Inconvenient truths: Don’t believe the greenwash
Экология и защита окружающей среды
While there are associated concerns about weapons and radioactive waste a government White Paper published last January found that nuclear power emits only 2 to 6 per cent of carbon per kilowatt-hour of that emitted by the cleanest fossil fuel natural gas.
So you drive a Prius, eat organic and boycott anything made in China but will that help to fight climate change? Simon Usborne faces the facts many ecologists would rather ignore
Tuesday, 3 March 2009
Cute animals will have to die
You may not have come across the Bewick's swan. The smallest swan found in Britain, it reaches our shores from its Siberian breeding grounds in October and, along with 65,000 other water birds, it splashes down in the wetlands of the Severn Estuary. It is, without doubt, very cute.
But soon, it will have to find somewhere else to feed. In a few years' time, hundreds of lorries and cranes are set to sling 10 miles of steel and concrete across the most beautiful and ecologically diverse of estuaries, flooding the swans' habitat. Could anything be more of an affront to the eco-minded? The call would seem to be as clear as they come: save the swans, say no to construction.
But it isn't that simple. All that steel and concrete will become the Severn Barrage which, by harnessing the tides, would provide 5 per cent of Britain's electricity, with no nasty carbon emissions. So, which to choose: clean electricity, or the protection of birds and beasts?
It's a tough call, but one we may have to get used to. Last year, the EU set a target for the UK to increase the proportion of its energy gained from renewable sources such as wind, water and the sun from 1.8 per cent to 15 per cent in 12 years.
The House of Lords' European committee called the target "extremely challenging". Others call it unachievable. Either way, the Government is forced to seek more options than a few offshore wind turbines and there's going to be some serious cute collateral along the way.
We need nuclear power
"The whole universe runs on nuclear energy, so why not us?" argues the environmental scientist James Lovelock. While there are associated concerns about weapons and radioactive waste, a government White Paper published last January found that nuclear power emits only 2 to 6 per cent of carbon per kilowatt-hour of that emitted by the cleanest fossil fuel, natural gas. And it factored in everything from the uranium mining through to power-plant decommissioning.
About 18 per cent of the UK's electricity is currently generated by nuclear power, with all but one of our existing plants scheduled for decommissioning before 2023. We need to build more now because, however much we'd like it to, wind power cannot be relied on to generate enough electricity at the times when it is needed. As John Constable, the director of policy and research at the Renewable Energy Foundation, said in December: "To generate 30 or 40 per cent of our electrical energy from wind power would present unmanageable and unaffordable difficulties at the present."
Even Sweden has just announced plans to overturn a 29-year ban on atomic plants. "I'm doing this for the sake of my children and grandchildren," said Center party leader Maud Olofsson.
Counting food miles will get you nowhere
It's true that our suppers have never travelled so far to reach our plates asparagus from Peru, green beans from Kenya, lamb from New Zealand. Importing bananas and kiwis is one thing (they don't grow so well in Kent) but surely it's madness to fill our supermarket aisles with butter, apples and beans from the other side of the world?
Well, not necessarily. The food miles argument is perhaps one of the most criminally oversimplified in the whole green debate.
First, it's worth looking at just how much food we do import. According to the Department for Environment and Food's latest figures, we are 61 per cent self-sufficient; crucially, when it comes to foods we can produce here, that figure rises to 74 per cent.
But what of the relatively small percentage of food we do ship in? The food miles argument would have it that a leg of lamb's carbon hoofprint is in proportion to the number of miles it travels. But that ignores the concept of scale. Say a small local farm produces 10 tons of lamb, and has a lorry that can carry one ton at a time. And say it is 100 miles from the nearest market. You get lamb with 100 food miles, but the farmers have to make 10 trips to transport their meat.
Meanwhile, lamb from a bigger farm 500 miles away would travel 500 food miles, but they've got a 10-ton lorry so they do it in one trip. Sure, the big truck guzzles more gas than the little one, but not five times as much, so the carbon footprint of the far-flung lamb is smaller.
OK, that's a fictional example. But there have been more rigorous studies. Adrian Williams, an agricultural researcher at Cranfield University, has called the food miles argument "foolish: provincial, damaging and simplistic". Williams and his team have looked at the relative carbon footprints of produce grown locally and thousands of miles away, taking into account factors such as fertilisation, irrigation, means of transportation and harvesting methods not just the number of miles from field to fork.
Williams showed that apples from New Zealand may be "greener" than those grown locally because the climate there allows for much greater yields, and farms rely mostly on electricity generated by renewable sources. A study at New Zealand's Lincoln University showed that lamb shipped to Britain produced one-quarter of the CO2 emissions of British lamb when you accounted for the relative reliance on fertiliser and energy-hungry irrigation systems, as well as the method of transport shipping emissions have been shown to be about one-60th of those produced by air travel.
