Let's Revisit Earth's Ice Accumulation

He has shown that he cannot understand "accumulation of 2% per decade of Greenland's ice mass balance."

The growth and decay of ice sheets is driven by a balance
between accumulation of snow on the surface, primarily in
the high-elevation interiors, and the melting, runoff, evapor-
ation, sublimation and iceberg calving that takes place
primarily along the lower-elevation margins. The mass
balance of the Greenland ice sheet, in particular, is of
increasing importance to scientists and policymakers, as
rising air and ocean temperatures have increased the rate of
melting and the velocity of calving outlet glaciers, con-
tributing to a rising sea level (Lemke and others, 2007). The
net mass balance of the Greenland ice sheet has been the
subject of much recent work (e.g. Alley and others, 2007;
Rignot and others, 2008; Wouters and others, 2008; Zwally
and others, 2011). Additionally, investigators have studied
the surface mass balance, primarily accumulation, using
point measurements (Benson, 1962; Ohmura and Reeh,
1991; Dibb and Fahnestock, 2004; Bales and others, 2009),
automated weather stations (e.g. GC-Net: http://cires.
colorado.edu/science/groups/steffen/gcnet/), remote sensing
(Drinkwater and others, 2001; Kanagaratnam and others,
2001; Hawley and others, 2006), and more recently, using
climate models constrained by observations (Box and others,
2004, 2013; Bales and others, 2009; Burgess and others,
2010; Hanna and others, 2011). Spatially extensive ground-
based profiles of accumulation rates, however, are rare
(Benson, 1962). The spatial variability of accumulation on
varying length scales is difficult to determine with point
measurements or climate models, especially when local
topography is considered.
Here we derive spatially extensive measurements of
accumulation along a 1009 km traverse from

1700m a.s.l.
in northwest Greenland to the

3200m a.s.l. center of the
ice sheet. We trace internal reflecting horizons (IRHs) in
400MHz ground-penetrating radar (GPR) data. We use
density profiles collected along the traverse to calculate
electromagnetic wave speed through the snow and firn in
order to determine the depth of the IRHs, and date the IRHs
using snow/firn chemistry data from cores collected at each
end of the traverse.

The 0.022 m w.e.a-1 increase we find implies a ~10%
change in average accumulation in the dry-snow area of the
ice sheet in the past 52 years. The significance of this result
is that increased accumulation, as seen on the East Antarctic
ice sheet by Davis and others (2005), driven by the increased
ability of warmer air to hold moisture, is also evident inland
on the Greenland ice sheet. Box and others (2013) found a
~1.2% decade-1 increase over the 20th century, and our
result is consistent with this, if slightly higher. The signifi-
cance of this for the mass balance of the Greenland ice
sheet, is that at least some of the increased mass loss from
melting at the lower-elevation margins of the ice sheet is
balanced by the small increases in mass gain from increased
accumulation in the higher-elevation interior.

jwoodward48 wrote:Let's be quite clear

jwoodward48 wrote: Let's look at the actual paper!

the two percent growth per decade of the Greenland ice mass balance report reads:The growth and decay of ice sheets is driven by ...

the two percent growth per decade of the Greenland ice mass balance report reads:
The mass balance of the Greenland ice sheet, in particular, is of
increasing importance to scientists and policymakers ...

the two percent growth per decade of the Greenland ice mass balance report reads: The net mass balance of the Greenland ice sheet has been the subject of much recent work (e.g. Alley and others, 2007;
Rignot and others, 2008; Wouters and others, 2008; Zwally
and others, 2011).

the two percent growth per decade of the Greenland ice mass balance report reads: Additionally, investigators have studied
the surface mass balance, primarily accumulation, using
point measurements (Benson, 1962; Ohmura and Reeh,
1991;

the two percent growth per decade of the Greenland ice mass balance report reads: Spatially extensive ground-based profiles of accumulation rates, however, are rare (Benson, 1962).

the two percent growth per decade of the Greenland ice mass balance report reads: Here we derive spatially extensive measurements of
accumulation along a 1009 km traverse from 1700m a.s.l. in northwest Greenland to the 3200m a.s.l. center of the ice sheet.

the two percent growth per decade of the Greenland ice mass balance report reads: The significance of this for the mass balance of the Greenland ice sheet, is that at least some of the increased mass loss from
melting at the lower-elevation margins of the ice sheet is
balanced by the small increases in mass gain from increased
accumulation in the higher-elevation interior.

The significance of this for the mass balance of the Greenland ice sheet, is that at least some of the increased mass loss from melting at the lower-elevation margins of the ice sheet is balanced by the small increases in mass gain from increased accumulation in the higher-elevation interior.

