Climate Sensitivity and timing

[skierinvermont]

If you guys don't want to talk arctic, then don't talk bout other factors.

why should we spend 99% of this thread talking about the least important feedback?

[noiv]

> why should we spend 99% of this thread talking about the least important feedback?

Re-phrase this to 'most underestimated' and the answers will be far more interesting. If you consider your math about forcing of CO2 and vapor as correct, why you resist to move to what's missing?

[TerryM]

You have terribly confused the issue.

I agree there are two separate issues affecting surface temperature. 1) The change in albedo that alters the global energy budget. I addressed this point already (<.3W/m2 seasonal ice free= .1C cumulative warming, <.7W/m2 annual ice free=.2C cumulative warming)

2) The issue you bring up. The energy from summer solar insolation instead of going into melting the ice goes into increasing temperature. Instead of melting 16,400 cubic km of ice each summer, we will only melt 15,000, or 12,000 maybe. So you have to melt 1,400, or 3,400 etc. cubic km less. You haven't altered the amount of energy. You have only altered whether the summer insolation goes into melting or temperature increase.

However, in the fall you are likewise generating an equal quantity less ice. Which means that an equal quantity of energy released results in lower temperatures rather than phase transition.

Because near equal amounts of ice are melted and re-frozen each fall it cannot have an effect on temperature. In so far as you have to use less energy to phase transition from ice to water for 3,000 cubic km less ice each summer, you also have to use less an equal amount less energy in phase transition from water to ice each fall. You are melting and refreezing near equal amounts of ice each summer and fall. There is no net effect on temperature. 1 billion fewer Joules are used for melting ice (converting potential energy to kinetic energy), 1 billion fewer Joules are used for freezing ice (converting kinetic to potential energy)

Skier

Kinetic energy doesn't enter into the equation at all.

At present we have an energy imbalance that is sufficient to melt 800³km more ice than the previous year. This energy is presently seen as latent heat, without the ice it presents itself as sensible heat.

We melt off far more than this on an annual basis, and the heat of fusion in the fall freeze up is buried within this additional amount. It will still cycle, keeping summers cooler and winters warmer, but the 800³km is an addition, and this pulse won't be affected.

Even if as your paper says there was no net radiant energy gain, the energy that at present is being used to melt ice that is not replaced annually will remain as a sensible heat gain pulse that accumulates each year and that needs to be accounted for. Additional cloud cover, while it will limit incoming shortwave radiation will also blanket longwave radiation from escaping into space.

This is about as basic as the physics gets. Kinetic energy isn't involved.

Terry

[The_Global_Warmer]

why should we spend 99% of this thread talking about the least important feedback?

You don't have to, you have free will to talk about whatever you want.

[skierinvermont]

> why should we spend 99% of this thread talking about the least important feedback?

Re-phrase this to 'most underestimated' and the answers will be far more interesting. If you consider your math about forcing of CO2 and vapor as correct, why you resist to move to what's missing?

It is not underestimated. I have already provided the forcing for scenarios with FAR less snow and ice than present, and it does not remotely compare to CO2 or water vapor.

[skierinvermont]

Skier

Kinetic energy doesn't enter into the equation at all.

At present we have an energy imbalance that is sufficient to melt 800³km more ice than the previous year. This energy is presently seen as latent heat, without the ice it presents itself as sensible heat.

We melt off far more than this on an annual basis, and the heat of fusion in the fall freeze up is buried within this additional amount. It will still cycle, keeping summers cooler and winters warmer, but the 800³km is an addition, and this pulse won't be affected.

Even if as your paper says there was no net radiant energy gain, the energy that at present is being used to melt ice that is not replaced annually will remain as a sensible heat gain pulse that accumulates each year and that needs to be accounted for. Additional cloud cover, while it will limit incoming shortwave radiation will also blanket longwave radiation from escaping into space.

This is about as basic as the physics gets. Kinetic energy isn't involved.

Terry

I already explained that this is wrong. In a less ice world, you use less incoming energy to melt ice, but you also use an equal amount more energy reducing kinetic energy instead of re-freezing in the fall. There is no net accumulation.

Also cloud cover is a strong net negative forcing in the arctic.

[skierinvermont]

You don't have to, you have free will to talk about whatever you want.

When people stop stating misinformation about arctic sea ice I will be glad to.

[dabize]

When people stop stating misinformation about arctic sea ice I will be glad to.

The issue here is one of perspective and perceived intent. We all make errors of fact due to ignorance. Some of us even admit it. If you really think that those of us who think that changes in the Arctic are central to this subject are lying to you, you'd better get ORHwxman to ban the lot of us. Otherwise you're out of line, just as verg was when he used the term "prevarication".

If disagreeing with you on the relative importance of Arctic sea ice in influencing global climate counts as "misinformation", perhaps you ought to rent an echo chamber rather than participate on online discussions.

