160-year-old flower helps monitor climate change

Here's a thing. When on Monday we published a blog relating to the early appearance of spring flowers this year, we didn't really look outside the UK bubble, simply publishing a list of flowers - snowdrops, daffodils - which have been seen blooming this balmy January.

But it turns out that this is going on around the world. And thanks to some 150-year-old records, these early-blooming flowers could provide a key for monitoring the effects of global warming.

In the mid-nineteenth century, the American naturalists Thoreau and Leopold (amazing names, right?) kept very detailed records of which flowers bloomed where, and when. And the fact that they did means that flowers are one of our best sources for tracking the progress of climate effects on the environment across more than a hundred years.

“We’re seeing plants that are now flowering on average over three weeks earlier than when they were first observed – and some species are flowering as much as six weeks earlier,” said Charles Davis, Professor of Organismic and Evolutionary Biology at Harvard University. “Spring is arriving much earlier today than it has in the past.”

What Thoreau and Leopold (STILL amazing names) help to show is that 2010 and 2012 are the two warmest springs on records. They also enable us to track flower responses to the warming earth: apparently flowers bloom around 4 days earlier for every degree warmer that it gets.

“Thoreau and Leopold are icons of the American environmental movement and it is astonishing that the records both kept decades ago can be used today to demonstrate the impacts of climate change on plant flowering times,” says Professor Richard Primack of Boston University.

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