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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But they already are happening.
Yes, food costs are aligned with fuel costs. But they're also aligned with rainfall. The Horn of Africa is suffering its worst drought in at least 60 years, and with no end in sight. Grain prices rose 20% last year mostly due to shortages brought on by the Russia drought. If the current drought in the United States continues on, water shortages will begin to cause massive changes in our ability to feed our own people.
More research into fending off tropical and other diseases is always a good thing. But, of course, there's no vaccine for heat; if a place is too hot or too dry to sustain life and livestock--that is, if what was once lush and verdant turns brown and barren due to a changing climate--people have no choice but to leave. And if there are too many people, who will take them? Who will want to?
No, yonzabam is absolutely correct. The people of earth are headed toward some very harsh times. I truly feel a large-scale Malthusian Catastrophe is imminent.
most regions that suffer the most deaths from heat waves are those that aren't used to it. Sub-polar regions. This could be prevented by domicile infrastructure improvements. Install air conditioning in places that generally don't have it because of neccesity.
People in equatorial and sub tropical regions are used to high temperatures, its the people that are not adapted to heat and don't have the tools to survive through it, that are mostly facing life and death situations.
Drought is a common normality in any climate. At any one time on Earth, there is a region experiencing less rainfall than previously recorded. As it is also common for regions to experience excessive rainfall and flood. Both climate extremes are documented in pre-modern civilizations' litterature and legends.
..and nymore,
What does this mean?
It means you both just quoted a banned members post that reveals a members Home addy and other personal info.,,and left it here hanging even after the post was removed.
Congratulations, your action exceeds your intellect..
..again.
Modify your post immediately
Indeed!!
Rules of the Road clearly state not to quote obvious troll postings.
....enjoy yer, vacation
Reported.
Seconded.
What a nice response to being called out for a mistake. How very mature.....
Or perhaps it wasn't a mistake, given the animosity of the response. Hmmmm....
Yes, droughts have happened all through history. And many times, civilizations have had to relocate or face extinction when mired in one. But relocating a thousand tent-dwelling sheepherders then was a substantially easier task than finding room for and relocating, say, five million hungry and thirsty Somalis.
Climate Change theory has long predicted that many currently-productive agricultural areas would turn to non-productive desert as a result of warming and changing climate patterns. And that is precisely what seems to be happening. The drought in the Horn of Africa is "unprecedented" in modern times. It may have happened before--but there were nowhere near the number of people.
Telling someone to drop dead is not an opinion.
Correct!
I just don't see how a few industrial countries can hault the Earth's oceans from rising. Moving to higher ground is the only reasonable solution.
The Earth is changing and warming. No matter the causes or present politics, we must, as a species, plan for a new coastline. This may be man's great acheivement in history's future, planning ahead of time and solidifying a structural plan.
Its almost insane to think the landscapes and shallow waters of today will last the test of time, let alone ice.
PRESS RELEASE: New study details glacier ice loss following ice shelf collapse
An international team of researchers has combined data from multiple sources to provide the clearest account yet of how much glacial ice surges into the sea following the collapse of Antarctic ice shelves.
The work by researchers at the University of Maryland, Baltimore County (UMBC), the Laboratoire d'Etudes en Géophysique et Océanographie Spatiales, Centre National de la Recherche Scientifique at the University of Toulouse, France, and the University of Colorado’s National Snow and Ice Data Center (NSIDC) details recent ice losses while promising to sharpen future predictions of further ice loss and sea level rise likely to result from ongoing changes along the Antarctic Peninsula.
“Not only do you get an initial loss of glacial ice when adjacent ice shelves collapse, but you get continued ice losses for many years—even decades—to come,” says Christopher Shuman, a researcher at UMBC’s Joint Center for Earth Systems Technology (JCET) at the NASA Goddard Space Flight Center. “This further demonstrates how important ice shelves are to Antarctic glaciers.”
Shuman is lead author of the study “2001-2009 elevation and mass losses in the Larsen A and B embayments, Antarctic Peninsula“ published online today in the Journal of Glaciology.
An ice shelf is a thick floating tongue of ice, fed by a tributary glacier, extending into the sea off a land mass. Previous research showed that the recent collapse of several ice shelves in Antarctica led to acceleration of the glaciers that feed into them. Combining satellite data from NASA and the French space agency CNES, along with measurements collected during aircraft missions similar to ongoing NASA IceBridge flights, Shuman, Etienne Berthier of the University of Toulouse and Ted Scambos of the NSIDC produced detailed ice loss maps from 2001 to 2009 for the main tributary glaciers of the Larsen A and B ice shelves, which collapsed in 1995 and 2002, respectively.
“The approach we took drew on the strengths of each data source to produce the most complete picture yet of how these glaciers are changing,” Berthier said, noting that the study relied on easy access to remote sensing information provided by NASA and CNES. The team used data from NASA sources including the Moderate Imaging Spectroradiometer (MODIS) instruments and the Ice, Cloud, and land Elevation Satellite (ICESat).
The analysis reveals rapid elevation decreases of more than 500 feet for some glaciers, and it puts the total ice loss from 2001 to 2006 squarely between the widely varying and less certain estimates produced using an approach that relies on assumptions about a glacier’s mass budget.
The authors’ analysis shows ice loss in the study area of at least 11.2 gigatons per year from 2001 to 2006. Their ongoing work shows ice loss from 2006 to 2010 was almost as large, averaging 10.2 gigatons per year.
