Another “Warm” Winter
Submitted by Bill Caulfeild-Browne
Astronomically, winter begins with the December solstice, around December 21st, and runs until the March equinox, around March 21st. Climatically however, particularly at our latitude, winter can be defined as the four months comprising December 1st through to March 31st. This column will look back at our cold season using those months.
All four months were warmer than they were in the 20th century. December was higher by 2.7C, January by 4.4C, February by 3.4C and March by 1.9C. The past mean for these months, averaged, was -4.7C; this winter the average was -1.6C.
In other words, our winter in Tobermory was over three degrees Celsius warmer than in the past. This is consistent with the trend of the last twenty years and with most Global Circulation Models. They forecast that winter temperatures would show greater evidence of climate change than summer temperatures – and they do. Our summers are very little changed.
It is well known that the Arctic is warming even faster than we, at 45 degrees latitude, are. This is further evidenced in Northern Ontario where the differences are larger than here.
Precipitation has also changed. We are seeing drier winters although the trend is less obvious. This winter we received 191 mm of moisture (rain/snow combined) whereas the last century averaged 248 mm over the same four months – 30% more than now.
This does not bode well for long-term lake levels, though it has to be said that the Lake Superior watershed has a large effect on Lake Huron, not just our local precipitation. While warmer weather may increase rainfall, it also hastens evaporation – especially where there is little or no ice-cover, as was the case this winter. We only experienced one-quarter of the usual ice-cover.
April is seesawing – we’ve had -7C and +24C in the last two weeks! Stay tuned – real spring will come soon.
