In which I post an abstract question about the maximum:

[XemaSab]

So in the course of a day, the hottest time is well after noon. In the summer, the hottest time is well after the solstice.

Would the same be true with global warming?

If we stopped carbon emissions now, would the earth keep getting hotter until some unforeseen future point? :shrug:

[mike_c]

1. yes....

The atmosphere and especially the oceans are a massive thermal mass-- remember the high specific heat of water?-- so the amount of energy necessary to perturb the thermal equilibrium way overshoots the current planetary energy maintenance budget. I don't know if I stated that clearly-- I'm pretty wonked tonight. Remember the paper we read about hysteresis in ecosystems? That's the basic idea-- once the system has been pushed out of equilibrium it moves to an alternative steady state, and simply removing the push does not reverse the change of state.

[XemaSab]

2. Are you high?

Should I be? :smoke:

This sort of makes sense, but I'm not quite following what you're saying. :P

[mike_c]

3. nah, but that sounds like a good idea....

LOL-- no, I'm just cross-eyed from working long hours today.

[XemaSab]

4. Alright

I guess I'm asking about not just a change of state (as would occur in a see-saw or a punctuated equilibrium model) but assuming that there's a continuum.

If there's a continuum, is there enough "momentum" to take us further?

(and ps probably the merlot didn't help with my understanding :P )

[mike_c]

8. yes....

Think of it this way-- the average amount of solar energy trapped within the biosphere has been rising ever since atmospheric CO₂ levels began to rise a hundred or so years ago, but it didn't have much effect on climate because all the liquid water simply absorbed it without much change in temperature. Water can do that. It gave us a long lag time before we saw clear responses-- which we're only just beginning to see. But now the biosphere temp is beginning to rise because a MASSIVE amount of additional energy has been captured-- think about how much energy it takes to do that-- so the system is headed for a new, and presumably hotter, stable state. Simply slowing down or even stopping CO₂ enrichment won't restore the earlier stable state for a long time-- the system likely has to be perturbed back somehow, and will likely have a long lag time going in that direction too.

[XemaSab]

10. One of the recent threads floating around here threw out the number of 600 years to return to a

normal carbon load and preserve our present climate.

Like, wow.

So I know that water is the big heat sink for the planet. Will the water be releasing heat at a rate that maintains 2007 heat levels, or will the water be releasing more and more heat for years to come until it reaches a new equilibrium? Or are you saying that the capacity of the planet's water to absorb heat has been saturated? And if so, will temperatures keep going ever upwards despite human efforts to slow it?

(btw, if you haven't read "The World Without Us," it's teh awesome read. :P

[mike_c]

11. the capacity of the planet's water to absorb energy...

...without an increase in temperature APPEARS to be maxed. That is the 64K question of the day, of course, and no one knows the answer. But climate change indicators seem to be changing state quite a bit faster than earlier models predicted and that suggests that the energy buffering capacity of all that liquid water in the biosphere is no longer keeping up with annual energy inputs.

[XemaSab]

13. So this would seem to imply almost a buffering lag

Where the water absorbed more energy than it could hold, then spit it back out.

Otherwise, it wouldn't make sense to see such a big change so rapidly. All the industrial outputs in the world would not create a massive collapse of the sea ice in so rapid a time without some other factor involved. (methinks)

[mike_c]

15. not really-- think of the planetary specific heat like it's a sponge...

...that you keep dripping water onto at a steady rate. It just absorbs it for a while-- maybe a long while-- and the surrounding environment stays dry. After a while it becomes saturated-- that's the transition from a steady state "dry environment" to a steady state "wet environment", and now any more water that drips will just make the environment wetter. All the water has been there all along, but it's only now that it's having an effect. And if you turn off the spigot, the environment will stay wet for quite a while (and the rate at which it drys has nothing much to do with the rate that water dripped in the first place-- that's about as far as I can stretch this metaphor...).

For a long time the thermal mass of the biosphere-- largely all the liquid water on the Earth and in the atmosphere-- has been our energy sponge. It absorbed the extra energy the atmosphere trapped without becoming significantly hotter. Now it is getting hotter, but that's not really the point-- the point is that the amount of energy it took to accomplish this was HUGE beyond imagining, and it is still there. Not static, but a flux that is shifting to a new steady state, one that is just a bit hotter-- but remember, even a few degrees difference on a global scale represents immense amounts of energy.

I know I'm not articulating this well. Now I really am going to go get stoned and then go to bed.

[XemaSab]

16. I know that water is the global heat sink

On a short term scale, atmospheric water transports heat from the tropics towards the poles, and on a longer term scale, ocean water does the same.

How are both of those combined related to planetary specific heat?

I guess the dum-dum question before I can get back to my original question is how CO2 and other greenhouse gasses store heat? Like water? Or notsomuch? :shrug:

Or, to simplify the dum-dum question: do they store heat, or just reradiate it? :shrug:

[mike_c]

17. greenhouse gases don't really"store" heat....

