A major consequence of this phenomenon is that the optimum temperature for plant growth generally rises when the air is enriched with CO2…[this] suggests that the temperature at which many plants grow best will rise by about 5C… even the most extreme warming projected by the IPCC will not adversely impact the majority of the plants on earth.
Pressing on with the joy of CO2 in a more conventional manner, a word of thanks to the Cats who said they liked the classroom presentation. Pupils who were paying attention in the class would have noticed that this is chapter 13 not chapter 14.
First some comments on the story that John kindly posted regarding the termination of field trials on CO2 enrichment at the Horsham research station in Victoria. It is very strange and quiet likely a scandal that this work was terminated. The only rational justification is to continue the work more efficiently in glasshouses.
When I first posted on the benefits of CO2 years ago some Google scientists promptly turned up with criticism drawn selectively from Wikipedia that the extra growth meant less quality and the benefits did not appear on less fertile soils. Doh! If there is some other major limiting factor like water or phosphorus of course no amount of CO2 or other additional growth factors will make much difference.
The point is that CO2 is sub suboptimal everywhere and other shortages are local. The extra CO2 comes free of charge and careful economic calculations are required to assess the benefits of extra water and chemicals.
Sure enough the principal researcher at Horsham reported. “A key finding was that crops grown under elevated CO2 grow bigger but they will need more nitrogen and phosphorus to support them, and grain quality will decrease”.
Quality may or may not be an issue, certainly it is for wheat but that does not apply to all crops and if it pays to do so for quality reasons or simply for the bulk then you apply more nitrogen and phosphorus (not to mention potassium and trace elements).
Turning back to Dr Idso’s paper, there is enough meat in it for two more post so I will give some more information here and save the rest for another class. The first post noted the increased growth of plants with additional CO2, most strikingly in woody trees, fruit and some vegetables (hence the use of CO2 enrichment in commercial glasshouses). It also noted enhanced water-use efficiency.
Amelioration of environmental stress.
This applies to soil salinity, low soil fertility, low light intensity, low temperature, herbivory and most strikingly high air temperature. The enhanced CO2 effect in percentage terms is “generally greater under stressful and resource-limited conditions than it is when growing conditions are ideal.” Obviously this is most interesting in relation to global warming (such as it is, that is to say not very much lately).
He replies to the concern that plants and trees may not be able to migrate fast enough to keep up with the anticipated warming, that is to save themselves from disaster by extending their range in the cooler direction (like the Barrier Reef moving towards NSW). His findings should cheer up the alarmists no end. He reported research that showed that the impact of a 300ppm increase in the aerial plant food rose from zero at 0C to 100% at 38C.
This is not really surprising when you consider that chemical reactions go faster at higher temperatures. Of course that effect ends up at some point but the research reported here suggests that the benefits of higher temperatures in real-world ranges are very large.
A major consequence of this phenomenon is that the optimum temperature for plant growth generally rises when the air is enriched with CO2…[this] suggests that the temperature at which many plants grow best will rise by about 5C.
That is, to say the least, a sensational result because it destroys the idea that crops and forests will be damaged by a rise of a mere degree or two. They will thrive on it! “Bring on 5C” they might say😊. Nerds will be interested in the mechanism for this effect in the chemistry of photosynthesis but I will not bother Lizzie with that here. The outcome is that even the most extreme warming projected by the IPCC will not adversely impact the majority of the plants on earth.
Next time the positive biospheric impacts including some massive figures for dollar value of additional agricultural production.
In the meantime, keep warm and be amused by the AEMO Data Dashboard.