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The Environmental Dangers of Backyard Fires Dear ELMNT: Backyard fire pits have become the latest musthave gardening feature. How bad are they on the environment?

The International Council for Science has narrowe world needs to meet in order to sustain our planet.



scientists de





Scientists Decide on Top 5 Issues for Sustainability

5 Steps to Clean Up Air Pollution These solutions can help improve air quality, wether it warms or not.



Temperate Zone Forest Fires Can Cool

Zero Gravity Burn

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Hello. Welcome to the first edition of ELMNT Magazine. The magazines name comes from the four classical elements: air, water, fire, and earth. We understand that by using sustainable practices, all of these elements can play a role in creating a better today and tomorrow. ELMNT's goal is to better inform people on how to use sustainable methods of creation, consumption and capitalization for everyday living and business. The magazine will work to inform about the environmental problems of today's world that can be fixed with simple modifications at the home or office. We aim to bring attention to current environmental issues including unsustainable resource consumption to bring longevity to the earth for years to come. ELMNT's team of writers have been working hard to create a grand opening of sorts for this first edition. Enjoy, John Taylor



BEIJING — Every day, the weather page of the popular New Beijing News gives lots of helpful advice, should readers wish to exercise early in the morning, climb a mountain or wash their car. But like other major newspapers in one of the most polluted cities in the world, it doesn’t tell them something really important: how clean is the air? This week, temperatures topped 40 degrees Celsius (104 degrees Fahrenheit). “Wear short sleeves,” it urged, next to a helpful drawing of a golf shirt. And, “No rain for the next two days, appropriate for washing your car.” (After rain, cars are often covered with lines of dust, like sand ripples at the beach, where water has dried after dropping through dirty skies.) The times of sunrise and sunset aren’t specifically mentioned, but it does say when the national flag will be raised and lowered at Tiananmen Square, because to know when the flag is flung skywards by a whitegloved People’s Liberation Army soldier is, quite simply, to know when it is dawn. To know when it’s reverently rolled up is to know when it is dusk. On Sunday, flag furling was at 19:47. The next morning it was unfurled at 4:51. Just no word about pollution.





Sixteen of the world’s 20 most polluted cities are in China, according to the World Health Organization, and pollution is a key reason thousands of wealthy Chinese emigrate to the West every year, despite the country’s ballooning riches. Expatriates can be reluctant to come and, once here, may limit their stay. Those here long-term worry, quietly or loudly, and try to get their children out for a minimum of four consecutive, lung-clearing weeks a year, on doctor’s advice. Of course, one can always check the Ministry of Environmental Protection’s Web site, which shows the national Air Pollution Index. Doubts about its accuracy are widespread. Greenpeace China notes that the W.H.O. has two air quality guidelines — one for the developed world and a less rigorous one for the developing world — and “China’s standards are lower than both.” So we turn to BeijingAir, the hourly Twitter feed run by the U.S. Embassy in Beijing, with data from independent monitors on the embassy grounds. On Sunday, BeijingAir read “Unhealthy” for PM2.5 (fine particulate matter that can enter the bloodstream via the lungs, considered particularly dangerous) and “Very Unhealthy” for ozone, which measures photochemical reactions between pollutants and sunshine.



(image) NASA areal satellite photographing smog over China.





By contrast, the Chinese government’s reading for that day was “Good.” The official index does not measure PM2.5 or ozone, instead calculating PM10 (larger particles that can often be expelled by coughing), nitrogen dioxide and sulphur dioxide. Everyone in Beijing can see and smell the pollution and, yet, many seem reluctant to face the problem squarely. Lack of information may be part of the reason, plus a sense of helplessness: what’s the point of railing against something you cannot change? Pollution is a byproduct of the government’s growth-at-all-costs economic policies. Tellingly, only in the last couple of years have people begun to use the word “smog.” Mostly, they say “fog.” When

progressive emission standards on motor vehicles. In late June, it announced a plan to integrate pollution management systems in China’s three biggest industrial regions, around Beijing in the north, Wuhan in the middle and Guangzhou in the south. The plan, which won’t take effect until 2015, is aimed at combating regional problems like acid rain, haze and smog. These “have become increasingly distinct in China in recent years and pose a severe threat to people’s health,” Zhang Lijun, vice minister of