And it's not just food and drink that can travel ethically. Williams carried out a study of the lives of 10,000 roses on sale in Britain in February. The total carbon footprint of flowers grown in heated greenhouses just over the Channel in Holland was six times greater than that of stems flown all the way from Kenya.
It looks as if the new generation of green shoppers who'll only buy local have something to think about over dinner. As Gareth Thomas, Trade and Development minister, said at a recent seminar on air freight: "Driving 6.5 miles to buy your shopping emits more carbon than flying a pack of Kenyan green beans to the UK."
An old banger beats a hybrid
Driving a banger might well be greener than zipping about in a hybrid car such as the Toyota Prius. The zeal with which green-minded drivers have embraced the Prius is scarcely credible, because the hybrid's eco-credentials are far from clear. Since its 1997 launch, the Prius, which combines a battery with a petrol engine, has become a big seller Toyota has shifted a million of the things, and drivers include a clutch of celebrities led by Leonardo DiCaprio and a symbol of everything a standard car is not: green, clean, virtuous.
But is it? Petrolheads have questioned Toyota's claims. Not always successfully; in 2007, an American market research company pitched too high when it published a report claiming that the Humvee, thought to be the worst-offending car on the road, had a smaller carbon footprint than a Prius. Further studies discredited that, but the researchers were on to something. Because the Prius uses a big battery to complement its engine, a Prius is green when it gets to the road, managing (Toyota says) a respectable 65.7mpg in mixed driving. But that hulk of a battery includes almost 14kg of nickel and the Prius, therefore, requires more energy to build than a standard car of a similar size.
And some road tests have questioned whether it's even that green on the road. Drivers claim their dashboard gauges rarely show the promised 65.7mpg. In one test, the motoring journalist Jason Dawe took part in an experiment in which a Prius and a BMW 520 diesel were driven 545 miles from London to Geneva, including 100 miles of urban driving. The Prius guzzled 11.34 gallons of fuel (48.1mpg) compared to the BMW's 10.84 gallons (50.3mpg). Yet the Prius owner would pay £15 in road tax (£115 for BMW), be exempt from the London congestion charge (£8 a pop) and get to feel smug.
Other studies suggest that a diesel doesn't even need to be new to out-green a Prius. One US-based sustainability engineer, Pablo Paster, calculated that Toyota's hybrid burns 1,000 gallons of fuel before its first mile, thanks to the energy required to make that battery. He compared the Prius to a 10-year-old Toyota Tercel, which puts in 35mpg but has paid off its manufacture carbon debt. Paster estimates that the Prius would have to travel 100,000 miles before it could better the Tercel's overall carbon footprint.
Coal is not a dirty word
The coal-fired power station is the ultimate symbol of the way we send clouds of carbon into the atmosphere yet the latest wisdom is that we should build more coal-fired power stations.
Why? Solar, wind and tidal power will only get us so much electricity. The other part of the solution may well involve a dirty, black rock we might have thought had been cast into history. Coal is seen as a key part of Britain's formula for green energy. Ed Miliband, Secretary of State for the Department for Energy and Climate Change, recently said the black stuff "has to be part of the energy mix, partly because there is an abundant source in Britain". Britain still has enough coal to power the country for a century and, in the longer term, "clean coal" is seen as a viable if imperfect way for developing countries to green up their power.
But how can coal be clean? The answer lies in a technique called carbon capture and storage (CCS). Traditionally, coal power plants belch tons of CO2 straight into the atmosphere. CCS power stations, or those fitted with the technology, would capture the greenhouse gas and bury it, usually in depleted oil or gas fields in, say, the North Sea. The Intergovernmental Panel on Climate Change estimates that a modern power plant with CCS could reduce CO2 emissions by 80 to 90 per cent compared to a standard plant.
The first pilot CCS plant began operation in Germany last year. The Schwarze Pumpe processing plant separates and squashes its CO2 emissions to one-500th of original volume before pumping the gas into cylinders for transport and burial 1,000 metres underground in a gas field. In the next few weeks, the German energy company E.ON is expected to get approval to build a plant at Kingsnorth, in Kent.
The prospect of Britain's first new coal-fired power station for 30 years horrifies green campaigners, and Kingsnorth has seen clashes between police and protesters who say CCS is expensive, requires huge amounts of energy itself and won't greatly cut emissions for decades. But "clean" coal has momentum.
Organic farming doesn't add up
Organic must be good, right? Better food, free from nasty pesticides, packaged in recycled cardboard (preferably brown), with a bit of soil thrown in to confirm its wholesome provenance; better for us, better for the cows and chickens and lambs and fruit and veg, better for the planet.
