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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Records happen all the time, of course. But it pays to remember that each record sets a new higher mark, one that is, ostensibly, harder to beat. If a record is set one year, then broken the next year, then broken again the year after that, there's clearly something changing. Hottest, coldest, driest, wettest--in a neutral and unchanging climate, such superlatives would be used very rarely after a long period of record-keeping. The fact that we're hearing them so often from scientists these days is indicative of the current situation.
Well said.
Warming is apparent.
All over the universe.
Gracias Senor
I'll buy that
you would have to go back several billion..to when Earth had little to no atmosphere
Here's the headline: "Media Myth Debunked: Almost No Temperature Records Broken in Last Week's 'Record-Breaking Heat'"
Here's the statement by JBastardi: " The truth is that only 34 records were broken last week."
I see nothing about all-time record highs in either of those. Do you? If so, please show me where I missed it.
Whoopsie! Now that the final report has been released, those denialists may be wishing they'd kept those complaints to themselves; the review found that not only was the BBC not biased toward those who accept climate change, it was actually doing a disservice by giving too much time to denialists.
A few quotes:
"Because so much of science involves uncertainty, it is open to attack from those who have never experienced that sensation. Purity of belief makes it easy for denialists to attract the attention of news organisations, but hard for them to balance their ideas against those of the majority. This can lead to undue publicity for views supported by no factual information at all.
"In its early days, two decades ago, there was a genuine scientific debate about the reality of climate change (although that attracted rather little attention). 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." (pages 66-72)
...and:
"For at least three years, the climate change deniers have been marginal to the scientific debate but somehow they continued to find a place on the airwaves."
...and:
"The impression of active debate is promoted by prominent individuals such as Lord Monckton and Lord Lawson. The BBC still gives space to them to make statements that are not supported by the facts."
...and:
"The BBC needs to continue to be careful when reporting on science to make a distinction between an opinion and a fact. When there is a consensus of opinion on scientific matters, providing an opposite view without consideration of 'due weight' can lead to 'false balance', meaning that viewers might perceive an issue to be more controversial than it actually is. This does not mean that scientists cannot be questioned or challenged, but that their contributions must be properly scrutinised. Including an opposite view may well be appropriate, but the BBC must clearly communicate the degree of credibility that the view carries."
Now if only we could get some of the U.S. news outlets to be as balanced and honest, we might actually make some headway. (NOTE: for purposes of this conversation, Murdoch-owned properties are not considered "news".)
Seriously, what a fallicious line of reasoning. The earths climate is constantly micro changing therefore it was never unchanging.
However, it was stable enough that creatures were able to adapt to the changes. Today, the changes are destroying variety because the it is changing too fast for the creatures to adapt.
It isn't the change, it is the rate of change for two reasons:
1) The eco-system which supports man cannot adapt quick enough. If the eco system breaks, man dies.
2) The rate of change is a rough indication of the force behind the change. If arctic sea ice melted over the next 500 years, I wouldn't really care. If it melts over the next 5 years, something serious is happening for that amount of heat to be produced. Whatever that thing is, it isn't going to go away when the ice is melted, it continues and continues until there is a new equilibrium.
This last point is what scares me. Scientists, despite what all the villagers with pitchforks say, are extremely cautious in predictions. That combined with the errors in the model, means that this situation could be much worse than everyone thinks.
Others of us refuse to go along with anyone's agenda without explicitly* examining the details.
* I like the freedictionary's definition of explicit.
ex·plic·it (k-splst)
adj.
1.
a. Fully and clearly expressed; leaving nothing implied.
b. Fully and clearly defined or formulated: "generalizations that are powerful, precise, and explicit" (Frederick Turner).
2. Forthright and unreserved in expression: They were explicit in their criticism.
3.
a. Readily observable: an explicit sign of trouble.
b. [snip, the only part not relevant]
[Latin explicitus, past participle of explicre, to unfold; see explicate.]
ex·plicit·ly adv.
ex·plicit·ness n.
Synonyms: explicit, categorical, definite, express, specific
These adjectives mean entirely clear and unambiguous: explicit statements; a categorical refusal; a definite answer; my express wishes; a specific purpose.
Antonym: ambiguous
8 minutes and 19 seconds. That's the time it would take for the disaster to take effect.