the air is bad it’s often blamed on the weather, as if pollution were inevitable and the real culprit is the wind, for not blowing it away. On a recent Air China flight from Shanghai to Beijing, the Australian pilot announced there wouldn’t be much to see out the window on landing “because of heavy smog.” It felt shocking to hear the problem described in such blunt terms. A private chat with a friend or taxi driver is one thing, but this was a Boeing 767 carrying more than 200 well-heeled Chinese. Beijing, smoggy? Would the pilot get into trouble?I strained to hear the Chinese translation. Sure enough, “There is fog in Beijing,” the flight attendant translated. We landed in very poor visibility, and on the taxi ride home, I smelled chemicals in the air. Of course, the government knows it has a problem and has introduced a slew of measures, including

environmental protection, said in an interview with China Daily, an official newspaper. It will also begin measuring ozone and fine particles, something campaigners have long called for. BeijingAir at the U.S. Embassy is already doing that, but not everyone can read the feed, because Twitter is blocked in China. To many Chinese, the $100 or so a year for a VPN, an overseas server that can bypass government censorship, is a lot of money. The figures don’t make for pretty reading. An American friend, mother of three small girls, says it is one of her favorite apps and has uploaded it to her



iPhone. I admire her attitude but find it hard to share her enthusiasm. More typical is the attitude of another friend: “I’ve stopped checking. There’s no point, it’s always the same.” — And it is. Regularly, fine particle readings exceed 100 (“Unhealthy”) or 200 (“Very Unhealthy.”) The scale runs from 0 to 500. Up to 50 is “Good,” over 300 is “Hazardous.” When it’s “Very Unhealthy” or “Hazardous” you just know. The city whites out, the air smells acid and smoky, trees and buildings begin to fade in the distance. Occasionally it registers 500, which means it’s off the scale, and that’s truly scary. Sometimes, it says “Good” or, more often, “Moderate.” Here, that means — Great! We beam at the sky, which seems very blue to us. I just checked. The PM2.5 reading is 123, which means “Unhealthy for Sensitive Groups.” Could be worse. — Alan Cowell on a muted anniversary of the London terrorist attacks.

More typical is the attitude of another friend: “I’ve stopped checking. There’s no point, it’s always the same.”




Dear ELMNT: Backyard fire pits have become the latest must-have gardening feature. How bad are they on the environment? -- Michael O’Laughlin, Tigard, OR


With Fall setting in and the mercury starting to drop, many of us want to extend our time outdoors, and sitting around a backyard fire pit has become one of the most popular means to do so. But even though it may be fun—s’mores anyone?—it is not good for the environment, especially during times when air quality is already poor. It’s hard to assess the larger impact of backyard fire pits on local or regional air quality, but no one questions the fact that breathing in wood smoke can be irritating if not downright harmful. According to the U.S. Environmental Protection Agency (EPA), so-called fine particles (also called particulate matter) are the most dangerous components of wood smoke from a health perspective, as they “can get into your eyes and respiratory system, where they can cause health problems such as burning eyes, runny nose and illnesses such as bronchitis.” Fine particles also aggravate chronic heart and lung diseases, and have been linked to premature deaths in those already suffering from such afflictions. As such, the EPA advises that anyone with congestive heart failure, angina, chronic obstructive pulmonary disease, emphysema or asthma should steer clear of wood smoke in general. Children’s exposure to wood smoke should also be limited, as their respiratory systems are still developing and they breathe more air (and air pollution) per pound of body weight than adults. Geography and topography play a role in how harmful wood smoke can be on a communitywide level. People living in deep, steep-walled valleys where air tends to stagnate should be careful not to light backyard fires during


smog alerts or other times when air quality is already poor. Lingering smoke can be an issue even in wide-open areas, especially in winter when temperature inversions limit the flow of air. The Washington State Department of Ecology reports that about 10 percent of the wintertime air pollution statewide can be attributed to fine particles from wood smoke coming out of wood burning stoves. While a wood stove may be a necessary evil as a source of interior heat, there is no excuse for lighting up a backyard fire pit during times when you could be creating health issues for your neighbors. Another potential risk to using a backyard fire pit is sparking a forest fire. Some communities that are surrounded by forestland voluntarily institute seasonal burn bans so that residents won’t inadvertently start a forest fire while they are out enjoying their backyard fire pits. If you live in one of these areas, you probably already know it and would be well advised to follow the rules. If you must light that backyard fire pit, take some precautions to limit your friends’ and family’s exposure to wood smoke. The Maine Bureau of Air Quality recommends using only seasoned firewood and burning it in a way that promotes complete combustion—small, hot fires are better than large smoldering ones—to minimize the amount of harmful smoke. The moral of the story: If you need to burn, burn responsibly.





