Category Archives: Vulnerability Paradigm

New Thesis “The Influence Of Landfall Variation On Tropical Cyclone Losses In The United States As Simulated By HAZUS” By K. Sharp 2009

There is an excellent new M.S. Thesis which I would like to alert you to. The topic fits within the vulnerability framework which, as reported frequently on my weblog, is an effective way to deal with risk from climate and other environmental variability and change. The Thesis is

Sharp, Kevin, 2009, M.S. Thesis: The influence of landfall variation on tropical cyclone losses in the United States as simulated by HAZUS. Department of Geography, University of Colorado, 67 pp.

The abstract reads

Sharp, Kevin Joseph (M.A., Geography)

The Influence of Landfall Variation on Tropical Cyclone Losses in the United States as Simulated by HAZUS

Thesis directed by Dr. William R. Travis

“Tropical cyclone losses in the United States have shown an increasing trend since the beginning of the 20th century. This is mainly due to increased exposure along America’s coast. The amount of coastal property at risk persistently increases due to inflation, wealth increase, and population growth. When researchers have normalized the loss record to remove the influence of exposure and vulnerability change, no trend can be discerned in the damage record. This has been used to refute the claim that tropical cyclones are becoming more potentially destructive, and to keep the locus of explanation firmly in socio-demographic trends. But physical variation, in storm size, intensity and location, still make a significant difference the impact of any individual storm event. This fact occasionally induces calls renewed efforts at hurricane modification and routinely evokes a sense of either or alarm at “close calls” that, except for a difference of a few miles in landfall location or a modest weakening of peak winds, separate hurricane disasters from catastrophes. This project examined the effect of landfall location on storm damage using the Federal Emergency Management Agency’s (FEMA) risk assessment HAZUS. Thirty-mile track shifts were prescribed for the top 10 most damaging storms in the normalized record since 1988. The alternate storms yielded drastically different damage estimates from the original storms, indicating large spatial variations in exposure. Each landfall shift resulted in a rank change in the overall normalized record. The damage record is dominated by individual extreme events like those used in this analysis, and although random, differences in landfall location would presumably average out in a long record. The fact that a few storms account for a large majority of losses, and that small differences in their landfall yield large differences in impact, points to a very large noise to signal ratio that would make it difficult to discern a climate-induced trend, and may also obscure some dimensions of socio-economic exposure and vulnerability trends.”

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Transcript of My Talk “Considering the Human Influence on Climate” At The George C. Marshall Institute

The Transcript of my presentation “Considering the Human Influence on Climate” by Dr. Roger A. Pielke, Sr. May 14, 2009 is now available, courtesy of the George C. Marshall Institute.  The transcript also includes questions from the audience along with my answers. The overview of the talk is also available.

Dr. Mike Macracken and I both have discussed the talk in weblogs (see and see).

Excepts from the transcript include the discussion on vulnerability where, I said

So what is my suggestion? There is no doubt in my mind that there are multiple types of human climate forcings. CO2 is important and we need to look at it, but there is a range of other forcings. Policymakers should look for win-win policies in order to improve the environment that we live in. The costs and benefits of the regulation of the emissions of CO2 into the atmosphere need to be evaluated together with all other possible environmental regulations. The goal should be to seek politically and techno-logically practical ways to reduce the vulnerability of the environment and society to the entire spectrum of human-caused and natural risks.

I want to give an example here. Figure 28 is from some work that I published about a year ago8 with respect to a Colorado report on climate change. In that report they took the IPCC model assessments and were trying to tell the water managers in Colorado and other parts of the west what the weather conditions are going to be for the next twenty, thirty, forty and fifty years into the future. I was asked to write a short essay, because they knew I disagreed with taking the IPCC models and using them on a regional scale. I said, “Let’s look at the natural variation in the past.” This is work by Connie Woodhouse at the University of Arizona. The graph in Figure 28 is tree ring data and is basically a measure of dryness in the western part of the United States go-ing back to about 800 A.D. What you see is that it goes up and down and the message of this data is that there were more serious droughts in the natural record prior to European settlement than there have been in the 20th century. That means that we are already at risk and we don’t know whether human disturbance of the climate system pushes us toward or away from having more frequent droughts. The bottom line is that because they have happened in the past, we need to be prepared for droughts anyway. That is a bottom-up, resource-based perspective; it is not one you can drive by changing CO2. I think this is a message that needs to be communicated.