At least some of the increased mass loss is balanced by the small increases in mass gain.

IBdaMann wrote:

jwoodward48 wrote:Let's be quite clear

We don't need to be. We can let the report be clear. After all, it's written in simple, clear and straightforward English. BYOC (Bring You Own Comprehension)

jwoodward48 wrote: Let's look at the actual paper!

Yes, let's...

the two percent growth per decade of the Greenland ice mass balance report reads:The growth and decay of ice sheets is driven by ...

a balance between accumulation of snow... and... melting, runoff, evaporation, sublimation, and iceberg calving...

the two percent growth per decade of the Greenland ice mass balance report reads:
The mass balance of the Greenland ice sheet, in particular, is of
increasing importance to scientists and policymakers ...

the two percent growth per decade of the Greenland ice mass balance report reads: The net mass balance of the Greenland ice sheet has been the subject of much recent work (e.g. Alley and others, 2007;
Rignot and others, 2008; Wouters and others, 2008; Zwally
and others, 2011).

the two percent growth per decade of the Greenland ice mass balance report reads: Additionally, investigators have studied
the surface mass balance, primarily accumulation, using
point measurements (Benson, 1962; Ohmura and Reeh,
1991;

the two percent growth per decade of the Greenland ice mass balance report reads: Spatially extensive ground-based profiles of accumulation rates, however, are rare (Benson, 1962).

the two percent growth per decade of the Greenland ice mass balance report reads: Here we derive spatially extensive measurements of
accumulation along a 1009 km traverse from 1700m a.s.l. in northwest Greenland to the 3200m a.s.l. center of the ice sheet.

the two percent growth per decade of the Greenland ice mass balance report reads: The significance of this for the mass balance of the Greenland ice sheet, is that at least some of the increased mass loss from
melting at the lower-elevation margins of the ice sheet is
balanced by the small increases in mass gain from increased
accumulation in the higher-elevation interior.

Let me know if you need any of the above words explained to you.

the two percent growth per decade of the Greenland ice mass balance report reads: The significance of this for the mass balance of the Greenland ice sheet, is that at least some of the increased mass loss from
melting at the lower-elevation margins of the ice sheet is
balanced by the small increases in mass gain from increased
accumulation in the higher-elevation interior.

jwoodward48 wrote: This one paragraph proves my point.

jwoodward48 wrote: That's the point - they didn't measure the ice mass balance. They measured an increase in how much is added each year.

jwoodward48 wrote: But! If the amount that is taken away each year is more than the amount that is added each year...

IBdaMann wrote:
Here's an analogy.

I measure a certain depth of ice. Because of regular seasonal changes, the ice has discernible layers, one for each year (cycle of seasons). I can measure both the amount of ice that accumulated each year as well as the total ice accumulation over the particular period covered by the depth in question.

I notice that each individual year had a definitively measurable positive amount of ice accumulation that year. I also notice that the overall accumulation rate was 2% per decade.

Now - does this mean that the net accumulation was a loss?


.

spot wrote: You neglected to say whether the ice at the bottom is melting or not. that's why we use the phrase net.

Surface Detail wrote: LOL at IBdaMann's inability to comprehend the simplest of relationships!

Surface Detail wrote: Think of the ice balance as your bank balance. You've had a 2% rise in income, ...

The growth and decay of ice sheets is driven by a balance between accumulation of snow on the surface, primarily in the high-elevation interiors, and the melting, runoff, evaporation, sublimation, and iceberg calving that takes place primarily along the lower-elevation margins.

The mass balance of the Greenland ice sheet, in particular, is of increasing importance to scientists and policymakers...

...as rising air and ocean temperatures have increased the rate of melting and the velocity of calving outlet glaciers, contributing to a rising sea level (Lemke and others, 2007).

The net mass balance of the Greenland ice sheet has been the subject of much recent work (e.g., Alley and others, 2007; Rignot and others, 2008; Wouters and others, 2008; Zwally and others, 2011).

Additionally, investigators have studied the surface mass balance, primarily accumulation, using point measurements (Benson, 1962; Ohmura and Reeh, 1991; Dibb and Fahnestock, 2004; Bales and others, 2009), automated weather stations (e.g., GC-Net: http://cires.colorado.edu/science/groups/steffen/gcnet/), remote sensing (Drinkwater and others, 2001; Kanagaratnam and others, 2001; Hawley and others, 2006), and more recently, using climate models constrained by observations (Box and others, 2004, 2013; Bales and others, 2009; Burgess and others, 2010, Hanna and others, 2011).