Rather, they convert radiant energy at other wavelengths to infrared, trapping much of that energy in the biosphere where other matter can store it. Molecular bonds absorb energy, then re-emit it, undergoing some energetic warping and unwarping in the process and re-emitting the energy at lower wavelengths. The problem with GHGs is that they absorb electromagnetic radiation at a variety of high energy on-its-way-back-into-space wavelengths but then re-emit it in the IR range of the spectrum that just bounces around inside the atmosphere. All energy transformations generate some waste heat, but converting, say, visible light to IR really heats things up fast. What happens to matter that absorbs that IR? It gets hotter.

"How are both of those combined related to planetary specific heat?"

The specific heat of matter is the amount of energy it must absorb in order to increase its temperature by some unit amount, i.e. a measure of it's ability to absorb energy without changing temperature. The Earth's biosphere has high specific heat because it is so full of liquid water, a substance with an outstanding high specific heat (all those hydrogen bonds absorb LOTS of energy).

[XemaSab]

18. Duh, sorry

I knew much of that at one time, but spending the last few years in environmental consulting... :P

To misquote "Don't Tell Mom the Babysitter's Dead": "Consulting rots your brain." :P

But back to the original topic, I never really got the whole "Lag of the maximum" premise, I mean it made sense intuitively but on a scientific basis I never really understood why.

Maybe it's that water takes a long time to release its heat?

(For the number of classes that began with a discussion of water.. :P I swore at one time that to get a science degree you should have to take a class on the physics of water and never revisit the subject again :P )

[mike_c]

19. hmmm..., do you remember this...?

I know, it's a cop out, but I really am up WAY past my bedtime:

Catastrophic shifts in ecosystems.

http://www.sense.nl/SENSE_INCLUDES/docs/Scheffer_2003_TREE2.pdf

[XemaSab]

23. I totally remember that, yeah

So I guess your point is that we've already tipped the see-saw and the other side will keep falling until it hits the ground.

I think my original question assumes it's not a see-saw but a continuum. :shrug:

[truedelphi]

39. I, for one, loved the sponge analogy.

Having spent more time in math classes than science classes, I tend to think of everything as being a progression of equalities (if it involves the same subject or scenario)

Your sponge analogy gave me the insight to work with in terms of the Climate Change.

If you aren't a teacher, you sure could be one any day.

[XemaSab]

41. Mike c's a university prof

where I got my degree. :P

To be frank, he's basically the dude who introduced me to DU. :toast:

[truedelphi]

6. Are they implying thatthe clouds of smoke drifting off the many Bongs

are as Cheeech would put it, "Making it so mucchch hotter, mawn!"

[XemaSab]

7. I think the implication was that mike_c was saying something so profound

that either I'm too dumb to get it or I'm too sober to get it... :P

That being said, pot smoke is more about particulates than CO2.

The foam in this beer I'm drinking, however... :P

[truedelphi]

12. Still drinking foamless beer (even if it means we

Keep the earth a live another ten thousand years or so,) is a depressing idea.

Although there is always WHISKEY!

[XemaSab]

14. Taliskers

:9

[GliderGuider]

21. Now there's a man with good taste.

Talisker is second in my estimation only to Lagavulin - the nectar of the Gods.

[XemaSab]

24. I'm not a man

:P

[GliderGuider]

26. Oops. Trapped by a colloquialism yet again.

And also by a cultural bias about women and whisky... Sorry about that.

[XemaSab]

28. No worries

:D

[truedelphi]

5. Speaking as someone who doesn't even know the meaning of

One or two of the words the poster before me used in their excellent response here, I would add that there is also the factor of sunspots and what not.

I hate to latch onto one of the GOP's talking points that Global Warming may not be man made (I do believe that a large part of it is manmade) but I have seen data from independent scientists that offers credence to the fact that the unusual sunspot activity has us in a bind.

I also am dubious about some of the research about temperatures in certain cities being so much higher. For instance, in the Chicagoland area, they moved the weather station that recorded the temperatures from its old position near Lake Michigan to the far outer suburbs. Just doing that makes the temperature in Chicago something like six to seven degrees hotter. (It has always been "cooler near the lake" for obvious reasons.)

What is convincing to me about the state of calamity now occurring is the vast changes in flora and fauna - upper New York state gardeners are doing very well with Virginia plants and flowers. My mother, a Chicago resident, has adopted two canaries. The yellow pair stay in her yard almost all summer (They belong a good 350 miles south of her - a real indicator of the global warming phenomenon.)

And of course the most heart-breaking of proofs- the polar ice caps melting away while the puzzled polar bears try to maneuver around and capture enough food for their young.

