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Separating climate fact from factoid

Only colossal changes in the energy industry will stop global warming. But first people need to get their facts straight, says David MacKay. Interview by Derek Brower

IF YOU leave your DVD player on stand-by all day instead of shutting it off then you're consuming the same amount of energy that it takes to ship the entire thing by plane from China, where it was made.

If you read that and didn't blink, then you've probably been infected by a global-warming disease, one that leaves you unable to tell fact from factoid, truth from hogwash.

If you're reading this on the first leg of a return flight across the Atlantic, then by the time you get home again you'll have pumped into the atmosphere more than a third of the carbon each human emits, on average, every year.

That one's true. The global annual per capita carbon footprint is about five tonnes of CO2, and that flight would use up a hefty chunk of it. (If you're from an energy-hogging country like Australia, the UK or the US, then your pollution count is far higher.) Think about it next time you're totting up your frequent-flyer miles. Indeed, consider that in the course of that to and fro across the Atlantic, the amount of energy you'll have spent is about the same as leaving a 1 kilowatt (kW) fire on, non-stop, for an entire year.

When everyone from scientists to politicians to journalists are batting forth statistics about climate change – gigatonnes here, 2°C temperature rises there – it's hard to keep the truth straight. And, says David MacKay, it can be dangerous to get it wrong.

MacKay is a professor of natural philosophy in the physics department of the University of Cambridge, UK. And he's also an eloquent spokesman about what the world – and especially his own country – can do to arrest global warming.

Understanding the issues

His book, Sustainable Energy – without the hot air came out in December 2008 (and in May 2009 in the US). It's a realist's guide to what renewable and other non-hydrocarbon sources of energy could do, and what they can't. Climate change literature is now a bustling industry of its own, but if there is one book that gives the reader a clear-eyed understanding of the issues, this is it.

The work is a masterpiece of forensic analysis, with dollops of humour and common sense strewn throughout. Taking the typical Briton as his model, he calculates what his or her daily energy needs are – about 125 kW hours a day (kWh/d), excluding imports of goods – and what proportion of them might feasibly come from green energy.

It's a fairly gloomy conclusion. The UK's theoretical supply from a range of sustainable energy sources could meet the bulk of demand. But politics and the country's talent for saying no to new developments means that the maximum UK citizens will ever get from renewables is likely to be around 18 kWh/d. That means green energy would contribute a paltry 15% or so of demand.

Saying no to renewables sometimes makes sense. There are some good reasons, for example, why the UK won't ever rely on wind for the bulk of its power (see p24). To do so, points out MacKay, would require wind farms spread across land the size of Wales. But then there are silly reasons, such as the old squawk that wind turbines kill birds. Yes, they do. In Denmark, a world leader in wind energy, they kill around 30,000 birds a year. But road traffic in the country kills 1 million birds a year. In the cat-loving UK, meanwhile, 55m birds tragically meet their end between feline paws each year. When it has touched on birds, suggests MacKay, the debate about wind power has become emotional, often ignoring facts.

His book is full of similar comparisons. One target of his thesis is the notion that "every little helps" in the fight to stop global temperature rises. When he set out to write his book, the UK had developed a fixation for switching off mobile phone chargers. "All the energy saved in switching off your charger for one day is used up in one second of car-driving," writes MacKay. "The energy saved in switching off the charger for one year is equal to the energy in a single hot bath." Obsessively switching off the charger, he says, is like bailing out the Titanic with a teaspoon.

That's not to say people shouldn't be conscious of their energy consumption. MacKay himself rarely flies anymore and hasn't driven in 17 years. And part of his book concerns his quest to cut the energy consumption of his household. He checks his meter every week, he says, trying to localise the next energy-wasting enemy. Yet his book steers clear of the big ethical questions – should, for example, historical polluters take more responsibility that new ones? – giving readers a slew of facts so they can straighten their own arguments.

MacKay is no preacher of an impending immediate apocalypse, either. Freakish weather patterns seen in recent years – such as the blistering hot summer of 2003 that killed thousands in Europe – are likely to become more frequent as long as nothing is done to reverse global warming, he says. But the real catastrophe, if nothing is done now, awaits "the people living on your street in 200 or 300 years".

That's part of the problem in persuading people – and especially elected politicians – to act quickly. Averting disaster for people who don't yet exist is a difficult sell. Critics of the global-warming discourse, such as Bjorn Lomborg, author of The Skeptical Environmentalists, say problems like malaria, HIV/Aids and poverty are more pressing. Yet, points out MacKay, there are other good reasons to press on now. Europe's security-of-supply worries make the case for sustainable energy on their own. "Forget about climate change; in 2050 we don't want to be living on gas as we do now", relying on "some son-of-Putin" for supplies.

And hydrocarbons, being finite, will eventually run out, too (see p26). So what's the solution? "We need an energy plan that adds up," says MacKay. Existing proposals, from the UK's nuclear and renewables drive, to the EU's 20-20-20 programme, to US President Barack Obama's green shift are steps in the right direction, but nowhere near the scale required. To supply the UK alone, says MacKay, the country needs roughly a 100-fold increase in wind power, a five-fold increase in nuclear generating capacity and cables connecting "Surrey to the Sahara", where solar panels in the desert could be one of the most promising ideas of all.

It needs to start happening quickly. Batteries are improving and, MacKay hopes, the electric car could soon go mainstream. But to meet primary energy needs, construction of infrastructure must begin imminently – and on a scale hardly on the radar at present. If it happens, the future could even be bright for the oil and gas companies that, uniquely, have the expertise and project-management skills to handle such large projects, says MacKay.

If it doesn't happen, we'll have to get used to a hotter climate. MacKay says his next book could be about "geo-engineering" – the steps needed to adapt to a world of rising temperatures, melting ice caps and flooded lowlands.

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