Cutting the emissions of twaddle

SHOULD you, an environmentally conscious citizen, walk or cycle?

Nature, you might think, refined Shank’s mare over millennia, so it must be the perfect mode of transport. Physics professor David MacKay disagrees; using our legs to push the pedals of a bike, he claims, is at least twice as efficient as pounding the ground.

In his book Sustainable Energy without the hot air, MacKay seeks to cut “emissions of twaddle”. Getting off fossil fuels is important. “We are all encouraged to make a difference but many of the things that allegedly make a difference don’t add up,” he writes. Twaddle emissions are high because people don’t look at the facts and do the sums. MacKay does both.