Scientists propose a set of safe limits for human impacts on Earth. The scale of humanity’s impact on the globe is becoming ever more apparent: we have wiped out species at a rate to rival great extinction events of all geologic time as well as contributing to a rapidly acidifying ocean, dwindling ice caps and even sinking river deltas. Now an international group of 29 scientists has taken a preliminary stab at setting some concrete environmental thresholds for the planet. Johan Rockström of Stockholm University and his colleagues have proposed nine “planetary boundaries” online in the September 23 Nature. (Scientific American is part of the Nature Publishing Group.) The boundaries, dealing with climate change, ocean acidification, chemical pollution and others, are meant to set thresholds, or safe limits, for natural systems with respect to human impact, although exact numbers have not yet been determined for some. “We have reached the planetary stage of sustainability, where we are fiddling with hard-wired processes at the global Earth-system scale,” Rockström says. “What are the Earth-system processes that determine the ability of the [planet] to remain in a stable state?”



(this photo) The photo continued from the previous page is a trail in North Caroline.

The research takes as its desired stable state the Holocene epoch, the 10,000 years since the last ice age during which human civilization has flourished, and attempts to identify the key variables that might push planetary cycles past safe thresholds. So, for example, the key variable for climate change is atmospheric carbon dioxide concentration as well as its attendant rise in the amount of trapped heat. At present, atmospheric CO2 has reached 387 parts per million (ppm), well above the preindustrial figure of 280 ppm. The estimated safe threshold identified by the scientists, including NASA climatologist James Hansen, is 350 ppm, or a total increased warming of one watt per square meter (current warming is roughly 1.5 watts per square meter). “We begin to quantify, very roughly, where we think these thresholds might be. All have huge error bars,” says ecologist Jonathan Foley, director of the University of Minnesota’s Institute on the Environment and one of the authors. “We don’t know exactly how many parts per million it would take to stop climate change, but we think it starts at about 350 ppm.” Humanity has already pushed past the safe threshold in two more of the nine identified boundaries—biodiversity loss and available nitrogen (thanks to modern fertilizers). And unfortunately, many of the processes affect one another as well. “Crossing one threshold makes the others more vulnerable,” Foley adds. For example, biodiversity loss “on a really hot planet is accelerated.”



“We begin to quantify, very roughly, where we think these thresholds might be. All have huge error bars,” says ecologist Jonathan Foley, director of the University of Minnesota’s Institute on the Environment and one of the authors. “We don’t know exactly how many parts per million it would take to stop climate change, but we think it starts at about 350 ppm.” Several scientists laud the effort but criticize the precise thresholds set. Biogeochemist William Schlesinger of the Cary Institute of Ecosystem Studies argues that the limits on phosphorus fertilizer are too lenient and can allow “pernicious, slow and diffuse degradation to persist nearly indefinitely.” Allowing human water use, largely for agriculture, to expand from 2,600 cubic kilometers today to 4,000 cubic kilometers in the future will allow further degradation at such environmental disaster sites as the drying Aral Sea in Asia and seven major rivers, including the Colorado in the U.S., that no longer reach the sea, notes David Molden, deputy director general for research at the International Water Management Institute in Sri Lanka. (One cubic kilometer of water equals about 264 trillion gallons.*) Even the 350-ppm limit for carbon dioxide is “questionable,” says physicist Myles Allen of the Climate Dynamics Group at the University of Oxford. Instead he thinks that focusing on keeping cumulative emissions below one trillion metric tons might make more sense—although that means humanity has already used up more than half of its overall emissions budget.

(above) From the Apalatian Trail Photo by: Dan Howard

The International Council for Science has narrowed down five top challenges the world needs to meet in order to sustain our planet. - Christie Nicholson reports



scientists decide on


We need to develop better observation systems to record global and regional environmental change.

observing — Determine those institutional, economic and behavioral responses that will make global sustainability possible.

responding — encourage innovation in technology and policy to achieve sustainability.

encourage —

- Christie Nicholson

Clearly, these issues represent an overarching, general strategy. The next step, already underway, is to create an organized and focused international structure that can make these five recommendations a reality—and soon: the ICSU hopes for significant progress in all five areas within the next decade.

Anticipating and recognizing disruptive environmental change to quickly manage it.

confining —

It’s the environmental question of our time: what sustainable practices can keep our planet optimally habitable? Now a group of international scientists has published a report outlining five key areas of concentration necessary to protect the environment, as well as human societies and economies. The report was published by the International Council for Science (ICSU) and the International Social Science Council.

