Ray, the key problem with the analysis you cite is that it does not deal very well with the issue of extreme weather conditions. If drought spreads as a result of global warming, the level of CO2 in the atmosphere is irrelevant as H2O is an absolute requirement for plant growth. I also object to calling CO2, free fertilizer. It's not really fertilizer as that term really applies to exogenous nitrogen and phosphorus that are responsible for amino acid, nucleic acid and high energy phosphate production in plants. Again, CO2 concentration is irrelevant as long as it is not zero if the plant has access to usable nitrogen and phosphorous.
Alan,
We've been through this before. The technical summary of the latest IPCC report stated specifically that there was
low confidence that hurricanes, droughts and floods have been increasing since the 1950's.
Of course, one can always create computer models to show that there is a
risk of that happening in the future, but what's interesting is that the same report states there is
high confidence that precipitation levels (rainfall) have been increasing during the same period, and high confidence that heat-wave temperatures have been increasing.
Both of those 'high confidence' descriptions make sense to me in a world that is currently in a slight warming period. I say 'slight' because an average global increase of around 1 degrees C during the past 150 years or so, doesn't sound alarming to me, especially when that increase is referenced to the sometimes uncomfortably cool temperatures that existed around the end of the Little Ice Age which extended to the beginnings of industrialization in the early 19th century.
In a slightly warming climate one would expect evaporation to increase and therefore rainfall, which is not a bad thing. One might expect that increased rainfall would result in increased flooding. The fact that there is no strong evidence that flooding, on a global scale, has been increasing, despite increasing rainfall (according to that great authority on climate issues, the IPCC), would suggest that mankind's increasing use of water, through the construction of dams, is the reason for this lack of a corresponding increase in flooding, globally.
As regards the claimed increase in heat-waves, it's not clear from the evidence presented, to what extent such increases are influenced by the Urban Heat Island effect. Where were the thermometers located that measured such increases during heat waves?
The proposition that increased CO2 levels are causing the current warming is not scientifically verified. That the UHI effect is real can definitely be verified.
I also object to calling CO2, free fertilizer. It's not really fertilizer as that term really applies to exogenous nitrogen and phosphorus that are responsible for amino acid, nucleic acid and high energy phosphate production in plants.
I'm using the term fertilizer according to its broad meaning of 'something that enhances growth'. It's true that the term 'fertilizer' is usually associated with industrially produced chemicals such as Nitrogen and Phosphorus, that cost money and labor to produce and apply to the soil. The term can also be associated with any type of manure that is applied to the soil, which also involves labor.
The beauty of CO2 is that it's a fertilizer (oops! 'growth-enhancing chemical') that doesn't require any manufacturing or distribution costs. The plants grab it from the atmosphere and take it into the soil through root growth. Ain't nature wonderful!
[/quote]Again, CO2 concentration is irrelevant as long as it is not zero if the plant has access to usable nitrogen and phosphorous. [/quote]
And of course access to water, which you know is an absolute requirement for plant growth.
If it's true that an increase in CO2 levels is the main cause of the current warm period, and if it's true that increased precipitation has resulted from such warming, as the IPCC has stated with 'high confidence', then the consequences of spending trillions of dollars to reduce CO2 levels will not only be a general reduction in plant growth due to lower CO2 levels, but also less available water to irrigate such plants, which will reduce crop production even further.
In order to compensate for such reduced crop growth, we would not only have to spend additional funds to make available more chemical fertilizers but also additional funds on desalination plants on the coast and long irrigation pipelines. That approach doesn't seem at all sensible to me. It sounds more like 'shooting oneself in the foot', especially when alternative energy supplies tend to increase the over all cost of energy.
There is also the issue of the 'greening of the planet'. Are you suggesting that we should also apply fertilizers and water to all the natural forests to compensate for the lack of CO2 in the atmosphere?
One of the negative consequences of human development and rising populations is the significant deforestation that has taken place for agricultural purposes, and which continues to take place in many countries. The remaining forests really appreciate that extra CO2 we are giving them as a by-product of our energy production.
I'd also be interested in any research that supports your contention that plants can thrive in close to zero concentrations of CO2, provided they have adequate fertilizers and water. Perhaps you are referring to the C4 type of plants that can utilize CO2 more efficiently than the C3 types of plant.
C3 plants are far more common than C4 plants. The C3 type plants includes most small-seeded cereal crops such as rice, wheat, barley, rye, millet, oats; and also soybean, peanuts, cotton, sugar beets, spinach and potato.
Outside the agricultural system most plants, trees and grasses are of the C3 type. About 85% of all plants are of the C3 type.
There seems to be a general lack of research on the effects of significantly reduced CO2 levels and how such reduced growth might be reversed through other interventions such as increased use of fertilizers, water and genetic modifications.
However, I came across one very detailed article which specifically addresses such issues and reveals the complexities and uncertainties.
http://onlinelibrary.wiley.com/doi/10.1111/j.1469-8137.2010.03441.x/pdfThe following comments near the Conclusion in the pdf, I found particularly interesting.
"A plethora of past work strongly suggests that the increase in [CO2] that occurred between 15 000 and 10 000 yr ago may have been large enough to have had a profound impact on crop productivity, and hence on human subsistence patterns (Sage, 1995; Fig. 9). In general, glacial conditions would have been a hostile environment for C3 crops because of low [CO2], as well as drier soils and higher seasonal variation (Richerson et al., 2001). As the interglacial period commenced, the onset of rising [CO2] and other climatic changes would have removed an environmental limitation to the development of agriculture (Sage, 1995).
Increasing [CO2] during the interglacial period may have directly enhanced plant productivity and may have reduced the effects of interactive stressors, such that crop production could be sustained year after year within human societies (Sage, 1995).
Anthropologists are beginning to incorporate the importance of CO2 into their ideas on agricultural development.
For example, Bettinger et al. (2009) attributed the development of agriculture to the combined effects of climatic and cultural changes, including increasing [CO2]."