Arctic sea ice could completely melt away by the summer of 2015

[The_Global_Warmer]

Greenland has been off-set by thermal expansion coming to nearly a complete stop.

The 1990's do not look much faster to me. Current levels are 42-43MM with the most recent data with this chart(not seen here yet) and we haven't hit the peak yet.

[ORH_wxman]

Greenland has been off-set by thermal expansion coming to nearly a complete stop.

The 1990's do not look much faster to me. Current levels are 42-43MM with the most recent data with this chart(not seen here yet) and we haven't hit the peak yet.

The data is here for you to play with....sea level rise was definitely higher in the 1990s than it has been in the 2000s...particularly since 2004 when we have really slowed the rate of rise.

http://sealevel.colorado.edu/files/2012_rel4/sl_ns_global.txt

The rate of sea level rise from 1992-2004 is double the rate of sea level rise from 2004-2012 (most current monthly value as end point). That includes almost no sea level rise from 1992-1995. Really, the big difference is between 1996-2004 and 2004-2012.

[TerryM]

The data is here for you to play with....sea level rise was definitely higher in the 1990s than it has been in the 2000s...particularly since 2004 when we have really slowed the rate of rise.

http://sealevel.colorado.edu/files/2012_rel4/sl_ns_global.txt

The rate of sea level rise from 1992-2004 is double the rate of sea level rise from 2004-2012 (most current monthly value as end point). That includes almost no sea level rise from 1992-1995. Really, the big difference is between 1996-2004 and 2004-2012.

Any idea when this summer's data will be added?

Terry

[FPizz]

I hope they start offering some cruises through this region.

[ORH_wxman]

Any idea when this summer's data will be added?

Terry

Probably pretty soon, I believe they update it every couple of months if I'm not mistaken.

[TerryM]

Thanks

The chart on their home page really shows the effect of precipitation over land last year. I was west in Canada most of the summer and everything from the Great Lakes to the Rockies was under water. Massive floods in Australia and Pacific islands as I recall.

I've bookmarked the site - this summers rise will be interesting.

Terry

[The_Global_Warmer]

The data is here for you to play with....sea level rise was definitely higher in the 1990s than it has been in the 2000s...particularly since 2004 when we have really slowed the rate of rise.

http://sealevel.colo...l_ns_global.txt

The rate of sea level rise from 1992-2004 is double the rate of sea level rise from 2004-2012 (most current monthly value as end point). That includes almost no sea level rise from 1992-1995. Really, the big difference is between 1996-2004 and 2004-2012.

I am not sure why you continue to ignore the most up to date data, the College research group has data into May, NOAA has updated through July. Don't you work for NOAA? Why would you overlook their data, I am going to assume you either think NOAA is not reliable, or didn't know they run this data, or didn't know it was updated. which in reality is no different than the other three groups putting it out. Except this more current and with it being more current shows more sea level rise.

This includes no sea level rise from late 2005 to late 2007 when it declined a bit, then another big dip during the Nina's and heavy flooding. Ultimately all of that water coming out of Greenland catches up hence the large SLR rise from the middle of 2011 to now. Counting on natural factors that hide the Greenland contributions won't last, luckily the oceanic heat content went from large rises to near standstill since the mid 2000s or sea level rise would be climbing quite bit faster.

The most recent data has:

2005.5636: 18.49

2005.5879: 19.77

2005.5614: 19.81

Or Cherry Picking I could use 2007 which shows the same as 2005 or even slightly below at the most updated time frame so far in 2012, about 6-8 weeks from the typical yearly max.

2012.5603: 41.82

2012.5874: 43.38

2012.6144: 42.34

http://ibis.grdl.noaa.gov/SAT/SeaLevelRise/LSA_SLR_timeseries_global.php

Once again, you have no even mention on the sudden near flat-line of thermal expansion's role in Sea Level Rise.

[The_Global_Warmer]

Using the CU Group data. To be more fair I used the last 10 data points, instead of 5, which would show a larger disparity. There was no text data from 1992. So guessing at the satellite Sea Ice derived level would do no good, so I just used 1993. Which had large variances in end points for the 10th one. To add more fairness into this I added in an extra one on each end of the time Frame. But then again comparing 1992-2004 to 2004-2012 is not fair at all because one sample is larger than the other. So let's add 1996.

