Could longer growing cycles negate CO2 levels?

Question

What effect will global warming have on plant life? Wouldn't a 30% increase of CO2 levels, increased water vapor and longer warmer seasons increase the growing cycle of plants? if so, how would this effect temperatures?

I hear endless reports of positive feedback to global warming, (i.e. increased water vapor, less ice to reflect solar radiation, oceans releasing more CO2) But I never hear of any negative feedback responses. I would like to learn more about these and find out why they do not counter the increased CO2 levels.

Answer 1

Spencer at all, did a study that showed that water vapour was a negative feedback.

http://blog.acton.org/uploads/Spencer_07...

Spencer explains this more in everyday language in his testimony before congress:

It is certainly true that (1) greenhouse gases warm the lower atmosphere, (2) carbon dioxide is a greenhouse gas, and so (3) increasing carbon dioxide concentrations can be expected to warm the surface. But one must ask: To what extent? Climate modelers know that the direct surface warming effects of even a doubling of carbon dioxide concentrations would be very small – only about 1 deg. F, probably sometime late in this century. The greatest concern, then, centers around the positive feedbacks exhibited by climate models which amplify this small warming tendency. But just how realistic are these positive feedbacks? The latest published comparison of the sensitivity of climate models to changes in radiation reveal that all climate models tested are more sensitive than our best available radiation budget satellite data suggest (Forster and Taylor, 2006, Fig. 3). Taken at face value, this means that all the models produce too much global warming.

Most researchers who believe in substantial levels of global warming claim that water vapor feedback is surely positive, and strong. They invariably appeal to the fact that a warming tendency from the extra carbon dioxide will cause more water vapor to be evaporated from the surface, thus amplifying the warming. But again we see a lack of understanding of what maintains tropospheric water vapor levels. While abundant

amounts of water vapor are being continuously evaporated from the Earth’s surface, it is precipitation systems that determine how much of that water vapor is allowed to remain in the atmosphere -- not the evaporation rate. This, then, is one example of researchers’ bias toward an emphasis on warming processes (water vapor addition), but not cooling

processes (water vapor removal). The fact that warmer air masses have more water vapor is simply the result of the greater amounts of solar heating that those air masses were exposed to;  it is not evidence for positive water vapor feedback in response to increasing carbon dioxide levels.

Climate models are usually validated by comparing their average behavior, such as the monthly average temperature at different locations, to observations of the real climate

system. But recently, it has been persuasively argued that meaningful validation of climate models in the context of their feedbacks can only be made by comparing the instantaneous

relationships in climate models and observations (Aries and Rossow, 2003; Stephens, 2005). For instance, daily changes in clouds, radiation, and temperature can be measured by satellites during interannual variations in the climate system. This makes physical sense, since it is at daily time scales where most weather action takes place. At UAH, we have begun doing just that, and we have documented a negative

feedback due to changes in precipitation systems (Spencer et al., 2007, now in peer review for publication). As rain system activity and tropospheric warmth reach peak levels during tropical intraseasonal oscillations (ISOs), we measured an increase in outgoing infrared radiation (Fig. 3) which was traced to a decrease in cirrus cloudiness (Fig. 4). This evidence, at least at the intraseasonal time scale of the ISO, supports Lindzen’s controversial “infrared iris” hypothesis of climate stabilization (Lindzen et al., 2001).

Answer 2

Whilst some plants can benifit from increased CO2 this will be limited by water shortage, shortage of nutrients etc. All of which are aggravated by climate change. Whats more as the climate warms the ability of plants to act as a sink for C02 decreases.

http://environment.newscientist.com/chan...

Water vapour in the atmosphere will increase so with more evapouration, we will see more heavey rain (and flooding) and more drought. Again bad news for plants.

Ice reflecting solar radiation back into space, the frozen poles are the most important areas for this. The only plant life that will be affected is that in areas of heavy long lasted snowfall. Overall these plants will suffer because they will not be able to adapt, think how different the plantlife is in different climatic regions.

Answer 3

Of course.

The temperature of the planet has been fluctuating since it was formed without any help from mankind.

More CO2 in the atmosphere is good for plant growth and all life, that's where all the fossil fuels came from.

The CO2 we are putting into the atmosphere is coming from the carbon that was absorbed by past plant life, it was in the air when the planet had much higher levels of CO2, before modern humans were on the scene and life on our planet was much more prolific.

We aren't adding anything to the atmosphere that wasn't already there before.

Answer 4

A little, but the data shows that any effect will be small.  It certainly won't be enough to "negate CO2 levels".

Look at this graph.

http://gaw.kishou.go.jp/cgi-bin/wdcgg/qu...

The little squiggles are nature doing its' thing. CO2 falls a bit during summer when plants are active, and rises during the winter. The huge increase is us, burning fossil fuels.

The plants are nowhere near keeping up with us.  Doubling plant mass might get them close.  But what you're talking about is no more than a 10% increase.

Likely less.  Another impact of global warming is moving precipitation away from the equator and toward the poles.  That has the effect of slowing plant growth where it is currently the strongest.

It's true that negative feedbacks exist.  Clouds are likely the strongest.  But they're a mixed bag.  Some clouds cause cooling, others warming.

And so most all scientists believe positive feedbacks will dominate for many years.  And some possible positive feedbacks, such as releasing methane from permafrost, are really scary.

Answer 5

wow, allotta blah blah blah here. Have you ever seen trees dying from heat stress? longer, hotter grow seasons doesn't mean tropical rainforest conditions will spread.