2014 Greenland melt season discussion thread

[LithiaWx]

Here is the incorrect plot that I posted earlier:

As several people pointed out, the red line labeled 2012 should read 2013, which was a very mild year for GIS mass loss.

Here is the current and correct plotL

And now notice that the red line labeled 2012 is correct (2012 was a record year for GIS mass loss). As anyone can see, 2014 nearly tied 2012 for net mass loss.

Marietta, continuing to deny the data does nothing for your credibility.

I'm not denying data. The graph is suspect but I'm more inclined to believe it's accuracy after this post. It's hard to take seriously a graph that was so wrong at one point. It was also argued to be correct for days to weeks by a certain poster that I won't name, despite data that was to the contrary. I didn't realize that they have apparently corrected the graph.

You're barking up the wrong tree regarding my credibility. I'm on your "side" so please check yourself. I can't stand, I mean really can't tollerate alarmism. There are a handful of posters that turn everything into a worst case epic meltdown scenario. I believe that those methods are counterproductive when it comes to getting a point across that can be taken as credible. So again, some caution is rightfully taken imo when the graph we are talking about was in error in such a horrible fashion. I do thank you for pointing out the correction though, you do learn something new everyday if you try.

[The_Global_Warmer]

Good stuff Phillip.

That is to be expected. Grace data shoukd be fully processed over the next couple of weeks

[chubbs]

Interesting recent paper describing regional variation in glacier outflow and surface melting. Wide range of outflow trends among Greenland's individual glaciers.  Fulltext available below.

 

http://www.pnas.org/content/early/2014/12/12/1411680112

 

Laser altimetry reveals complex pattern of Greenland Ice Sheet dynamics

Beata M. Csathoa,1, Anton F. Schenka, Cornelis J. van der Veenb, Gregory Babonisa, Kyle Duncana, Soroush Rezvanbehbahanic, Michiel R. van den Broeked, Sebastian B. Simonsene, Sudhagar Nagarajanf, and Jan H. van Angelend

We present a new record of ice thickness change, reconstructed at nearly 100,000 sites on the Greenland Ice Sheet (GrIS) from laser altimetry measurements spanning the period 1993–2012, partitioned into changes due to surface mass balance (SMB) and ice dynamics. We estimate a mean annual GrIS mass loss of 243 ± 18 Gt·y−1, equivalent to 0.68 mm·y−1 sea level rise (SLR) for 2003–2009. Dynamic thinning contributed 48%, with the largest rates occurring in 2004–2006, followed by a gradual decrease balanced by accelerating SMB loss. The spatial pattern of dynamic mass loss changed over this time as dynamic thinning rapidly decreased in southeast Greenland but slowly increased in the southwest, north, and northeast regions. Most outlet glaciers have been thinning during the last two decades, interrupted by episodes of decreasing thinning or even thickening. Dynamics of the major outlet glaciers dominated the mass loss from larger drainage basins, and simultaneous changes over distances up to 500 km are detected, indicating climate control. However, the intricate spatiotemporal pattern of dynamic thickness change suggests that, regardless of the forcing responsible for initial glacier acceleration and thinning, the response of individual glaciers is modulated by local conditions. Recent projections of dynamic contributions from the entire GrIS to SLR have been based on the extrapolation of four major outlet glaciers. Considering the observed complexity, we question how well these four glaciers represent all of Greenland’s outlet glaciers.

[LithiaWx]

are the models still forecasting a major major torch over the southern 1/3 of Greenland?

[chubbs]

A summary of the 2014 melt season is now available at link below. The charts posted above by Phillip were correct. No GRACE data yet to compare to the albedo derived estimate for 2014.

 

http://polarportal.dk/en/nyheder/arkiv/2014-season-report/

 

.

 

 

[SVT450R]

A summary of the 2014 melt season is now available at link below. The charts posted above by Phillip were correct. No GRACE data yet to compare to the albedo derived estimate for 2014.

 

http://polarportal.dk/en/nyheder/arkiv/2014-season-report/

 

greenland mass.png.

It's interesting how close 2014 is to 2012 yet surface melt conditions were closer to 2013 then 2012 going through the melt season.  I guess calving was a much bigger player this season just seems a little odd IMO.

