There have been many claims that various plant types benefit from warmer weather. One mode of reasoning is that a plants stomata close earlier in higher CO2 environments. Recent studies show, however, that, while this is true, the consequence of this is making the plant more susceptible to heat stress because of an inability to cool itself due to decreased evaporation rates.

http://phys.org/news/2014-07-discovery-i...

So while crop yields may be better in non heat-stressed environments for these types of plants in other environments where they regularly receive heat stress the outcome will not be so good.

Edit: I see Kano merely repeats what I have already stated yet ignores the rest of my post including the link. Here is a link to the actual paper as they now have it up.

http://www.nature.com/nature/journal/vao...

"To adapt CO2 intake to water loss, plants regulate the development of stomatal gas exchange pores in the aerial epidermis. A diverse range of plant species show a decrease in stomatal density in response to the continuing rise in atmospheric CO2"

"Elucidation of these mechanisms advances the understanding of how plants perceive and relay the elevated CO2 signal and provides a framework to guide future research into how environmental challenges can modulate gas exchange in plants."

You can get the rest of the information in the full version.

C4 plants are evolved from a time when CO2 levels were so low that plants had problems with photosynthesis, most of the C4 plants are grasses which are relatively recent evolution.

Actually theorectically C3 plants are the ones to benefit most from more CO2, but surprisingly C4 plants seem to benefit as well.

There is so much B.S. about CO2 and water requirements, as CO2 increases the amount of water required by plants reduces, because their stomata open less, this is not just theory this is fact, in the arid regions of Australia for one instance, vegetation has increased by 14% since 1980 as measured by NASA satellites.

There is also zero evidence that rainfall will decrease with warming, warming causes more evaporation and more precipitation, also proven by history 6000yrs to 9000yrs ago our world was a warmer place, the Sahara had rivers and lakes, forests in china where there is savanah and deserts, a time when all the great civilization began.

So I am sorry that when it comes to plants more CO2 is all good, the only thing bad is yes a few plants will be slightly less nutritous but that wont matter because there will be more available to eat.

As much as I know you want to paint a black picture about CO2 I suggest you stay away from discussing its affect on vegetation as you will lose the argument everytime.

As for temperature, well every plant has an optimum temperature, some plants can cope with a wide range, some not , but they will grow where it is best suited for them, plants are not static, deserts can change to savanah, savanah can change to woodland and vice versus as conditions change.

My biggest qualm with the comments regarding 'warmer is better' (or the other favourite that more carbon in the atmosphere icnreased plant growth) is that both disregard the critical (or limiting) variable to a plant's growth. In some circumstance warmth may be a limiting factor (although warmth may change the species composition and coverage).

For example in Australia (mainly in the southern forests) the temperatures will increase, however the rainfall will decrease. In these parts of Australia rainfall, soils, topography etc. are usually more limiting than 'warmth'. Therefore decreased rainfall coupled with increased temperatures will not be "better" for te native forests in these areas. Most the crops in these areas similarly are limited by rainfall (a drought in the UK wouldn't even be called a dry spell in the agricultural regions in Australia).

So yes, CO2 can assist plant growth (in a laboratory) but in the real world it will have little to no effect unless it is increased significantly beyond the current trends (which then have huge consequences for the natural environments and human life).

Probably not. With constant climate and water supply, addition CO2 will cause plants to grow faster but faster growing plants tend to be less nutritious. Adding CO2 does not necessarily increase food supply. More importantly, the climate affects have a more severe effects on crops. You have no doubt noticed that food costs have soured in America this year; that is a direct result of the deep blizzards in the mid-west and the severe drought in California.

Good question and I entirely agree with you linlyons. Plants do not benefit from warmer temps. BUT WAIT A TIC. Your models are based upon tree ring data which ASSUMES that tree benefit from warmer temps.

So which do you wish to throw out??? The tree ring data???

LOL, it cracks me up when you try to deny the very BASIS of your own precious little theory. It really goes to shows how much faith you have in your climate "science".

Oh sorry, you want to specify that weeds are going to be the only plants that benefit. You crack me up.

Out of curiosity, what is a "serious" weed. Does it differ from the weeds that are jokesters?

Its true some plants benefit from warmer temperatures. Is this good? Well, one of the plants that is really benefiting from climate change is poison ivy. You be the judge. :)

Just to add to mintie's point CO2 is far out weighed when water becomes the limiting factor.

i'm wondering what c5 plants will do.

There have been several posts about C4 plants, from Zippi, and maybe others.

What are they? Are they relevant to global warming? Or increased CO2?

Did anyone honestly look up what C4 photosynthesis is, why it's better, and how common it is?

Maybe it's time to do that.

http://www.marietta.edu/~spilatrs/biol103/photolab/c4photo.html <== interesting.

http://wc.pima.edu/~bfiero/tucsonecology/plants/plants_photosynthesis.htm <== better.

Since C4 plants seem to be presented as benefiting from extra CO2,

it would seem useful to know what plants use C4 photosynthesis.

http://www.cropsreview.com/c4-plants.html <== Also interesting.

"C3 Photosynthesis: Adaptive Value: More efficient than C4 and CAM plants under cool and moist conditions and under normal light because requires less machinery (fewer enzymes and no specialized anatomy). Most plants are C3.

"C4 Photosynthesis: Adaptive Value: Photosynthesizes faster than C3 plants under high light intensity and high temperatures because the CO2 is delivered directly to RUBISCO, not allowing it to grab oxygen and undergo photorespiration. Has better Water Use Efficiency because PEP Carboxylase brings in CO2 faster and so does not need to keep stomata open as much (less water lost by transpiration) for the same amount of CO2 gain for photosynthesis.

"Examples of C4 species are the economically important crops corn, sugarcane, sorghum, and millets, as well as switchgrass. Other examples consist of serious weeds ..."