Like ants living near the edge of an atomic bomb range, that would be it for the Queen and the Colony.
Its like worrying about sun burn while standing next to a ticking bomb with no time display.
It could go off at any time, or it could not at all.
Science is Insanity
You do Know that every one of The Climate Models..all show a faster "rate" of warming in time,,and that's problematic for everyone.
Facts dont blog,,nor testify either for the side that's paying.
You post doesn't make sense. When i talk to my parents, I don't use calculus for the simple reason that they don't understand calculus. When I post on this site, i don't use numbers because the denialists on here don't understand numbers or else chose not to use their numeric data honestly.
If you understand numbers, great. I'll debate numbers with you. However, as for being explicit, the numbers are a set of data. They require interpretation, they are not explicit. If you think numbers as an indicator of the system state are 'explicit' as defined above, you shouldn't be using numbers either.
But its the state of the unknown that changes the nature of prediciting the future also.
When a record is broken, its something that has never been recorded before. It is not known when the record will be broken again, if at all, so predictions of another change are only guesses.
Arguing numbers on this site is like arguing over blood pressure readings when the patient is exhibiting all the macro level symptoms of a coronary. At some point, the macro level interpretation is more accurate than the collected numerical data.
I agree with Neo's approach and logic, but there are possible problems with the data. To deny that is unrealistic, but there is no point debating that here because denialists don't want the truth, they just want to find petty flaws to point to, as if it invalidates the whole thing. So I prefer the high level data that is less deniable: species are disapearing, glaciers and permfrost are melting , the artic sea ice is going, etc..
Link
Link
Link
Aside: All posts infringing upon the name-calling rule get flagged. Always.
I am no denialist. And Neapolitan gave a good answer.
Asking a question is not a juvenile action.
Name calling, however, is.
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So calling people 'juvenile' when that word is an accurate description of their level of debate is 'name calling'?
Interesting. I will be more circumspect in my choice of words in future. I will also be much more vigorous in my denouncements of their unscientific comments.
Is calling people 'unscientific' name calling?
Um, some confusion. In my analogy, i meant to contrast direct measurement with using numbers that have to be put into a model to derive a measurement.
In the analogy, the patient is the earth. Measuring temperatures daily is like measuring blood pressure. As Nea said, the overall trend is clear. However, since the trend is based on a collection of data that has to be processed, it is possible to argue the points. Maybe serious scientists wouldn't argue but denialists find flaws.
The larger data, larger in terms off being already 'processed' is less easily nitpicked. By analogy, what Nea is pointing out is that if the overall position of a number points on the edge of the arctic ice cap is moving closer to the North pole, the ice is shrinking. The denialists are saying, no, no there are problems with the data, some places it is growing, some places it is shrinking... The larger data is the volume of hte artic seaice. This is less easily nitpicked since it is fairly complete. that was what I meant.
However, at the end of the day, any process, geo physical or emotional, that requires a conclusion is essentially touchy feely. This is more true for a complex system than for a simple ones but I think it would be difficult if not impossible to find a decision process that didn't use some sort of a classifier. Here, we HAVE TO make a decision. This isn't abstract geophysics where we can just trade models, publish our results and go home. We have to decide public policy. It will be an irrational process based on interetations of models, not a numeric process. To be clear, this decision HAS to be touchy feely because, whether based on numbers or not, it is a complex model which is the scientific equivilent of touchy feely.
There will be some overestimates, but these ought to be balanced by an equal number of underestimates. To attempt to discredit such data as worthless is just another example of denialist nit picking and straw clutching.
Hurricane Wilma, the strongest North Atlantic hurricane on record happened in 2005. But your question is flawed, as you can't attribute any single weather event to a record global temperature year.
Hurricane Rita was the 4th strongest on record, and Hurricane Katrina the 6th strongest.
So, 3 of the 6 strongest hurricanes on record happened in 2005.
I'd hazard a guess that the overestimates dwarf the underestimates. Using guesses as real data and factoring them into the climate average and asking the public to believe such claims is just plain wrong.
Not sure why you keep talking about 2005. But at any rate, it can't be done. Something else that can't be done: finding an example of extreme weather in 2005--or, say, 2011--that scientists know with 100% certainty was not caused by a changing climate.
so people that believe the warming is caused by a natural, cyclical, physical and chemical process opposed to "its man's doing" is unscientific?