Or have we been fooled by the virtuous glow of organic brands? There's a reason a kilo of organic carrots at the online supermarket Ocado costs £1.49 while a bag of standard carrots the same size costs 95p. Organic food is more expensive to farm. That's because, per acre, the yield is usually lower than for standard crops because organic fertilisers aren't as effective. And smaller farms are often less efficient in harvesting, processing, transporting and associated carbon emissions (see food miles).
Organically reared livestock provide less meat per acre, and their impact is greater than that of vegetables. According to the Department for Environment and Food, 75 per cent of the greenhouse gas methane on farms is emitted directly by ruminants cattle and sheep. But feed for organic animals is higher in roughage and low in concentrates, resulting in higher methane output per beast. A study by Dr Andy Thorpe at the University of Portsmouth suggested that 200 cows emit the annual equivalent methane to a family car driven 111,850 miles.
Then there's the perception that to buy organic is to support the small farm down the lane. The food giants knew a good thing when they saw it (the UK organic industry is now worth £1.5bn a year) and, since the 1990s, they have invested heavily in small organic firms: Cadbury's gobbled up Green & Blacks, and Dean Foods, America's biggest dairy producer, gulped down Rachel's Organics.
So the organic principle is good in some ways the taste of food, the lack of pesticides but "organic is best" isn't always true.
Ancient forests must be axed
It isn't picturesque but it is practical. It sounds ruthless, but wheezy old trees can't suck up the carbon like they used to. A tree absorbs roughly 1,500 tonnes of CO2 until it reaches 55 years of age, after which absorption slows. And when that tree decomposes, it belches all the CO2 back out again. So although the results won't be terribly scenic, if we were utterly rational, our trees should get the axe after reaching their CO2-hoovering peak. The wood can then be used to make furniture, houses and many of the products we currently manufacture from less sustainable materials. We should then plant fresh seedlings to farm.
Nature needs GM crops
The public image of genetically modified foods lies somewhere between that of asbestos and nuclear weapons. Think GM and many of us picture tomatoes being cloned in laboratories with nasty strip lights and bubbling test tubes, or campaigners in white suits tearing up "frankencrops" in fields of undisclosed location.
But for many of those pondering the future of food, GM doesn't evoke such horrors it's the answer to a potential global crisis taking root in fields from Bedfordshire to Brazil. The price of feeding a global population of more than six billion is its huge environmental impact.
According to the latest report from the Intergovernmental Panel on Climate Change, agriculture with all its chugging tractors, fertiliser production and farting cows accounts for 14 per cent of greenhouse gas emissions, throwing out tonnes of carbon dioxide, nitrous oxide and methane. That's more than the world's cars, trucks, trains, ships and planes put together. In fact, UN figures suggest meat production alone churns out more greenhouse gases than transport.
An easy solution would be to reduce the posterior emissions of ruminants by eating less beef, but before we all go semi-veggie, perhaps we should give bioengineers, and their genetically modified carrots, a second chance. One third of agriculture's greenhouse emissions are caused by the production of nitrogen-based fertilisers. Some of the biggest names in GM are developing crops whose greater efficiency would mean higher yields for less fertiliser.
And it's not only in the food industry that GM could benefit the environment. Engineered corn would improve the efficiency of biofuels, which, thanks to the huge areas of land required to produce each barrel, and the energy required to run the mega-farms, frequently result in more carbon emissions than they save. Meanwhile scientists in Hawaii are engineering algae that "grows" biofuel, while in Boston a company is turning maize into plastic. And it doesn't stop there; scientists in Norwich have added the genes of snapdragon flowers to tomatoes to create a purple fruit rich in antioxidants which has been shown to stave off cancer in mice.
Almost 10 years ago, Sir Robert May, who was the Government's chief scientific adviser at the time, said people who were anti-GM displayed "the attitude of a privileged йlite who think there will be no problem feeding tomorrow's growing population".
Carbon offsetting doesn't pay
Dreamed up by politicians and businessmen rather than climate change scientists, carbon offsetting has been described by Friends of the Earth as "a smokescreen to avoid real measures to tackle climate change". In the same way as the medieval church allowed monied folk to buy their way out of sin, so offsetting is designed to allow the wealthy to salve their consciences for all those shopping trips to Dubai. It would be far greener not to "spend" the carbon in the first place. And that's without going into the impossibility of accurately calculating how much carbon is emitted on any given flight and ensuring the "offset" doesn't involve planting a tree that will end up emitting even more carbon.
China might be the solution
We've all seen "Made in China" stamped on disposable goods but you're now likely to find the same stamp on solar panels, wind turbines and the rechargeable batteries used by electric vehicles. According to a Climate Group report, China is on the way to overtaking developed countries in creating clean technologies. The world's largest emitter already leads the world in terms of installed renewable capacity. With its own coastal cities threatened by flooding, and soaring world demand for its green technology, China is on the way to becoming a "low-carbon dragon economy".
