To: tejek who wrote (835642 ) 2/10/2015 11:50:08 AM From: Brumar89 Respond to Northern Hemisphere Snow CoverFebruary 4, 2015 Euan Mearns Global Snow Lab 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. 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).The annual cycle in N hemisphere snow cover varies between 3 million sq kms (August) and 50 million sq kms (January). Note that the small negative gradient of the regression is biased by the missing summer data for 1968, 1969 and 1971 although beginning the regression in 1972, a small negative gradient remains. January is normally but not always the month with highest snow cover. Occasionally February takes the prize. Scrolling down through the months from February the amount of snow cover reduces quickly as it melts reaching a minimum in August. August is always the low point. August is an important marker month that will differentiate between a warming and a cooling world. When August snow area begins to increase this would mark the beginning of a new era of snow accumulation. From September the snow area expands again. Winter comes early in some parts of the world. The data time series for each month are actually remarkably uniform and, as already has been mentioned for the six months September to February, snow area has been increasing 1967 to 2014. And for the six months March to August snow area has been decreasing with time. August August is an important month and maps for August 1967 and 2014 are shown below. It is worth looking at 2014 first. There was 2.59 million sq kms of snow and of that, 2.17 was on Greenland. The rest of the northern hemisphere was effectively snow free; presumably the summer snow fields on mountain glaciers are too small to be picked up at this resolution. Compared with August 1967 it can be seen that the Rocky Mountains, the Alps, the Himalayas and Baffin and Ellesmere Islands in Northern Canada had August snow back in 1967 that now melts.August snow maps Click on maps and they will open in separate browser window that will ease comparison between pairs of maps. August snow anomalies January A look at the January chart above shows that January snow cover has been consistently between 45 and 50 million square kms since 1967, though a regression shows a gradual increase with time. However, January 1967 ticks up while January 2014 ticks down and this gives a false picture on the anomaly maps displayed below. I therefore also include anomaly maps for 1968 and 2013 which reverses this random annual bias. January snow maps January anomaly maps Snow and CO2 The figure below shows how there is no obvious connection between rising CO2 levels and declining snow cover. This of course does not prevent the IPCC from claiming that there is.Discussion Perhaps the most significant aspect about the trends in global snow cover since 1967 is how little it has actually changed. Even though the January maximum shows a positive gradient, it is effectively a flat line. The January anomaly distribution is effectively down to “random weather”.http://euanmearns.com/northern-hemisphere-snow-cover-2/
