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Don Paul: Western New York is in a warming climate paradox

Climate scientists look at longer time spans involving ice and sediment cores to judge climate change. I tend to look at trends over the last couple of decades in judging climate change, especially on a regional and local scale.

In that time frame, I hadn’t detected very much of a trend on local lake-effect snow accumulations which had consistency for more than a couple of years, if that much. I had assumed less frequent assaults of arctic air would eventually outweigh warmer Lake Erie temperatures. The latter, those lake temperatures, are mainly tied to our warming climate. Eventually, my assumption is likely to become reality. However, that has not yet been the case in the mean, going all the way back to 1930. In other words, that time has not yet arrived.

With all the ups and downs from year to year over all that time, our yearly mean has crept up.

Most evidence points to this trend being tied to warmer lake temperatures (accelerated since the 1980s) and declining ice cover, leading to more evaporation and more moisture availability to the lake-effect process. Thus far, the atmospheric warming in our immediate vicinity in the winter has been insufficient to cause consistent reductions in lake-effect snows over the years. But here is what is projected from now until the end of the century within increasingly reliable regional climate models. Overall, the models project a gradual shifting in the timing of the lake snow season and contraction in snowfall accumulations.

The contraction is not necessarily drastic, and that is where the greatest uncertainty lies. We know eventually we’ll get less snow as warming continues, but how much less is modeled with lower confidence.

In a recent AMS Journal of Climate study, projected reductions in arctic air incursions tied to anthropogenic/human activity-related warming are modeled to go down by 74 percent and 87 percent by 2050 and 2100, respectively. That will mean further declines in ice cover, but it will also mean less arctic air to make for the required temperature contrast between relatively mild lake temperatures and the colder air about 1 mile aloft to produce the rising motion which leads to lake-effect precipitation.

In other words, you can have wide open lakes but if at some point you seldom have true arctic air, you will have less lake-effect generated.

Here is a measure of the decline in lake ice averaged over all five of the Great Lakes which has already occurred over the years. It has to be kept in mind that Lake Erie — being the shallowest lake — is the only one of the five which has more frequent nearly total surface freezing.

Of course, we’ve seen the predicted drastic declines from 1980s climate models in the Arctic Ocean verify in this satellite imagery time lapse. That is, this is actual imagery and not a model.

So far, primary data sources such as the Rutgers Global Snow Lab show the expected decline in snow cover has developed in the mean over a continental scale.

Periods of mean global warming and cooling are never uniform around the world, and past ice and sediment cores show this lack of uniformity. While the global mean warms, there can be pockets of relative cold which persist. Regionally, the amount of warming here has not been as great as in other parts of the temperate climate zone. So, at this point we haven’t yet reached a “tipping point” for climatically related reduced lake snow as a consistent trend.

We will have some lighter snow years, skiers and snowmobilers. But the fat snowy climate lady hasn’t sung yet.

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