[chubbs]

It's interesting how close 2014 is to 2012 yet surface melt conditions were closer to 2013 then 2012 going through the melt season.  I guess calving was a much bigger player this season just seems a little odd IMO.

These estimates are based on surface albedo. GRACE data will provide ground truth.

[The_Global_Warmer]

albedo is paramount.  Can't keep having it getting lower and lower and spreading and spreading or melt will get out of hand fast.

[SVT450R]

These estimates are based on surface albedo. GRACE data will provide ground truth.

Indeed it will be interesting to see the GRACE data when it comes out for the rest of the melt season.  Here is GRACE up to June 2014 from the Arctic report card.

 

Between the beginning of June 2013 and the beginning of June 2014, which corresponds closely to the period between the onsets of the 2013 and 2014 melt seasons, there was virtually no net change in cumulative ice sheet mass. The very small 6 Gt (Gigatonne) loss during that 12 month period, just 2% of the mass loss of 294 Gt between 2003 and 2013, indicates a slowing in the rate of ice mass loss. The negligible June 2013 to June 2014 mass loss follows a 474 Gt mass loss between June 2012 and June 2013, the largest annual loss observed in the GRACE record. A GRACE mass estimate cannot be obtained for July 2014, because the GRACE K-Band ranging system was switched off during that month to preserve battery life.

 

 

Fig. 3.3. Monthly mass anomalies (in Gigatonnes, Gt) for the Greenland ice sheet since April 2002 estimated from GRACE measurements. The anomalies are expressed as departures from the 2002-2014 mean value for each month. For reference, orange asterisks denote June values (or May for those years when June is missing).

[PhillipS]

Indeed it will be interesting to see the GRACE data when it comes out for the rest of the melt season.  Here is GRACE up to June 2014 from the Arctic report card.

 

Between the beginning of June 2013 and the beginning of June 2014, which corresponds closely to the period between the onsets of the 2013 and 2014 melt seasons, there was virtually no net change in cumulative ice sheet mass. The very small 6 Gt (Gigatonne) loss during that 12 month period, just 2% of the mass loss of 294 Gt between 2003 and 2013, indicates a slowing in the rate of ice mass loss. The negligible June 2013 to June 2014 mass loss follows a 474 Gt mass loss between June 2012 and June 2013, the largest annual loss observed in the GRACE record. A GRACE mass estimate cannot be obtained for July 2014, because the GRACE K-Band ranging system was switched off during that month to preserve battery life.

 

 

Fig. 3.3. Monthly mass anomalies (in Gigatonnes, Gt) for the Greenland ice sheet since April 2002 estimated from GRACE measurements. The anomalies are expressed as departures from the 2002-2014 mean value for each month. For reference, orange asterisks denote June values (or May for those years when June is missing).

 

How do you get a value of 294 Gtons of mass loss between 2003 and 2013?  According to the chart you posted, June 2003 was about 1400 Gtons over the baseline and 2013 was more than 1500 Gtons below the baseline, adding up to around 2900 Gtons of mass loss between 2003 and 2013.  Did you mean 2940 Gtons total mass loss?  Or an average annual mass loss of 294 Gtons?

 

Here is the current net mass balance chart from polarportal .dk:

 

It looks like 2014 will end with around 450 Gtons of mass loss, close to the 2012 record.

[SVT450R]

How do you get a value of 294 Gtons of mass loss between 2003 and 2013?  According to the chart you posted, June 2003 was about 1400 Gtons over the baseline and 2013 was more than 1500 Gtons below the baseline, adding up to around 2900 Gtons of mass loss between 2003 and 2013.  Did you mean 2940 Gtons total mass loss?  Or an average annual mass loss of 294 Gtons?

 

Here is the current net mass balance chart from polarportal .dk:

 

It looks like 2014 will end with around 450 Gtons of mass loss, close to the 2012 record.

 

Here is the whole report i should have included a link in my earlier post.  http://www.arctic.noaa.gov/reportcard/greenland_ice_sheet.html  I believe what they meant by 294GT loss represents the yearly average for the 2003-2013 period.  You have to keep in mind that the polar portal sea level contribution graphic is an estimate and can change.  In the link chubbs posted earlier they mention that the calculated sea level contribution can be overestimated because of high elevation melting that does melt and is picked up by sensors but may refreeze before making it's way to the ocean but it's included to the sea level contribution. I find it a little hard to believe that 2014 will be close to 2012 for the yearly mass balance loss.  The GRACE mass balance image i posted represents the entire year with both mass loss and gain with the orange marks representing the month of June. 

