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?
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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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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.
Link
Also, for the most part, I don't believe that opposition papers are deliberate obfuscation, but sometimes show that accepted, cited, and built upon tenets of proAGW works aren't quite the bastion of science they are held up to be. That is, sometimes they show that the work presented as proof of theory could prove any number of things and cannot be claimed as proof of anything, in particular.
"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."
WHAT?!? Besides none of us knowing the honesty of anyone we do not know very well, we disagree completely on this. While you may think that the whoring of science to the end of an otherwise good ideal of less resource consumption and pollution is the moral high ground, I find the notion of loose science in favor of some positive outcome to still be morally repugnant. Moral scientists would be those that are science purists and refuse to accept gross assumption, numerical results with a plus or minus 300%, or standard deviation greater than 200%, etc. regardless of whether or not it yields a general positive or negative change in behavior or policy. Taking the presumptuous position, at this time, that we understand climate on the scale of a few decades, much less centuries, well enough to assign attribution and/or prognosticate is truly arrogant and certainly not the moral high ground, given our lacking observations.
*Some* of the AGW opposition papers, or ones in the middle (ones that simply show that other papers do not prove what they say they do), neither pro nor anti AGW, are among the most "moral" in the realm of science.
You state that the big papers have yet to be refuted. Well, that's just it. Those big papers are exactly the ones that use circumstantial evidence as proof and are dealing with some barely detectible signal within the noise and there is no way to refute them without better observational data. Prime examples of the moral bottom feeders in science. A great example is GISS data in the Arctic.
And then someone else assumes they are correct and writes another paper building on that weak result. And another... And another... (Wash, rinse, and repeat.) And then you get to today, where an entire collection of works is built on a foundation of assumption without any proof whatsoever. You like the word "facts", but, quite honestly, I see few facts. Mostly just conjecture. Once we have better data, using the GISS-Arctic example, who can say what we'll really find? How does our current temperature really compare to the 30s and 40s in the Arctic? To say that we know, outside of that of a very few long-running, well-sited stations, is truly arrogant and certainly the moral low ground. To assume that we know how the Arctic today, as a whole, compares to 80 years ago, and then build on that notion by applying or coupling it to some other trend, is far worse.
Yes, it was a glacial epoch. And it is coming too town soon.
5- 15-50-100-1000 years or so.
I think we agree on a lot. I don't have a problem with your statement about rinse-wash-repeat. But the physical theory ("the big physical basis") behind all the rinse-repeat-etc. remains undefeated.
I agree it is a theory. But saying it is only a theory is meaningless without defining context. If you want the standard of proof that applies to thermodynamics, chemistry, or physics, you will never be happy. It is a large complex system and no theory will ever describe any complex system completely. If, on the other hand, you want the standard of proof that corectly applies to large complex systems, global warming has never been defeated.
The main thrust of the papers is that the world is warming due to man made CO2. That is a hugely important issue. For you to complain about that is similar to reducing psychology to behaviorism. The theory behind reducing it to that is sound (from a certain perspective) but it throws the baby out with the bathwater.
I have no problems with articles that attack global warming, cast doubt on it, etc as long as the goal is finding the truth. Most of the articles against global warming that are published, especially in the popular press (or quoted here) are not about the truth but about using scientifically couched rhetoric and half truths to persuade popular opinion. If you apply your standard of science to these articles, they are much worse than the arcticles by the scientists you consider whores.
Given how important this issue is, given the data as it is, we need to make a decision. How, then, would you approach climatology? Remember, we can't wait, we have to decide now. What is your decision?
In a report by its governing body, the BBC Trust, the corporation was urged to focus less on opponents of the majority consensus in its programmes.
It said coverage should not be tailored to represent a false balance of opinion if one side came from a minority group.
The report was partly based on an independent review of coverage by Steve Jones, Professor of Genetics at University College, London.
Although he found no evidence of bias in BBC output, he suggested where there is a scientific consensus it should not hunt out opponents purely to balance the story.
He highlighted climate change as an example along with the controversy over the Measles, Mumps and Rubella vaccine potentially leading to autism.
On climate change, Professor Jones said there had been a drizzle of criticism of BBC coverage arising from a handful of journalists who have taken it upon themselves to keep disbelief alive.
The report says: In its early days, two decades ago, there was a genuine scientific debate about the reality of climate change. Now, there is general agreement that warming is a fact even if there remain uncertainties about how fast, and how much, the temperature might rise.
But critics accused Professor Jones of using the report as a cover to push the BBCs green agenda.
