In this Reuters story (15 December 2009) they report: “Describing a ‘runaway melt’ of the Earth’s ice, rising tree mortality and prospects of severe water scarcities, Gore told a UN audience: ‘In the face of effects like these, clear evidence that only reckless fools would ignore, I feel a sense of frustration’ at the lack of agreement so far.”
Now to most people, “rising tree mortality” raises the specter of a world with less greenery. But how does real world data compare with the virtual modeled world? Is the world getting less greener? Is there any hint of the virtual world in the real world data?
Satellite data for the real world (not the one Mr. Gore lives in) can help give us an idea.
Globally net primary productivity (NPP) has increased. As the IPCC’s WG II report (p. 106) says:
Satellite-derived estimates of global net primary production from satellite data of vegetation indexes indicate a 6% increase from 1982 to 1999, with large increases in tropical ecosystems (Nemani et al., 2003) [Figure 1]. The study by Zhou et al. (2003), also using satellite data, confirm that the Northern Hemisphere vegetation activity has increased in magnitude by 12% in Eurasia and by 8% in NorthAmerica from 1981 to 1999.