Nature Clim. Change 5, 127–131 (2015); published online 12 January 2015; corrected after print 28 January 2015 In the version of this Letter originally published, in equation (1) and in the explanatory sentence following the equation, jTFP should have read rTFP. In the second line of the equation, jDJOj,t should have read rDJOj,t.