I’ve been looking for the robins for weeks now. Already, my yard was cranking out a riot of birdsong. The bluebirds were here. The song sparrow was trilling. Where were the robins?
This morning, almost as if on cue, they showed up. Dozens of them. They hopped about the yard and ate like mad.
But here’s the question: In general, are they showing up earlier now than usual? Is spring springing sooner because of global warming?
Scientists say it is.
This morning, the U.S. Geological Survey reported on a study that found the “green wave” of spring — the budburst on trees and other plants — has already shifted.
The work was based on data collected by citizen scientists participating in its “Nature’s Notebook” program, which tallies all sorts of observations related to when plants flower and when mammals, amphibians, fish, insects and birds change their behavior.
Yesterday, the Union of Concerned Scientists sponsored a press conference in which researchers detailed declines in spring snow cover, longer allergy seasons and shifts in phenology — the timing of plant and animal life cycles — due to climate change.
The scientists reported that, on average, March temperatures in the U.S. are 2.1 degrees Fahrenheit hotter now than since the 1880s, when reliable record-keeping began.
Across the country, the first leaves on plants have started appearing several days earlier than they used to.
Ornithologists are tracking shifts in bird migration.
If the birds arrive early, are the insects feed upon emerging earlier as well? In some cases, changes are in sync. In other cases, not.
Jake Weltzin, executive director, US National Phenology Network, said scientists are looking for the “biological footprint” of seasonal variations — and finding them.
Perhaps most interesting was the report of Lewis Ziska, a US Department of Agriculture plant physiologist who has been studying the nexus of plant biology, climate change and public health.
He’s been looking at how rising CO2 levels affect the nutritional content of food — and the urushiol content of poison ivy. (The skin irritant becomes more potent, alas.)
And sadly for allergy-sufferers, he’s finding that earlier springs and later autumns make for longer, more intense pollen seasons.
He’s found that since the early 1900s, the amount of pollen a ragweed plant produces has doubled with even this small amount of CO2 change.
I’ll be looking at these changes locally as spring progresses.
For today, however, I’ll simply enjoy the birdsong.