U.S. is experiencing an extreme heat event this week (Masters @ WU). This heat wave is the consequence of a strong, stationary high pressure system over the central U.S., and it will move to the east over the next few days. Back on July 14th The Capital Weather Gang did a nice write up on the forecast of the heat wave. At the end of this blog are links to my previous blogs on heat waves and human health.
When thinking about weather, climate, and extreme events an important idea is “persistence.” For example, a heat wave occurs when there are persistent high temperatures. Persistent weather patterns occur when high and low pressure systems get large and stuck; that is, they don’t move. In the Figure below, you need to imagine North America and the United States. There is a high pressure center over the proverbial Heartland. With blue arrows I have drawn the flow of air around the high pressure system, and in this case moist air. There is moisture coming from the Gulf of Mexico and, in fact on the date when this was drawn, from the Pacific. This is common in the summer to see both the Gulf of Mexico and Pacific as sources of continental moisture.
Figure 1: Schematic of a high pressure system over the central United States in July. While generic, this is drawn to represent some of the specifics of 2011. The green-shaded area is where there have been floods in 2011. The brown-shaded area represents sustained drought in the southern part of the nation.
At the center of this high pressure system there is a suppression of rain, because the air is moving downward. This sets up a situation where the surface heats from the Sun’s energy. There is not much mixing and cooling, because of the suppression of the upward motion that produces rain. Hence, if this high pressure system gets stuck, then there is persistent heat. This is a classic summer heat wave.
Let’s think about it some more. There is lot of moisture being drawn around the edge of the high pressure system, and this moisture contributes to the discomfort of people. People – just a short aside about people: if we think about heat and health, then we are concerned about people’s ability to cool themselves. It is more difficult to cool people when it is humid because sweat does not evaporate. Suppose that in addition to this moisture, there is a region where the ground is soaked with water from flooding. Then on top of already moist air coming from the Gulf, there is local evaporation into the air being warmed by the Sun. If on the interior of the high, where the rain is suppressed, there is hot, wet air, then it becomes dangerous heat.
It’s not easy to derive a number that describes dangerous heat. But in much of the eastern U.S. a number that somehow combines temperature and humidity is useful. Meteorologists often use the heat index. It’s the summer time version of “it’s 98 degrees, but it feels like 105.” For moist climates, the heat index is one version of the “it feels like” temperature. Jeff Masters tells me that in Newton, Iowa yesterday, July 17, 2011, the heat index was 126 degrees F. (see here, and 131 F in Knoxville, Iowa on July 18)
Another measure of heat and humidity is the dew point; that is, the temperature at which dew forms, and effectively limits the nighttime low. The dew points in Iowa, South Dakota, Minnesota, and Wisconsin are currently very high and setting records. Here is a map of dew point for July 19, 2011.
Figure 2: Exceptionally high dew points centered on Iowa.
Now if I was a public health official, and I was trying to understand how a warming planet might impact my life, then here is how I would think about it. First, the Gulf of Mexico and the Pacific are going to be warmer, and hence, there will be more humid air. This will mean, with regard to human health for the central U.S., heat waves will become more dangerous, without necessarily becoming hotter. It is also reasonable to expect heat waves will become more frequent and last longer, because those persistent, stuck high pressure systems are, in part, forced by the higher sea surface temperatures. If I am a public health official here is my algorithm – heat waves are already important to my life, and they are likely to get more dangerous, more frequent, and of longer duration. But by how much? Do I need to know by how much before I decide on a plan for action?
If I think about the air being more humid, then I might expect to see trends in the heat index. I might expect to see trends in dew points, and trends in the nighttime minimum temperatures getting higher. (That’s where a greenhouse effect really matters.) I worry about persistent heat, warm nights, and the inability of people and buildings to cool themselves. I worry about their being dangerous heat in places where people and emergency rooms are not used to dangerous heat – not acclimated to heat – not looking for heat-related illness.
Let’s go back to the figure. Rain is suppressed in the middle of the high pressure system, but around the edge of the high pressure system it will rain; there will be storms. (see Figure 3 at the end) The air around the edge of high is warm and very wet. Wet air is energetic air, and it is reasonable to expect local severe storms. (See Severe Storm on Lake Michigan) And if the high pressure is persistent, stuck, then days of extreme weather are possible. If this pattern sets up, then there is increased likelihood of flooding. If I am that public health official, then I am alerted to the possibility of more extreme weather and the dangers thereof. But, again, can the increase of extreme weather be quantified? Do I need to quantify it before I decide on a plan of action?