Additional reporting by Helen Brown
А также другие работы, которые могут Вас заинтересовать
|45355.||Рекуррентные сети||91.5 KB|
|В связи с этим были предприняты попытки дополнить искусственные нейронные сети обратными связями что привело к новым неожиданным результатам. Таким образом под воздействием входных сигналов х1 и х2 на выходе сети в момент времени t вырабатываются сигналы y1t и y2t а в следующий момент времени под воздействием этих сигналов подаваемых на вход вырабатываются новые выходные сигналы y1t1 и y2t1. Для всякой рекуррентной сети может быть построена идентичная сеть без обратных связей с прямым распространением сигнала поэтому для...|
|45356.||Направления исследований в области искусственного интеллекта||30.5 KB|
|Второй подход в качестве объекта исследования рассматривает системы искусственного интеллекта. Третий подход ориентирован на создание смешанных человекомашинных или как еще говорят интерактивных интеллектуальных систем на симбиоз возможностей естественного и искусственного интеллекта. Сообщения об уникальных достижениях специалистов в области искусственного интеллекта суливших невиданные возможности пропали со страниц научнопопулярных изданий много лет назад.|
|45357.||Области применения систем искусственного интеллекта||47 KB|
|В распознавании образов имеется хорошо разработанный математический аппарат и для не очень сложных объектов разработаны системы классификации по признакам по аналогии и т. Алфавит признаков придумывается разработчиком системы. Экспертные системы Экспертными системами называют сложные программные комплексы аккумулирующие знания специалистов в конкретных предметных областях и тиражирующие этот эмпирический опыт для консультаций менее квалифицированных пользователей. В этом случае говорят что происходит обучение экспертной системы.|
|45358.||Обучение игровых программ||41 KB|
|Таким образом накопление позволяет либо экономить время либо достичь лучшего качества игры за то же время путем использования несколько большего дерева. Оно позволяет программе в ходе игры улучшать свои оценивающие функции. Качество игры зависит от подходящего выбора весовых коэффициентов k1 k2 k3 .|
|45359.||Подготовка входных параметров||28 KB|
|Естественно что незначимые параметры не следует включать в список параметров входного вектора X. Однако на практике часто бывает трудно и даже невозможно установить какие из параметров предметной области являются значимыми а какие нет. Поэтому на первом этапе в вектор X включают как можно больше параметров избегая только те из них незначимость которых очевидна.|
|45360.||Многообразие образовательных учреждений, их специфика||66 KB|
|Учреждения профессионального образования. Прием граждан для получения среднего профессионального высшего профессионального и послевузовского профессионального образования проводится на конкурсной основе по заявлениям граждан. Вне конкурса при условии успешной сдачи вступительных экзаменов в государственные и муниципальные образовательные учреждения среднего профессионального и высшего профессионального образования принимаются: детисироты и дети оставшиеся без попечения родителей; детиинвалиды инвалиды I и II групп которым не...|
|45361.||Школьный класс как малая социальная группа: характеристика, структура, уровни развития. Межличностные отношения и методы их изучения||60.5 KB|
|План Признаки коллектива Характеристика класса как ученического коллектива Структура класса Формальная неформальная Отсутствие структуры складывающаяся структура 2 или более группировок Уровни развития класса стадия 1 2 3 и последующие Межличностные отношения в классе звезды предпочитаемые отвергаемые изолированные Методы изучения межличностных отношений в классе социометрия выявление лидера Признаки коллектива: Общая социально значимая цель. В хорошо организованных коллективах проявляются взаимопомощь и...|
|45362.||Изучение, обобщение и распространение передового педагогического опыта. Анализ опыта учителей-новаторов||39 KB|
|Критерии педагогических инноваций Новизна оптимальности результативность массовость 7. Причины нереализованности педагогических новаций. 3 Изменение характера отношения учителей к самому факту освоения и применения педагогических новшеств. Внедрение достижений педагогической науки Инновационная направленность деятельности учителей включает и вторую составляющую внедрение в практическую педагогическую деятельность результатов психологопедагогических исследований.|
|45363.||Диагностика результатов обучения школьников. Проверка и оценка работы школьников в процессе обучения||50.5 KB|
|План Диагностика качества обучения определение цель принципы формула Контроль Понятие контроля Виды контроля Формы контроля Методы контроля Требования к контролю Тест как метод контроля Проверка Оценка 1. Принципы диагностирования обученности: Систематичность разнообразие постоянство форм методов средств контроля. Необходимость контроля на всех этапах обучения. Понятие контроля.|