I asked one of the IPCC authors whether his model results fall inside or outside of this envelope. He said it falls inside of the envelope. The bottom line is that in spite of what the IPCC models state, we need to do something. In fact, if you are a strong advocate of the IPCC models, factor that into your vulnerability assessment, but don’t consider that is the universe of what could happen in the future, because that is not what has happened in the past. You can also see this is a very chaotic signal and it never repeats itself. We have a different environment now with different CO2, land use, and aerosols. We do not know our trajectory, and here is how I propose that we move forward: we need a bottom-up, resource-based focus rather than relying on downscaling from global climate models. I have done a lot of work on downscaling and showed that you are not really adding anything with downscaling. I can talk about that at another time, if you like. The IPCC focus is top down, meaning you take a global model and downscale it and give it to the resource people and say, “this is what is going to happen in 2030 or 2040.” I think that is a mistake. What we need to do is look at the risks that the resources face.

Figure 29 shows one example of that: water resource vulnerability. How can we reduce our vulnerability to problems with water quality and water quantity? Obviously in the west that is a major issue. There are a variety of threats: natural landscape change, land management changes, long-term weather variability and change, human population demands, animal and insect dynamics, industrial and vehicular emissions and so forth, and they all interact with each other. We should look at our vulnerability to risk with today’s society and what we anticipate the society might be ten, twenty, or thirty years from now and try to make our system more robust to these resources. We should make our system robust to risk from the environment and from human activity, rather than relying on these IPCC models to tell us what is going to happen to the future and assuming that we can actually control climate, which I think is hubris. We can’t say that we have to prevent human intervention in the climate system; we are already intervening in the climate system.”

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A New Paper “A Continent Under Stress: Interactions, Feedbacks And Risks Associated With Impact Of Modified Land Cover On Australia’s Climate” By McAlpine Et Al 2009

The research group led by Clive McAlpine of the University of Queensland is one of the most preeminent climate science research groups in the world.

Climate Science has already weblogged recently on one of their papers (see), and another outstanding contribution is listed below which documents even more the major role of landscape change on climate. The paper is

McAlpine, C.A., J. Syktus, J.G. Ryan, R.C. Deo, G.M. McKeon, H.A. McGowan, and S.R. Phinn, 2009:A continent under stress: interactions, feedbacks and risks associated with impact of modified land cover on Australia’s Climate. Global Change Biology, in press. doi: 10.1111/j.1365-2486.2009.01939.x

The abstract reads

“Global climate change is the major and most urgent global environmental issue. Australia is already experiencing climate change as evidenced by higher temperatures and more frequent and severe droughts. These impacts are compounded by increasing land use pressures on natural resources and native ecosystems. This paper provides a synthesis of the interactions, feedbacks and risks of natural climate variability, climate change and land use/land cover change (LUCC) impacting on the Australian continent and how they vary regionally. We review evidence of climate change and underlying processes resulting from interactions between global warming caused by increased concentration of atmospheric greenhouse gases and modification of the land surface. The consequences of ignoring the effect of LUCC on current and future droughts in Australia could have catastrophic consequences for the nation’s environment, economy and communities. We highlight the need for more integrated, long-term and adaptive policies and regional natural resource management strategies that restore the beneficial feedbacks between native vegetation cover and local-regional climate, to help ameliorate the impact of global warming.”

With respect to the policy implications of their analysis, they write

“The evidence provided here can be considered in the wider context of policy decisions affecting Australian land use and land cover. It provides a basis for including LUCC in climate risk management analyses by documenting the previously ignored feedback of the land surface on regional climate. Such analyses is useful to inform policy development in terms of balancing the beneficial effects of increased deep-rooted woody vegetation cover (in terms of climate, salinity risk, resilience, biodiversity, carbon storage) against higher costs (in terms of loss of land available for agriculture and human settlement).”

