BasketCase said:
The beginning state: you've got a hundred pounds of rose bushes in your back yard, in an atmosphere that's 1% carbon dioxide. Your roses are comfy, but growing slowly and not producing many seeds (which is how plants grow when their conditions are okay but not great).
Now somebody builds a factory next door, and the carbon dioxide level goes up to 2%. The rose bushes get happy; they start growing faster and producing more seeds. Plants can't see rates of change; all they can sense is the current level of carbon dioxide. All they know is that their primary food source is richer than normal.
So they start growing, and producing more seeds. Eventually you've got two hundred pounds of rose bushes, and the carbon dioxide level starts dropping. But as long as the CO2 level is above normal, the bushes keep growing, and the CO2 level keeps going down. Eventually, some of your bushes die, until it's the bushes that are going down and CO2 that's going up again.
as I expected, you are now suddenly talking INDIVIDUAL plants - we were discussing plants in the sense of photosynthetic boimass before.
How long will a rosebush flourish with 1% Co2 if before it grew at 2%?
I can tell you - 1 generation of rosebushes at most! THis is utterly insignificant if you talk 'plants take up the higher CO2' because that is a process that requires said CO2 to be in a plant for a long time period! If it is stored in a bush for a few decades, but then released and NOT taken up by a new bush of the same size, then it was NOT taken out of the circulation for good, but only temporarily.
And that is exactly the problem we have atm: we take a HUGE bunch of CO2 out of storage (fossil fuels), and there is no adequate mechanism to get it to be stored again within a timeframe of a few hundreds to thousands of years.
Aside from that, we combine the resulting heating with other ways of turning up the heat - methane, e.g., and taking CO2 out of LIVING storage, while we also lower the extant storage capability.
The system is self-stabilizing, but nobody said it had to be exact about it, and that's how most of Mother Nature works. Self-balancing, but sloppy. The above cycle has been witnessed and verified with many different species, plants and animals, by everybody from gardeners to ecologists to the discovery channel to every encyclopedia I ever read.
Why do you still harp on about 'self-stabilizing' - it isn't! It CAN be, and in a closed system with hardly varying boundary conditions, it ususally is - but we are CHANGING the boundary conditions BEYOND the values in which said stability exists!
I ignored your "long run" comment because it was malarkey. Plants grow pretty darn fast. My back lawn transformed from bare, empty earth to completely choked with six-foot-high weeds in ONE MONTH. They grew right through the weedblock. Nothing stopped them except planting a back lawn.
You didn't really get what I meant. I wasn't talking individual plants, but rather addressing biomass in ecosystems.
Your weed-blocked back yard was, btw, unnaturally bare! There SHOULD have been a plant cover there, that's why it came back so fast.
A better comparison would be:
How long will it take for a subtropical forest to grow in Germany in a place where today grows a mixed deciduous forest of temperate climate if the German climate slowly becomes subtropical (no frosts, higher mean temp, etc)?
Because THAT is what you would (among other things) need if 'plants' really took up all the CO2 we release from fossil fuels. A subtropical forest would have to grow here (or some other plant cover that stores MORE CO2 that our ciurrent forests - current forests can't store more, as CO2 is not their limiting factor) if mroe CO2 is to be stored here. Can you guess how long it would take, even if it was planted?
(hint: at LEAST a thousand years until it roughly reached equality with the current system, until it stored more - amybe a few thousand, maybe even never? Rainfalls etc may be wrong....)
Your last part is malarkey also--plants can grow indefinitely as long as there's a CO2 surplus, because the primary engine for recycling CO2 into oxygen is.....the ocean. The ocean has three times more surface area than the land, and is also three-dimensional, providing a gigantic spawning ground for waterborne plants.
Untrue - you missed the important point again! There are OTHER FACTORS BUT CO2 that limit plant growth - that is also true in the ocean.
Edit: The part at the top could still be a scenario for an ecological disaster caused by humans. Try this: plants grow to take up the planet's excess CO2, causing a CO2 crash, and suddenly the planet is a wee bit too cold.....
Earth history has a nice example for the cycle you are talking about here! In the Mississippian, CO2 levels were high, plants grew like crazy (mind you, it took hundreds of thousands of years for the vast swamp forests to develop), on into the Pennsylvanian. A lot of the CO2 got stored in peat (today coal). So much, in fact, that the athmospheric CO2 level DROPPED - despite a lot of volcanism. But the sea levels were high, which menat that a lot of continental crust was just under water - mean lot of swamps in which plants can grow fast and store CO2.
During the permian, conditions changed - for one thing, sea levels dropped (continents came out of the water and water got stored in ice caps) and by the Triassic most of the world looked pretty barren and dry. A long temr cycle, where more CO2 led to more plants, and more plants led to less CO2 (because much was stored, not re-released when the plant died). But, as you cna see from this very short narration, there's a BUNCH of other factors involved, and they take time.
Today, we have a change that is way too fast to be taken up in thi way. CO2 skyrockets, and even if it will be bound in phytoplankton and land plants that binding will take a much longer time that current ecosystems can stand the heat.
