Net primary production (NPP) represents the net carbon that is fixed (sequestered) by a given plant community or ecosystem. It is the combined product of climatic, geochemical, ecological, and human effects. In recent years, many have expressed concerns that global terrestrial NPP should be falling due to the many real (and imagined) assaults on Earth’s vegetation that have occurred over the past several decades—including wildfires, disease, pest outbreaks, and deforestation, as well as overly-hyped changes in temperature and precipitation.
The second “National Assessment” of the effects of climate change on the United States warns that rising temperatures will necessarily result in the reduced productivity of major crops, such as corn and soybeans, and that crops and livestock will be “increasingly challenged.” Looking to the future, the National Assessment suggests that the situation will only get worse, unless drastic steps are taken to reduce the ongoing rise in the air’s CO2 content (e.g., scaling back on the use of fossil fuels that, when burned, produce water and CO2).
All in tune with the Climate Change Alarmists' Liturgy.Craig quickly puts that argument behind him when he asks is that REALLY the case and, of course, the answer is NO!
Observational data indicate that just the opposite is occurring (see, for example, the many studies reviewed previously on this topic here)
Craig then cites the lateststudy from the research team of Li et al. (2017)
Working with a total of 2,196 globally-distributed databases containing observations of NPP, as well as the five environmental variables thought to most impact NPP trends (precipitation, air temperature, leaf area index, fraction of photosynthetically active radiation, and atmospheric CO2 concentration), Li et al. analyzed the spatiotemporal patterns of global NPP over the past half century (1961–2010).
Results of their analysis are depicted in the figure below, which shows that global NPP increased significantly from 54.95 Pg C yr-1 in 1961 to 66.75 Pg C yr-1 in 2010 (Figure 1a). That represents a linear increase of 21.5 percent in the last half-century. In quantifying the relative contribution of each of the five variables impacting NPP trends (Figure 1b), Li et al. report that “atmospheric CO2 concentration was found to be the dominant factor that controlled the interannual variability and to be the major contribution (45.3%) of global NPP.”
Repeating that last sentence:
Liet al. report that “atmospheric CO2concentration was found to be the dominant factor that controlled the interannual variability and to be the major contribution (45.3%) of global NPP.”