Arguments
Do growing glaciers disprove global warming?
Posted on 6 September 2007 by John Cook
A common skeptic tactic is citing studies out of context to misrepresent their significance. While globally, glaciers are shrinking, there are isolated cases where glaciers are growing. These anomalies are seized upon as proof against global warming. For example, a growing glacier in the Himalayas (Fowler 2006) is frequently mentioned, "confounding global warming alarmists" despite the fact that satellite measurements observe "an overall deglaciation of 21%" from 1962 to 2007 across the Himalayas.
Another region gaining recent attention is the Californian Whitney glacier on Mount Shasta which has grown 30% over the last 50 years. The reason Mount Shasta is bucking the trend is explained by scientist Erik White: "Mount Shasta is right at the very northern end of areas influenced by El Nino and were at the southern end of areas affected by La Nina. So between the two we get to see the benefits of that which means more snow and rain in this area."
This is confirmed by another study A precipitation-dominated, mid-latitude glacier system: Mount Shasta, California (Howat 2007). Howat concludes that while temperature is often a dominant factor on glacier volume changes, in the case of Mount Shasta, precipitation dominates. However, they predict the warming temperature trend will eventually dominate resulting in near total loss of Mount Shasta’s glaciers by the end of the century.
Are many glaciers growing?
The World Glacier Monitoring Service tracks mass balance measurements for a sample of glaciers from around the world. The following table shows the glacier mass balance over 2002 and 2003 (negative values indicate shrinkage):
While a small percentage of glaciers are increasing in mass, the overwhelming majority are shrinking and the shrinking trend is increasing (eg - 77% in 2002, 94% in 2003). However, a statistically significant trend is better calculated over a longer time period.
Long term global trends in glacier shrinkage
Globally, glaciers are shrinking in area and thickness and the melt rate has accelerated dramatically since the mid-1990s. The National Snow and Ice Data Center have calculated global change in glacier volume - their results show glaciers are shrinking at an alarming rate.
I am not familiar with the number of glaciers. Do you know what percent this is or how they represent all glaciers?
"Preliminary mass balance values for the year 2006 are now available from more than 80 glaciers worldwide. The continuous mass balance statistics below are calculated based on the 30 glaciers in 9 mountain ranges*** with long-term data series back to 1980. The statistics for the year 2005 are based on 29 glaciers from 9 regions, and the preliminary values for the year 2006 result from 27 glaciers in 8 regions. The related statistics and figures will be updated as soon as the missing data becomes available."
It concerns me that only 30 datasets are used out of a total of 80...that looks very like cherrypicking.
In any event glacier melt is a response to GW and acts as a buffer in the system. It has indirect effects on CO2 lockup by increasing groundwater and mineral transfers (land biomass increase); by moderating ocean temps/salinity and mineral availabilty so increasing oceanic biomass.
The datasets cover the period 1960 - 2005 but a lot are very recent - 1980 onwards - from my understanding of the world chart, some 13 extra datasets have been included since 2001 ( I could be mis-interpreting the chart!)which, to my mind, would skew the resultant.
Environmental Effects of Increased Atmospheric Carbon Dioxide
which includes the following graph of glacier shrinkage ;-
This data goes back a lot longer than the data in John's article above and tends to refute his conclusions.
Any comments?
You'll have to look in the original linked document for the graph I'm afraid...