Tuesday, March 22, 2016

Will plants' response to increased CO2 make heatwaves more intense than thought?

The report by Peter Hannam below seemed like a possible real concern if ever we do get global warming.  But I somehow knew that they would have ignored something important so I looked up the underlying journal article -- abstract thereof also reproduced below.  It is all just modelling rubbish.  When Warmist models show predictive skill will be the time to take notice of them.  It hasn't happened yet.

But there is something amusing in the article nonetheless. They seem to base their claims on how an individual leaf stoma reacts to higher CO2 but forget to look at  the whole plant.  That higher CO2 levels will produce bigger plants and hence more stomata seems to be overlooked.  With more stomata the overall water release may remain unchanged.

Warmists are such a laugh!  Junk science all the way.  It's such junk that even a humble social scientist like me can see through it.  And shifty old Peter Hannam swallows it all hook, line and sinker.  He must never ask any questions

Peter Hannam

Heatwaves in the northern hemisphere may become as much as 5 degrees warmer than previously estimated by mid-century because plants' response to higher carbon dioxide levels has been miscalculated, according to new research by Australian scientists.

As atmospheric levels of the greenhouse gas increase, plant stomata – the tiny pores on leaves that open to take in CO2 and let out water vapour – won't need to open as much.

"There's less water vapour being lost so you have a net warming effect," said Jatin Kala, a lecturer from Murdoch University and lead author of the paper that was published Monday in Nature Scientific Reports.

The researchers used data from 314 plant species across 56 field sites to examine how plants responded. Existing climate models had assumed all plants would trade water for carbon in exactly the same way.

Needle-leaf forests, tundra and agricultural land used for crops would likely suffer the biggest temperature increases. Heatwaves from Europe to China were likely to become 3-5 degrees hotter than the already higher base expected from global warming, Dr Kala said.

"These more detailed results are confronting but they help explain why many climate models have consistently underestimated the increase in the intensity of heatwaves and the rise in maximum temperatures when compared to observations."

The results do not necessarily apply to southern hemisphere regions to the same extent. "We don't have an observation of how Australian vegetation will respond to rising CO2," he said.

CSIRO, the Bureau of Meteorology and the ARC Centre of Excellence for Climate System Science developed the Australian Community Climate and Earth System Simulator (ACCESS) model used in this study.


Impact of the representation of stomatal conductance on model projections of heatwave intensity

Jatin Kala et al.


Stomatal conductance links plant water use and carbon uptake, and is a critical process for the land surface component of climate models. However, stomatal conductance schemes commonly assume that all vegetation with the same photosynthetic pathway use identical plant water use strategies whereas observations indicate otherwise. Here, we implement a new stomatal scheme derived from optimal stomatal theory and constrained by a recent global synthesis of stomatal conductance measurements from 314 species, across 56 field sites. Using this new stomatal scheme, within a global climate model, subtantially increases the intensity of future heatwaves across Northern Eurasia. This indicates that our climate model has previously been under-predicting heatwave intensity. Our results have widespread implications for other climate models, many of which do not account for differences in stomatal water-use across different plant functional types, and hence, are also likely under projecting heatwave intensity in the future.


Posted by John J. Ray (M.A.; Ph.D.).

1 comment:

Wireless.Phil said...

The northern hemisphere is hotter than the southern hemisphere and the north has more people than the south.

As for plants:

How much carbon dioxide do plants give off?

Answer 1:

During their lifetimes, plants generally give off about half of the carbon dioxide (CO2), that they absorb, although this varies a great deal between different kinds of plants. Once they die, almost all of the carbon that they stored up in their bodies is released again into the atmosphere.
As you may know, plants use the energy in sunlight to convert CO2 (from the air) and water (from the soil) into sugars. This is called photosynthesis.Plants use some of these sugars as food to stay alive, and some of them to build new stems and leaves so they can grow. When plants burn their sugars for food, CO2 is produced as a waste product, just like the CO2 that we exhale is a waste product from the food we burn for energy. This happens day and night, but since photosynthesis is powered by sunlight, plants absorb much more CO2 than they give off during the daytime. At night, when photosynthesis is not happening, they give off much more CO2 than they absorb. While they're alive, overall, about half of the CO2 that plants absorb is given off as waste.
When you look at a tree, almost all of the body of the tree is made of sugars, which are made from carbon (from CO2) and hydrogen and oxygen (from water). When the tree dies, it rots as decomposers, like bacteria, fungi,and insects eat away at it. Those decomposers gradually release almost all of the tree's stored carbon back into the atmosphere as CO2. Only a very small portion of the carbon in the tree ends up staying in the soil or washing out to sea without changing back into CO2.

Note ScienceLine Moderator:
Actually, the oxygen from water is split off to form O2 gas, and only the hydrogen ends up in the sugar. That seems important.
Correction made by Jeff, Appalachian State University.


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