The time frames or not even. But I tried to highlight the 3 most closest time frames equal to the most current updated 3 with the CU group data. No where does it appear a double rate took place before 2004-2012. Even as a cherry picked sample, 2004-2012 the most recent data shows the largest change around 30MM

1993.1766 -7.964

1993.2038 -7.276

1993.2309 -3.217

1993.2852 -0.266

1993.3124 0.897

1993.3395 -5.577

1993.3667 -8.576

1993.3938 -6.969

1993.4210 -1.445

1993.4481 0.760

1993.4753 -1.914

1996.1901 1.465

1996.2172 -0.514

1996.2444 -3.211

1996.2715 -4.014

1996.2987 1.275

1996.3258 5.397

1996.3530 3.422

1996.3801 -0.768

1996.4073 -2.177

1996.4344 -0.285

1996.4887 7.902

2004.1988 34.668

2004.2259 33.494

2004.2531 31.202

2004.2802 28.536

2004.3074 34.281

2004.3345 28.784

2004.3617 30.730

2004.3888 28.171

2004.4160 27.036

2004.4431 25.793

2012.2075 50.785

2012.2346 56.309

2012.2618 54.458

2012.2889 52.406

2012.3161 51.122

2012.3432 48.814

2012.3704 53.174

2012.3975 53.888

2012.4247 56.258

2012.4518 58.336

If I add 2007, I can manipulate the data to show about a 25MM rise using the last three data points. 25/5 = 5MM/YR. Obviously that is not the case.

2007.2122 34.889

2007.2394 40.145

2007.2665 44.965

2007.2937 41.847

2007.3208 37.179

2007.3480 31.327

2007.3751 37.323

2007.4023 41.302

2007.4294 40.979

2007.4566 39.602

[csnavywx]

In the past, the GHGs lagged temperature though...so its not really comparable. Sea level rise has not been accelerating to alarming levels despite the loss of ice in Greenland. It is still unclear whether Antarctica is contributing to sea level rise or not despite the GRACE measurements. There is contradicting literature there. The IPCC's AR4 in 2007 projected Antarctica to gain ice mass as the temperature warmed during the 21st century due to increased snowfall which is likely what drives their fairly unalarming sea level rise projection through 2100....actually matching up closely with the current rate that would yield about 10 inches of sea level rise by 2100. Their projection was 7-23 inches.

Greenland is losing ice at a faster rate, but not at a rate that is drastically affecting sea level rise. It would have to accelerate exponentially to become a huge factor in the next several decades. Greenland is an interesting case though. I've seen some literature that suggests it could contribute to several inches of sea level rise by 2050. I find this extremely unlikely, but we will absolutely no doubt be able to see it very quickly in the next several years if it is going to do that.

Eh, careful here. I like your cautious attitude, but we're wandering close to chicken/egg argument territory. What is relatively clear is that about 90% of warming came after CO2 increases started in past cycles. While CO2 did not initiate the warming in those cycles, there's a pretty clear link between it and subsequent warming. The only difference this time is that CO2 initiated it. Would that make a difference? Probably, if we were talking about the same kind of time frame that past cycles occurred on. The difference in "dCO2/dt" is an order of magnitude faster this time around. Kind of changes things.

There are reasons the IPCC suite did not catch the (critical) break in sea ice. Part of it has to do with resolution issues (which regional modeling and better obs can help resolve). Another part are feedbacks that are not captured or for which parameterization is inadequate (or needs tweaking).

Edit: for sloppy proofreading.

[ORH_wxman]

Friv, you are not computing linear trends correctly...you should be using linear regression...not cherry picking a group of points. This is why you get an upward trend in global temperatures even if you start with 1998 which was far warmer than the past year...because linear regression is the most accurate way to calculate a trend with a lot of data points and noisy data.

I could add on the most recent 3 months that show a bump upward in sea level and it would not change my numbers much at all...this is because linear regression doesn't over-value the most recent points.

I will show you graphically just so we can stop the mathematical nonsense with text:

Here is the linear trend using the CU data from 2004-2012:

That amounts to 2.15mm per year of sea level rise on the CU data...that is fact, not opinion.

