The State of Earth's Terrestrial Biosphere: How is it Responding to Rising Atmospheric CO2 and Warmer Temperatures?
Findings and Conclusion
In the Introduction of this report we outlined two conflicting views that are held with respect to the potential effects of rising atmospheric CO2 concentration and warmer temperatures on the productivity of Earth's biosphere. One view, held by climate alarmists and based primarily on computer model projections, posits that increases in CO2 and global temperature will have devastating effects on terrestrial vegetation, potentially causing the extinction of numerous species of plants. The opposing view, offered by climate skeptics, maintains that the alarmist projections are wholly incorrect and that rising temperatures and atmospheric CO2 concentrations will lead to significant increases in the growth and productivity of Earth's plants everywhere they are found.
In evaluating the relative correctness of these two contradictory viewpoints, we have presented a metaanalysis of the peer-reviewed scientific literature to see how the planet's vegetation has responded to the recent century-long increases in both atmospheric CO2 and temperature, which increases should be providing some indication as to what the future holds, right now! And based on that analysis, we conclude the following:
| - Satellite-based analyses of net terrestrial primary productivity (NPP) reveal an increase of around 6-13% since the 1980s. |
| - Earth's land surfaces were a net source of CO2-carbon to the atmosphere until about 1940. From 1940 onward, however, the terrestrial biosphere has become, in the mean, an increasingly greater sink for CO2-carbon. - Over the past 50 years, global carbon uptake has doubled from 2.4 ± 0.8 billion tons in 1960 to 5.0 ± 0.9 billion tons in 2010. |
3. The observed greening of the Earth has occurred in spite of all the many real and imagined assaults on Earth's vegetation over this time period, including fires, disease, outbreaks of pests, deforestation, and climatic changes, primarily in temperature and precipitation.
4. The atmosphere's rising CO2 content - which alarmists consider to be the chief culprit behind all of their concerns about the future of the biosphere (via the indirect threats they claim it poses as a result of CO2-induced climate change) - is most likely the primary cause of the observed greening trends.
5. Looking to the future, Earth's plants should be able to successfully adjust their physiology to accommodate a warming of the magnitude and rate-of-rise that is typically predicted by climate alarmists to accompany the projected future increase in the air's CO2 content. Factoring in the plant productivity gains expected to occur as a result of the aerial fertilization effect of the rising atmospheric CO2 concentration, plus its transpiration-reducing effect that boosts plant water use efficiency, the world's vegetation is seen to possess the ideal mix of ingredients to reap a tremendous benefit.
Considering all of the above, the recent "greening of the Earth" observed by a host of scientists will likely continue in the years and decades to come.