We need to have pertinent & accurate forecasts of future environmental conditions and their consequences for people.

forecasting —

01 02 03 04 05






5 STEPS TO CLEAN UP AIR POLLUTION These solutions can help improve air quality, whether it warms or not. Even as the U.S. explores the complex challenges of global warming, air pollution remains widespread and dangerous. Millions of Americans live in areas that have recognized air pollution problems. Grave health effects—including death— are all too common. And the threat is not just to people: dirty air sickens and kills plants and animals and creates ugly haze that obscures spectacular views. Five policy changes could make the air we breathe cleaner and healthier: Clean up coal-fired power plants. Coal plants are one of the largest contributors to atmospheric particulate matter which are linked to worsened asthma and increased rates of heart attacks and premature death—as well as greenhouse gases and toxic substances, including mercury. We need to immediately reduce these emissions once and for all. Strengthen ozone air standards voluntarily. In March 2008 the Environmental Protection Agency issued new national air quality standards limiting ozone smog. President George W. Bush overturned recommendations for stronger protections. The American Lung Association, along with several states and public health and environmental groups, challenged those decisions in court. But now the EPA could voluntarily remand its 2008 decision and issue new standards that truly protect people and ecosystems. Clean up oceangoing vessels. Cruise ships, container ships and tankers emit staggering amounts of smog-forming nitrous oxides, sulfur dioxide, heat-trapping carbon dioxide and particulates, among them black carbon. New evidence shows that pollution from

these vessels reaches surprisingly far inland. The U.S. government has requested that the International Maritime Organization (IMO) create an “emissions-control area” in American waters, including off Alaska and Hawaii. Although the U.S. signed the International Convention for the Prevention of Pollution from Ships, it cannot enforce those requirements until the IMO grants the right to create the control areas along its coastlines. Improve the pollution monitoring network. The instruments are installed only in about 1,000 of the nation’s 3,141 counties, and budget cuts have forced states to reduce the number of sensors or staff who maintain them and analyze the data. The EPA should work with scientists and state officials to lower monitoring costs and expand the ability to track pollutants. Enforce the law. Since 1970 the Clean Air Act has driven the nation’s ability to curb air pollution. But rules have eroded as political decisions have taken the place of scientific ones and as delay after delay in enforcing specific requirements have mounted until only costly lawsuits prompt action. America must continue to reduce air pollution; the health and lives of people and ecosystems depend on it.



Lucien Bronicki on Geothermal Energy The chairman and chief technology officer of Ormat Technologies weighs in on the hurdles facing his industry



What technical obstacles currently most curtail the growth of geothermal energy? What are the prospects for overcoming them in the near future and the longer-term? Geothermal can be divided in two. We have the power plants which convert the heat, in the form of steam or hot water out of the ground, and of course we have the resource itself. Geothermal has been used for more than 100 years. Wherever you had steam coming out of the ground, you could put a steam turbine and you are in business. It is a little bit more complicated, but this is the basic idea, and the steam, after going through the turbine and the cooling tower, finds its way into the atmosphere, which means that you deplete not only the heat but also the aquifer. So, for instance, at the Geysers, which is still the largest single geothermal field in the world, output dropped substantially in the last 40 years not because the Earth got cooler but because the aquifer was depleted. What Ormat's contribution was to the state of the art was to extend the range of possible resources which can be used, the resources which are at lower temperatures. You still need a temperature difference, but you have extended the range by using the Organic Rankine Cycle, which is an old invention but was never really used for anything. Also, most of our plants are air-cooled, which means that we inject everything. And therefore the sustainability of the system is extended, because you don't consume the water. Of course there are places where there is sufficient supply of cold water from rain and so on, which is called natural recharge. But in most places today water is a problem, not only for geothermal but for coal-fired plants, for nuclear plants, for any



(previous page) An image taken by NASA of a geothermal cloud covering the Kuril Islands.