[noiv]

> I have already provided the forcing for scenarios with FAR less snow and ice than present, and it does not remotely compare to CO2 or water vapor.

Would you mind to include permafrost? And your numbers are backed in the literature by ... ?

[tacoman25]

> I have already provided the forcing for scenarios with FAR less snow and ice than present, and it does not remotely compare to CO2 or water vapor.

Would you mind to include permafrost? And your numbers are backed in the literature by ... ?

Well, if you read the first post, the OP is mainly concerned with a doubling of CO2 and climate sensitivity to that with this thread. Technically, the potential melting of permafrost and CH4 release is a separate issue.

[TerryM]

I already explained that this is wrong. In a less ice world, you use less incoming energy to melt ice, but you also use an equal amount more energy reducing kinetic energy instead of re-freezing in the fall. There is no net accumulation.

Also cloud cover is a strong net negative forcing in the arctic.

I don't know why you are fixated on kinetic energy.

The back and forth with latent heat in spring and fall is a given. What I'm pointing out is that the additional energy that each year at present is being used to melt a huge block of ice that isn't refrozen, will in the near future present itself as sensible heat that will add itself cumulatiely to the sensible heat being experienced first in the Arctic, then in the NH and at some point globally.

This only adds to the earth's energy balance in the sense that additional CO2 and CH4 sources will certainly be melted out of permafrost and subsurface clathrates at increasing rates.

If you are cooking some soup, the sensible heat of the ingredients spikes if the water boils off. The incoming energy doesn't change but suddenly everything starts burning.

If you leave your cooler in the sun, when the last icecube is gone the beer cans heat up at an alarming rate after remaining at a steady temperature until then.

Large amounts of this sensible heat will be used up evaporating water adding to the cloud cover that will both block incoming radiation and outgoing radiation. This is what allowed cold blooded animals and plants that can't deal with freezing to live in the polar regions without winter sun the last time we faced such conditions.

Once we've got these basics agreed to we can work out what percentages of this heat pulse will be felt when the Arctic is ice free at different times of the season. But please forget about kinetic energy, it has nothing, even remotely to do with the subject.

Terry

[noiv]

> the OP is mainly concerned with a doubling of CO2 and climate sensitivity to that with this thread. Technically, the potential melting of permafrost and CH4 release is a separate issue.

You want to exclude CO2 released by thawing permafrost from climate sensitivity? Sorry, but are we talking about same planet?

[tacoman25]

> the OP is mainly concerned with a doubling of CO2 and climate sensitivity to that with this thread. Technically, the potential melting of permafrost and CH4 release is a separate issue.

You want to exclude CO2 released by thawing permafrost from climate sensitivity? Sorry, but are we talking about same planet?

The main concern with permafrost as I understand it is methane release, not CO2. But there is a lot of uncertainty there.

What is more certain is that we will probably see a doubling of CO2 concentration from the 280 ppm seen prior to the 20th Century. Thus the questions raised by the OP.

[TerryM]

taco

What multiplier do you prefer for CH4. I've seen everything from 20 to 102 depending on the time frame being used.

My contention would be that as long as the concentration is climbing, the highest multiplier must be used as the CH4 is being replaced faster than it's decaying.

Terry

[PhillipS]

Well, if you read the first post, the OP is mainly concerned with a doubling of CO2 and climate sensitivity to that with this thread. Technically, the potential melting of permafrost and CH4 release is a separate issue.

The value for climate sensitivity has to include feedback processes driven by the doubling of CO2. Albedo change is one of those feedbacks. There is a

recent post

on Tamino's Open Mind blog on albedo change and its equivalent radiative forcing.

The

potential

observed and continuing melting of permafrost, with its associated release of the GHGs CO2 and CH4, is certainly on-topic for a discussion of climate sensitivity. It is one of the more significant feedback processes. Given the magnitude of the reservoir of carbon stored in permafrost, this feedback to increasing CO2 is very important to understand.

Here's an excerpt from Open Mind on the albedo change:

Here’s the annual average solar power falling on snow/ice covered areas, together with a linear trend (note this does not include the dramatic change in 2012, which isn’t over yet):

The net change estimated as the difference of the beginning and ending values of the trend line is about 880 TW. If spread over the entire surface of the earth, and if the difference in TOA albedo between snow/ice-covered and uncovered regions is 0.2, this accounts for a total climate forcing of about 0.34 W/m^2.

We can instead estimate the net change using a lowess smooth rather than a linear trend:

In this case the net change is about 1150 TW. If spread over the entire surface of the earth, and if the difference in TOA albedo between snow/ice-covered and uncovered regions is 0.2, this accounts for a total climate forcing of about 0.45 W/m^2.