In their conclusions, they summarize their major points in the following text

“A number of lessons can be drawn from this paper that have wider implications beyond Australia:

1. The current global climate change agenda needs to recognize that climate change is a multidimensional issue, and that LUCC must be included in global and regional strategies to effectively mitigate climate change (sensu Feddema et al., 2005; Pielke, 2005).

2. A coordinated research effort is required to address the multidimensionality of climate change, including the role of LUCC and its dynamic interaction with increased concentrations of anthropogenic greenhouse gases. This requires evaluating: (i) the capacity of reforestation to ameliorate the impact of climate change at a regional scale; and (ii) if so, how much vegetation is required and where it should be located?

3. Reducing deforestation in the tropics and subtropics needs to be a global priority. This requires a strong and coordinated global and regional effort through a combination of regulatory frameworks and well constructed carbon markets to halt deforestation and actively facilitate reforestation. This would have additional benefits for a wide array of ecosystem services that underpin environmental sustainability.”

This paper is recommended to anyone who wants to learn that landscape changes are a first order climate forcing, and that a focus on reducing vulnerability to the entire spectrum of environmental variability and change (and not just the effects of increased atmospheric concentrations of CO2) is very much needed.


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Article In Western Water Law “Wet Winter In Arizona’s High Country Brings Worries About Floods – Not Drought”

There is an informative article in the publication Western Water Law and Policy Reporter by M. Becker titled “Wet Winter In Arizona’s High Country Brings Worries About Floods – Not Drought”.

Excerpts from the excellent article read

“A wet January and February throughout Northen Arizona drained by the Salt and Verde rivers followed a December that was the 11th wettest month in more than a century of recording keeping on the Salt and Verde River watersheds……See “Reservoirs Full to the Brim, More Rain Due,” Payson Roundup, February 17, 2009.”

“The precipitation has left the Salt and Verde Rover reservoirs brimming at about 21 percent above normal. Roosevelt Dam is a t 100 percent capacity. This capacity level means that lake levels are at the highest levels ever.”

“These reservoirs hold enough water to get the Phoenix area through three to five years of drought”.

Climate Science has often discussed the issue of drought in the western United States, and has concluded that the claims of almost perpetual droughts in the coming years is not scientifically robust. Examples of the Climate Science weblogs that discuss this issue include

Comments on a New Report on Climate Change in Colorado: A Synthesis to Support Water Resources Management and Adaptation for the Colorado Water Conservation Board by Ray et al. 2008

The wet winter this year in Arizona should be yet another wake-up call to policymakers who are using multi-decadal regional climate predictions, assuming that they have skill, when the real world data indicates otherwise.  The southwest USA has not moved into a perpetual drought due to the addition of carbon dioxide into the atmosphere.


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Comment On “Debate Over Climate Risks – Natural or Not” On Dot Earth

There is an interesting discussion on going at Andy Revkin’s weglob Dot Earth on the topic Debate Over Climate Risks – Natural or Not,  which invites responses to the statement,

“One clear-cut lesson [of this study] seems to be that human-driven warming, for this part of Africa, could be seen as a sideshow given the normal extremes. Tell me why that thought is misplaced if you feel it is.”

 This subject was initiated by a Science article by Shanahan et al  and subsequent news item on April 16 2009 by Andy Revkin which includes the text

“For at least 3,000 years, a regular drumbeat of potent droughts, far longer and more severe than any experienced recently, have seared a belt of sub-Saharan Africa that is now home to tens of millions of the world’s poorest people, climate researchers reported in a new study.