Spatially extensive ground-based profiles of accumulation rates, however, are rare (Benson, 1962).

The spatial variability of accumulation on varying length scales is difficult to determine with point measurements or climate models, especially when local topography is considered.

Here we derive spatially extensive measurements of accumulation along a 1009 km traverse from ~1700 m a.s.l. in northwest Greenland to the ~3200 m a.s.l. center of the ice sheet.

We trace internal reflecting horizons (IRHs) in 400 MHz ground-penetrating radar (GPR) data. We use density profiles collected along the traverse to calculate electromagnetic wave speed through the snow and firn in order to determine the depth of the IRHs, and date the IRHs using snow/firn chemistry data from cores collected at each end of the traverse.

jwoodward48 wrote:
Like Into said (I think), ice moves around. Especially when it's...

Under pressure.

jwoodward48 wrote:
But! If the amount that is taken away each year is more than the amount that is added each year...

Tim the plumber wrote:

jwoodward48 wrote:
Like Into said (I think), ice moves around. Especially when it's...

Under pressure.

What would the increase in gradient be from the center of Greenland to the coast for a 80m rise in ice altitude over 400km to the outlet?

What would you expect the resultant percentage gain to the flow rate to be?

Tim the plumber wrote:

jwoodward48 wrote:
But! If the amount that is taken away each year is more than the amount that is added each year...

Growth in mass balance!!

Mass balance is the amount of ice there is with the amount there was taken away.

If that number is negative then there was a loss. If it grows then there is more ice.

jwoodward48 quoted in his signature:
IBdaMann wrote: No, science doesn't insist that, ergo I don't insist that.

jwoodward48 wrote: You're ignoring melting. If nothing melted, sublimated, calved, etc., you'd be entirely correct.

jwoodward48 wrote: "Were you there?" Yeah, no. Please don't use Creationist arguments.

jwoodward48 wrote:

Tim the plumber wrote:

jwoodward48 wrote:
Like Into said (I think), ice moves around. Especially when it's...

Under pressure.

What would the increase in gradient be from the center of Greenland to the coast for a 80m rise in ice altitude over 400km to the outlet?

What would you expect the resultant percentage gain to the flow rate to be?

Hmm? What gradient? Pressure? Height? Temperature?

I have no clue what the outflow of mass is.

jwoodward48 wrote:

Tim the plumber wrote:

jwoodward48 wrote:
But! If the amount that is taken away each year is more than the amount that is added each year...

Growth in mass balance!!

Mass balance is the amount of ice there is with the amount there was taken away.

If that number is negative then there was a loss. If it grows then there is more ice.

You're right! That is the mass balance.

Now, if we are observing the amount of ice added to the top every year, is that...

a. Different from the mass balance
b. The same as the mass balance
c. Equivalent to the square root of hippos minus homeopathy
d. Your mom

(Hint: It's not b.)

IBdaMann wrote:

jwoodward48 wrote: "Were you there?" Yeah, no. Please don't use Creationist arguments.

Please don't EVADE the topic of your blind faith.

jwoodward48 wrote:

IBdaMann wrote:

jwoodward48 wrote: "Were you there?" Yeah, no. Please don't use Creationist arguments.

Please don't EVADE the topic of your blind faith.

Doesn't change the fact that you used a stupid argument. I've been known to do that too. Just stop, please. I'll even forget that you made it.

jwoodward48 wrote: Have you ever personally verified either Special or General Relativity?

IBdaMann wrote:

jwoodward48 wrote: Have you ever personally verified either Special or General Relativity?

You'll have plenty of time to change the topic once we nail down the truth of this matter, i.e. your blind faith in AGW and AGW's effect on the Greenland ice mass balance, and the EVASION this topic requires of you.

A. Have you made any personal observations about changes in the Greenland ice mass balance?

B. Do you believe the net Greenland ice sheet ice mass balance is decreasing year-to-year (present tense) due to AGW?


.

jwoodward48 wrote:As for B, I honestly don't know. I'd have to look into it some more. I'm inclined to say yes, but I'd need more information to be sure.

jwoodward48 wrote: Stop evading. Have you made any personal observations about changes in the Greenland ice mass balance?

jwoodward48 wrote: I'd have to look into it some more.

jwoodward48 wrote:
There is a 2% rise in the accumulation rates at the surface. So if it used to be 100 meters a century, now it's 102.

If there was a greater rise in the opposing "force", that is, the rate of ice leaving the glacier, then the glacier is shrinking. Otherwise, it's growing. (Or staying the same, if the rates are equal, but that's rather unlikely.)