[WeatherRusty]

Before everyone jumps on skier, please realize his figures relating water vapor feedback versus arctic albedo change are compiled and averaged globally as a radiative forcing, or something which alters the TOA energy balance. The global water vapor feedback wins this comparison hands down.

The changes in arctic albedo have a larger impact on region temperature and weather patterns such as the location and amplitude of jet streams. Also, increases in water vapor over the arctic are hugely important to enhancing the local greenhouse effect and arctic amplification.

[skierinvermont]

I don't know why you are fixated on kinetic energy.

The back and forth with latent heat in spring and fall is a given. What I'm pointing out is that the additional energy that each year at present is being used to melt a huge block of ice that isn't refrozen, will in the near future present itself as sensible heat that will add itself cumulatiely to the sensible heat being experienced first in the Arctic, then in the NH and at some point globally.

This only adds to the earth's energy balance in the sense that additional CO2 and CH4 sources will certainly be melted out of permafrost and subsurface clathrates at increasing rates.

If you are cooking some soup, the sensible heat of the ingredients spikes if the water boils off. The incoming energy doesn't change but suddenly everything starts burning.

If you leave your cooler in the sun, when the last icecube is gone the beer cans heat up at an alarming rate after remaining at a steady temperature until then.

Large amounts of this sensible heat will be used up evaporating water adding to the cloud cover that will both block incoming radiation and outgoing radiation. This is what allowed cold blooded animals and plants that can't deal with freezing to live in the polar regions without winter sun the last time we faced such conditions.

Once we've got these basics agreed to we can work out what percentages of this heat pulse will be felt when the Arctic is ice free at different times of the season. But please forget about kinetic energy, it has nothing, even remotely to do with the subject.

Terry

Kinetic energy is just another way of saying 'sensible heat.' Sensible heat is present as increased kinetic energy of molecules.

The factor you are describing only becomes important when the arctic is annually ice free or if the rate of melt slows (or reverses). Until then we are likely to continue converting 800 cubic km of ice to water every year, which acts as an ice cube in a glass of water.

Also the long-term trend is 300 cubic km not 800. Which means that the earth has been melting ice at a rate of .62W/m2 since 1979. If the rate of melt starts slowing down, the extra energy would begin to alter surface temperatures instead of being used to melt ice. This ONLY happens if the ice melt starts to slow down.

Finally, if ice melt slows or stops and some or all of this .62W/m2 rate of melting ends up creating sensible heat instead, it is not a never ending accumulation that occurs. Once the surface warms enough to re-emit energy at a rate .62W/m2 faster, the imbalance is ended.

.62W/m2 amounts to .18C of warming. Thus the maximum effect we are talking about (all the ice melts and there is none left to melt) is .18C of warming.

The mechanism you are speaking of, does not effect climate sensitivity because it doesn't effect the global energy budget. The mechanism you are describing (along with deep ocean heat absorption) basically explain why there is a lag from forcing to full temperature response. It is covering up warming (and then suddenly it becomes uncovered), not creating it.

[skierinvermont]

The main concern with permafrost as I understand it is methane release, not CO2. But there is a lot of uncertainty there.

What is more certain is that we will probably see a doubling of CO2 concentration from the 280 ppm seen prior to the 20th Century. Thus the questions raised by the OP.

Yes but climate sensitivity includes feedbacks, such as CH4 and CO2 release. I'm not sure if CO2 feedbacks would be included since the CO2 value is parametrized.

[WeatherRusty]

Well, if you read the first post, the OP is mainly concerned with a doubling of CO2 and climate sensitivity to that with this thread. Technically, the potential melting of permafrost and CH4 release is a separate issue.

Equilibrium climate sensitivity is a measure of the final surface temperature response to a radiative forcing the equal of that produced by a doubling of CO2.

There are short term and long term considerations. Short term are responses such as cloud feedback, water vapor feedback and lapse rate feedback. These are thought to play out on the decades to century time frame requiring the oceans time to warm through their thermal inertia.

Longer term responses ( time to reach equilibrium) include surface albedo changes from ice and vegetation coverage, permafrost melting, methane clathrate hydrate degassing, warmer ocean CO2 solubility etc.

A doubling of CO2 produces a radiative forcing of 3.7W/m^2. The so called Planck Response to this forcing is a bit less than 1.2C of warming. This is the black body temperature response directly due to increased downward thermal radiation from Earth's own atmosphere. Its like shining a 3.7W stronger light bulb equally over a 1 square meter surface and experiencing a 1.2C increase in the surface temperature.

The climate sensitivity involves any and all system changes to this 1.2C of warming which serve to further add to the warming or subtract from it. The consensus of the many climate sensitivity studies falls in a range generally between +2C and 4.5C, with something near 2.8C deemed most likely for short term equilibrium factors. Again, these are thought to play out on the decades to century time frame.