Still with the figure - what about that region of extended drought and the heat from the high pressure system? Dehydration becomes a more important issue. As a public health official, I start to see the relation of the heat event to other aspects of the weather, the climate. I see the relation to drought. I see the flood, and it’s relation to the winter snow pack and spring rains.
So what I have presented here is to look at the local mechanisms of the weather – what are the basic underlying physics responsible for hot and cold, wet and dry – for moist air? If I stick to these basic physics, and let the climate model frame the more complex regional and global picture, what can I say about the future? Do I have to have a formal prediction to take action? Here in 2011, I see drought and flood and hot weather and warm oceans that interact together to make a period of sustained, dangerous heat. It does not have to “set a record” to convey the reality of the warming earth. It tells me the type of event that is likely to come more often, of longer duration, and of, perhaps, of greater intensity. If I am a public health planner, then I can know this with some certainty. The question becomes, how do I use that information in my planning?
r
Figure 3: Radar loop showing precipitation around the edge of the large high pressure system in the middle of the continent. July 19, 2011.
Previous Blogs on Heat Waves
Hot in Denver: Heat Waves (1)
Heat Waves (2): Heat and Humans
Heat Waves (3): Role of Global Warming
Reader Comments
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You may be right--but the ice continues to rapidly melt, and there is no known mechanism by which a year-to-year reversal would be initiated.
That is terrible news but you know what the globe is too hots just look at the dots. My red dots are more and bigger than your less and smaller blue dots.
Only eleven were in the sample required to swim long distances; would you expect that to be compared to a much larger sample size that didn't have to swim long distances?
Even if the other sample size were, let's say, 1000 or something ridiculous, still the fact that only eleven had to swim long distance yields too small of a sample size to really compare the two with any real certainty.
And still, unless there is a comparison of the overall rate to a future or past study, nothing is being shown here that isn't common sense.
Added: Actually, looking at the other percentage (18%), I'll bet the other sample size was also eleven. It would make sense to keep the samples size about the same size. If I get time, I'll see if I can find it in the actual study.
Friday July 22, 2011 - 12:00 EST
Adelaide has had its coldest morning in three years, with the mercury dipping to 1.3 degrees Celsius at 6:20am.
It was close to zero at Adelaide Airport's monitoring point.
The temperature went below zero in some areas of South Australia, with -3.2 degrees at Nurioopta in the Barossa Valley, -1.9 at Kingscote on Kangaroo Island and -4.2 degrees recorded at Renmark Airport.
The coldest temperature was recorded at Gluepot with -5.5 degrees.
It hit -4.9 degrees in Yongala and Yunta.
Don McGuffie from the weather bureau says the cold morning had forecasters checking the record books.
"That's the coldest morning [in Adelaide] since the 28th of July 2008, when a minimum of 0.7 was recorded and the record minimum for Adelaide is -0.4 which was recorded on the 16th of July 1982," he said.
- ABC
Link
That's a very subjective opinion. You're certainly entitled to it, but that, of course, doesn't make it true. It's convenient for a person to simply claim that they've "seen a great many papers" that were invalid; stating that gives one license to dismiss anything that goes against a person's own beliefs. But it may not be the most intellectually honest way to approach a subject so complex.
The coldest in three years?! That is definitely a sign of cooling!
Arctic also sees heat wave, on course for record ice melt
Area of sea ice the size of Pennsylvania melts every day, data show
By Andrea Mustain
OurAmazingPlanet
updated 7/20/2011 7:06:47 PM ET
This year could be well on its way toward earning a dubious spot in the record books.
Arctic sea ice has melted away with astonishing speed in the first half of July, at an average rate of about 46,000 square miles per day, according to the National Snow and Ice Data Center (NSIDC) in Boulder, Colo.
That's equivalent to an area roughly the size of Pennsylvania melting into the sea every 24 hours.
"That's relatively fast," said Julienne Stroeve, a research scientist at the NSIDC.
Already, sea ice extent %u2014 how far ice extends across the ocean %u2014 this year is below the extent for the same time in 2007, a year which, in September, saw the lowest sea ice coverage ever recorded.
As of July 17 this year, sea ice covered 2.92 million square miles of the frigid Arctic Ocean. That may sound like a lot, but it's 865,000 square miles below the 1979 to 2000 average.
However, Stroeve said, much of what happens in the coming days depends on the weather.
Advertise | "Unless things change in the next few weeks, we might have a new record for July," Stroeve told OurAmazingPlanet. "Certainly overall, we think the ice is thinner overall leading up to this season than it was in 2007."
The ebb and flow of Arctic sea ice is a yearly occurrence. Each fall, as Northern Hemisphere temperatures drop, ice extends outward, away from the land and out over the ocean; each spring, with the onset of warmer weather, the ice recedes. However, the reach of the sea ice has declined steadily since satellite records began in 1979.
