Vanishing Ice

I often think how much I enjoy data analysis, and how much I view data collection and organization as a tedious chore. It’s one of the reasons I consider myself so lucky; I usually don’t do the tedious stuff, instead I swoop in after others (often, a host of others) have done the hard part while I get to do the math (which, in case you haven’t noticed, is the part I love). But I acknowledge the truly astounding amount of work required to get me that data. The effort required, the time required, the hours upon days upon months upon years upon centuries of work, is the raw material for my fun time.

One of the best examples is glacier data. Measurements of glaciers began in earnest in the 19th century, and the collected work is truly that of legions of researchers. Some have even pored over historical records and geological data to extend our knowledge back before they themselves were born, and that’s a lot of work in itself. Now imagine taking all that data, from over a century of diligent efforts, on tens of thousands of glaciers around the world, and putting it all into a useable form so guys like me can work our statistical magic. Just thinking about how much work that all is, makes my head spin.

But that’s what the hard workers have been doing. The pinnacle of their achievement is the collected data holdings of the World Glacier Monitoring Service, headed by Michael Zemp in Switzerland. The thoroughness, the care, the diligence of their efforts are truly impressive.

Zemp and a host of others have just published a new paper reporting analysis of all that data. The results reveal just how different the last few decades have been, not just compared to the preceding hundred years or so, but probably compared to all of recorded history.

The data fall into three broad categories. Glaciological data result from measurements taken of individual glaciers at individual locations (often, a large number of individual locations), primarily based on “stake and pit” measurements in which researchers put a stake in the glacier to use as a marker to measure over time how much the glacier grows or shrinks. Geodetic data estimates glacier volume changes (and by deduction, mass changes) from repeated mapping from the ground, the air, and space. Front variation data records the changes of the front of the glacier, which can be extended to remote areas by remote sensing, and even back in time by the study of clearly dated historical documents. Some front variation data extend as far back as the little ice age, i.e. the 16th century.

One of the results is the extent of glaciers, organized into 19 regions spanning the globe:

Clearly the global average is at its minimum, as are most of the regions of the world. Another is the ratio of advancing glaciers to retreating ones:

Again, the global average is at its minimum, as are most of the regions of the world.

The main result is that not only are the world’s glaciers shrinking overall, the rate of glacier retreat was significantlyl higher in the 1990s than in preceding decades, and significantly higher in the first decade of the 21st century than in the 1990s. The problem isn’t abating, it’s getting worse. There’s certainly been no “pause” or “hiatus” in the wasting away of the world’s glaciers. But perhaps the overall result is best summarized by quoting from the paper itself:

The worldwide retreat of glaciers is probably the most prominent icon of global climate change. The causality of global warming and melting ice is obvious and well understood, at least in principle, by the general public… In this regard it is noteworthy that the global glacier sample shows a largely homogeneous retreat both at the centennial timescale and also over the past few decades. This homogeneous change in a sample covering a wide range of response times is also strong evidence that these changes are not the results of random variability but of globally consistent climatic forcing (cf. Reichert and others, 2002; Roe, 2011)…

To re-iterate that this isn’t just “natural variation”:

Recently, Marzeion and others (2014) showed that glacier mass changes in the late 19th and the first half of the 20th century can be explained satisfactorily by natural variability, whereas the ice loss of the past few decades requires that anthropogenic forcing be included.

They also emphasize that we can expect more glacier loss to come:

With a view to climate change scenarios for the end of this century and corresponding studies related to the modelling of future glacier changes (Church and others, 2013, and references therein), we must anticipate further glacier loss far beyond historical precedent.

I repeat that the amount of work required to collect and organize this much information on this many glaciers, over such a wide-ranging area, over such a long span of time, is amazing. It’s not usually thought of as the “glorious” part of science, but it is the foundation, the bedrock on which science is built. All those who contributed have my thanks.

But from deniers, they only get derision. Anthony Watts posted about the paper, simply quoting the press release but not before the snide comment “From the UNIVERSITY OF ZURICH and the “lets ignore some of these other growing glaciers” department.” Nothing could be further from the truth. They didn’t ignore any glaciers at all, least of all the growing ones, in fact they tallied how many were growing and how many were shrinking. These days, the shrinking ones so vastly outnumber the growing it’s getting ridiculous. But for Anthony Watts, if he can find one growing glacier then he’s willing to dismiss the results of those who have spent a lifetime of hard work, organizing the many lifetimes of work of many others who came before them, just so he can persist in his make-believe world where glacier melt isn’t one of the iconic signs of global warming. Truly, his ignorance knows no bounds.