This is [OC], plotted in MS Excel. Data source:

https://www.extremeweatherwatch.com/cities/concord#:~:text=The%20highest%20temperature%20ever%20recorded,occurred%20on%20July%203%2C%201966.&text=The%20lowest%20temperature%20ever%20recorded,occurred%20on%20February%2016%2C%201943

Method was simply to scroll through the yearly data and note dates of first and last temperature of 32F/0C or lower. Probably could have automated it, but that would have taken at least as long as this did.

What are the dotted lines?

1 sigma! Almost forgot!

I would have put the spring dates at the top and fall ones toward the bottom. But whatever, this is just as effective at getting the main point across. (And Concord is not the only place where the growing season has gotten longer.)

Adding more than an extra month to the growing season in less than a century is astounding.

Is global warming helping us solve world hunger by giving us longer growing seasons?

Edit: Lots of interesting perspectives. Thanks for sharing.

>Concord is not the only place where the growing season has gotten longer.

True, but it's the one that I'm concerned with.

One might hope that's all there will be to it. We'll see.

80 years seems like too short of a timespan for this to meaningful, no?

Good question. What do all of you think?

Not a great deal more data than that available in most places here in the U.S. What about Europe?

The year is 2700. Frost has become non existent.. Man makes electromagnetic earth pole diverters to tilt planet at correct angles to form seasonal changes.

An extended growing season is certainly a benefit, but it’s likely to be offset by increased disease and pestilence, and shifts in temps/rain/humidity (that translate to loss or relocation of arable land).

And, come to think of it, in terms of “world hunger”, rice, corn and wheat are the big crops, and they are all single-harvest products - what starts growing at the beginning of the season is what you (hopefully) get at the end. A slightly longer season might mean more indeterminate tomatoes, but doesn’t necessarily translate to more or even better wheat, etc. At the local/home-garden level a longer season certainly would be useful (assuming no changes in normal growing conditions).

I see. That’s a bummer

Take what I'm about to say with a grain of salt as my research is focused on the Acadian and Borel Forest regions. The increase in length of the growing seasons doesn't necessarily equate to an increase in biomass, especially for native species. This is due to the increase in likelihood and severity of climate disturbance (wind, drought,..ect) and shifts in yearly temperatures and precipitation having a stronger negative impact compared to the position impact of a longer growing season.

That's not how that works. It's going to make regions that can normally farm unable to farm. And that's just the start of the problems. Unless you mean just New Hampshire which isn't a farm state.

Interesting that the growing season seems to short en from about 1950 to 1980

The benefits will be globally offset when America’s bread basket is no longer sustainable. If that happens, half the planet is fucked.

I’ve been looking at way too many midterms graphs lately

Yeah! The theory is that the explosion in industrial manufacturing post-WW2 released a bunch of sulfate aerosols that blocked sunlight

I had heard that increase in CO2 would make the planet greener. It was on Planet earth BBC. But your point is well taken.

>Good use case here for using Power Query in Excel - add this into the advanced editor window, pass the year and city as a variable, and you're away. Probably better to run it as a function, but I did this in 3 mins.
>
>let
>
>yr= "1976",
>
>city = "concord",
>
>src = Web.Page(Web.Contents("https://www.extremeweatherwatch.com/cities/" & city &"/year-" & yr)),
>
>tables = Table.Combine({src{1}[Data],src{2}[Data],src{3}[Data],src{4}[Data],src{5}[Data],src{6}[Data], src{7}[Data],src{8}[Data],src{9}[Data], src{10}[Data],src{11}[Data],src{12}[Data]}),
>
>#"Added Suffix" = Table.TransformColumns(tables, {{"Day", each _ & " " & yr, type text}}),
>
>#"Changed Type" = Table.TransformColumnTypes(#"Added Suffix",{{"Day", type date}, {"High (°F)", Int64.Type}, {"Low (°F)", Int64.Type}})
>
>in
>
>#"Changed Type"

A lot of American farmland is unsustainable regardless of climate trends. Large portions of US farmland exist in water scarce areas. The largest example being the famous Central Valley of California which is really a near desert. The whole valley the way until well north of Sacramento averages less than 20 inches of rainfall.

The dotted lines are the aggregate overall trend lines. The last frost days are coming later in the year and the first frost days are occurring later in the year.

Astounding, but in a bad way

What's the r value of those trend lines and why did you choose linear trendlines?

I think it’s long enough, there are lots of atmospheric science papers finding significant trends over such timeframes (or even shorter). There is the question of interdecadal variability and whether we’re just seeing certain long-term cycles…but I’d think 80 years would be enough to even avoid many of those.

What astounds me is that the present day is more or less the same as 80 years ago. What happened in the 70s?

That was a small bout of global cooling, probably caused by sulfurous air pollution. Fixing the acid rain problem made the climate change problem worse.

“More or less” requires explanation in the statement? Not sure what is ment by that? The ice age only requires a 5 degree drop in global climate which is more or less the same as now for example. As for the 70s we could be seeing the oil shortage show up as carbon dioxide influencing the spikes on the graph. Massive use to very little use of oil and I think that was when coal plants started to shut down. Although I could have my timing off on the coal. Or some other function of climate like the transition of change will create greater fluctuations as the weather sorts out temperature leveling.

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A longer growing season will produce higher yields than a shorter season, assuming weather, pests, disease, is the same.

Either you get the crops in early and can use longer maturity hybrids so they have more time to grow the crop or you still have time to replant or plant wet areas.

Additionally, longer season allows farmers to plant more acres helping to address the decrease in available farm labor.

I've noticed changes in fruiting of a local fruit tree where I live, too. When I was a child, a couple of decades ago, there were two fruiting periods: Feb-Mar and Oct-Nov. They've been fruiting once for a slightly extended period in Dec-Jan for the past 8-10 years now...

The 1910s and 1930s were some of the hottest on record, so I wonder how having those decades on the chart would change the perception.

Interestingly if you removed all the data in between the first and last dates there wouldn’t be much difference. Whilst the overall trend is clearly visible in the interim.

It's long enough. Without warming, those fitted lines would be nearly flat. A month added to the growing season is very significant.

don’t let this awesome data fool you. global warming is just a myth made by rich folk to make more money!

Well suppose I picked a quadratic fit...what would the physical justification of it be? I just picked it as the simplest fit.

The data should determine which trendline makes sense to use. Usually this is done by calculating r-values of various trendline fits. By publishing a linear trendline on the chart you're claiming the data has a linear pattern. I'm asking for the evidence you used to make that claim.

Ok, but I wasn't really trying to be all that rigorous about it. This was really an exercise to help my gardening, and I thought the result might be of general interest.