That sobering finding, published in the April 17th issue of Science magazine emerged from the first study of year-by-year climate conditions in the region over the millenniums, based on layered mud and dead trees in a crater lake in Ghana. “

The abstract of the Science article by Shanahan et al reads

” Although persistent drought in West Africa is well documented from the instrumental record and has been primarily attributed to changing Atlantic sea surface temperatures, little is known about the length, severity, and origin of drought before the 20th century. We combined geomorphic, isotopic, and geochemical evidence from the sediments of Lake Bosumtwi, Ghana, to reconstruct natural variability in the African monsoon over the past three millennia. We find that intervals of severe drought lasting for periods ranging from decades to centuries are characteristic of the monsoon and are linked to natural variations in Atlantic temperatures. Thus the severe drought of recent decades is not anomalous in the context of the past three millennia, indicating that the monsoon is capable of longer and more severe future droughts.”

Climate Science and our research papers have emphasized the large natural variations of climate that have occurred in the paleo-climate record and that these variations dwarf anything we have experienced in the instrumental record.

For example, in

Rial, J., R.A. Pielke Sr., M. Beniston, M. Claussen, J. Canadell, P. Cox, H. Held, N. de Noblet-Ducoudre, R. Prinn, J. Reynolds, and J.D. Salas, 2004: Nonlinearities, feedbacks and critical thresholds within the Earth’s climate system. Climatic Change, 65, 11-38,

our abstract reads

“The Earth’s climate system is highly nonlinear: inputs and outputs are not proportional, change is often episodic and abrupt, rather than slow and gradual, and multiple equilibria are the norm. While this is widely accepted, there is a relatively poor understanding of the different types of nonlinearities, how they manifest under various conditions, and whether they reflect a climate system driven by astronomical forcings, by internal feedbacks, or by a combination of both. In this paper, after a brief tutorial on the basics of climate nonlinearity, we provide a number of illustrative examples and highlight key mechanisms that give rise to nonlinear behavior, address scale and methodological issues, suggest a robust alternative to prediction that is based on using integrated assessments within the framework of vulnerability studies and, lastly, recommend a number of research priorities and the establishment of education programs in Earth Systems Science. It is imperative that the Earth’s climate system research community embraces this nonlinear paradigm if we are to move forward in the assessment of the human influence on climate.”

In an article specifically with respect to drought,

Pielke Sr., R.A., 2008: Global climate models – Many contributing influences. Citizen’s Guide to Colorado Climate Change, Colorado Climate Foundation for Water Education, pp. 28-29,

I wrote

“A vulnerability perspective, focused on regional and local societal and environmental resources, is a more inclusive, useful and scientifically robust framework to use with policymakers. In contrast to the limited range of possible future risks by current climate models, the vulnerability framework permits the evaluation of the entire spectrum of risks to the water resources associated with all social and environmental threats, including climate variability and change.”

Thus, regardless of the role humans play within the climate system (and it is much more than due to carbon dioxide increases; see), adaptation plans to deal with climate variations, beyond what occurred in the historical record, should be a priority.


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Another Example Of An Environmental Tradeoff – Reduced CO2 Emissions And Lower Fuel Cost Versus Personal Safety

Climate Science has often blogged on the need to assess the entire spectrum of effects when a particular environmental (or other) regulation is implemented (e.g. see and see).

In the April 14 2009 news there is a well written article by Ken Thomas of the AP which provides another example of the multi-faceted effects of particular decision with respect to the environment.

In this case, the issue is the benefit to the environment of reduced emissions of carbon dioxide and lower fueling costs from a  smaller passenger vehicle, versus the risk to the personal safety of you and your family.

The article is “Small cars get poor marks in collision tests” and reads

WASHINGTON — Micro cars can give motorists top-notch fuel efficiency at a competitive price, but the insurance industry says they don’t fare too well in collisions with larger vehicles.

In crash tests released Tuesday, the Insurance Institute for Highway Safety found that drivers of 2009 versions of the Smart “fortwo,” Honda Fit and Toyota Yaris could face significant leg and head injuries in severe front-end crashes with larger, mid-size vehicles.

“There are good reasons people buy mini cars. They’re more affordable, and they use less gas. But the safety trade-offs are clear from our new tests,” said Adrian Lund, the institute’s president.

Automakers who manufacture the small cars said the tests simulated a high-speed crash that rarely happens on the road. They also said the tests rehashed past insurance industry arguments against tougher fuel efficiency requirements. The institute has raised questions about whether stricter gas mileage rules, which are being developed by the government, might lead to smaller, lighter vehicles that could be less safe.