Now here is if I added some monsterous numbers to the end of the graph for the next dozen data points data points:

I raised the sea level 20mm in less than 4 months (unrealistic) and the linear trend increased from 2.15mm per year to 2.50mm per year....which is still well below the 1992-current trend of 3.1mm per year on the same data set. The linear trend of sea level rise has slowed since 2004 on the CU data regardless of what happens the rest of this year....again, this is fact, not opinion.

If you would like to link me to a text dataset from NOAA, I'd be happy to run numbers from there to see if they are different than CU's numbers.

[ORH_wxman]

Eh, careful here. I like your cautious attitude, but we're wandering close to chicken/egg argument territory. What is relatively clear is that about 90% of warming came after CO2 increases started in past cycles. While CO2 did not initiate the warming in those cycles, there's a pretty clear link between it and subsequent warming. The only difference this time is that CO2 initiated it. Would that make a difference? Probably, if we were talking about the same kind of time frame that past cycles occurred on. The difference in "dCO2/dt" is an order of magnitude faster this time around. Kind of changes things.

There are reasons the IPCC suite did not catch the (critical) break in sea ice. Part of it has to do with resolution issues (which regional modeling and better obs can help resolve). Another part are feedbacks that are not captured or for which parameterization is inadequate (or needs tweaking).

Edit: for sloppy proofreading.

I agree with you. I wasn't trying to suggest that there was no feedback in paleo times from CO2...just that this round of warming had the CO2 going up in tandem rather than lagging like during initial paleo warming events...so its very difficult to compare the evolution. Though paleo reconstruction does give us some hints on sensitivity.

[csnavywx]

I agree with you. I wasn't trying to suggest that there was no feedback in paleo times from CO2...just that this round of warming had the CO2 going up in tandem rather than lagging like during initial paleo warming events...so its very difficult to compare the evolution. Though paleo reconstruction does give us some hints on sensitivity.

Agree 100% here.

And this is where the IPCC's very conservative estimate gives me pause. They chose to omit key details for feedbacks (including critical ice dynamics) because of the uncertainty. Well, it's pretty certain we're already dealing with some of these very details. Omitting non-linear processes tends to invalidate projections very quickly, as we might logically expect.

[ORH_wxman]

Agree 100% here.

And this is where the IPCC's very conservative estimate gives me pause. They chose to omit key details for feedbacks (including critical ice dynamics) because of the uncertainty. Well, it's pretty certain we're already dealing with some of these very details. Omitting non-linear processes tends to invalidate projections very quickly, as we might logically expect.

For the sea ice this makes sense...however, for global temps, I think IPCC is too robust. The paper by Schmittner et al used paleo reconstructions to show that sensitivity was significantly lower than the IPCC average.

This is an interesting dynamic for IPCC though...their global temp projections (at least thus far) have been too high, yet their projection of arctic sea ice was far too slow in the melt (again, so far).

[The_Global_Warmer]

I am unclear on your point. Thermal expansion has nearly stopped, you won't even speak of it. So of course Sea Level rise will slow in response. If Greenland had not started losing ice at an increasingly accelerating rate sea level rise would have slowed down much further since thermal expansion slowed down. I am taking to task one point you have made.

Greenland is losing ice at a faster rate, but not at a rate that is drastically affecting sea level rise. It would have to accelerate exponentially to become a huge factor in the next several decades. Greenland is an interesting case though. I've seen some literature that suggests it could contribute to several inches of sea level rise by 2050. I find this extremely unlikely, but we will absolutely no doubt be able to see it very quickly in the next several years if it is going to do that.

Greenland's contribution to average sea-level rise increased from 2.3 mm per decade in 1996 to 5 mm per decade in 2005. This accounts for between 20% and 38% of the observed yearly global sea-level rise.^[40] Two-thirds of Greenland's sea level contribution is due to glacier dynamics (chunks of ice breaking off and melting), and one-third is from direct melting. As glacier acceleration continues to spread northward from its current focus in southern Greenland, the global sea-level rise contribution from the world’s largest island will continue to increase.

Since 2005. When thermal expansion abruptly slowed, Greenland has continued to lose more mass.

From the start of the Greenland melting season in 2005 through the end of the 2011 melting season Greenland lost about 2200km3/360km3 = 6.1MM.