thermal regeneration. Now, to build a power plant, our approach is to tailor-make the power plant to the resource. So it takes some engineering into do it, but I would say this is negligible. From the moment you have the permits to go on a site until you complete the plant and start it up is in the range of one year. But to explore the resource, which is done with geophysical methods similar to what is done in oil and gas, is more complex and takes longer. We need three elements, really, to have a good resource. One is to have heat. This is relatively easy to detect. But you need two other things. You need water, which is the element that brings the heat from the depths to the surface. And you need rocks which are the edge of fractures, a fault or a permeable, so that this water can flow, so that when you drill a well the water tends to flow into the well and come out. Then, of course, you also have to reinject it back. Both need permeability or a fault. And this exploration takes time. So, if we leave aside the site permitting, which also takes time, then exploration activities are something on the order of three years. And with the field development it may be even up to four years. As to the technical obstacles, there is the availability of companies which deal with the geophysical approach and then the availability of drilling rigs. Until about a year ago both were very difficult to get, and we had to buy our own rigs. Short-term I would say these availabilities are not an obstacle. Nobody knows for how long, but today they are available. Long term is an obstacle, because most of the geologists and even the drilling personnel are older people. Young people did not come to the (Right) These images were captured during a series of geothermal tests conducted by scientists from all over the world.

field. There were no programs of training, and whoever was available was grabbed by the oil industry. So today we are working with the University of Nevada, Reno, and with M.I.T. There is a renewed interest among students in going back to geology, hydrology. But this is something that takes time. And the people have left over the years with all the sitting and waiting. So if geothermal is to grow it's important to start it now, and in the U.S. many universities are now enrolling more students in this field. A lot of time was wasted in the U.S., because at the laboratories which are working on longterm projects and basic science, the budgets were reduced and geothermal was certainly not their priority. About three years ago the geothermal budget was cut to zero, and people left. Again, they were mostly not young people, so this was a big loss. Today there are signs that more money will go to the national laboratories and the universities. It may be one of the problems with geothermal is that it's not so well known in spite of the fact that until about one or two years ago, geothermal was producing the same amount of kilowatt-hours as wind in the U.S., but everybody knew about wind energy. Very few people knew about geothermal energy. As for the plants themselves, efficiencies have been made better, but we are close to the diminishing returns. Geothermal working at lower temperatures is material-intensive—we have big heat exchangers. And therefore the impact from the high material costs of the past few years impacted the cost of the power plant. But there is not much we can do from the point of view of drastically reducing it. The turbines are



(below) This image from Iceland shows a hot spring which gets its heat from geothermal energy.

extremely efficient; out of what the second law of thermodynamics allows you we are getting pretty close to the limit. And therefore the big changes that will occur are improving the exploration techniques so that the time is reduced and the probability to find the right spot for drilling the well is improved. Today I would say about one third of the wells are dry wells, low-production wells, which means that if you had better exploration accuracy, you could reduce the cost by one third. So there is a lot of gain there. Another thing that I have to stress is that the geothermal that I have been describing is what's called hydrothermal. There was a study by M.I.T. of what is called enhanced or engineered geothermal (EGS)—this is an approach that was developed by Sandia National Laboratory. There is much more hot dry rock in the world than areas I described that have both hot rocks and also water and faults or permeability. The idea of the hot dry rock is to drill at least two wells and, again by similar techniques to oil and gas, to make fractures between the two wells so you can have a kind of heat exchanger. You pump cold water on one side, it goes through these fractures and comes up. The estimate for the potential of hydrothermal

in the U.S. is between 10,000 and 20,000 megawatts, which is not negligible. It's not going to solve the problem, but it's not negligible. The potential of EGS with hot dry rock is 100,000 megawatts. But there are still many challenges. Unlike conventional geothermal, you now have to find rock which you can also fracture. And you have to spend energy to pump water through it. And you have to bring the water from another area if there is no water locally. And you have to be careful not to lose water in the operation. So these are additional energy loses for pumping, but this a big potential. It got a lot of interest, but we are unfortunately still many years away. We have a project which is partially supported by the DOE in cooperation with a number of universities and laboratories, but this is longterm. To start producing megawatt-hours this is, I would guess, 10 years away. Are there obstacles to scaling up geothermal to serve a larger national or global customer base? From this point of view geothermal is base load: 24 hours a day, seven days a week. Therefore, the utilities like it very much. There



(below) A construction site for

an up and coming geothermal energy harvesting company.