Or is anyone that is skeptical of conclusions based on 30 years of observations ignoring science?
Questioning is being scientific.
In science, the name of the game is proving all doubts of a theory false, not true. If a theory can not be proven false, with evidence through experiment, it is generally accepted.
23 Jul 2011
The greatest iceberg season in recent memory is drawing scores of visitors to Newfoundland's northern peninsula for a glimpse of the majestic sculptures.
"For this time of year, I've never seen so many icebergs -- and so big," said Paul Alcock of Northland Discovery Boat Tours in St. Anthony, N.L.
"It's a pretty spectacular sight out here right now," he said of at least 25 icebergs still looming within 16 kilometres of the town.
"For this time of year, you wouldn't expect to see much more than three or four."
The rare extravaganza is thanks to a nearby ice island that was part of a 260-square-kilometre chunk that split from Greenland's Petermann Glacier last August. That original piece has since broken into smaller bits.
One of the largest remaining pieces is the 50-square-kilometre ice island now floating about 20 kilometres off Labrador, south of Cartwright.
As it moves through the water, it "calves" or sheds pieces of ice that create the clusters of icebergs now attracting visitors from across Canada and parts of the U.S., Alcock said.
One of the highlights of his tour is a massive tabular slab that's about 1.6 kilometres long and 54 metres high.
"You've got waterfalls, you've got thick blue lines in the ice, you've got seals that are up on different places. It's almost like its own little habitat by itself. It's pretty amazing to see."
There's so much big ice that Alcock expects a record-long viewing season stretching into September.
"We had a gentleman a couple of days ago that got here from Montreal," Alcock said. "When he heard about it, that was it, he took a few days off work and made a beeline for Newfoundland to see them.
"People are left speechless."
Sara Weitkamp, a marine science technician with the U.S. Coast Guard, flew over the ice island Tuesday as part of the International Ice Patrol. She has completed 19 other similar missions.
"It's definitely the biggest piece of ice I've seen in my history of patrolling over the ocean," she said in an interview.
"There's a bunch of melt ponds and rivers that have started on it, just from the deterioration of it.
"It's amazing to think that something that big has lasted that long, down in an area that we patrol where we're used to seeing much smaller icebergs."
Charles Randell is president and CEO of C-Core, an engineering research and development corporation based at Memorial University of Newfoundland. He described how researchers placed eight beacons on the ice island to monitor its location, while satellite technology captures detailed images.
Information is passed on to the Canadian Ice Service, offshore operators, shipping officials and the International Ice Patrol, created after an iceberg sank the Titanic in 1912.
The giant ice slab shrank in the last week from 54.5 square kilometres measured Monday -- almost as big as the island of Manhattan -- to 49.5 square kilometres on Friday.
Randell has never seen anything like it.
"There have been ice islands, they're not unprecedented," he said. "Back as far as the late 1800s, there's actually a hand-drawn sketch of one off of St. John's that was reported to be eight miles long."
The size of last year's calving event off the Petermann Glacier has sparked debate about the potential role of ocean warming and climate change.
Randell stressed that he's not a climatologist, but said glacier ice is always moving.
"It's the tongue of this glacier that extends out through the fjord," he explained. "After a while, it gets so long and so narrow that a piece just breaks off."
The sheer size of the 260-square-kilometre break has driven theories that warmer seas are speeding up glacial movement.
But there are competing schools of thought on climate change and its effect, Randell said.
"We have seen warming trends over the period that we have been taking measurements. There's a camp that will say these are part of the natural cycles of the earth -- we have had ice ages before, and we may see them again."
For his part, Alcock has mixed feelings about what he calls "floating symbols of global warming."
"I'm excited about having these ice islands here, but there's part of me that's sad too because this is more evidence of climate change."
Alcock is also concerned about the number of impromptu tours being offered by local residents in small vessels not governed by the safety regulations his tour boat follows.
In an emailed statement Friday, spokeswoman Michele Boriel of Fisheries and Oceans Canada said the Canadian Coast Guard does not monitor the regular movement of small boats or pleasure craft, and there are no restrictions on viewing icebergs.
"Coast guard reminds boaters to exercise safe boating practices and keep in mind that icebergs can be dangerous and roll over at any time."
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