If we extrapolate that through the 2012 melt season adding 800km3 to it, now 3000km3/360km3 = 8.3MM

This places Greenland at over 50% of the global sea level rise in the most recent period since 2005. Of course it's not making a dent, thermal expansion fell off drastically. It wouldn't be anywhere near where it now if Greenland didn't pick things up.

To your point and my contention: Finding Several inches of sea level rise in the next 38 years extremely unlikely.

We will define extremely unlikely at 2 inches in the next 38 years.

2" = 5.08CM = 50.8MM.

1MM = 360GT =360KM3

50.8MM x 360 GT = 18288GT/360KM3 = 2 INCHES OF SLR FROM GREENLAND BY 2050 AT A RATE OF 481GT OR 481GT PER YEAR, THIS IS LOWER THAN THE 2005, 2007, 2008, 2010, 2011, AND 2012 MELT SEASONS.

Now onto Several INCHES: we will define this as 3-4 inches.

3" = 7.62CM = 76.2MM

76.2MM x 360 GT = 27432GT/360kM3 = 3 inches.

This requires a yearly loss of 721GT or 721KM3 slightly more than we have witnessed recently, likely less than 2012's melt season.

4" = 36,576GT

This requires a yearly loss of 962GT.

All I am asking is why you think over the next 38 years Greenland will have peaked in ice loss at the 2010-2012 levels.

[ORH_wxman]

I am unclear on your point. Thermal expansion has nearly stopped, you won't even speak of it. So of course Sea Level rise will slow in response. If Greenland had not started losing ice at an increasingly accelerating rate sea level rise would have slowed down much further since thermal expansion slowed down. I am taking to task one point you have made.

Since 2005. When thermal expansion abruptly slowed, Greenland has continued to lose more mass.

From the start of the Greenland melting season in 2005 through the end of the 2011 melting season Greenland lost about 2200km3/360km3 = 6.1MM.

If we extrapolate that through the 2012 melt season adding 800km3 to it, now 3000km3/360km3 = 8.3MM

This places Greenland at over 50% of the global sea level rise in the most recent period since 2005. Of course it's not making a dent, thermal expansion fell off drastically. It wouldn't be anywhere near where it now if Greenland didn't pick things up.

To your point and my contention: Finding Several inches of sea level rise in the next 38 years extremely unlikely.

We will define extremely unlikely at 2 inches in the next 38 years.

2" = 5.08CM = 50.8MM.

1MM = 360GT =360KM3

50.8MM x 360 GT = 18288GT/360KM3 = 2 INCHES OF SLR FROM GREENLAND BY 2050 AT A RATE OF 481GT OR 481GT PER YEAR, THIS IS LOWER THAN THE 2005, 2007, 2008, 2010, 2011, AND 2012 MELT SEASONS.

Now onto Several INCHES: we will define this as 3-4 inches.

3" = 7.62CM = 76.2MM

76.2MM x 360 GT = 27432GT/360kM3 = 3 inches.

This requires a yearly loss of 721GT or 721KM3 slightly more than we have witnessed recently, likely less than 2012's melt season.

4" = 36,576GT

This requires a yearly loss of 962GT.

All I am asking is why you think over the next 38 years Greenland will have peaked in ice loss at the 2010-2012 levels.

I was correcting your incorrect math trying to calculate a linear trend....that was my point.

As for the thermal expansion, of course it has slowed because the warming has slowed. That is not a surprise. As for sea level rise from Greenland? We are currently rising at about 2-3mm per year of which Greenland is contributing 15-30% since 2003 according to Long et al. That is at most 0.9mm per year. This is also a very high estimate as most sources have Greenland's contribution to recent sea level rise much lower. If this continued for another 38 years, then Greenland will have contributed 1.3 inches of sea level rise. If Greenland's contribution rises to 2mm per year (more than double current), then it would contribute 3 inches of sea level rise by 2050.

In order to reach "Several inches"...which I did not define, but was thinking of values around 5" (say, in the 4-6" range)...we would need to see Greenland's contribution of sea level rise actually exceed the current overall sea level rise starting now and continuing for the next 38 years. I find this unlikely. Perhaps you do not find it unlikely...which is fine. We will just agree to disagree on the point.

