http://www.nature.com/nature/journal/v461/n7263/full/461472a.html Climate change is represented by the change in radiative forcing. The data plotted is the fraction current value/boundary, except for ocean acidification and ozone depletion where the reciprocal values were used because lower values are bad, not good as for the other axes. For the phosphorus cycle the mean value of 9 was used as 8.5–9.5 was given in the table. The two systems whose boundaries are not yet determined were left out. OTOH, nitrogen and phosphorus cycle are part of the same earth system as defined by the authors but were plotted seperately. Thanks to User:Epipelagic who had some good ideas. I confused two comments so it should be Epipelagic in the change history, too. Sorry for that.