Glacial Addition

This is a follow on to Glacial Retreat, as I stumbled on another glacier related email while trying to find a response from JP.  For context, JP had effectively claimed that glaciers around the globe aren’t retreating at an unprecedented rate.  I responded, and he responded with this (tidied up a little):

In the past perhaps going back to the early 1980s, climate scientists in North America (NASA and NOAA) were publishing charts of global temperatures.  These showed rapid warming in the early part of the century perhaps to 1940 followed by rapid cooling perhaps to about 1975.  These published charts were accompanied by press articles at the time that talked about massive changes in glacial and arctic ice. These press reports were consistent with the reported NASA and NOAA data.  Glaciers were catastrophically melting and then advancing. Arctic ice was massively retreating, then advancing. The cooling from 1945 to 1975 was so marked and the glacial and arctic ice advance so significant that leading climate scientists at the time were speculating about a coming ice age. 

What follows is edited from my response to the highlighted claim.  Before I get into it however, a few clarifying comments regarding the surrounding text.

NOAA was founded in October 1970.  Glaciers have been monitored in a coordinated fashion by the US since 1957 when the World Data Center for Glaciology (WDC) was established.  The WDC was transferred from the US Geological Survey to NOAA in 1976.  NSIDC was created as a separate entity in 1982, and was eventually supported by not only NOAA but also NASA from the 1990s.  NASA is more interested in sea ice than glaciers per se, but even so there was no continuous monitoring of sea ice until 1979.  There was some imagery taken prior to that, by satellites that were not dedicated to the task.  The point here is that there are serious issues associated with claiming anything related to NASA and NOAA records of sea ice and glaciers prior to 1975.

---

The Quaternary Science Reviews article  Glacier fluctuations during the past 2000 years  is packed with interesting data and also some telling figures (although they are occasionally quite difficult to read).  Here are two that stand out for me, both from page 16:

The rubric below says:

Fig. 4. Glacial extent: yellow – glacier(s) smaller than now (end of 20th-early 21st centuries); pale yellow – glacier(s) smaller than maximum extent, but size is generally not well known (included here only if this status is clearly indicated in the original publications, mostly based on the ages of wood incorporated into till or overrun by glaciers); light green – glaciers present in the watersheds (only for lake-sediment records); light blue – glacier(s) advancing or expanded; dark blue – glacier(s) close to or at their maximum extent of the past 2 ka. Although a few glaciers experienced small-scale, intermittent advances during recent decades they were too minor to represent on this summary diagram. The empty cells indicate the absence of information on the glacier status. The descriptions of all series are listed in SM Table 1. The sequence of the series corresponds to the sequence of the records in the SM Table 1. Temperature reconstructions gridded at 50 years (50 year mean) (PAGES 2k Consortium, 2013).

and

From these people at least there is no evidence of glaciers “catastrophic melting and then advancing”.  Admittedly the time scale is not the most useful for looking at the last century, but what seems to be happening is that in the first half of the last century, either glaciers were close to (or at) their maximum extent or they were advancing and the number of advances has plummeted since the beginning of the 1900s which was already a decrease on where things were at the beginning of the 1800s – but it’s not zero unless, possibly, you were to exclude Canada and the USA.

---

My apologies to anyone who thought that “glacial addition” meant something like “glacial advance”.