I also think your numbers are off...that graph you showed above has Greenland losing 1400 gigatons since 2007...5 years. That is an average of 280 gigatons per year which comes out to 0.77mm per year of sea level rise. I'm not sure why you would use only melting seasons since Greenland gains mass again in the winter.

[dabize]

Don, dabize,

You are describing the thermal expansion properties of fresh water. Sea water does not expand as it cools from 4C to 0C.

http://www.kayelaby..../2_7/2_7_9.html

Verg

OK - sometimes ignorance is going to show!

Moving right along...........

[The_Global_Warmer]

Disagreeing doesn't get us further along in the discussion I am not trying to have a flame war argument, just want to know reasoning why

Basing on the facts of 360km3 per year. 2010-2012 pre melt Greenland dropped about 800km3 between those two years. 2012 melt's season will likely be in the 800km3 range, let's drop it down to 600km3 pre melt season 2013. So between the three years it would be 466km3 that number is hard to work with. let's use 2010-2015 at 500km3 per year as a starting point. If we assume each 5 year period up to 2050 will gain 100km3/yr.

decade 1: 550km3/yr = 5500km3

decade 2: 650km3/yr = 6500km3

decade 3: 750km3/yr = 7500km3

decade 4: 850km3/yr = 8500km3 total: 28,000km3/360km3 = 7.77CM or a bit over 3".

D1: 6000km3

D2: 8000km3

D4: 10000km3

D4: 12000km3 total: 36,000km3/360km3 = 10 CM or about 4 inches.

D1: 6500km3

D2: 10000km3

D3:13000km3

D4: 16000km3 total: 45,500km3 = 12.6cm or 4.9 inches

We have seen what has happened to the arctic sea ice and how our calculations can fall apart when albedo changes were not properly accounted for.

Greenland's albedo situation continues to get worse showing feed-backing taking place. Once the yearly snowfall is gone albedo plummets over the already established dirty ice that continues to expand up the slope of Greenland. The dirty ice albedo are 25-50% and make up a small but growing portion of the ice sheet.

The areas outside of Greenland will continue to warm and enhance this feedback overtime. I just can't see how it doesn't expand the melt season, lower albedo, dramatically increase melt.

38 years ago someone claiming the arctic ice sheet would lose 80% or more of it's September min volume would be laughed out of the room.

Ice's only defense is albedo and like the arctic sea ice, Greenland's land ice is losing it's defense, rather quickly.

[csnavywx]

For the sea ice this makes sense...however, for global temps, I think IPCC is too robust. The paper by Schmittner et al used paleo reconstructions to show that sensitivity was significantly lower than the IPCC average.

This is an interesting dynamic for IPCC though...their global temp projections (at least thus far) have been too high, yet their projection of arctic sea ice was far too slow in the melt (again, so far).

This is a double edged sword. If the sensitivity is really that low and the change in global temperature between now and the last glacial max was only 2.5-3C, then a 2-3C warming represents a drastically different world.

I think the main problem with the usage of UVic (the climate model they used) is its simplicity (although from a computing and bang-for-buck standpoint, it makes sense) -- even more simplified than most IPCC runs -- which make it inherently more insensitive to climate feedbacks. Hence, we round back to square one with the problems of using low-res GCMs. This is an area where I think regional higher-res models would excel. The Navy seems to think so at least... and this is why they are pursuing this avenue in conjunction with better obs.

As for the issue of undershoot on global temp predictions, I refer to OHC+Ice melt+Land Temp data, which suggest that the overall uptake of heat by Earth has only slowed (but not stopped). But, there's a simple explanation for this:

an increase in sulfate aerosols resulting from an increase of around 50% in coal consumption (from ~2200 mtoe (millions of tons of oil equiv) to ~3300 mtoe) globally in the last 10-12 years. Most of that increase comes from China and India where the regulatory structure is considerably more lax than the US or Europe. While sulfate aerosols can create a stabilizing blanket (via negative feedback through reduced insolation), it represents a kind of Faustian bargain in the longer term. More CO2 emissions would require additional SO2 emissions to offset it. At some point this backfires, mainly because sulfates don't tend to stick around nearly as long in the atmosphere as CO2 and they can cause nasty local problems (which leads the people affected by them to prod their respective governments to act to reduce them).

