what are the likely negative feedback systems that might mitigate anthropogenic climate change?

The atmosphere is not well mixed over large regions on the timescale of radiative transfer. If, by some complex fluid dynamics in the atmosphere, the temperature differences between regions increase contrary to the meteorological norm then increased radiation from warmer region will offset the general rise in temperature. To illustrate, consider a grossly simplified model in which the globe composed of two regions of equal area at temperatures T1 and T2. If the average temperature is 290 K and T1 - T2 = 12.8 K, a net negative feedback of 1 W/m^2 is produced. There is no evidence that temperature differences between regions have increased enough to significantly offset the radiative forcing from CO2.

Secondly biological activity may produce a negative feedback. The temperature of Lake Winnipeg has increased by 2 C. The increase is in line with global warming predictions for this latitude. The rise in temperature, together with an increased nutrient load, has caused a bloom of cyanobacteria (blue green algae). Cyanobacteria are inedible to the indigenous grazers and are also causing a eutrophication problem. The increase in algae biomass represents a reduction in atmospheric CO2, at least temporarily. The fate of the biomass is an open question and I have core samples in my laboratory to study this question. I also hold research grants associated with reducing the nutrient loading and I am looking for a biologist to hire for the project in 2009.

A number are known like the PDO which scientists have talked about for decades but in this 'climate, slight pun' the moment something like this is mentioned deniers jump all over it and say look this proves this or that.

The fact is the PDO affects mainly the north east pacific to the coast of the U.S. and it is probably responsible for the slightly cooler U.S. temps of the last couple of years. The PDO has been increased by a corresponding La Nina, but as this only lasts a couple of years on average when the La Nina fades the slight cooling trend will also ease.

http://en.wikipedia.org/wiki/Image:La_Nina_and_Pac...

The other of course is the Sun in the past it has changed output, the current slow start to the new solar cycle isn't really an indicator as there was a similar sunspot free period in the 50s with no noticeable cooling and it would only compare to the Maunder Minimum that some like to mention (a lot) if it went on for 50-60 years (which is unlikely)

http://en.wikipedia.org/wiki/Maunder_Minimum

And while we now have a long history of solar activity, no one who is being honest can predict what the Sun will do in the future as far as fluctuations in output go, and no reputable solar physicist does. Based on past activity there is as yet no reason to think that the 11 year cycle has stopped and in the last few months there have been a number of quite large sun spots.

http://sohowww.nascom.nasa.gov//data/REPROCESSING/...

Wood smoke

"No one wants to discuss how nature will heal herself." the whole premise of the IPCC and the rest of the scientific communities AGW theory is if we reduce (not stop) our co2 output, nature will (over some period of time) fix the problem. It is estimated that natural absorption is at the moment removing ~50% of the human co2 released.

The most important negative feedback system is probably the cap, and eventual reversal of human population increase. This is, of course, from the perspective of the planet and other life on earth. People tend to be egocentric, however, they don't see that less humans here on earth is not only better for the earth, but better for us in the long run.

Good question though. You used big enough words to discourage the less educated type to comment. I don't see a whole lot of the "skeptic" side commenting here :-).

All the natural cycles(biotic-abiotic) that influence transport, volatility, and chemical transition of the basic elements(ie; C,H, O, N). It can be weathering, oxidation<>reduction and simple halide fluctuations. While it may true most entail extremely long term studies. Certain systems do offer unique opportunities readily available due to their chemical structures, such as water, gas, and some soils types.

Here's a link that may have some value.

http://public.ornl.gov/ameriflux

When everything has caught on fire, and most of the humans, many critters, etc are gone.

There will be a renewal of the Mother.

Those who love money more than life, will be able to live hermetically for hundreds of years of a concrete and steel computer surrounding them, keeping them alive - they will finally have all the money, wealth and power. Yeah for them!

Their h*** will come when they find no one is left to Lord it over, so they will eventually eat each other alive.

Leaving a Brand New World.

There are so many parameters that interplay in ways we don't understand that we have no idea at all that we have any effect on climate. Nevertheless, here is one:

Higher temps might mean more evaporation which would generate more cloud cover which might deflect sunlight and thus have a cooling effect.

The main negative feed back will be the inevitable onset of the next ice age. Or from some points of view, that could be contrived to be a good thing. The other negative feed back before that will be aggression as a result of rising populations. people latch on to what ever they perceive to bring them success and as they do so, they perpetually accentuate bad learn-ed behaviour without much conscious thought about it. Governments seem to behave in the same way.

CO2 dissolution in oceans increasing to 'balance' excess in the atmosphere.

reflective atmospheric particulates such as so2 can lower the amount of solar radiation that enters the atmosphere. Resulting in a cooling effect.

I'm sure you're aware this is a side effect of burning fossil fuel GERDA.

ironic huh? more pollution could be the solution to global warming.

Increasing cloudcover, although unfortunately there will also be increasing atmospheric water vapor (positive feedback).

I hate to say it, but global warming will probably cause a lot of deaths through disease, lack of food and water, heat waves, etc. Decreasing population means decreasing anthropogenic GHG emissions. That's not quite looking at the bright side though.

In theory plants benefit from increasing CO2, but in practice I think the opposite will happen (due to increased droughts, heat waves, changing climate zones, etc.).

Unfortunately it's hard to find any bright sides.