Tim the Plumber wrote:
What is going to suddenly change?
The ability to recvoer from the trend.
What mechanisim will it be that alters?
There are a few possible, but once one is reached it is probable more will follow. The plant surviabilty range is the most likely as plants do not change range as quickly as animals and will be more vulnerable.
Plants rot and give off CO2 and methane etc as allways. What point will need to be achieved to get a positive feed back loop?
Not really a known since we have never seen a massive die off to be able to gauge the process, but there is a lot of carbon in the cycle that can be released.
What temperature rise will we have to see for this catastrophy to happen?
Not really known, which is the big concern. Just like playing Russian Roulette, you do not know when it will happen but you do know that playing long enough will see a nasty result.
What mechanisim will do this tipping?
Still not sure what you are trying to ask. The initial fialure of a few plant species and that impact on the other plant and animal species will cause additional stress on the survivors, which will in turn cause more failures to survive until there is a major extinction or something happens to cahnge the temperature trend that does not also cause major extinctions.
Why will it do it at this time?
Because the situation has been set for this path and we are pushing farther and farther down it.
The IPCC says that the worst case scenario is for a 6.4 degree c temperature rise by 2100 but this, I think, has been revised down to a more reasonable max of 3.2 degrees. That would give an expected foot or so of sea level rise. Do you have information that the IPCC has it wrong? They don't talk of a tipping point resulting in positive feedback.
So you were not asking about the tipping points related to the article, you were asking about other tipping points?