China and India's rapid coal consumption growth will slow in the relatively near term and we're already seeing the Chinese attempt to clean up urban pollution as the population becomes more vocal about it. As these trends play out, GHG based warming is likely to resume a strong march upward. A potential fly in the ointment or offsetting factor for this would be declining coal grades being used with time (as we chew through the better and more economical stuff), which tend to include higher sulfur content.

Depletion of economical coal, oil and gas reserves have a large part to play in this opera as well in the long term, but this is another topic.

[TerryM]

I'm not sure why you would use only melting seasons since Greenland gains mass again in the winter.

Are you proposing that mass gains in winter offset the summer melt?

I suppose one could argue that summit snowfall is evaporated from our ever warmer oceans at increasing rates, and that this acts to offset the run off during the melt season, the net loss/yr however takes both these actions into account.

As the ocean heats, it expands. Increased precipitation over land can mask the effect for short periods of time, but water, like other less euphonious substances flows down hill - and adds to sea level.

Terry

[ORH_wxman]

This is a double edged sword. If the sensitivity is really that low and the change in global temperature between now and the last glacial max was only 2.5-3C, then a 2-3C warming represents a drastically different world.

I think the main problem with the usage of UVic (the climate model they used) is its simplicity (although from a computing and bang-for-buck standpoint, it makes sense) -- even more simplified than most IPCC runs -- which make it inherently more insensitive to climate feedbacks. Hence, we round back to square one with the problems of using low-res GCMs. This is an area where I think regional higher-res models would excel. The Navy seems to think so at least... and this is why they are pursuing this avenue in conjunction with better obs.

As for the issue of undershoot on global temp predictions, I refer to OHC+Ice melt+Land Temp data, which suggest that the overall uptake of heat by Earth has only slowed (but not stopped). But, there's a simple explanation for this:

an increase in sulfate aerosols resulting from an increase of around 50% in coal consumption (from ~2200 mtoe (millions of tons of oil equiv) to ~3300 mtoe) globally in the last 10-12 years. Most of that increase comes from China and India where the regulatory structure is considerably more lax than the US or Europe. While sulfate aerosols can create a stabilizing blanket (via negative feedback through reduced insolation), it represents a kind of Faustian bargain in the longer term. More CO2 emissions would require additional SO2 emissions to offset it. At some point this backfires, mainly because sulfates don't tend to stick around nearly as long in the atmosphere as CO2 and they can cause nasty local problems (which leads the people affected by them to prod their respective governments to act to reduce them).

China and India's rapid coal consumption growth will slow in the relatively near term and we're already seeing the Chinese attempt to clean up urban pollution as the population becomes more vocal about it. As these trends play out, GHG based warming is likely to resume a strong march upward. A potential fly in the ointment or offsetting factor for this would be declining coal grades being used with time (as we chew through the better and more economical stuff), which tend to include higher sulfur content.

Depletion of economical coal, oil and gas reserves have a large part to play in this opera as well in the long term, but this is another topic.

That is an interesting explanation to the slowdown in recent global temp rise. I generally do not agree with the aerosol theory mostly because they increased right into the 1980s before the Montreal Protocol was put into place, yet the temperature didn't respond to the increase after 1976...instead, actually reversing the decline and sharply rising after 1976.

The recent slowdown coincides with increased aerosols too from China and India as you have explained...however, it also coincides with the Pacific decadal oscillation shifting, and the 1976 sharp rise also coincided with it. Basically, I think aerosols are not as large a factor as the PDO, but I could be wrong. There is no doubt that they cause cooling...but their levels do not match the temperature record as well as the alternative explanation which suggests to me that they are not the primary factor in offsetting GHG warming in the mid-20th century and the beginning of the 21st century.

But I'd certainly be willing to be convinced otherwise. I just haven't ever found any good papers that are able to demonstrate it. I suppose there is still a lot we have to learn about aerosols. Composition probably matters a lot too. Obviously if you blow enough of them into the air, you see a big cooling like during large volcano eruptions but our steady output of them doesn't seem to match the temp record well enough to be the main offsetter.