[TerryM]

Kinetic energy is just another way of saying 'sensible heat.' Sensible heat is present as increased kinetic energy of molecules.

The factor you are describing only becomes important when the arctic is annually ice free or if the rate of melt slows (or reverses). Until then we are likely to continue converting 800 cubic km of ice to water every year, which acts as an ice cube in a glass of water.

Also the long-term trend is 300 cubic km not 800. Which means that the earth has been melting ice at a rate of .62W/m2 since 1979. If the rate of melt starts slowing down, the extra energy would begin to alter surface temperatures instead of being used to melt ice. This ONLY happens if the ice melt starts to slow down.

Finally, if ice melt slows or stops and some or all of this .62W/m2 rate of melting ends up creating sensible heat instead, it is not a never ending accumulation that occurs. Once the surface warms enough to re-emit energy at a rate .62W/m2 faster, the imbalance is ended.

.62W/m2 amounts to .18C of warming. Thus the maximum effect we are talking about (all the ice melts and there is none left to melt) is .18C of warming.

The mechanism you are speaking of, does not effect climate sensitivity because it doesn't effect the global energy budget. The mechanism you are describing (along with deep ocean heat absorption) basically explain why there is a lag from forcing to full temperature response. It is covering up warming (and then suddenly it becomes uncovered), not creating it.

Skier

I've got to say that after some decades in the field I've never heard kinetic used in that way. However, it you wouldn't mind using sensible heat in the discussion it would make it easier for me as this is the term I'm familiar with.

The <300 km³ figure was accurate over a longer time span, but increasing GHG and feedbacks have raised this considerably, and 800 is the more recent figure.

You're right of course about my calculations adding nothing to the global energy budget, and also about the extra heat trying to radiate out into space. The longwave radiation will have difficulties getting past the cloud cover and the GHG blanket, but a portion will certainly escape.

Each day while ice remains to be melted we use up an amount of energy proportional to the volume of ice melted instead of having that energy manifest as sensible heat. When we get to a stage where there's a gap between the date that the last ice has melted and the first freeze up begins we're adding sensible heat to the budget. The huge figure I mentioned earlier (equivalent to about 1/2 of all the energy produced worldwide by man) won't kick in fully until there's 800³km that isn't available for melt at the end of the melt season. We don't have to have a permanent ice free Arctic, just one where the 800 isn't available.

A portion of the heat (a very small portion) will present itself each day we're without ice, and it's this very small proportion that will grow each year - rapidly I fear. I don't see a reason to expect a seasonally ice free arctic to be stable, but rather a transition to a permanently ice free Arctic. It's not a question of when the melt slows down, it's a question of when there's no ice left to melt (this excludes the million square k left when considering the Arctic as "ice free").

I'm not sure where you got the .62W/m figure. I'm coming up with about 2.5 J X 10²⁰ to melt the full 800³km of ice. That's a very large amount of energy, particularly considering that it's concentrated in the Arctic. If all of the additional heat the world is experiencing was being radiated out, we'd have no global warming to worry about. Additional water vapor and additional GHG's will make radiation less efficient. The idea that all this heat would be dissipated into space before the next spring comes around just won't fly.

The global energy budget isn't affected at all by my calculations, but the global heat budget is, since heat affects climate these factors have to be counted as affecting climatic sensitivity. As you point out it is the uncovering of energy that will be part of global warming, but unlike deep oceanic currents burying the heat for eons, this represents energy that has been hidden and will appear as sensible heat the moment there's no ice to melt.

Terry

[skierinvermont]

Skier

I've got to say that after some decades in the field I've never heard kinetic used in that way. However, it you wouldn't mind using sensible heat in the discussion it would make it easier for me as this is the term I'm familiar with.

The <300 km³ figure was accurate over a longer time span, but increasing GHG and feedbacks have raised this considerably, and 800 is the more recent figure.

You're right of course about my calculations adding nothing to the global energy budget, and also about the extra heat trying to radiate out into space. The longwave radiation will have difficulties getting past the cloud cover and the GHG blanket, but a portion will certainly escape.

Each day while ice remains to be melted we use up an amount of energy proportional to the volume of ice melted instead of having that energy manifest as sensible heat. When we get to a stage where there's a gap between the date that the last ice has melted and the first freeze up begins we're adding sensible heat to the budget. The huge figure I mentioned earlier (equivalent to about 1/2 of all the energy produced worldwide by man) won't kick in fully until there's 800³km that isn't available for melt at the end of the melt season. We don't have to have a permanent ice free Arctic, just one where the 800 isn't available.

A portion of the heat (a very small portion) will present itself each day we're without ice, and it's this very small proportion that will grow each year - rapidly I fear. I don't see a reason to expect a seasonally ice free arctic to be stable, but rather a transition to a permanently ice free Arctic. It's not a question of when the melt slows down, it's a question of when there's no ice left to melt (this excludes the million square k left when considering the Arctic as "ice free").