[csnavywx]

It's not completely unbelievable that 2014's SLR contribution is near that of 2012. Firn saturation in S/SW Greenland has become a problem recently. It's wasted down enough that instead of "soaking in", meltwater has a tendency to run off due to saturated and refrozen firn creating an increasingly impermeable near-surface layer. I'll post some papers on this when I get a chance.

[chubbs]

Still no GRACE data for ground truth  but the relatively large summer rise in sea level could indicate that there was a  large Greenland melt this summer.

 

[nflwxman]

Still no GRACE data for ground truth  but the relatively large summer rise in sea level could indicate that there was a  large Greenland melt this summer.

 

sealevelnoaa.png

Wow,  That certainly looks like the largest rise in sea level in the modern record.  Perhaps that is also related to the PDO+ and somewhat budding El Nino changing the global hydrology a bit?

 

For example, there was a pretty large drop in 2011 with the strong La Nina that redistributed precip more over S. Hemisphere continents. 

[AvantHiatus]

SLR is expected to pick up quite substantially. 1 meter by 2100 is the best case scenario without geoengineering.

[The_Global_Warmer]

Some of that is thermal expansion from the rising OHC but the trend is picking up.

[chubbs]

The Greenland GRACE data for 2014 has been posted on the DMI site. Ice sheet losses in 2014 were roughly midway between 2012 and 2013. The method 2 DMI chart posted above, which is based on albedo,  overestimated melt last year. Greenland contributed to sea level rise in 2014 but wasn't the sole factor in explaining the large summer SLR increase.

 

[SVT450R]

The Greenland GRACE data for 2014 has been posted on the DMI site. Ice sheet losses in 2014 were roughly halfway between 2012 and 2013. The method 2 DMI chart posted above, which is based on albedo,  overestimated melt last year. Greenland contributed to sea level rise in 2014 but wasn't the sole factor in explaining the large summer SLR increase.

 

Grace_curve_La_EN_20141100.png

Thanks for the update.  It will be interesting to see the final outcome for the yearly balance come spring when the winter accumulation is counted in.  Based on this graphic below there is the possibility of seeing a below average yearly mass loss for 2014.

 

[PhillipS]

Thanks for the update.  It will be interesting to see the final outcome for the yearly balance come spring when the winter accumulation is counted in.  Based on this graphic below there is the possibility of seeing a below average yearly mass loss for 2014.

 

 

It's been discussed many time - don't confuse GIS surface mass balance with net mass balance.  They are two very different values.  As Chubbs pointed out above, they've already posted the 2014 values and it was an above average melt season.

[SVT450R]

It's been discussed many time - don't confuse GIS surface mass balance with net mass balance.  They are two very different values.  As Chubbs pointed out above, they've already posted the 2014 values and it was an above average melt season.

I understand that but that's not the final outcome.  Yes it shows we lost mass for the summer but the entire yearly loss isn't final yet.  As i understand it's calculated from spring to spring as in May/June 2014-2015.  So if the surface is seeing above average mass gain it should to a degree show up in the yearly mass through winter but i could be wrong.

[chubbs]

Losses this year will probably be in the same range as 2004-9. Note this is far from "normal" since Greenland wasn't losing much mass prior to 2000. Note the 2013+14 data do indicate that the 5+10 year doubling curves are too steep.

 

[SVT450R]

Since it's hard to get a rough number based off the grace graphics i did a little research and found that April 2007 to August 2007 Greenland had lost roughly 238GT mass.  So i took the graphic to ms paint and ran a line from those date points and then dragged it over to this year to get a rough idea.  Yellow mark represents August.

 

[LithiaWx]

Not a great melt year but also it wasn't as bad as the alarmists were screaming about.  2014 was not 2012 that's for sure regardless of what some of those incorrect DMI charts showed.

[PhillipS]

Not a great melt year but also it wasn't as bad as the alarmists were screaming about.  2014 was not 2012 that's for sure regardless of what some of those incorrect DMI charts showed.

 

How do you know they are incorrect?  They use the GRACE satellite for calibration.