“If you were to take that argument to the nth degree, we should all be driving 18-wheelers. And the trend in society today is just the opposite,” said Dave Schembri, president of Smart USA.

Sales of small cars soared when gas prices topped $4 per gallon last year but have fallen off as gasoline has retreated to about $2 a gallon and the economic downturn has slowed car sales. The small cars are affordable — prices of the three cars tested range from about $12,000 to $18,000 — and typically achieve 30 miles per gallon or more.

The tests involved head-on crashes between the fortwo and a 2009 Mercedes C Class, the Fit and a 2009 Honda Accord and the Yaris and the 2009 Toyota Camry. The tests were conducted at 40 miles per hour, representing a severe crash.

In the fortwo collision, the institute said the Smart, which weighs 1,808 lbs, went airborne and turned around 450 degrees after striking the C Class, which weighs nearly twice as much. There was extensive damage to the fortwo’s interior and the Smart driver could have faced extensive injuries to the head and legs. There was little damage to the front seat area of the C Class.

Schembri said the test simulated a “rare and extreme scenario” and noted that the fortwo had received solid ratings from the government’s crash test program. The fortwo has received top scores from the Insurance Institute in front-end and side crash tests against comparably sized vehicles but in the front-end tests against the C Class, the institute gave the mini car poor marks.

In the Fit’s test, the dummy’s head struck the steering wheel through the air bag and showed a high risk of leg injuries. In the vehicle-to-vehicle test, the Fit was rated poor while the Accord’s structure held up well.

Honda spokesman Todd Mittleman said the tests involved “unusual and extreme conditions” and noted that all 2009 Honda vehicles had received top scores from the Insurance Institute.

In the Yaris test, the institute said the mini car sustained damage to the door and front passenger area. The driver dummy showed signs of head injuries, a deep gash on the right knee and extensive forces to the neck and right leg.

The Yaris has received good ratings in past front and side testing but received a poor rating in the crash with the Camry. Toyota spokesman John Hanson said the car-to-car test had little relevance to consumers because of its severity.

“It’s fairly obvious that they have an agenda here with regard to how smaller cars are going to be entering the North American market in larger numbers,” Hanson said.”

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New Paper “Increasing World Consumption Of Beef As A Driver Of Regional And Global Change: A Call For Policy Action Based On Evidence From Queensland (Australia), Colombia and Brazil” By McAlpine et al. 2009

Climate Science has urged a broader perspective on the role of humans within environment. There is a new paper which supports this view. It is

McAlpine, C.A., A. Etter, P.M. Fearnside, L. Seabrook, and W.F. Laurance, 2009: Increasing world consumption of beef as a driver of regional and global change: A call for policy action based on Evidence from Queensland (Australia), Colombia and Brazil, Global Environmental Change,19, issue 1, 21 – 33.

The abstract reads

“While the global community is seeking to reduce fossil fuel consumption, a parallel but equally important issue is the environmental impacts of increased world consumption of beef. We provide a comparative analysis and synthesis of the expansion of beef cattle production and its regional and global environmental impacts for Queensland (Australia), Colombia and Brazil. Evidence assembled indicates that rising beef consumption is a major driver of regional and global change, and warrants greater policy attention. We propose four policy imperatives to help mitigate escalating environmental impacts of beef: stop subsidising beef production and promoting beef consumption; control future expansion of soybeans and extensive grazing; protect and restore regrowth forests in grazing lands; and allocate resources to less environmentally damaging alternative land uses.”

The article includes the text

While the world is becoming increasingly carbon-conscious (Stern, 2006; IPCC, 2007a,b), a parallel but equally important issue is the impact on the biosphere of extensive land-use and landcover changes (LULCC) due to population growth and increased per-capita consumption levels (Pielke, 2005).