I'm not sure where you got the .62W/m figure. I'm coming up with about 2.5 J X 10²⁰ to melt the full 800³km of ice. That's a very large amount of energy, particularly considering that it's concentrated in the Arctic. If all of the additional heat the world is experiencing was being radiated out, we'd have no global warming to worry about. Additional water vapor and additional GHG's will make radiation less efficient. The idea that all this heat would be dissipated into space before the next spring comes around just won't fly.

The global energy budget isn't affected at all by my calculations, but the global heat budget is, since heat affects climate these factors have to be counted as affecting climatic sensitivity. As you point out it is the uncovering of energy that will be part of global warming, but unlike deep oceanic currents burying the heat for eons, this represents energy that has been hidden and will appear as sensible heat the moment there's no ice to melt.

Terry

Sensible heat is the proper term you are right.

It's not true that once we have ice free conditions in summer that the energy is present as sensible heat. And it is also not true that the effect is cumulative. Finally, the 300km3 figure is much more appropriate IMO. The 800km3 figure is only the last few years and I find it highly improbable that we continue net ice loss at that rate. The more rapid net melting of ice probably has had a substantial cooling effect on the planet the last few years.

Right now we melt 800 km3 more than we melt. That acts as a buffer, much the same way the deep oceans act as a buffer. It is like an ice cube in a glass of water. As long as we continue to melt 800 km3 more than we gain each year, the net melting of the expansive polar ice cap built up over the last few centuries will continue to act as a buffer, requiring net energy to melt it that would otherwise be present as sensible heat. Only if the rate of melt slows (perhaps because there is so little ice left) does that buffering effect diminish. It is possible that we have seasonally ice free conditions and yet continue to melt ice at a net annual rate of 800km3.

So that is the first point. We can have seasonally ice free conditions and continue to have net melting of ice at 300 or 800 km3 a year using just as much energy to melt as it does today.

This net melting of ice (an the energy absorbed by the deep oceans) is why the earth remains in a .9W/m2 energy imblanace. My calculations show that 300km3 of net melting/year requires the earth to have a net gain of energy of .62W/m2. If this melting ceases and all else remains equal, the surface would warm by .18C. A global warming of .18C would be enough to increase the rate of radiation by the same rate the ice cap is currently absorbing it.

In other words, the earth would gain sensible heat (instead of latent heat) at a rate of 2.5X10^16 Joules per year (which is equal to .62W/m2) until the surface warmed by .18C - enough to re-radiate an extra .62W/m2 back to space.

[TerryM]

Sensible heat is the proper term you are right.

It's not true that once we have ice free conditions in summer that the energy is present as sensible heat. And it is also not true that the effect is cumulative. Finally, the 300km3 figure is much more appropriate IMO. The 800km3 figure is only the last few years and I find it highly improbable that we continue net ice loss at that rate. The more rapid net melting of ice probably has had a substantial cooling effect on the planet the last few years.

Right now we melt 800 km3 more than we melt. That acts as a buffer, much the same way the deep oceans act as a buffer. It is like an ice cube in a glass of water. As long as we continue to melt 800 km3 more than we gain each year, the net melting of the expansive polar ice cap built up over the last few centuries will continue to act as a buffer, requiring net energy to melt it that would otherwise be present as sensible heat. Only if the rate of melt slows (perhaps because there is so little ice left) does that buffering effect diminish. It is possible that we have seasonally ice free conditions and yet continue to melt ice at a net annual rate of 800km3.

So that is the first point. We can have seasonally ice free conditions and continue to have net melting of ice at 300 or 800 km3 a year using just as much energy to melt as it does today.

This net melting of ice (an the energy absorbed by the deep oceans) is why the earth remains in a .9W/m2 energy imblanace. My calculations show that 300km3 of net melting/year requires the earth to have a net gain of energy of .62W/m2. If this melting ceases and all else remains equal, the surface would warm by .18C. A global warming of .18C would be enough to increase the rate of radiation by the same rate the ice cap is currently absorbing it.

In other words, the earth would gain sensible heat (instead of latent heat) at a rate of 2.5X10^16 Joules per year (which is equal to .62W/m2) until the surface warmed by .18C - enough to re-radiate an extra .62W/m2 back to space.

.Addressing the bolded paragraph.

Total agreement except for the final sentence. Once we have run out of ice to melt we can't continue to melt an additional amount. It is a buffer, a bank account we've been drawing down at an increasing rate, but once the account is emptied - thats it. We can't borrow on the deposit that will be made during the next winter, and that season will again be drawn down an additional 300 or 800 km³, that's why I say the effect is cummulative.

Unlike the deep ocean currents that will store heat away for a long while, the Arctic has been storing energy for a long while, we've been drawing annually on that at a greater rate than it's been accumulating.

