In 2050 there will be 9 billion people on earth. How to feed them

Have we reached 'peak farmland'? Patrick Barkham digs into a new book about food and the future, while Chris Newell provides a graphic summary of the challenges ahead

'Tis the season of harvest festivals and farmers are celebrating another bumper crop. British farmers have this year twice smashed the record for the world's highest-yielding wheat crop ever recorded, first in the Lincolnshire Wolds and then on a farm overlooking Holy Island in Northumberland.

Squeezing ever-higher yields from the same fields is one reason why the famous theories of Thomas Malthus, the cleric who predicted catastrophic famine and disease as population growth outstripped food production, haven't come to pass. During the last 40 years of the 20th century, when the world's population doubled from 3 to 6 billion, our annual production of grain rose even faster, nearly tripling over the same period.