[XemaSab]

9. I hear what you're saying with the weather stations

Not only have a lot of them been moved, but the urban heat island effect is for real... a few extra square miles of asphalt around each station has to be doing something. :P

[skids]

20. If you want to get into that level of detail...

...I suggest realclimate.org. They've dealt with the sunspot and weather station issue before. Those are not all their proponents crack them up to be.

At any rate the answer is probably, yes, we would continue to get hotter for a while after stopping CO2 emissions, because those set our equilibrium point, and it takes a while for the temoperature to actually catch up to the equilibrium point. So if the equilibrium point is at, say, to use a random number, 30, and it starts fallig by one per year, but we are still at 20, then the temperature would continue to rise until it was at the equilibrium point. To oversimplify it, if we moved towards equilibrium at 1 unit per year, we'd top out at 25.

A drastic example of what could happen is that the ice continues to melt until the albedo change feeds back into the system enough to release the trapped methane in permafrost and ocean clathrates. Then we'd have the earth adding its own greenhouse gasses and shifting its equilibrium point up all on it's own.

[truedelphi]

40. Thanks skids. I have long wanted the info on where to go to see all the

Connections.

My background is more towards technical writing than any understanding of the atmospheric situation. And as a tech writer, I get fascinated by things like the weather stations and their being shifted from their tradition placements - without too many who should know better even takng that fact into consideration. Plus in a certain sense it isn't fair - Chicago weather for instance is now determined by a climate far from the lake. When someone compares the temperatures of Chicago from thrity years ago with the temps today, it is really apples to oranges.

But people discussing these things here are far more brilliant than I could ever claim to be.

And I have long thought about the Climate Changes - my first creative "novel" at the age of nineteen (Way back in 1970) featured Earth Warmers that destroyed the ski slopes and snow of the sci-fi planet where my heroines gamely took on the roving gangs of Bad Boys.

[GliderGuider]

22. Amid all the talk about specific heat , don't forget the role of oceans as a carbon sink

CO2 lasts a long time, and its atmospheric residence time will increase as the oceanic carbon sinks saturate.

CO2 that stays in the air keeps trapping heat as long as it's there. If we stopped emitting CO2 today, the amount already in the atmosphere would keep converting solar radiation to infrared for well over a century. The only way out is to actually remove CO2 from the atmosphere. this would require stopping all use of fossil fuels and starting to make and store (or bury) charcoal at a furious rate (i.e. gigatonnes per year). Since that ain't gonna happen, we're toast - light golden toast right now, but getting darker all the time.

[XemaSab]

25. That's the answer I'm looking for:

"If we stopped emitting CO2 today, the amount already in the atmosphere would keep converting solar radiation to infrared for well over a century."

Thanks. :toast:

[mike_c]

27. that's part of the hysteresis....

Stopping the perturbation won't return the system to a previous steady state-- it has to be PUSHED back.

[XemaSab]

29. A Sisyphean task, no doubt.

Call me a pessimist, but I think we're totally hosed. :(

[mike_c]

31. who you callin' a sisyphean, beeotch...?

:rofl:

[XemaSab]

33. You, ya hippie

:P

[XemaSab]

30. On, and it looks like a century is the half-life for CO2 in the atmosphere

Add that to the fact that we're not looking to turn this ship around anytime soon, and it would take us a lot longer than 100 years to get back to comparable levels.

Ocean turnover notwithstanding.

[GliderGuider]

34. Yep.

That's why I say "well over a century". It turns out that modeling the atmospheric half-life of CO2 is a non-trivial task because of the dynamic nature of the various sinks (soil, vegetation, oceans etc.), but it has been approximated with an impulse response equation. I remember running across the equation a few months ago, and if I can find it again I'll post it, just for shits and grins.

[Viking12]

32. Technical point: CO2 doesn't convert solar radiation to infrared.

The solar radiation is collected at the earth's surface and re-emitted as IR. GHGs then absorb the IR on its way out to space.

[GliderGuider]

35. Correction noted, thanks.

[mike_c]

36. I thought GHGs emitted in the IR spectrum....

OK-- they do, but now I understand that one of the vibrational states of the C-O bond ABSORBS IR, then re-emits it back into the atmosphere, making CO₂ enriched atmosphere (and other GHGs) more opaque to IR transmission. We're essentially talking about the same thing-- I was referring to the back radiation in the diagram you posted, but I forgot that CO₂ was absorbing in the IR as well as emitting there.

[Viking12]

37. You got it....

when you say making CO2 enriched atmosphere (and other GHGs) more opaque to IR transmission.

Solar radiation is short wave and does not get absorbed by GHGs on the way in. It's the longwave IR that's emitted from the earth's surface which is then trapped by GHGs.

[truedelphi]

38. This may not be the best discussion of the Climate Changes ever posted, but it is the best one that

I have seen... Is there a way to make sure it is archived??

(For all I know, all threads are archived, but I'd love to see this one in a DU Hall of Science.)