 Tighter controls over the expansion of the beef industry and livestock fodder crops such as soybeans represent a priority global and regional strategy to halt tropical deforestation. This would make a major contribution to reducing carbon emissions and to biodiversity conservation, maintaining ecosystem services and relatively cooler, moister climates in the deforested and adjacent regions (Betts, 2008). Policy makers have been slow to recognise this two-way link between the biosphere and the climate system (Foley et al., 2003a; Pielke et al., 2007). Avoiding future deforestation through reducing the consumption of beef therefore represents a win–win scenario for carbon sequestration, protecting biodiversity and maintaining regional hydrological cycles and a wide array of other ecosystem services. Controls on deforestation need to be accompanied by tighter controls over the introduction and spread of exotic grasses by the beef industry as a priority for reducing the regional environmental impacts of cattle.

Climate Science applauds the McAlpine et al paper which recommends a multi-dimensional assessment of an environmental issue, rather than  a narrow focus on carbon emissions as promoted by the IPCC reports.

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A Excellent Seminar At The University of Colorado at Boulder “What Goes Around Comes Around” By Gregory R. Carmichael

On Friday, March 6 2009, Professor Gregory R. Carmichael of the Department of Chemical & Biochemical Engineering at The University of Iowa presented one the most insightful talks I have ever attended. The title of this talk was “What Goes Around Comes Around”.

There were several very important findings that were presented, which include

1.We know that regional control strategies are needed to meet local air quality targets”. [from slide 4]

This perspective recognizes that it is regional weather and climate that needs to be focused on in order to improve air quality.

2. with respect to air pollution Large and small sources combine resulting in a global reach of pollution…..The majority of impacts are domestic, BUT Intercontinental transport of PM2.5 is associated with 100,000 premature mortalities world-wide of adults 30 years and older. Intercontinental transport of PM2.5 into USA results in ~1200 excess deaths! (tightening the U.S. 8-hour O3 standard from 84ppbv to 75ppbv, is annually projected to prevent 1,300 to 3,500 premature deaths in the United States at a cost of $7.6-8.8 billion USD each year [EPA, NAAQS RIA, 2008]) [from slide 11]“.

The global reach of pollution that Professor Carmicheal finds is in agreement with one of the findings in the 2005 NRC report that

“Regional variations in radiative forcing may have important regional and global climatic implications that are not resolved by the concept of global mean radiative forcing. Tropospheric aerosols and landscape changes have particularly heterogeneous forcings.”

3. As air quality standards become more stringent the importance of distant sources increases. [The] contribution of Asia pollution to  [the] USA is growing — we estimate that it is nullifying 15% of our emission reduction efforts !!”

This conclusion also supports the 2005 NRC conclusion that is presented under #2.

4. Full application of advanced emission control technologies can reduce health impacts in China by 43% in 2030; optimized saves 80% of costs”.

Professor Carmichael showed that this benefit also results in an 8% decrease in greenhouse gas emissions even with a focus on air quality benefits 

This conclusion shows that by focusing on improving air quality can also result in a reduction of greenhouse gases. However, as shown in #5, delaying the reduction of certain types of aerosols (e.g. sulphates) in order to retain a global average radiative cooling will result in early deaths than otherwise would not occur.

5. “350,000 excess deaths per year in India and China due to outdoor exposure risk for each 20mg/m3 (of fine aerosols of less than 2,5 microns). In addition to a WHO estimate of 381,000 and 407,000 (deaths) for China and India, respectively, from indoor air pollution caused by solid fuel use.”

This conclusion documents the immediate benefit of reducing fine particles in the atmosphere regardless of the impact on the emissions of greenhouse gases.

The only part of his talk which I disagreed with was his conclusion to decrease black carbon emissions faster than sulfates [from slide 19]. As Professor Carmichael reports in #4, excess deaths can be reduced if fewer fine particles are emitted into the atmosphere that is breathed. It does not matter if these are sulphates or black carbon (or other aerosols).  A delay in reducing sulphates simply to retain their globally cooling effect would condemn many people to an early death.


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Risk To Lives To Cold Weather In The United Kingdom

There is an interesting statement on the risk associated from cold in the United Kingdom from the UK Met Office Website (see).