is a small difference between winter and summer, as with any thermal power plant, nuclear power plants in particular, but it is base load. So when the utilities buy geothermal, they don't have to have standby power in the form of gas turbines as they do with windmills. So this is not an obstacle. The other obstacle that we don't have is that even if you have to build a power line, this power line is a dedicated power line. This power line is used 24 hours a day. If you build a power line for a wind or a solar plant, the capacity of this power line is only used during a certain number of hours. Which means that your return on investment is smaller for this power line. Can the existing energy infrastructure handle growth in geothermal energy? Or does that,need further modification also? I will give you two examples where power lines were built in the U.S. for geothermal. One is in the Imperial Valley, where we and other developers participated in building a dedicated line from the valley to the network of Southern California Edison. And there is one dedicated line in Nevada which goes

from one specific power plant to the network of California. So there are at least two cases that it was done. But many geothermal resources are really close, and this is how we look for new prospects—we look at where the power line is. If the power line is too far and this means permitting and so on, for all practical purposes, we keep it for the future and we don't develop it because the permitting is a very, very important element, at least in the U.S. Just to offer an example which was given by the governor of Nevada at one of the events the geothermal industry had: to get the permits for exploratory drilling for oil takes three weeks. For geothermal, it's six months. Why? Because people know exactly what to do and what to ask for. Given the current economic crisis, can your industry get the necessary capital (from public or private sources) to adequately finance its growth? Of course it does have an impact, but from the point of view of, say, the projects Ormat has on the way, we are not yet impacted. This is because of the way we have been building in the last few



(below) A collection of images

from a resent collaborative photo project from people around the world.

years: We use our own funds that we are able to raise for a construction loan. The construction loan is the loan that you need when the risk is the largest, which is building, drilling, and so on. And therefore if you want to close financing, it's very complicated. It takes a very long time. We did it in the beginning, but when we got more at ease with capital we decided as a policy to do projects where we can spend our own funds during this period and then go for financing when the plant is operating. But this is a big problem. No question. I assure you if this situation is not going to change, it will impact not only the newcomers but established companies like ours also. One word about Ormat because we are a special animal—we are vertically integrated. We actually started from solar energy. And we went into geothermal because solar was too expensive; we went into geothermal trying to sell equipment, but this was too small for the utilities. So we became a developer. First we were just a niche contractor for supplying our equipment but were also installing it. And then slowly when we got richer we started to keep equity in what we built, and this enabled two things. One is that we don't have margin upon margin upon margin. We are able to compete because if you have to subcontract, everybody has to get a margin on it. Of course we do subcontract a lot, but most of the time we don't have a prime contractor. We are the prime contractor. We don't have an engineering firm. And this enabled going on much smaller projects than the 1,000-megawatt coal-fired plant to keep the margins low. From a strategic standpoint, which is the bigger competitor for geothermal: incumbent coal, oil and gas technologies or other alternative energy technologies? In the U.S. the main competitor is coal, which has the lowest price; you still have areas where the cost of producing electricity from coal is three cents or less. But this is not for the long term—if the EPA rules limiting the emission of mercury pass, the additional scrubbers will double the price of the electricity produced. I am not even speaking, of course, about carbon sequestration—nobody knows how much that will cost. So everybody is guessing.

Longer term the main competitor is gas, because gas is much more environmentally friendly. A combined cycle plant is the most efficient way of using hydrocarbons. A gas-fired combined cycle plant is cheaper than a coal-fired plant. So this is a very tough competitor. But the gas prices today are of course are much lower than they were a year ago, when they were high enough in Nevada, for instance, that we were the cheapest source of electricity. Is there a cost target that you and others in your industry are aiming to achieve in, say, five years? I think that if we are successful in getting less than 30 percent or 35 percent dry wells and accelerating different elements, we probably will be below 10 cents, something around eight cents, for [a kilowatt-hour of ] base-load electricity.



Will essential ocean currents be altered by climate change? By: Nancy Bazilchuk





Every second, a vast quantity of cold, dense seawater equal to six times the combined flow of every land river on Earth streams over an oceanfloor ridge that stretches between Greenland and Scotland. This deep southbound current, flowing from the Norwegian, Iceland and Greenland seas into the North Atlantic, is the lower limb of the Gulf Stream and its northerly extension, a great conveyor belt of ocean heat and salt that transports warm tropical water north from the equator. Most climate change models predict global warming will slow these flows, in part by altering a key component of the Atlantic’s circulation, called deep-water formation. If that happens, northern Europe will cool—or warm less severely—as the rest of the globe swelters. Understanding the role that deep-water formation plays in driving this grand circulation pattern, more formally called the Atlantic Meridional Overturning Circulation (AMOC), will help scientists predict how global warming will affect climate—both in and beyond the Northern Hemisphere. Shifts in the Atlantic’s circulation patterns will alter African and Indian monsoon rainfall as well as hurricane patterns in the South Atlantic, resulting in “a profound impact on the global climate system,” according to a team of international scientists asked by the U.S. government to evaluate the potential for abrupt climate change. Oceanographers have been using moored acoustic Doppler current profilers and temperature sensors for the last decade to measure deep water as it pours over the Greenland–Scotland Ridge on its way south. They’re both trying to establish the natural yearly and decadal variations in its creation as well as look for evidence of changes from human-generated temperature increases. “Our assumption is that when we are studying the exchange between the North Atlantic and the Nordic Seas, that this deep conduction and cooling of ocean water is important to the AMOC,” says Svein Østerhus, an oceanographer at the Bjerknes