“This study shows where the tracking of sea level rise is heading in terms of the level of detail possible and the instrumentation that can be brought to bear,” Scambos said. “We’re showing that glacier changes can start fast, with a single climate or ocean ‘bang’, but they have a long persistence.”
More information
The article is available online on the Journal of Glaciology Web site.
An animation showing ice edge changes for the Larsen B ice shelf and its adjacent tributary glaciers is available online, at http://svs.gsfc.nasa.gov/goto?3803. A map showing elevation changes of tributary glaciers is available at http://etienne.berthier.free.fr/images/ElevationCh ange_2001to2006_LarsenB.jpg
A companion paper, “The triggering of sub glacial lake drainage during rapid glacier drawdown: Crane Glacier, Antarctic Peninsula,” by the same three authors, led by Scambos, is also available online in the Annals of Glaciology in the issue “Earth's Disappearing Ice: Drivers, Responses and Impacts.”
Link
This is, for the most part, a self-policing blog. Therefore, when someone is perceived to be out of line, someone else will be there to throw the flag. Count on it.
Higher ground? So simply find new places to live for the nearly three billion people who will be affected by rising sea levels? Not to mention the hundreds of trillions of dollars in infrastructure that will be lost and in need of replacement? Miami? New York City? Tampa? Nassau? Panama City? Buenos Aires? Rio? Bangkok? Jerusalem? Singapore? Tokyo? Just relocate the teeming throngs of residents of those and thousands of other low-lying cities and towns?
Not gonna happen. If we lack the money and the willpower to invest more wisely in relatively inexpensive long-term solutions to the burning of fossil fuels now, what would make you believe we'll have it then?
well that sounds a lot like excuses. If people wanted to live, they would move. Like Zebras. What's the point in wishing the tides from coming inland?
and how about massive, continent-long structures like break water channels, man can move the Earth, why not move the earth instead of people.
You have to do something besides gambling on turning off the power for 30 years will stop anything, especially the ocean. Fossil records prove otherwise.
China moved miilion plus populated communities for dam construction.
Dive Bourbon Street, Scuba for free, Huge azz beers too!
Let 'em eat cake, huh? You're entitled to your own opinion, of course. But I guess I just feel differently about my fellow man.
(And even if we could create "massive, continent-long structures like break water channels"--which would be an immense technical and logistical feat, not to mention an incredible expensive one--there's still the simple matter of feeding everybody.)
Look, nobody is talking about "turning off the power for 30 years". What we're saying is, instead of pretending that the current paradigm is fine because doing so further enriches the most profitable industry the world has ever know, why don't we start looking for solutions now?
That's a peculiarly cynical outlook, I must say. ;-)
Anyway, just so you know: 1) Overpopulation problems are exacerbated by a lack of food, something climate change is already bringing on. 2) In a warming climate, it's far easier for diseases to develop and spread. IOW: if our demise will come at the hands of either thing you mentioned, our lack of action on climate change will surely speed things along...
Sure. But if you build something above sea level and then the sea rises, who's to blame?
I'm all for solutions. And any great acheivement is expensive. the darn international space station is expensive and that won't last as long as a beach in south africa will.
dismantling oil companies won't help feed people.
let em eat cake huh? ask that question to the universe and its answer will be...I AM CAKE, DEAL WITH IT YOU BRAIN WITH ARMS AND LEGS.
The fossil fuel industry is to blame.
haha
east africa, surrounded by the world's largest deserts, might not be a great example to cite when talking about drought since the industrial revolution or the end of disco.
Absolutely. We are doing so at this moment.
reading about a few bad ones in china:
1810, 1811, 1846, and 1849
"Four famines in China"
45 million estimated deaths
Double Whammy.
Population decrease by the pandemic caused millions of more to starve due to the nature of farming society.
Also this "In addition to the currently projected
scarcities of freshwater and cropland, the UK
Treasury-commissioned Stern Report
estimates that by the middle of the century
200 million people may be permanently
displaced “climate migrants”—representing a
ten-fold increase over today’s entire
documented refugee and internally displaced
populations. Although this is considered high
by many experts, broad agreement exists
about the risks of large scale migration and
the need for better preparation. Most
displaced persons traditionally relocate within
their home countries, but in the future many
are likely to find their home countries have
diminishing capabilities to accommodate
them. Thus the number of migrants seeking
to move from disadvantaged into relatively
privileged countries is likely to increase. The
largest inflows will mirror many current
migratory patterns—from North Africa and
Western Asia into Europe, Latin America into
the US, and Southeast Asia into Australia."
from 2025 Global Trends final report
ironically all of the best places to move to away from famine and flood are the ones with free cake.
That's a lot. And just think: the world now has 6 times the people it did then. On an "inflated" basis, then, that would be about 270 million people now, or the combined populations of Japan and Russia.
I dunno. Sounds like trouble to me.
Huh? What is free cake?
I don't know...society is generally smarter about hygene. I'm reading about the cooking standards of year past. Parasites play rolls in famine deaths of the past too.
There are too many variables to draw conclusions of past famines to ones that haven't even happened yet.
Prior to WWII, the United States wasn't as giving as it is today in Food and Monetary aide to other nations.
Apparently according to the Discovery Channel, the Loch Ness Monster has moved to Alaska. This proves even pop-up book characters migrate to other environments.
Hmmm... maybe. Are you speaking for yourself or for all the other people who don't want to die?
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