By Elisa Jiménez Alonso
“Oh, the barnyard is busy in a regular tizzy, and the obvious reason is because of the season, Ma Nature’s lyrical, with her yearly miracle – spring, spring, spring” sang the cast of the 1954 musical “Seven Brides for Seven Brothers”. The characters of the film, set in 1850, would have been thoroughly surprised if they had experienced spring as early as the US is experiencing it this year. In a modern adaptation, the characters would be singing their song to herald the start of spring nearly a full month earlier.
Evidence has been mounting for about 10 years, that spring is starting earlier and earlier due to climate change. However, the USA National Phenology Network* has recently released a new set of maps that prove just how far spring’s onset is ahead of schedule.
Image: A new set of scientifically backed maps produced by the USGS-led USA National Phenology Network shows just how unusually early spring is arriving in the United States, 2017. USANPN, public domain.
The research also shows a strong link between an early spring and climate change. A warm February like the one experienced in the US this year – the second warmest on record – is four times more likely to happen in today’s climate than in 1900.According to the 2017 calendar, the first day of spring should be 20 March, but in some parts of the US the first green shoots arrived as early as mid-January. Dr Jake Weltzin, a USGS ecologist and the executive director of the USA-NPN, said “while these earlier springs might not seem like a big deal – and who among us doesn’t appreciate a balmy day or a break in dreary winter weather – it poses significant challenges for planning and managing important issues that affect our economy and our society.”
For instance, an early spring can affect human health, making the pollen season longer and more intense. It can also bring disease-carriers like ticks and mosquitos earlier than usual. Furthermore, an early spring disrupt the rhythm between plants and pollinators; this can have significant impacts for agriculture, biodiversity and species distribution.
Image: How do you know when spring has begun? Is it the appearance of the first tiny leaves on the trees, or the first crocus plants peeping through the snow? The Spring Leaf Index is a measure of these early season events in plants, based on recent temperature conditions. This model allows us to track the progression of spring onset across the country. The map shows locations that have reached the requirements for the Spring Leaf Index model (based on NOAA National Centers for Environmental Prediction Real-Time Mesoscale Analysis temperature products). USANPN, public domain.
*Phenology is the study of periodic plant and animal life cycle events and how these are influenced by seasonal and interannual variations in climate, as well as habitat factors.
Explore USANPN’s Phenology Visualisation Tool by clicking here.
Cover photo by by Unsplash/Pixabay (Public Domain)