Rutgers University is the curator of the NASA / NOAA northern hemisphere snow cover data base that can be accessed via their excellent web site Global Snow Lab. The left margin of the home page allows access to daily, weekly and monthly maps, monthly departure (anomaly map), snow and monthly anomalies (charts) and a data download link. Anomalies are based on a comparison with the 1981 to 2010 mean. All in all it is an impressive resource.
I have not come across this valuable resource before and seldom if ever hear or see the data discussed. Intuitively I feel that snow cover should be a sensitive indicator for climate change and global warming. Where I stay in NE Scotland is on the edge of the northern hemisphere snow belt. Sometimes, when it is cold, we will get a snowy winter, like this year. Other years we get no snow at all. Snow is a sensitive indicator for climate. So what does the data have to say? At first glance remarkably little (see chart below). The mid-winter peaks and late summer troughs have been remarkably stable for a planet rumoured to be melting under the burden of atmospheric CO2 and it is necessary to interrogate the data in some fine detail to tease out the interesting story that the data have to tell.
In summary, for the six months September to February snow area has actually been increasing 1967 to 2014! That has to be a surprise. And for the six months March to August snow area has been decreasing. The trends are generally very gradual and barely significant. But what the data show is that the northern hemisphere is getting snowier winters accompanied by more rapid melt in spring and summer. The latter is not surprising since we know that the lower troposphere is warming (at least we think we know that to be the case).
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