From the INSTITUTE OF PHYSICS and the “back to modeling the future” department: Spring to come 3 weeks earlier to the United States
Scientists have projected that the onset of spring plant growth will shift by a median of 3 weeks earlier over the next century, as a result of rising global temperatures
The results, published today (Wednesday 14th October), in the journal Environmental Research Letters, have long term implications for the growing season of plants and the relationship between plants and the animals that depend upon them.
The researchers, based at the University of Wisconsin-Madison, US, applied the extended Spring Indices to predict the dates of leaf and flower emergence based on day length. These general models capture the phenology of many plant species.
Their results show particularly rapid shifts in plant phenology in the Pacific Northwest and Mountainous regions of the western US, with smaller shifts in southern areas, where spring already arrives early.
“Our projections show that winter will be shorter – which sound greats great for those of us in Wisconsin” explains Andrew Allstadt, an author on the paper. “But long distance migratory birds, for example, time their migration based on day length in their winter range. They may arrive in their breeding ground to find that the plant resources that they require are already gone.”
The researchers also investigated so-called ‘false springs’ – when freezing temperatures return after spring plant growth has begun. They showed that these events will decrease in most locations. However a large area of the western Great Plains is projected to see an increase in false springs. “This is important as false springs can damage plant production cycles in natural and agricultural systems” continues Allstadt. “In some cases, an entire crop can be lost.”
These researchers are working on a NASA Biodiversity Grant, with the goal of assisting people working in conservation of public land in the US. As such, the researchers have provided much of their data freely on their website: http://silvis.forest.wisc.edu/
“We are expanding our research to cover all kinds of extreme weather, including droughts and heat waves” concluded Allstadt. “We are particularly interested in how these affect bird populations in wildlife refuges.”
As is typical for “science by press releases”, they don’t bother to mention the name of the study, which is pretty lame for IOP since they not only issued the press release, but they published the study too. So, I looked it up; it’s more RCP8.5 modeling madness.
On the plus side, the authors made everything open source, which is commendable. But what you don’t see in the press release is an admission of uncertainty; like the late great Yogi Berra’s famous line “It’s tough to make predictions, especially about the future.“, they concede “…global climate change may have complex and spatially variable effects on spring onset and false springs, making local predictions of change difficult” .
I find this map they provide interesting in the context of the press release since it seems a good part of the middle U.S. might not see that 3 week earlier onset by 2100.
Spring plant phenology and false springs in the conterminous US during the 21st century
Andrew J Allstadt, Stephen J Vavrus, Patricia J Heglund, Anna M Pidgeon, Wayne E Thogmartin and Volker C Radeloff
The onset of spring plant growth has shifted earlier in the year over the past several decades due to rising global temperatures. Earlier spring onset may cause phenological mismatches between the availability of plant resources and dependent animals, and potentially lead to more false springs, when subsequent freezing temperatures damage new plant growth. We used the extended spring indices to project changes in spring onset, defined by leaf out and by first bloom, and predicted false springs until 2100 in the conterminous United States (US) using statistically-downscaled climate projections from the Coupled Model Intercomparison Project 5 ensemble. Averaged over our study region, the median shift in spring onset was 23 days earlier in the Representative Concentration Pathway 8.5 scenario with particularly large shifts in the Western US and the Great Plains. Spatial variation in phenology was due to the influence of short-term temperature changes around the time of spring onset versus season-long accumulation of warm temperatures. False spring risk increased in the Great Plains and portions of the Midwest, but remained constant or decreased elsewhere. We conclude that global climate change may have complex and spatially variable effects on spring onset and false springs, making local predictions of change difficult.