Researchers have found that the earlier Arctic ice begins to melt in the spring, the greater the overall melt for the year as a whole.
In 2011, in the Chukchi Sea, near Alaska, and the Barents, Kara and Laptev Seas, near Finland and Russia, NASA researchers found melt began two weeks to two months earlier than the 1979 to 2000 average.
Story: Polar bear cubs die as ice melts, swims get longer
This year, much of the Arctic has been in the grip of a warm spell.
Like the conditions that sparked the heat wave running roughshod over huge parts of the United States, a high pressure system has been parked over the Beaufort Sea, north of Alaska, since June, bringing warmer temperatures to the Arctic as a whole. Air temperatures at the North Pole are a full 11 to 14 degrees Fahrenheit (6 to 8 degrees Celsius) warmer than usual.
In addition, high pressure systems are associated with clear skies, Stroeve said, so the ice is often at the mercy of the sun's rays for the full Arctic day, prompting further melting.
Although Stroeve said a change in the weather could dramatically change the ultimate fate of the Arctic's sea ice for 2011, she said a new record isn't out of the question.
"It's too early to say we're going to have a new record low," Stroeve said, "but I would say it's certainly possible with the way things have been going."
Link
See what happens when my red dots are bigger than your blue dots and are more numerous?
Just another frog sitting in the pot of warming water oblivious to his surroundings.
It isn't? Gee I'll take your word for it. Ok what about the hundreds of other ones that show more red dots than blue dots and more of them also? Are those all wrong too?
Volume: 197, Issue: 1-3, Publisher: Elsevier, Pages: 323-335
ISSN: 03781127
DOI: 10.1016/j.foreco.2004.05.023
PubMed: 223382700029
Abstract
Characteristics of tree species may uniquely situate them to withstand environmental changes. Paleoecological evidence indicates that the geographic ranges of tree species have expanded and contracted several times since the last glacial epoch in response to directional environmental changes. For most tree species, these range fluctuations have been accomplished without any apparent loss of genetic diversity. A possible explanation that distinguishes most trees from many herbaceous plants is that much of the genetic variation within tree species is found within rather than among their populations. Thus, the extinction of a relatively large proportion of a tree species' populations would result in relatively little overall loss of genetic diversity. Furthermore, phylogeographic studies indicate that for some tree species, habitat heterogeneity (elevation, slope aspect, moisture, etc.) in glacial refugia may have preserved adaptive genetic variation that, when recombined and exposed to selection in newly colonized habitats, gave rise to the local adaptation currently seen. The maintenance of genetic diversity in the face of extensive habitat fragmentation is also a concern. Many forest trees, however, may be buffered from the adverse effects of habitat fragmentation. First, the longevity of individual trees may retard population extinction and allow individuals and populations to survive until habitat recovery occurs. Second, considerable evidence is available that both animal and wind-pollinated tree species in fragments experience levels of pollen flow that are sufficient to counteract the effects of genetic drift. The combination of individual longevity, high intra-population genetic diversity and the potential for high rates of pollen flow should make tree species especially resistant to extinction and the loss of genetic diversity during changing environmental conditions.
http://www.mendeley.com/research/response-of-fore st-trees-to-global-environmental-changes/
Things change when it gets hot or cold!
LOL!
but they may be fine as they adapted from Brown Bears
of Ireland. Remember CB? Erin go Bragh
Evolution
Skeleton mounted in quadrupedal posture
Both the cave bear and the brown bear are thought to be descended from the Plio-Pleistocene Etruscan bear (Ursus etruscus)[8][9][22] that lived ~5.3 Mya to 10,000 years ago. The last common ancestor of cave bears and brown bears lived between 1.2 and 1.4 million years ago.[23] The immediate precursor of the cave bear was probably Ursus deningeri (Deninger's bear), a species restricted to Pleistocene Europe ~1.8 Mya to 100,000 years ago.[24][25] The transition between Deninger's bear and the cave bear is given as the last Interglacial, although the boundary between these forms is arbitrary and intermediate or transitional taxa have been proposed, e.g. Ursus spelaeus deningeroides,[26] while other authorities consider both taxa to be chronological variants of the same species.[27]
Cave bears found in different regions vary in age, thus facilitating investigations into evolutionary trends. The three anterior premolars were gradually reduced, then disappeared, possibly in response to a largely vegetarian diet. In a fourth of the skulls found in the Conturines, the third premolar is still present, while more derived specimens elsewhere lack it. The last remaining premolar became conjugated with the true molars, enlarging the crown and granting it more cusps and cutting borders. This phenomenon known as molarization improved the mastication capacities of the molars, facilitating the processing of tough vegetation. This allowed the cave bear to gain more energy for hibernation while eating less than its ancestors.[28]
[edit] Recovery of fossil DNA
In May 2005, scientists in California succeeded in recovering and sequencing nuclear DNA of a cave bear that lived between 42,000 and 44,000 years ago. The procedure used genomic DNA extracted from the animal's tooth. Sequencing the DNA directly (rather than first replicating it with the polymerase chain reaction), the scientists were able to recover 21 cave bear genes from remains that did not yield significant amounts of DNA with traditional techniques.[29] This study confirmed and built on results from a previous study using mitochondrial DNA extracted from cave bear remains ranging from 20,000 to 130,000 years old.[23] Both show the cave bear to be more closely related to the brown bear and polar bear than the American black bear, but having split from the brown bear lineage prior to the diversification of distinct eastern and western brown bear lineages and prior to the split of brown bears and polar bears. The divergence date estimate of cave bears and brown bears is ~1.2-1.4 Mya.[23]
[edit] Causes of extinction
Recent reassessment of fossils indicate the cave bear probably died out 27,800 years ago. It has been suggested that a complex set of factors, rather than a single factor, led to the extinction.[30] [31]
Chaucer wisdom.
