“We know that getting hit is part of the sport.” -Boxer Frank Buglioni
Thirty-two degrees is a magic number in sugaring because without it sap doesn’t flow. A freeze at night and then a thaw during the day creates pressure in the trees. During a run, the sap migrates from the high pressure environment in the trees to the low pressure environment outside the trees, through the tapholes. The run will last as long as there’s a discrepancy between the internal tree pressure and the external, barometric pressure. This might last eight hours, or 24, or 48 (though the longer it goes, the slower the flow gets).
Another important number is 60 degrees, which I kind of look at as the temperature at which spring starts to happen. At 60 the microbes – the bacteria, yeasts, fungi that are in your spouts, sap lines, sap tanks – wake up from their winter slumber and really start to dance. In the early season microbial loads might be 1,000 per milliliter of sap, but above 60 degrees, that number can double every 20 minutes. (And keep in mind that the temperatures in your lines, or in your greenhouse of a plastic truck tank, can be much higher than air temperatures, so really any time it’s above 50 degrees sugarmakers start to take notice.) Do that double-every-20-minutes math over the course of a season and your microbial loads can grow to a trillion parts per milliliter; early-season sap is so clear it looks like water, late-season sap is so cloudy it looks like milk. Eventually, the microbial loads slime up the inside of a taphole and the sap stops running, even if you get a return to ideal temperatures late in the season.
Temperatures above 50 and 60 also affect the physiology of the trees. The warm temperatures influence the sap biochemistry as the tree begins to ramp up to break bud, which affects the flavor.
So. When sugarmakers tell you that ideal sap weather is 25 at night and 45 during the day, that’s the Goldilocks zone – not too cold, not too hot. If we could control the weather with a thermostat, that’s what we’d set it to. But we play the hand we’re dealt, which over the last two weeks in our bush looked something like this:
Date High Low
2/16 31 19
2/17 32 11
2/18 54 12
2/19 52 41
2/20 44 21
2/21 45 14
2/22 58 34
2/23 69 35
2/24 72 40
2/25 69 35
2/26 36 22
2/27 51 21
2/28 51 30
3/1 68 53
The first thing that jumps out at you are the highs. At least three of them represent the warmest temperatures ever recorded in February in over 100 years of record keeping. It makes you wonder how far back you’d have to go to see seventies in February – the Pleistocene? According to the Weather Channel, the freak warmth happened because there was a big slug of high pressure in the North Pacific that made the jet stream dip in a way that funneled colder air to the west and warmer air to us – a sort of reverse of the polar vortex two years ago that funneled the arctic air to us. But it’s impossible not to also consider the role CO2 emissions and climate change are playing in this. Five or six years ago physicists started advocating for a semantic change: they said global warming should really be called global weirding, because weather is complicated, and non-linear, and the best bet as to how rising CO2 levels were going to manifest in future day-to-day weather conditions were anybody’s bet; in other words, it was too simple to say things are going to get hotter; more precisely, things were going to get weird. Wetter and drier. Hotter and colder. Unpredictable.
Sugaring season over the past 5 years has born this out. In 2012, our season ended March 17, which at the time was unprecedented. No one had ever seen 80s in mid-March. In 2013 the sap season was “normal” – it tracked with seasonal averages – though then we had 90s in May, a foot of snow on Memorial Day weekend, and then enough rain in June to come within 0.07 inches of an all-time record. In 2014, spring didn’t come until April – there were still three feet of snow in the mountains on April 1. 2015 was a cold repeat -- we made the majority of our crop in April. Last year winter never showed up – people were making syrup on Groundhog Day. And then this year.
In other words, weird.
I’m concerned. Mostly for the trees. Some popple and red maple on southern hillsides are already breaking bud here. There’s no way they’re not going to get smoked by a freeze, and this on the heels of drought conditions last summer which already have the trees a little stressed.
But the concern is ecological. (I guess moral, too, as our national conversation about how to mitigate climate change seems to be devolving.) From a human-industry perspective, we’re doing all right. We’ve had to take some punches, and scramble to get ready so early (I started tapping in mid-January), but if you look at the lows in that list we got five freezes, which means we got five “runs.” With the help of technology these days, you can gather a lot of sap each time it runs. Nothing has been normal – the start date, the timing of the runs, walking around the woods in a T-shirt in February. But to date we’re at about 8 gallons per tap, which is closing in on what in the good old days was considered a crop. With vacuum we strive to get up around 16 or 17 gallons per tap. They’re calling for good temps next week, and if we get them, and if the sap is still on flavor and hasn’t gone “buddy,” we might still get there. Of course, more of this warmth next week and we could be done.
How are you other sugarmakers doing?