“An amber alert is triggered when there is a high possibility of a particularly cold spell occurring in the next few days. This is important as there are over 25,000 excess deaths each winter in this country, many of which are preventable. Action taken at this stage can greatly benefit vulnerable groups as the cold weather arrives.”

This is why we need a comprehensive assessment of the vulnerability of society to climate, rather than a focus on the narrow view expressed in the 2007 IPCC assessments of climate change. The current protracted period of well below average temperatures and periods of snow in the UK should be a wake-up call to policymakers that they need to think more broadly in terms of climate policy, than their nearly exclusive focus on the human input of carbon dioxide.

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Can The Everglades Be Restored To Its Original, Pre-European Condition?

The Everglades Restoration Plan, while a very important and beneficial environmental project,  intends to “restore the magnificent River of Grass [the Everglades]“. As they also write

Marjory Stoneman Douglas wrote about the problems of the Everglades in 1947, describing a ecosystem that was beautiful yet already clearly suffering…..The Comprehensive Everglades Restoration Plan will capture freshwater destined for sea – the Everglades’ lifeblood – and direct it back to the ecosystem to revitalize it. It will improve water supplies for people and farms, too. The nation’s largest such project, it will cost $7.8 billion and take more than 20 years to develop.”

Having visited  Everglades National Park many times, it is a worthy goal to seek this. However, unfortunately, as we and others have shown, the weather (and thus the hydrology and ecology) of the Everglades are affected by what occurs throughout central and southern Florida. The amount of freshwater today (from rain), unfortunately, is significantly less then it was prior to European disturbance. 

Recently, I was asked to summarize what we have found in our studies of Florida. This information is given below.

Three dimensional modeling of south Florida began with the paper

Pielke, R.A., 1974: A three-dimensional numerical model of the sea breezes over south Florida. Mon. Wea. Rev., 102, 115-139.

This study found that a spatial grid increment of 11 km was needed in order to accurately represent the sea breeze convergence patterns which form on many days over this region, and that focus thunderstorm activity over the peninsula. The curvature of the coastline, Lake Okeechobee, as well as wetlands exerts a major influence on these convergence zones. An example of this relationship is shown in Figure 1.

Figure 1:  Vertical velocity prediction 9.5 hours after simulated sunrise and composite radar map for equivalent times for June 29, 1971.

This study built on the pioneering research on sea breezes of Estoque (1962 : The sea breeze as a function of prevailing synoptic situation. J. Atmos. Sci., 19, 244-250).

A number of research papers followed that further elucidated the role of the surface in south Florida in affecting the region’s weather. These include:

Observationally related papers include

The specific paper

Marshall, C.H. Jr., R.A. Pielke Sr., L.T. Steyaert, and D.A. Willard, 2004: The impact of anthropogenic land-cover change on the Florida peninsula sea breezes and warm season sensible weather. Mon. Wea. Rev., 132, 28-52.

provides a demonstration of the major role that landscape change has had on south Florida. The change in landscape is illustrated in Figure 2 from].

Figure 2.  USGS land-cover data for (left) pre-1900 natural land cover and (right) 1993 land use.

This study had the following major conclusions:

  1. The region has become about 10-15% drier on average in July and August as a result of the conversion of the natural landscape. A major reason is the loss of wetlands which, in the past, provided significant water vapor input to sea breeze generated thunderstorms.
  2. The region has higher daytime temperatures and lower nighttime temperatures [of several degrees Celsius in places] as a result of the landscape change.
  3. There are local exceptions to #1 and #2 such as slightly cooler temperatures along the coast due to an invigorated sea breeze (since it is warmer inland during the day), as well as small regions of enhanced rainfall associated with the patterning of the landscape  which produce local areas of increased low level wind convergence.

An important implication from this study is that attempts to mitigate changes to the south Florida hydrology and ecology as part of the Everglades Restoration Project cannot result in the return to the climate regime that existed prior to the large scale landscape disturbances of the 20th century. While the Everglades Restoration Plan should be pursued, there should be no illusion that the hydrology and ecology can be restored to what it was originally when first settled.



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