In the following paragraph you're using rephrasing the same argument, and the response is the same. Each year will see 300 to 800 km3 less ice frozen than is melted, and the energy will be seen as sensible heat that must either heat the globe or be radiated away.

In the second last paragraph you claim that as the world heats, it radiates that heat away at the same rate. If this were true, there would be no global warming - clearly not the case.

In the final period you give your math for a melt of 300km³, rather than doing a he said she said, let's use PIOMAS's math. They were working with 280, which we both agree is too small. My contention that the latest figures are more accurate since the world hasn't cooled noticeably in the last few years, but may still be contentious. It we split the difference and double the figure used by PIOMAS we get to 5.6 km³.

From PIOMAS:

"To melt the additional 280 km³ of sea ice, the amount we have have been losing on an annual basis based on PIOMAS calculations, it takes roughly 8.6 x 10¹⁹ J or 86% of U.S. energy consumption."

Doubling their figure for sensible energy released brings us to 1.72 X 10²⁰ J. It's not your math, it's not my math, it's their math.

While considerably less than my earlier figure - which I'd still argue is correct - this is still a huge amount of heat to contend with. Wiki gives the world's annual energy consumption as:

5.0x10²⁰ J total world annual energy consumption in 2010^[161][162]

so the new figure we're talking about is about the amount of energy we consume world wide every 3 years.

I skipped over your first paragraph because by splitting the difference with you on the 300/800 figure I assume we could come to an agreement. The balance of the paragraph is just what I've been arguing, the rapid melting of the ice is having, and has been having a substantial cooling effect on the planet in the last years. Once that "substantial cooling effect" is gone, things are going to heat up fast.

Terry

[skierinvermont]

.Addressing the bolded paragraph.

Total agreement except for the final sentence. Once we have run out of ice to melt we can't continue to melt an additional amount. It is a buffer, a bank account we've been drawing down at an increasing rate, but once the account is emptied - thats it. We can't borrow on the deposit that will be made during the next winter, and that season will again be drawn down an additional 300 or 800 km³, that's why I say the effect is cummulative.

Unlike the deep ocean currents that will store heat away for a long while, the Arctic has been storing energy for a long while, we've been drawing annually on that at a greater rate than it's been accumulating.

In the following paragraph you're using rephrasing the same argument, and the response is the same. Each year will see 300 to 800 km3 less ice frozen than is melted, and the energy will be seen as sensible heat that must either heat the globe or be radiated away.

In the second last paragraph you claim that as the world heats, it radiates that heat away at the same rate. If this were true, there would be no global warming - clearly not the case.

In the final period you give your math for a melt of 300km³, rather than doing a he said she said, let's use PIOMAS's math. They were working with 280, which we both agree is too small. My contention that the latest figures are more accurate since the world hasn't cooled noticeably in the last few years, but may still be contentious. It we split the difference and double the figure used by PIOMAS we get to 5.6 km³.

From PIOMAS:

"To melt the additional 280 km³ of sea ice, the amount we have have been losing on an annual basis based on PIOMAS calculations, it takes roughly 8.6 x 10¹⁹ J or 86% of U.S. energy consumption."

Doubling their figure for sensible energy released brings us to 1.72 X 10²⁰ J. It's not your math, it's not my math, it's their math.

While considerably less than my earlier figure - which I'd still argue is correct - this is still a huge amount of heat to contend with. Wiki gives the world's annual energy consumption as:

5.0x10²⁰ J total world annual energy consumption in 2010^[161][162]

so the new figure we're talking about is about the amount of energy we consume world wide every 3 years.

I skipped over your first paragraph because by splitting the difference with you on the 300/800 figure I assume we could come to an agreement. The balance of the paragraph is just what I've been arguing, the rapid melting of the ice is having, and has been having a substantial cooling effect on the planet in the last years. Once that "substantial cooling effect" is gone, things are going to heat up fast.

Terry

Sorry Terry, you're just wrong and I urge you to re-read and think over this again. Perhaps Rusty can provide some clarification.

Let me restate the primary points and Rusty can agree or disagree:

1. The cooling effect of melting ice disappears only when we stop melting ice at a net annual rate. It does not disappear just because there is no ice for part of the year. For example, if the arctic stops melting next year and we maintain the same volume of ice as last September, the cooling effect would cease and we would warm more. Or for example, if there is no ice in September, but ice volume in all other months continue to decline at 400km3, that would have the same cooling effect as melting 350km3 in all months including September.

2. The cooling effect of melting 300km3 has had a cooling effect of .18C on surface temperatures. When the net melting ceases, the surface will warm by .18C. (Assuming net absorption by the oceans does not increase which in all likelihood it would so we would probably warm by less than .18C.)

I agree with the figure that it takes 1.72 X10^20 Joules per year to melt that much ice and that this would otherwise go into warming the oceans, surface and atmosphere as sensible heat.