[LithiaWx]

How do you know they are incorrect?  They use the GRACE satellite for calibration.

 

Use GRACE data not a model at this point.  The year is over, the black and white numbers are in.

[PhillipS]

Use GRACE data not a model at this point.  The year is over, the black and white numbers are in.

 

Yes, the black and white (well, red and white) number are in.  DMI posted the updated GRACE data a while back.  Here is the latest plot which, I believe, includes all of 2014.

 

 

And they also have a report on the 2014 Greenland Ice Sheet conditions [link] .  An excerpt:

 

The Greenland Ice Sheet contributed approximately 1.2 mm to sea-level rise

 

Satellite observations since 2002 show that the Greenland Ice Sheet is not in balance and that the loss of ice from calving of icebergs and surface melting exceeds the overall mass input from snowfall. The Greenland Ice Sheet has lost about 250 Gt/year of mass over the past decade. One Gt is 1 billion tonnes and is equivalent to 1 cubic kilometer of water. A loss of mass of 100 Gt of ice corresponds to a sealevel rise of 0.28 mm.

 

Satellite measurements from 2003 to 2012 thus show an average mass loss from the ice sheet equivalent to a sea-level rise of about 0.7 mm per year. Initial calculations for 2014 (see Box 2 on page 3) indicate an amount of melting that results in a sea-level rise of up to 1.2 mm. However, 2012 remains the record year, with a mass loss that is equivalent to a sea-level rise of 1.3 mm.

 

So the GIS lost around 400 km3 (400 Gtons) of ice in 2014, second only to 2012.  I find that concerning, if not alarming.

[SVT450R]

Yes, the black and white (well, red and white) number are in.  DMI posted the updated GRACE data a while back.  Here is the latest plot which, I believe, includes all of 2014.

 

 

And they also have a report on the 2014 Greenland Ice Sheet conditions [link] .  An excerpt:

 

The Greenland Ice Sheet contributed approximately 1.2 mm to sea-level rise

 

Satellite observations since 2002 show that the Greenland Ice Sheet is not in balance and that the loss of ice from calving of icebergs and surface melting exceeds the overall mass input from snowfall. The Greenland Ice Sheet has lost about 250 Gt/year of mass over the past decade. One Gt is 1 billion tonnes and is equivalent to 1 cubic kilometer of water. A loss of mass of 100 Gt of ice corresponds to a sealevel rise of 0.28 mm.

 

Satellite measurements from 2003 to 2012 thus show an average mass loss from the ice sheet equivalent to a sea-level rise of about 0.7 mm per year. Initial calculations for 2014 (see Box 2 on page 3) indicate an amount of melting that results in a sea-level rise of up to 1.2 mm. However, 2012 remains the record year, with a mass loss that is equivalent to a sea-level rise of 1.3 mm.

 

So the GIS lost around 400 km3 (400 Gtons) of ice in 2014, second only to 2012.  I find that concerning, if not alarming.

But that's not even close to reality as the recent GRACE update shows a loss of only half of that and once spring is updated it will bring the yearly loss to roughly 175GT or possibly less.

[PhillipS]

But that's not even close to reality as the recent GRACE update shows a loss of only half of that and once spring is updated it will bring the yearly loss to roughly 175GT or possibly less.

 

Please share a link to the source of that.

[SVT450R]

Please share a link to the source of that.

Previous page my post #172 gives you rough idea?

[PhillipS]

Previous page my post #172 gives you rough idea?

 

I had to back and look at your post #172.  Are you seriously saying that you feel your games with MS Paint trump the DMI report when it comes to determining the GIS net mass balance for 2014?  Seriously?!

 

Okay, I'll play with MS Calculator a bits and see what numbers come up.  From the DMI 2014 report: the GIS contributed 1.2 mm to global sea level rise last year, and 100 Gtons of ice amount to 0.28 mm of sea level rise.  So typing 1.2 / 0.28 * 100 in Calculator and hitting = gives me 428.57 Gtons of ice lost last year, but given the uncertainty of the numbers it's probably better say the the GIS lost around 400 Gtons of ice last.  400 Gtons of ice being equivalent to 400 km3 of ice, of course.  Since the record year 2012 caused 1.3 mm of sea level rise and has been reported as 450 Gtons of ice, I think the value of 400 km3 is reasonable.