Cave bear (upper right) along with other animals depicted in rock art from the Les Combarelles cave
What makes you think brown bears won't be next on the list after Polar Bears?
Much colder then wasn't it?
If it isn't NOAA or NASA why bother.
Do they even have dot maps?
Not in the mood right now!
Red dots are winning what you talking about? But I do know how to make the blues dots win that way you will be in a better mood.
Well would you like to see more blue dots on that map than red dots?
I'm not about to hash out how hundreds and thousands of papers and research projects exhibit the behavior.
Maybe just consider what has been noted when you get around to examining a paper about a research task, if you can.
Nope podcast already determined it wasn't a dream.
Link
Not according to Hugh Willoughby!
Or Frank Marks!
No! Perhaps, once I figure out how many I need. I will after they are built.
I am pretty close to what size they need to be and how many.
Sorry it works at any scale as long as force 1 is greater than force 2 it works.
the earth sort of does it naturally with undersea caverns
yes, land formations help form ocean currents
Buster is just cooling the surface synthetically
instead of moving earth, move water
thus, theorectically, cooler surface temperatures can knock down massive destructive hurricanes to beneficial good rain soaking tropical storms and depressions
do i have this right?
Your funny! I also know that 244,800,000 cubic ft every six seconds must flow through them to get the cooling I need to weaken a hurricane or to restore arctic ice. What do you get?
That would be good to stop a drought condition. You are correct. Look up Sea mounts and how they cause upwelling. The idea improves what natrually occurs in nature. In fact the sea mount off South Carolina also helped me formulate my idea.
Link
I agree about the problem of reading all of the papers. However, my personal 'trees' experience has been the opposite of yours.
The papers that deny global warmign exists, overall, are written by frauds and hacks and published on hack paid for websites.
That doesn't take away from the fact that many papers that support global warming are in error in some way or another. However, the type of error is much different in that they are nto deliberate obfascation of facts. Often, the errors are due to suggesting a model given the data, and then finding that model doesn't quite fit reality, that another factor needs to be added in or that simplifying assumptions need to be made to allow calculation in a reasonable time frame. These errors in modeling are well described, at least in the sense that the limits to the models are well described.
I can believe that a social bias exists a priori (e.g. going in to each paper) on the part of the scientist. However, the scientists who are publishing papers supporting global warming are morally honest at least and the big physical basis to the theory is correct.
This is in direct opposition to the denialist papers that are scattered all over the place in terms of science and proof. Though this blog is very unscientific, I take the anti-global warming comments here as an amateur reflection of the positions anti global warming scientist (using that term losely) take: it is not happening, it is a conspiracy, it has happened before so it doesn't matter, etc..
I don't have a model that makes me believe one way or the other because I can't follow the details enough to calibrate any model to outcome. If you want me to predict ocean level rise in 100 years... I can't do it. It is too complex. However, I look around and the physical macrovariables that are easy to understand match the severe global warming predictions.
Not one of the explanations given here by the anti global warming people has explained the change in glaciers or artic seaice, the melting permafrost, etc.. Not one of them has countered any of the basic science of global warming theory. Not one of them has taken a moral position to care about the planet.
In short, I believe in social bias in scinetific papers, there are too many examples not too: behaviorism, Chomsky-ism (if that is an ism) and so on. I can also believe that many small papers are published that just find a open space in the herd and claim it without finding a first principle basis. But the big papers, the ones that make serious claims, have yet to be refuted.
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