What do people make of this?

http://www.guardian.co.uk/environment/2011/sep/15/new-atlas-climate-change

Thanks for the reminder stewgreen. Too often alarmist claims are put out an alarmist projection. Sometimes they slip in a retraction, or a qualification. The Greenland maps are an easier and quick example. More importantly is the rate of ice melt. This alleged to be the greatest contributor to sea level rise, which in turn is meant to be the most visible sign of dangerous, if not catastrophic, human-caused <del datetime="2016-02-26T23:04:47+00:00">global warming</del> climate change. I remember Velicogna 2009 which proclaimed

In Greenland, the mass loss increased from 137 Gt/yr in 2002 – 2003 to 286 Gt/yr in 2007 –2009, i.e., an acceleration of 30 ± 11 Gt/yr2 in 2002–2009.

Yet, just three years later Sheppard + 45 (with Velicogna as one of the others - and used in IPCC AR5 WG1) in Table 1 shows a different picture based on the longer period 1992-2011. For both papers to be correct, Greenland would need to have been gaining ice in 2000-2001 and 2010-2011. In other words, the shorter period of 2002-2009 was just a blip. If this is the case, it will be confirmed by future studies

According to DMI who monitor the Greenland Ice there is a mean gain of 300Gt in mass of ice on Greenland (1990-2013). 2011-2012 saw zero gain which created a bit of a stir at the time, and is still shown on the DMI graph. I seem to recall that the next year was above the mean but could be wrong. as it is not shown. 2014-15 was below the mean but still had a gain of just over 200Gt and the current year is pretty normal so far.

Data can be found at
http://www.dmi.dk/en/groenland/maalinger/greenland-ice-sheet-surface-mass-budget/

Top: The total daily contribution to the surface mass balance from the entire ice sheet (blue line, Gt/day). Bottom: The accumulated surface mass balance from September 1st to now (blue line, Gt) and the season 2011-12 (red) which had very high summer melt in Greenland. For comparison, the mean curve from the period 1990-2013 is shown (dark grey). The same calendar day in each of the 24 years (in the period 1990-2013) will have its own value. These differences from year to year are illustrated by the light grey band. For each calendar day, however, the lowest and highest values of the 24 years have been left out.

I'd expect that for there to be a mean value some years are greater than the mean and some years less. I'd also expect that some regions of Greenland will show a loss most years depending on the weather patterns that year, but over a decent amount of time these regions will change. But the Greenland is melting horror story seems well established unfortunately.

Sandy S

The graphs you referred to show surface mass balance, the resultant of snowfall and melting over the ice sheet surface.For most of the year this will be positive, with a negative period in Summer.

Unfortunately surface mass balance is not the only variable. Like wet cement, the ice sheet flows out into glaciers and ends up calving icebergs.

When you take calving into account the overall mass balance becomes negative over the year.

To quote the text just above the graphs on your DMI page

Note that the accumulated curve does not end at 0 at the end of the year. Over the year, it snows more than it melts, but calving of icebergs also adds to the total mass budget of the ice sheet. Satellite observations over the last decade show that the ice sheet is not in balance. The calving loss is greater than the gain from surface mass balance, and Greenland is losing mass at about 200 Gt/yr.