I know that the plural of anecdote is not data, and all that. I also know that memories can get weird sometimes. BUT, when I was a kid, it was inescapably winter by the first week of November. Now here it is a couple of days from December and it’s pushing 60 outside. I think this fall we’ve had maybe five days where the high temperature was below 45 or so. Seems to me like the summers are starting earlier and lasting longer, while fall, spring, and winter are getting appreciably shorter. What’s more, winters are getting milder. I remember freezing my ass off day in and day out during my childhood winters; now I think I can remember maybe five days in the past few years where the high temperature was below 20.
So has climate change reached the Midwest? Or is this a combination of mixed memories and limited data making me draw the wrong conclusion?
What I’ve noticed is that the cold weather comes later than it used to, mid January or even close to February. Which leads to my crackpot theory that our calendar is fast, and that we think it’s December when it’s really just October.
In my part of the Midwest, I can’t say I’ve really noticed anything too out of the ordinary. Yes, last winter was pretty mild, but within the past 15 or so years, we got nailed with three blizzards (IIRC). As a kid, I just vaguely remember one: 1979. We already had our first snow a few weeks ago (which, to me, is really early), but it’s been mild since then. Growing up, I don’t remember the cold and snow really kicking in until early January. (I’m 42, for reference.) Anecdotally, it seems like the weather is perhaps a bit more extreme (in that a snowy winter is really snowy, and a warm winter is unusually warm), but that’s really hard to sort out with such a relatively small sample space (I remember perhaps the last 30-35 winters.)
You can get any conceivable* graph out of the NOAA. I picked one region of Minnesota at random, and it definitely shows that the average temperature in November has been extremely high in multiple years the last two decades, and that the extremes in the other directions have been a lot fewer than what was the norm in the previous century.
Of course picking climate change from simple variability is hard enough at the global level, or the doubters would be limited to the truly ignorant, but the smaller region you pick the higher the odds you’re not looking at climate change.
Of course, the odds of a trend being a true change in climate increases when the local trend matches larger regions all the way up to global, so personally I wouldn’t be making plans that assumed Minnesota winters would go back to “normal” any time soon.
OK, well, the data does seem to fit my memory. The coldest winters have all been since 1990 for me. But so have the warmest. So, definitely more extreme and erratic.
Actually, scratch that. I was reading the chart wrong. For Nov-Feb temps, the coldest winter was 1976, followed by 2013 in my lifetime. The majority of the coldest winters in my lifetime have been since 1993. So have the warmest winters. Precipitation-wise, it’s a bit more erratic. We had a spike of snowy winters from the mid-80s to mid 90s, and then again in the mid 2000s Three of the four driest winters since 1975 have also been in that timeframe. Of course, three of the biggest snowfalls in Chicago history have occurred since 1999.
So, pretty much does follow my memory of “more extreme.” There is an upward trend on temperature and precipitation, as well, of course.
Those are just median figures, though. It’s highly variable depending on specific areas. In the Kansas City area, for example, the median freeze season is actually a couple of days longer, while in other parts of Missouri it’s 7-8 days shorter.
We frequently read reports of "Highest rainfall in November since 1908, or “hottest December day since the 1950’s” as ‘confirmation of GW’. This seems to ignore the obvious fact that there was more rain in November or hotter days in December way back then.
Related to that, one should check the fun short video about how steroids in the human body can be compared to human released CO2 in the atmosphere. When the warming increases, the chances of more home runs or more warm days follows.
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The greenhouse gases that we're adding to the atmosphere from the burning of fossil fuels are the steroids of the climate system. The atmosphere has very small amounts of greenhouse gases that occur naturally so by adding just a little bit more of those greenhouse gases by the burning of fossil fuels to the air we change the background state of the climate system.
We increase the temperatures just a little bit but that increase of temperatures is enough to shift the odds toward a much greater chance for extreme heat events and extreme precipitation events.
Normally you’d expect record lows and record highs to balance that over time, but now we’re getting almost three record highs for every record low. So, just as a baseball player on steroids can occasionally strike out, the climate system with increased greenhouse gases can still experience record cold temperatures but the chances of record high temperatures are still much greater.
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Ponds used to freeze over often enough in the Willamette Valley, Oregon that having ice skates in the back of the closet wasn’t uncommon … these ponds haven’t froze over in living memory … breaks my heart we’re getting California weather …