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Feedback Process.


Eureko

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Could you name a list of feedback process that you think could happen as a product of the global warming?

It could also be interesting if you tell if they have positive or negative consecuences for the system, I mean if it feed it back to grow temperatures or to cold the Earth.

And also, could you link them between each other?

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Haha, it is not my homework.

Let´s see if I can explain good:

A feedback process or mechanism is the one that, inside a system, make one of its properties by the same mechanism to grow till the infinite or to decrease a property till cero or another equilibrium. Also there´s the homeostasis, this process makes a one way variable going to its opposite. For example, in the human body, when you have heat your body swets so you get colder and your temperature doesn´t increase till your death, so this helps you. In ecology, for example, the growing population of a predator makes its prey decrease, but this dicrese makes the predators population decrease too, since they depend of their food, and this makes, once again grow the prey population... etc.

This mechanisms are common in Live Sciences, and I´d like to know what examples do you all think about what could happen to the Earth system (feedback occurs in systems) because of the global warming such as, for example, the melting poles will make decrease the albedo effect that they do and this will make temperatures rise even faster.

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There are many other feedback processes. This is an excellent question, and I look forward to the responses. Be sure, however, to avoid the political tangents that often come when asking questions like this. They are very annoying and distracting, and do nothing to further our understanding of the global climate system. Also, make sure any data and percentages that people share are supported with citations and evidence, not just made up or "spun" to suit their ideology. :)

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A random list of feedback systems I have heard about potentially resulting from climate change:

+ Change in snow/ice cover amplifying heating or cooling.

+ Melting permafrost releasing additional CO2 and CH4.

+ There's also some CO2 and rocks containing CO2 trapped in glaciers.

+ Climate change could kill large quantities of vegetation, resulting in decreased CO2 absorption and increased CO2 release as they decay.

+ Increased temperatures decrease amount of CO2 absorbed by oceans.

 

? Increased heat can increase moisture -- water vapor is a greenhouse gas, but additional cloud cover will increase albedo.

 

- If the ocean currents are stopped by climate change, very bad things happen to both ocean life and land life.

- Desertification will increase the amount of sand blown to sea; this will provide an iron source for algal blooms since large portions of the ocean are iron deficient.

- Lengthened growing season will allow some plants to better absorb more CO2.

- Increased ice cover will reduce the amount of CO2 absorbed by oceans allowing volcanic CO2 to accumulate, whereas decreased ice cover will increase CO2 absorbed by the ocean (relevant to ice ages).

 

---

 

There's feedback loops all over the place. These might not be correct, and are certainly not exhaustive.

 

If we somehow activate a powerful positive feedback loop, we will regret it. This is actually what scares me about global warming, not the warming itself.

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That was so great. They sound pretty good for me. I already herd about many of these ones (never though about the desert´s sand). I find this a very interesting field to study about from global warming, if we could modelize all this with functions it would be a nice "computer game".

This scares me too, have you herd about Lovelock´s wonderland?

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Interesting. I've read that the decades-long practice of stopping all small fires in forest areas near human-populated areas has actually lead to more forest fires because of denser buildup over time. That sounds like an example of this.

 

The key point seems to be that these feedback factors are not always immediately obvious, and have to be studied and examined carefully over time.

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For those who don't know what a 'feedback' is, it is basically a reaction to a change in the Earth's climate system which either amplifies or dampens the initial warming. Note that unlike, say, CO2 feedbacks don't "force" initial climate change, they respond to it, and the response either makes it worse (positive feedback) or brings the system back closer to initial conditions (negative feedback). Right now, the net feedback is overall positive, The basic physics says doubling CO2 gives about 1.2 C of warming without feedbacks (except the negative T^4 feedback from radiated thermal flux). Right now, however, with feedback we should get ~3 C per 2x CO2 (IPCC 2007), especially with water vapor contribution (warmer air holds more water vapor which is a greenhouse gas and amplifies warming).

 

A summary of our understanding is as follows:

 

Temperature (Planck) feedback: The major negative feedback on climate change (as Earth warms it radiates more according to Planck's law), and completely understood.

 

Water vapor feedback: Strongly positive, but still some uncertainty in its magnitude due primarily to the upper troposphere contribution

 

Lapse rate feedback: A major negative feedback that offsets part of the water vapor feedback; well understood conceptually (lapse rate change follows the moist adiabatic lapse rate approximately, so for a given warming at the emission to space altitude there's less warming at the surface) but magnitude depends on other feedbacks

 

Sea ice feedback: Less ice, more open ocean with less albedo. More solar radiation absorbed than reflected. Positive, but magnitude is uncertain

 

Cloud feedback(s): There are many cloud feedbacks, on amount, height, optical thickness, etc., and different for different cloud types and at different latitudes. Overall, today's models produce cloud feedbacks ranging from approximately neutral to positive.

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The key point seems to be that these feedback factors are not always immediately obvious, and have to be studied and examined carefully over time.

 

I agree here. Unexpected feedback loops the main trouble with messing around with complex systems, correct?

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