[ORH_wxman]

Are you proposing that mass gains in winter offset the summer melt?

I suppose one could argue that summit snowfall is evaporated from our ever warmer oceans at increasing rates, and that this acts to offset the run off during the melt season, the net loss/yr however takes both these actions into account.

As the ocean heats, it expands. Increased precipitation over land can mask the effect for short periods of time, but water, like other less euphonious substances flows down hill - and adds to sea level.

Terry

No, but Friv was quoting summer melt figures as if they were annual totals. The annual total mass loss will be less than whatever is lost in the summer because it gains some of it back during the winter.

[tacoman25]

This is a double edged sword. If the sensitivity is really that low and the change in global temperature between now and the last glacial max was only 2.5-3C, then a 2-3C warming represents a drastically different world.

I think the main problem with the usage of UVic (the climate model they used) is its simplicity (although from a computing and bang-for-buck standpoint, it makes sense) -- even more simplified than most IPCC runs -- which make it inherently more insensitive to climate feedbacks. Hence, we round back to square one with the problems of using low-res GCMs. This is an area where I think regional higher-res models would excel. The Navy seems to think so at least... and this is why they are pursuing this avenue in conjunction with better obs.

As for the issue of undershoot on global temp predictions, I refer to OHC+Ice melt+Land Temp data, which suggest that the overall uptake of heat by Earth has only slowed (but not stopped). But, there's a simple explanation for this:

an increase in sulfate aerosols resulting from an increase of around 50% in coal consumption (from ~2200 mtoe (millions of tons of oil equiv) to ~3300 mtoe) globally in the last 10-12 years. Most of that increase comes from China and India where the regulatory structure is considerably more lax than the US or Europe. While sulfate aerosols can create a stabilizing blanket (via negative feedback through reduced insolation), it represents a kind of Faustian bargain in the longer term. More CO2 emissions would require additional SO2 emissions to offset it. At some point this backfires, mainly because sulfates don't tend to stick around nearly as long in the atmosphere as CO2 and they can cause nasty local problems (which leads the people affected by them to prod their respective governments to act to reduce them).

China and India's rapid coal consumption growth will slow in the relatively near term and we're already seeing the Chinese attempt to clean up urban pollution as the population becomes more vocal about it. As these trends play out, GHG based warming is likely to resume a strong march upward. A potential fly in the ointment or offsetting factor for this would be declining coal grades being used with time (as we chew through the better and more economical stuff), which tend to include higher sulfur content.

Depletion of economical coal, oil and gas reserves have a large part to play in this opera as well in the long term, but this is another topic.

Are you inferring that coal is the reason global temp rise has slowed the past 10 years or so? I haven't seen any solid proof of that. The PDO turning negative seems like a much more evidenced answer.

[The_Global_Warmer]

No, but Friv was quoting summer melt figures as if they were annual totals. The annual total mass loss will be less than whatever is lost in the summer because it gains some of it back during the winter.

That is completely untrue.

From the start of the Greenland melting season in 2005 through the end of the 2011 melting season Greenland lost about 2200km3/360km3 = 6.1MM.

If we extrapolate that through the 2012 melt season adding 800km3 to it, now 3000km3/360km3 = 8.3MM

I specifically stated what the numbers represented. There was zero deception. Those can't be misconstrued as annual totals it says the end of the melt season. Poorly written and not properly constructed but plainly stated and defined.

I can see how that could seem like I was describing annual melt.

[csnavywx]

That is an interesting explanation to the slowdown in recent global temp rise. I generally do not agree with the aerosol theory mostly because they increased right into the 1980s before the Montreal Protocol was put into place, yet the temperature didn't respond to the increase after 1976...instead, actually reversing the decline and sharply rising after 1976.

The recent slowdown coincides with increased aerosols too from China and India as you have explained...however, it also coincides with the Pacific decadal oscillation shifting, and the 1976 sharp rise also coincided with it. Basically, I think aerosols are not as large a factor as the PDO, but I could be wrong. There is no doubt that they cause cooling...but their levels do not match the temperature record as well as the alternative explanation which suggests to me that they are not the primary factor in offsetting GHG warming in the mid-20th century and the beginning of the 21st century.

