As snow flurries continued to cause disruption across the country today, spring may feel further away than ever. But recent winters have been ending earlier than ever before, according to a new assessment of Britain's wildlife that reveals global warming could be disrupting the delicate balance of nature.
The analysis confirms that spring and summer are occurring earlier, but also shows that this trend appears to be accelerating. The shift could pose problems for animals, birds and fish that rely on springtime flowering of plants to supply food for their young.
Stephen Thackeray, a biologist at the Centre for Ecology and Hydrology in Lancaster, who co-led the research said: "This is about the desynchronisation of events during the year. Animals and birds time their reproduction to coincide with periods when there will be an abundance of food. If changes mean there is not enough food available then this could have negative consequences for their offspring."
The new study compiled 25,000 records of springtime trends for 726 species of plants, animals, plankton, insects, amphibians, birds and fish across land, sea and freshwater habitats. It analysed them for changes in the timing of lifecycle events, such as egg laying, first flights and flowering, a science known as phenology.
The results showed that more than 80% of trends between 1976 and 2005 indicated earlier seasonal events. On average, the study showed the seasonal timing of reproduction and population growth shifted forward by eleven days over the period, and that the change has accelerated recently.
Thackeray said: "This is the first time that data have been analysed with enough consistency to allow a meaningful comparison of patterns of changing seasonal timing in the UK among such a diverse range of plants and animals."
The study used records drawn from the work of thousands of volunteers who, as part of the UK phenology network, have made painstaking observations of the behaviour of wildlife in gardens and public spaces. It also relies on professional scientists, who have analysed habitats such as the plankton content of water drawn from lakes and coastal waters.
The research, published in the journal Global Change Biology, found large differences between species in the rate at which seasonal events have altered. Changes have been most rapid for many organisms at the bottom of food chains, such as plants and the animals that eat them. Predators have shown slower overall changes in the seasonal timing of their lifecycle events. This could spell problems, as the seasonal timing of reproduction is often matched to the time of year when food supply increases, so that offspring receive food needed to survive. A key question, the scientists say, is whether animals higher up the food chain can adapt to the faster rates of change in the plants and animals they feed on.
Sarah Wanless, who also co-led the research, said: "It is important to realise that this analysis doesn't identify which predator-prey relationships are most at risk from disruption due to changes in timing. What is does do is highlight that the recorded changes need urgent investigation, particularly for species with high economic or conservation importance."
Not all of the species showed a shift to earlier lifecycle events. Some, such as seabirds, now lay their eggs later in the year than they did before. But the scientists said the overall results show that climate warming is having an impact, and that the effect could get worse as temperatures continue to rise.
Richard Smithers of the Woodland Trust said: "Phenology is the canary in the cage. The results of this new study make real our changing climate and its potential to have profound consequences for the complex web of life."
Thackeray said it was difficult to generalise about how the changing climate has affected individual species across Britain, because most of the observations were for specific locations. One study found that oak trees were producing leaves 0.9 days earlier each year, while another found blue tits had changed their time of egg laying by 0.3 days a year. Other research found that hazel flowered a day earlier, and orange tip butterflies took their first flights 0.7 days earlier.
The study involved scientists from 12 UK research institutions, including Butterfly Conservation, Freshwater Biological Association, People's Trust for Endangered Species and the National Pollen and Aerobiology Research Unit at the University of Worcester.
Many of the organisations have now started follow-on research to see which species could be negatively affected by the change in timings and what could be done to help.
Writing in the journal, the scientists warn: "If current patterns and rates of phenological change are indicative of future trends, future climate warming may exacerbate trophic mismatching, further disrupting the functioning, persistence and resilience of major ecosystems and having a major impact on ecosystem services."