"Our assumption is that when we are studying the exchange between the North Atlantic and the Nordic Seas, that this deep conduciton and cooling of ocean water is important the the AMOC"



Deep-water formation is just what it sounds like: As the Atlantic’s surface waters travel north they become cooler and denser, so that by the time they reach the Arctic they are cold enough to sink to the ocean bottom. The sinking water pulls warm surface waters like the Gulf Stream north, which in turn leaves a void that pulls deep, colder water south. If global warming inhibits the formation of deep water, the flows across the Greenland–

Scotland Ridge should slow. But it’s not that simple. Between the 1950s and the 1990s, the deep water in the Nordic Seas was both warmer and increasingly less salty. As a result, “we had quite remarkable changes in deep-water formation,” Østerhus says. Nevertheless, the flow of deep water headed south over the Greenland– Scotland divide has remained stubbornly stable



The thermohaline circulation is mainly triggered by the formation of deep water masses in the North Atlantic and the Southern Ocean and Haline forcing caused by differences in temperature and salinity of the water.

COOL SEAWATER WARM SEAWATER Temperature increase over the past 100 years.

Surface currents are generally wind driven and develop their clockwise spirals in the northern hemisphere and counter-clockwise rotation in the southern hemisphere because of the imposed wind stresses. Deep currents are driven by density and temperature gradients. These currents, which flow under the surface of the ocean and are thus hidden from immediate detection, are called submarine rivers. Deep water formation is the movement of deep water in the ocean basins is by density driven forces and gravity. The density difference is a function of different temperatures and salinity. Deep waters sink into the deep ocean basins at high latitudes where the temperatures are cold enough to cause the density to increase.

for the past 50 years, Østerhus and his colleagues reported a paper in Nature late last year. The reasons for these counterintuitive findings are not clear, he says. It may be that deep water is pooling behind the Greenland–Scotland Ridge, providing a reservoir from which older deep water can flow when production is slowed. Østerhus’s colleague, Detlef Quadfasel, an oceanographer at the University of Hamburg, thinks that part of the

explanation is that “this is a nonlinear system—it can simply jump from one state to another.” Now Østerhus will travel in January to the other place on the planet where deep water forms— the Antarctic. The Weddell Sea off Antarctica is home to the coldest, densest deep water on Earth. Østerhus’s mission will be to retrieve data from a string of high-tech monitors put in place there



last February, with the hope of understanding how Antarctic deep-water formation affects the churning of the Atlantic’s currents far to the north. There is very little information on deepwater formation in the Antarctic, and Østerhus will collect basic data on temperatures, velocities and salinity that will form the foundation for later comparisons. “Deep-water formation in the Arctic and Antarctica are of equal importance, and they are linked,” he says. “Deep water formed in the Arctic can be traced the whole way south to Antarctica and deep water formed in the Weddell Sea can be traced as far north as Ireland. A change in the Antarctic deep-water formation may have an impact on the circulation of the North Atlantic.” As Østerhus and his colleagues scramble to understand what’s going on at the most distant edges of the Atlantic, roughly two dozen other projects are measuring the Atlantic’s flows elsewhere, including a string of instruments from the Bahamas to Morocco. And in late September an international team proposed that the entire network be transformed into a more formal international monitoring effort in the hopes of helping humankind prepare for what global warming will bring. “We rely on climate forecasting models to understand climate change, but not all models are in agreement,” says William Johns, a University of Miami oceanographer who helped write the abrupt climate change report for the U.S. government. “We have to refine these models to get some idea of what we are going to have to get adapted to—and exactly how much warming we will get in the North Atlantic depends on how much this circulation really does slow down.”

The graph to the right shows average rise in temperature of the Pacific Ocean over the past 100 years.