But I'd certainly be willing to be convinced otherwise. I just haven't ever found any good papers that are able to demonstrate it. I suppose there is still a lot we have to learn about aerosols. Composition probably matters a lot too. Obviously if you blow enough of them into the air, you see a big cooling like during large volcano eruptions but our steady output of them doesn't seem to match the temp record well enough to be the main offsetter.

The Clean Air Act provisions were put into place in 70, 77, and 90.

I don't have a ton of time this morning, but I'll post a few things when I get back from work this afternoon with regards to aerosols. This effect in tandem with natural cycles does a pretty good job of simply explaining temp trends.

[donsutherland1]

The Clean Air Act provisions were put into place in 70, 77, and 90.

I don't have a ton of time this morning, but I'll post a few things when I get back from work this afternoon with regards to aerosols. This effect in tandem with natural cycles does a pretty good job of simply explaining temp trends.

Quick question:

Is there a site where one can get the annual emissions and atmospheric concentration for various aerosols? I've seen the GISP2 data, but that only goes to 2000. I've also seen a paper that has some data up to 2005.

[Vergent]

Quick question:

Is there a site where one can get the annual emissions and atmospheric concentration for various aerosols? I've seen the GISP2 data, but that only goes to 2000. I've also seen a paper that has some data up to 2005.

Aerosol optical depth is the fundamental measurement of quantity and distribution of aerosols. This map shows the average distribution of aerosols from June 2000 through May 2010, measured by the Multi-angle Imaging Spectroradiometer (MISR). Red indicates high concentrations of aerosols, beige indicates low concentrations. (NASA map by Robert Simmon, based on MISRdata.)

http://earthobservatory.nasa.gov/Features/Aerosols/page5.php

This is through 2010

[TerryM]

Quick question:

Is there a site where one can get the annual emissions and atmospheric concentration for various aerosols? I've seen the GISP2 data, but that only goes to 2000. I've also seen a paper that has some data up to 2005.

Skier had posted a graph and I believe some links relating to this on another thread.

Terry

[skierinvermont]

Are you inferring that coal is the reason global temp rise has slowed the past 10 years or so? I haven't seen any solid proof of that. The PDO turning negative seems like a much more evidenced answer.

The decline in TSI alone can account for most of any slowdown. Perhaps some slight contribution from an increased occurrence of Ninas possibly associated with the -PDO.

[skierinvermont]

The data is here for you to play with....sea level rise was definitely higher in the 1990s than it has been in the 2000s...particularly since 2004 when we have really slowed the rate of rise.

http://sealevel.colo...l_ns_global.txt

The rate of sea level rise from 1992-2004 is double the rate of sea level rise from 2004-2012 (most current monthly value as end point). That includes almost no sea level rise from 1992-1995. Really, the big difference is between 1996-2004 and 2004-2012.

As Friv's graph shows 1994, 2004, and 2012 all fall very close to the linear trend line. This necessarily means that the trend 1994-2004 and 2004-2012 are the same. There has been an abrupt step up recently which has had a large effect on the post-2004 trend. Such is the risk of using such short periods for analysis. It remains to be seen what happens after this abrupt step up.. do we temporarily stabilize or even decline, do we continue to rise at the long-term rate of 2.8mm/yr, or does the abrupt rise continue? I would guess option #2 to be most likely.

Also I am confused by Friv's statement that there has been little/no thermal expansion since 2004. As the second graph he posted shows, 0-2000m expansion since 2004 has been only slightly below the long-term rate. No definitive conclusions should be drawn from such a short period given the magnitude of the error bars.

[ORH_wxman]

As Friv's graph shows 1994, 2004, and 2012 all fall very close to the linear trend line. This necessarily means that the trend 1994-2004 and 2004-2012 are the same. There has been an abrupt step up recently which has had a large effect on the post-2004 trend. Such is the risk of using such short periods for analysis. It remains to be seen what happens after this abrupt step up.. do we temporarily stabilize or even decline, do we continue to rise at the long-term rate of 2.8mm/yr, or does the abrupt rise continue? I would guess option #2 to be most likely.

The trends really aren't that close if you are using linear regression on the data. Though he never gave me a text data link for that other graph he posted that came from NOAA...so maybe that one is closer on the two time periods than the CU dataset I used.