Among them are former Tory Chancellor Lord Lawson, who was accused by the Government chief scientific adviser, Sir John Beddington, of making incorrect claims in An Appeal To Reason, the peer book on climate change.
Lord Lawson, chairman of the sceptical Global Warming Policy Foundation, said the fact that carbon dioxide levels were rising leading to global warming was not under dispute. However, he added, its extent and effect could not be explained by majority scientific opinion alone.
He said: The BBC is already extremely one-sided on this issue. They have a settled view which is politically correct.
The idea that because scientific opinion falls largely on one side you can't have a debate is outrageous. Because theres a strong majority in basic science doesn't mean the issue is off the table, yet the BBC says it should be.
The foundation's director, Dr Benny Peiser, said the report would lead to biased coverage of climate change and stifle any real debate.
He said: This is nothing the BBC has not been doing for the past 10 years, however. They are completely biased on the issue of climate change and this is nothing more than an effort to push their green agenda.
Dr David Whitehouse, the foundation's editor and a former BBC science correspondent, said the corporation had lost the plot when it came to science journalism.
He said the corporation was grouping sceptics with deniers which would result in a lack of valid scientific input to its reports.
He said: A sceptic is not a denier, all good scientists should be sceptics. The BBC has got itself into a complete muddle.
In seeking to get the science right it has missed the journalism which is about asking awkward questions and shaking the tree.
But the BBC Trust defended the report. A spokesman said: The report is not suggesting that climate change sceptics will not have a place on the BBC in future.
The point Professor Jones makes is that the scientific consensus is that it is caused by human activity. Therefore the BBC's coverage needs to give less weight to those who oppose this view, and reflect the fact that the debate has moved on to how to deal with climate change.
http://www.express.co.uk/posts/view/260164/Uproar -as-BBC-muzzles-climate-change-sceptics
Global warming is mainly the result of CO2 levels rising in the Earth’s atmosphere. Both atmospheric CO2 and climate change are accelerating. Climate scientists say we have years, not decades, to stabilize CO2 and other greenhouse gases.
To help the world succeed, CO2Now.org makes it easy to see the most current CO2 level and what it means. So, use this site and keep an eye on CO2. Invite others to do the same. Then we can do more to send CO2 in the right direction.
CO2 Data Set:
Original data file posted by NOAA-ESRL on Tuesday July 5, 2011
Measuring Location:
Mauna Loa Observatory, Hawaii
Data Source:
Scripps CO2 Program UCSD / Scripps Institution of Oceanography
Why is CO2 significant?
Carbon dioxide (CO2) is the chief greenhouse gas that results from human activities and causes global warming and climate change. To see whether enough is being done at the moment to solve these global problems, there is no single indicator as complete and current as the monthly updates for atmospheric CO2 from the Mauna Loa Observatory.
What is the current trend?
The concentrations of CO2 in the atmosphere are increasing at an accelerating rate from decade to decade. accelerating from decade to decade. The latest atmospheric CO2 data is consistent with a continuation of this long-standing trend.
What level is safe?
The upper safety limit for atmospheric CO2 is 350 parts per million (ppm). Atmospheric CO2 levels have stayed higher than 350 ppm since early 1988.
And more science on impacts:
Recent ecological responses to climate change support predictions of high extinction risk. Ilya M. D. Maclean1 and Robert J. Wilson. PNAS July online early edition.
Abstract
Predicted effects of climate change include high extinction risk for many species, but confidence in these predictions is undermined by a perceived lack of empirical support. Many studies have now documented ecological responses to recent climate change, providing the opportunity to test whether the magnitude and nature of recent responses match predictions. Here, we perform a global and multitaxon metaanalysis to show that empirical evidence for the realized effects of climate change supports predictions of future extinction risk. We use International Union for Conservation of Nature (IUCN) Red List criteria as a common scale to estimate extinction risks from a wide range of climate impacts, ecological responses, and methods of analysis, and we compare predictions with observations. Mean extinction probability across studies making predictions of the future effects of climate change was 7% by 2100 compared with 15% based on observed responses. After taking account of possible bias in the type of climate change impact analyzed and the parts of the world and taxa studied, there was less discrepancy between the two approaches: predictions suggested a mean extinction probability of 10% across taxa and regions, whereas empirical evidence gave a mean probability of 14%. As well as mean overall extinction probability, observations also supported predictions in terms of variability in extinction risk and the relative risk associated with broad taxonomic groups and geographic regions. These results suggest that predictions are robust to methodological assumptions and provide strong empirical support for the assertion that anthropogenic climate change is now a major threat to global biodiversity.
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