However, once the surface has warmed by .18C, it would be able re-radiate 1.72X10^20 Joules to space per year. As I calculated that happens to be equal to a rate of .62W/m2. It is more normal in climate science to deal with large energy imbalances as globally averaged rates (W/m2) than in Joules/year. However it doesn't make any difference which units we use.

Your paragraph

"In the second last paragraph you claim that as the world heats, it radiates that heat away at the same rate. If this were true, there would be no global warming - clearly not the case."

makes no sense. The earth increases its radiation only after the surface has warmed (ie global warming). In this case it has to warm .18C to be able re-radiate 1.72X10^20 Joules to space per year. Or a rate of .62W/m2.

[WeatherRusty]

Sorry Terry, you're just wrong and I urge you to re-read and think over this again. Perhaps Rusty can provide some clarification.

Let me restate the primary points and Rusty can agree or disagree:

1. The cooling effect of melting ice disappears only when we stop melting ice at a net annual rate. It does not disappear just because there is no ice for part of the year. For example, if the arctic stops melting next year and we maintain the same volume of ice as last September, the cooling effect would cease and we would warm more. Or for example, if there is no ice in September, but ice volume in all other months continue to decline at 400km3, that would have the same cooling effect as melting 350km3 in all months including September.

2. The cooling effect of melting 300km3 has had a cooling effect of .18C on surface temperatures. When the net melting ceases, the surface will warm by .18C. (Assuming net absorption by the oceans does not increase which in all likelihood it would so we would probably warm by less than .18C.)

I agree with the figure that it takes 1.72 X10^20 Joules per year to melt that much ice and that this would otherwise go into warming the oceans, surface and atmosphere as sensible heat.

However, once the surface has warmed by .18C, it would be able re-radiate 1.72X10^20 Joules to space per year. As I calculated that happens to be equal to a rate of .62W/m2. It is more normal in climate science to deal with large energy imbalances as globally averaged rates (W/m2) than in Joules/year. However it doesn't make any difference which units we use.

Your paragraph

"In the second last paragraph you claim that as the world heats, it radiates that heat away at the same rate. If this were true, there would be no global warming - clearly not the case."

makes no sense. The earth increases its radiation only after the surface has warmed (ie global warming). In this case it has to warm .18C to be able re-radiate 1.72X10^20 Joules to space per year. Or a rate of .62W/m2.

This is complicated and difficult to pinpoint where you two disagree.

Skier....you get 0.18C warming as a result of 0.64W/m^2 converted to sensible heat as opposed to latent heat of fusion. This is a black body calculation (before any feedback or absorption efficiency considerations). You have extrapolated (added?) the regional energy budget difference to the global radiative forcing, not sure you can do that.

Some portion of the additional energy absorbed by the seasonally increased period of open water is retained by the system. It is taking generally less energy with increasing time to expose a given expanse of open water, since much of the ice has thinned. Not all the additional energy subsequently lost from the arctic is by radiation, some is advected away by currents and wind.

Intuitively, I would expect a greater impact than only 0.18C. Grow a northern hemisphere ice sheet and increase albedo, in addition to a prolonging a colder regional outcome, you decrease the average global temp significantly. The reverse should also be true. On a smaller scale such as if dealing only with the arctic sea ice the total effect is more than just a black body temperature response. The climate is sensitive beyond the direct impact of the initial forcing.

[skierinvermont]

This is complicated and difficult to pinpoint where you two disagree.

Skier....you get 0.18C warming as a result of 0.64W/m^2 converted to sensible heat as opposed to latent heat of fusion. This is a black body calculation (before any feedback or absorption efficiency considerations). You have extrapolated (added?) the regional energy budget difference to the global radiative forcing, not sure you can do that.

Some portion of the additional energy absorbed by the seasonally increased period of open water is retained by the system. It is taking generally less energy with increasing time to expose a given expanse of open water, since much of the ice has thinned. Not all the additional energy subsequently lost from the arctic is by radiation, some is advected away by currents and wind.

Intuitively, I would expect a greater impact than only 0.18C. Grow a northern hemisphere ice sheet and increase albedo, in addition to a prolonging a colder regional outcome, you decrease the average global temp significantly. The reverse should also be true. On a smaller scale such as if dealing only with the arctic sea ice the total effect is more than just a black body temperature response. The climate is sensitive beyond the direct impact of the initial forcing.

Rusty - we're not including the change in albedo. The primary reason loss of ice causes warming is the change in albedo. On that I agree. What Terry is arguing is that the fact that in addition to this, you no longer have ice to melt means that the energy that went into melting before now goes into sensible heat.

