Spring is arriving ever earlier in the northern hemisphere. One sedge species in Greenland is springing to growth 26 days earlier than it did a decade ago. And in the US, spring arrived 22 days early this year in Washington DC.
The evidence comes from those silent witnesses, the natural things that respond to climate signals. The relatively new science of phenology – the calendar record of first bud, first flower, first nesting behaviour and first migrant arrivals – has over the last three decades repeatedly confirmed meteorological fears of global warming as a consequence of the combustion of fossil fuels.
Severe Flooding, Against a Background of Wind Turbines: November 2012, Tyringham, Bucks. (Image: T. Larkum)
Researchers say the evidence from the plant world is consistent with the instrumental record: 2016 was the hottest year ever recorded, and it was the third record-breaking year in succession. Sixteen of the hottest years ever recorded have happened in the 21st century.
The most dramatic changes are observed in the high Arctic, the fastest-warming place on the planet, according to a study in Biology Letters. As the polar sea ice retreats, the growing season gets ever longer and arrives earlier.
The pattern is not consistent: grey willow sticks to its original timetable, and dwarf birch growth has advanced about five days earlier for each decade. But the sedge, almost four weeks ahead of its timetable in a decade, holds the record, according to a study that observed one plot at a field site in west Greenland, 150 miles inland, for 12 years.
“When we started studying this, I never would have imagined we’d be talking about a 26-day per decade rate of advance,”
says Eric Post, a polar ecologist at the University of California, Davis, department of wildlife, fish and conservation biology, who has been studying the Arctic for 27 years.
“That’s almost an entire growing season. That’s an eye-opening rate of change.”
Read More: The Guardian