Farming the land and the oceans

Last week's Science featured a fascinating global map of human impact on the world's oceans (top), produced by Halpern et al. The complicated mapping exercise concludes that 41% of the world's oceans are strongly affected by multiple human stresses.

The map is a fascinating - "stark" in the words of Science - aquatic sibling to the global agricultural land use maps that are generated by Navin Ramankutty and colleagues by blending satellite observations and agricultural data. The latest cropland and pasture land datasets (bottom) are described in a recent Global Biogeochemical Cycles paper entitled "Farming the Planet". The data shows that ~34% of the planet's ice-free land surface has been converted for human agriculture.

Unlike the ocean maps, the land use maps only reflect locations that has been directly transformed by human activity, and one form (agriculture) of human activity at that.

It'd be terrific to unite the scientists studying terrestrial and marine systems to create a ocean+land dataset of human disturbance that includes all forms of resource extraction on land (including agriculture).