GHG emissions from marine methane hydrate and terrestrial permafrost may have
acted as positive feedbacks (DeConto et al., 2012)...
Redistribution of C has
acted as a positive feedback to orbitally - forced glacial - interglacial variations (ice ages)-- but this depends on some particulars and isn't necessarily a general feature applicable to every geologic age -LRB-?).
This is what I get out of it: the Arctic - ice - albedo situation is more complicated than earlier thought (due to clouds, sun - filled summers, dark winters, etc), but NET EFFECT, the ice loss and all these other related factors (some negative feedbacks)
act as a positive feedback and enhance global warming.
Many doubt the authors» conclusions that increasing vapor
acts as positive feedback to [CO2] increases.
This acts as a positive feedback on the surface warming, because water vapor itself is a powerful greenhouse gas that, like CO2, absorbs and re-emits longwave radiation back to the surface.
Increased CO2 levels then
acted as a positive feedback to cause increased warming.
Cloud formation not only
acts as a positive feedback but as negative feedbacks as well.
Geologically CO2 has always lagged, this does preclude
it acting as a positive feedback.
Not exact matches
And that additional water vapour would in turn cause further warming - this being a
positive feedback, in which carbon dioxide
acts as a direct regulator of temperature, and is then joined in that role by more water vapour
as temperatures increase.
The device is the first touch display BlackBerry in RIM's lineup and features a new type of display technology known
as ClickThrough that makes the entire glass - front display
act like a button, ensuring
positive feedback when making selections or typing.Â
[1] CO2 absorbs IR, is the main GHG, human emissions are increasing its concentration in the atmosphere, raising temperatures globally; the second GHG, water vapor, exists in equilibrium with water / ice, would precipitate out if not for the CO2, so
acts as a
feedback; since the oceans cover so much of the planet, water is a large
positive feedback; melting snow and ice
as the atmosphere warms decreases albedo, another
positive feedback, biased toward the poles, which gives larger polar warming than the global average; decreasing the temperature gradient from the equator to the poles is reducing the driving forces for the jetstream; the jetstream's meanders are increasing in amplitude and slowing, just like the lower Missippi River where its driving gradient decreases; the larger slower meanders increase the amplitude and duration of blocking highs, increasing drought and extreme temperatures — and 30,000 + Europeans and 5,000 plus Russians die, and the US corn crop, Russian wheat crop, and Aussie wildland fire protection fails — or extreme rainfall floods the US, France, Pakistan, Thailand (driving up prices for disk drives — hows that for unexpected adverse impacts from AGW?)
Perhaps all of this newly freed up ice - cold water at the poles is temporarily
acting as a negative
feedback, but
as it absorbs more of the solar radiation, over time, it will transform into what we rightly think: a predominately
positive feedback system, rapidly intensifying the warming.
The atmosphere and surface might very well heat up from enhanced GHE, but
as soon
as water vapor
feedback kicks in it will actually
act as both a
positive and a negative
feedback.
As the total cloud cover increases, the first effect
acts to reduce the warming (a negative
feedback) while the second effect
acts to increase it (
positive feedback).
Release of hydrates below retreating ice sheets could therefore
act as a hitherto neglected
positive feedback during warming episodes.
Re: «atmospheric water vapor
acts as feedback magnifier» How do you quantify and validate the global magnitude of impacts (INCLUDING CLOUDS) or even whether they are
positive or negative?
«The
positive ice - albedo
feedback acts to amplify the climate change
as a consequence of the melting of sea ice and ice sheets in the Northern Hemisphere.
CO2 can
act as both a primary driver, if humans burn fossil fuels to increase CO2 levels, and a secondary driver (part of the
positive feedback loop) if CO2 levels increase naturally
as a result of other forcings which cause a warming and which, in turn, lead to increased CO2 levels.
«He also * claims * clouds have negative
feedback, completely neglecting studies that show clouds to have both negative and
positive feedback» he does indeed state that clouds can
act as a
positive and negative
feedback, but he claims that he believes based upon his own observations that mostly clouds
act as a negative
feedback, might I also say that this observation is also made by Professor.
And that additional water vapour would in turn cause further warming - this being a
positive feedback, in which carbon dioxide
acts as a direct regulator of temperature, and is then joined in that role by more water vapour
as temperatures increase.