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This is not actually "indisputable" evidence. First, do we know that the date cherry trees blossom is controlled by temperature? This question isn't addressed
by radford-neal 5y ago
This is not actually "indisputable" evidence.
First, do we know that the date cherry trees blossom is controlled by temperature? This question isn't addressed in the linked post, or in the document it links to with the data. They seem to just assume it must be the case.
However, the fact that the dates show very little change until the late 19th century is reason to doubt that temperature controls the date, since there is other evidence that temperatures (globally, at least) varied significantly over that time.
An alternative is that the date is primarily controlled by amount of sunlight, whose seasonal variation has of course not changed over the last thousand years. Presumably, one could resolve this question by looking at actual temperatures in Kyoto versus flowering date, in recent years.
Second, the variability in the date seems to decrease quite markedly in the late 19th century. That happens to be when the Meiji restoration occurred, accompanied by huge changes in Japanese society, including industrialization. It's also when the source of the dates starts to be mostly newspaper reports.
The initial change in the late 19th century is a narrowing of the spread in dates, with no change in mean. Then the mean date starts to get earlier, declining about linearly starting around 1900. One should note that it is generally accepted that CO2 didn't start to have a substantial effect on climate until about 1950, so a decline starting in 1900 is not obviously attributable to global climate change.
Alternative explanations for the decline include local climate change (unrelated to CO2 levels, but perhaps due to industrialization), changes in reporting, and changes in which cherry trees are being looked at.
- throwawaylinux 5y agoIt disappoints me to see this kind of article so uncritically received here. This is on par with, say, a "scientific" article claiming that the lack of a changing trend in the date of the Canadian wheat crop harvest is indisputable evidence that climate change does not exist. As well as the possible influences you list there are many more - changes in local water or air chemical content, changes in cultivation techniques, planting arrangements, chemical treatments (fertilizer, pesticide, herbicide, etc), changes in the biology of the plant due to natural or artificial selection, changes in pests or other influences of introduced or changing balances of plants/animals/fungi/bacteria. And surely many more I haven't listed. Come on HN, I've seen you fiercely argue the finer points of computer science, rocketry, quantum mechanics and pounce on any slight inconsistency or omission! You don't need to throw rational thinking out the window when you read something that seems like it is "on your side". There exists far stronger evidence of climate change than this.
- neolog 5y agoIt's easier to see nuance in an area you're an expert in.
- throwawaylinux 5y agoIn this case though it's not nuance but blatant gaps and bad logic. In this case it is because it's easy to shut down your rational thinking when confronted with something that seems to affirm your beliefs. An equivalent article that used the flowering date of a different plant to as "indisputable evidence" for the non-existence of global warming would have been rightly torn to shreds on here.
- fallingfrog 5y ago“ Then the mean date starts to get earlier, declining about linearly starting around 1900. One should note that it is generally accepted that CO2 didn't start to have a substantial effect on climate until about 1950..” I think it’s because the trend line is smoothed out over +\-50 years data, or something like that. Or it might be hand drawn. I’m going to download the raw data and see what the trend line looks like using fewer data points.