Climate models suggest that forest fires drive global warming by releasing greenhouse gases. The resulting climate change then lengthens the forest fire season and increases the number of fires each year, thereby pumping more greenhouse gas into the atmosphere and further exacerbating atmospheric warming. But a new study says that despite emitting heattrapping methane and carbon dioxide into the atmosphere, fires in temperate zone (or boreal) forests may actually cool the climate significantly, because they leave behind a landscape that reflects sunlight. Jim Randerson and his colleagues at the University of California, Irvine, measured the amount of radiation being absorbed and reflected by an area in central Alaska's Donnelly Flats that was ravaged by a fire in 1999. They found that the burning boreal forest immediately released large amounts of greenhouse gases. These gases absorb the sun's radiation and trap heat in the atmosphere, thereby causing warming in the first year after the fire. Black ash from the blaze fell on snow and sea ice, which soaked up additional solar radiation. During the spring following the fire, however, the researchers noted that the area had fewer trees and that the exposed snow reflected more sunlight, slightly offsetting the increased amount of absorbed energy. As the area recovered from the fire in the following years, deciduous birch

and aspen trees replaced the charred conifers. In summer, the bright green leaves reflected more light compared with the darker spruce needles of the prefire forest. In winter, because the new trees had lost their leaves, the snow-covered ground was exposed and reflected more sunlight. Using satellite images of nearby areas scarred from fires over the past eight decades, the researchers measured how the reflectivity of a fire-ravaged landscape changes over time. In the 80 years following the fire, the researchers predict that the surface reflection will cancel the impact of greenhouse gases initially emitted from the fire and, while causing local cooling, the fire would have no net effect on the global climate. The study, which appears in today's issue of Science, focused on the boreal forests of the northern hemisphere, and Randerson predicts that fires in the tropics may have a different role in global climate because of the lack of snow. The lighter-colored tropical forest canopies also reflect radiation and exert a cooling effect, according to Ken Caldeira, a climate scientist at the Carnegie Institution in Washington, D.C. Whereas losing the dark, boreal forests to fire may have a local cooling effect and no overall influence on global climate, destruction of the tropical forests could contribute to global warming, making it "doubly important to protect tropical forests," Caldeira says. Randerson's findings have implications for treeplanting projects designed to sequester carbon by trapping it in forests. If large areas are reforested, he says, "it might be that you accumulate carbon in the forest, but you might darken the surface, too." Darkening the surface with forests could cause more radiation to be absorbed, which in turn could lead to climate warming. "Planting forests everywhere isn't necessarily going to lead to net global cooling, and forest fires don't necessarily lead to net global warming," sums up Chris Field, also from the Carnegie Institution. "It reminds us that we need to have a sophisticated, multidimensional view of the way ecosystems affect climate."

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ZERO GRAVITY BURN Robert A. Altenkirch, dean and professor in the College of Engineering and Architecture at Washington State University, has conducted combustion experiments as part of the National Aeronautics and Space Administration microgravity research program over the past 20 years. His recent experiments on the space shuttle provided a better understanding of fire safety in space. Here is his response: Fires on earth are anchored by gravity, but the combustion gases are hot and light, so they rise. As the flame goes up, more air is sucked into the base of the fire, feeding more oxygen to the fire and making it burn more strongly. In space, where we have little or no gravity, there is nothing to make fires go up, and the fire has a harder time obtaining a supply of oxygen. In the microgravity of the orbiting space shuttle, oxygen molecules can only get to a fire by either being pushed into it by something like a fan--which would take the place of the suction of air into the fire on the earth--or by diffusing through the fire gases, much like ink or oil spreads out on the surface of water. The diffusion process is slower than the suction created by flames on earth. The

result is that the combusting gases also have to diffuse outward to obtain new oxygen, so the fire becomes bigger. But as its area grows in size, more heat is lost through radiation, just as heat radiates from a fireplace or campfire. If enough heat is lost the burning material will be cooled below its ignition temperature, and the fire will go out. This usually doesn't happen on the earth because air is drawn in fast enough to supply the fuel. Fires on a spacecraft would most likely be the result of an accident, such as an overheated electrical wire. Lighting a fire where there is little or no gravity would be easier than on the earth, but once it gets going it would be less of a threat than on earth. "By studying the way things burn in a new combustion laboratory carried on the space shuttle we can learn more about how to prevent and control fires on earth. We are also learning how to utilize heat and combustion in the difficult conditions of space where they will be essential for manufacturing materials, such as ultrapure semiconductors, in orbit."



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