This is true. But it is a tiny amount of energy globally annually. I actually did the math wrong. It's not .62W/m2... it's .0062W/m2. This is a ridiculously small rate of energy that is used to melt ice. It would only take a tiny (.0018C) amount of warming globally to 'compensate' for that. And this warming would only take place once we stopped having net annual ice loss. And it is not 'cumulative.' Once the earth warmed .0018C, it would effectively radiate away this extra .0062W/m2 that previously was going into melting ice.

And you can take regional or global energy imbalances and convert them into surface warming. This is the so called 'waming in the pipeline.' The reason why the earth would continue to warm even if CO2 stopped rising is due to the .9W/m2 global energy imbalance, of which melting sea ice is a tiny fraction (.0062Wm2).

.0062W/m2 makes a lot more sense too. The global energy imbalance is .9W/m2 which is almost exclusively due to heat storage by the oceans reducing surface temperature rise. Only a tiny fraction of this imbalance (.0062W/m2) is due to melting of arctic sea ice. Perhaps a combined .02-.05W/m2 is due to melting of glaciers, ice caps, and sea ice combined. But when we talk about global energy imbalance, ice melt is rarely even discussed. It's just not significant.

[tacoman25]

Rusty - we're not including the change in albedo. The primary reason loss of ice causes warming is the change in albedo. What Terry is arguing is that the fact that you no longer have ice to melt means that the energy that went into melting before now goes into sensible heat.

This is true. But it is a tiny amount of energy globally annually. I actually did the math wrong. It's not .62W/m2... it's .0062W/m2. This is a ridiculously small rate of energy that is used to melt ice. It would only take a tiny (.0018C) amount of warming globally to 'compensate' for that. And this warming would only take place once we stopped having net annual ice loss. And it is not 'cumulative.' Once the earth warmed .0018C, it would effectively radiate away this extra .0062W/m2 that previously was going into melting ice.

.0062W/m2 makes a lot more sense too. The global energy imbalance is .9W/m2 which is almost exclusively due to heat storage by the oceans reducing surface temperature rise. Only a tiny fraction of this imbalance (.0062W/m2) is due to melting of arctic sea ice. Perhaps a combined .02-.05W/m2 is due to melting of glaciers, ice caps, and sea ice combined. But when we talk about global energy imbalance, ice melt is rarely even discussed. It's just not significant.

It just seems like some people are convinced no matter what that the Arctic is a huge factor in AGW spiraling out of control, when in fact there just really isn't much evidence that this is the case.

[skierinvermont]

Somebody should check my math.

We're talking about 1X10^20 Joules.

(1X10^20)/365/24/60/60 = x joules per second

x / 510,000,000,000,000 (surface area of earth in m2) = .006W/m2

[TerryM]

Skier

I haven't abandoned the thread. I'm trying to clean up some of the stuff for a short article I'm writing & I'll post a short version of it here when I'm done.

One of the things I think we could agree on is the increasing volume loss we're recording each year.

Below are the opening lines.

338, 580, 641, 842, 952 - What's next number in the sequence?

The numbers above are the average cubic kms of Arctic sea ice lost each year in the last 30 yrs, 20 yrs, 10 yrs, since 2017 and since 2010.The sequence is obviously not linear, but rather shows a rapidly increasing rate of melt.

Using a figure of less than 800/yr doesn't seem to fit with the direction things are moving. the averages keep climbing as more positive feedbacks pile on.

I've got an out of town dinner to attend this evening, so won't get back until at least tomorrow.. I think you're conflating J and J/sec, but can't look at it at the moment.

Terry

[skierinvermont]

The graph Friv posted in the other thread illustrates what I am saying. Melting of sea ice is only a tiny fraction of the energy imbalance. The total imbalance is roughly .9W/m2. The closing of the entire imbalance would amount to .3C of warming (.6C including feedbacks). The closing of the sea ice imbalance alone would amount to .0018C of warming (.04C including feedbacks).

[TerryM]

Somebody should check my math.

We're talking about 1X10^20 Joules.

(1X10^20)/365/24/60/60 = x joules per second

x / 510,000,000,000,000 (surface area of earth in m2) = .006W/m2

We're in the same ballpark (or at least within an order of magnitude)

The calculations I used are

To melt 1 gram of ice requires 334 Joules of energy.

1 km3 of water weighs 1x10^15grams

therefore

it takes 3.34x10^17J to melt 1km3 of ice.

If we take the average:

for the last 30 years - 1,12892x10^20J

for the last 20 years - 1.93720x10^20J

for the last 10 years - 2.14094x10^20L

average since 2007 - 2.77860x10^20J

average since 2010 - 3.17968x10^20J

These seem to match with what PIOMAS has come up with.

Can you explain why you're putting seconds into you're calculations? Not trying to be snarky, i just don't understand, we're talking energy not power.

Another dinner out of town - this social stuff is distracting, but needs to be dealt with. I'll be back late tonight or tomorrow.

Terry