Climate scientists across the world are busy trying to calculate the lasting impact that global warming could have on our planet, and new findings bring the issue into sharp focus. Researchers in the US predict that spring could be arriving almost a whole month earlier by the year 2100 - and it may not look quite like the spring we're used to either.
The study used two well-known indicators of the season to reach its conclusions: 'leaf out' (when leaves first start appearing) and 'first bloom' (when flowers begin to bloom). By analysing data logged since 1950 and then extrapolating it forward to 2100, the scientists predicted that spring will end up arriving an average of 23 days earlier than it does today, and its arrival time is set to be a lot more erratic too.
The study's predictions show potential for 'false springs', where the weather starts to get warmer and then goes back to freezing - and that's a big problem for flowers and plants that rely on the prompts of nature to start growing. The team, from the University of Wisconsin-Madison, the US Fish and Wildlife Service and the US Geological Survey, looked at data across the whole of the continental United States and their number-crunching suggests the change is going to be most noticeable on the west coast of the country.
Another potential complication is the behaviour of bird migratory patterns and the insects that plants rely on for pollination. Birds tend to rely on day length as migratory prompts, whereas plants are more likely to rely on temperature. As the study points out, bird populations stand the greatest chance of survival if they can change their annual travel plans to match with the shifting seasons, but plants don't have that same choice.
"Earlier spring onset may cause phenological mismatches [relating to animal and plant life cycles] between the availability of plant resources and dependent animals, and potentially lead to more false springs, when subsequent freezing temperatures damage new plant growth," reads part of the report. "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."
The report, published in Environmental Research Letters, found that the rate of change from 1950 to 2005 was likely to continue in some areas, but not all. By averaging out "internal climate variability" - large-scale disruptions, including the movement of warm ocean known as water El Niño - and assessing data from many different climate models, the researchers attempted to focus as much as possible on changes caused by the so-called greenhouse effect.
Of all the seasons, spring is particularly vulnerable to a more unpredictable climate because it relies on a gradually improving spell of warm weather - a natural process that a few days of frost or rain can impact. The researchers say further study and more accurate prediction models are required to assess just how much of an impact the shifting seasonal calendar is going to have on animals and plant life, and with that in mind, they've created an online repository of weather data for others to tap into.