More Evidence, As If We Needed It, of Global Warming, part three

I am posting this on the day on which Europe is having its warmest May on record, passing previous records by a long ways. The ways I am keeping cool is by sitting under ceiling fans and not doing much except writing. But this series of essays is not about global temperatures directly, but about their effects on the seasonal activities of plants.

I conducted a sixteen-year study of budburst dates in Oklahoma deciduous trees, and I found that winter buds opened in spring earlier and earlier each year, consistent with global warming. The results were highly significant. I did not, however, have time to publish this study in a scientific journal before I retired. I decided instead to publish it on my website. Here is the link to the article, with illustrations. Please note that the mailing address on the cover page is now obsolete; you may contact me through the website email link (stanriceauthor@gmail.com).

I here address an interesting point about this research, aside from its unsurprising conclusion. And that point is, how do we avoid bias?

Here is a photo of mulberry buds.

Everyone is biased, including scientists. The people who proclaim themselves to be unbiased (politicians, industry leaders) are in fact the most biased people in the world. Scientists are much less biased, and for good reason. The process of scientific research requires specific steps to be taken to deliberately avoid bias. So, when I conclude that global warming is occurring, a politician (such as the infamous Oklahoma Senator Jim Inhofe, who said whatever oil companies paid him to say) could accuse me of being biased. This is true, but I, unlike him, deliberately designed my research to minimize the bias. Take that, Jim Inhofe! I cannot tell him this, because he died in 2024.

Here is how I did it. For sixteen years, I walked around and noted the budburst dates of a couple of hundred trees. In the back of my mind, I was thinking that the sixteenth year would have much earlier budburst dates than the first year. That, of course, is bias. But budburst is a continuous process. If you note down the very earliest date on which the buds appear to reawaken in the spring, you get an early budburst date; if you note down the first date that the leaves or flowers emerge from the bud, you get a medium budburst date; if you note down the date on which the leaves or flowers are fully expanded, you get a late budburst date. I had to choose some indicator of budburst; I chose the date on which the bud swelled just enough to allow the tissues inside the bud to be visible. And once I had chosen this indicator, I had to stick with it for sixteen years. You can see this in the color photos I included in the article, and in these blog essays.

The technical term for choosing a standard of measurement is construct validity. You can read about it in my book about the adventure of scientific discovery.

There is, in addition, a tradeoff between how detailed your observation can be and how many observations you can make. You cannot measure everything everywhere. When it comes to spring budburst studies, they fall into two categories:

First, satellite measurements. Satellites can measure buds turning green in the spring over hundreds of square miles. This allows the results, such as earlier budburst, in any one location to be generalizable over a larger area. This gives satellite measurements external validity, that is, they are valid not just for the area in which the measurements were made.

Second, there are ground-based studies, such as mine. I am sure of the budburst date and species for each tree. But, as I openly admit in my article, the external validity of ground based studies is limited.

I will explain, in the next essay, yet one more interesting point about scientific research into global warming.