First and first springs

From flowering trees to migrating butterflies, spring events are happening more and more quickly due to global warming.

Posted at 8:00 am

Philippe Robitaille-Grou

Philippe Robitaille-Grou
The press

In 1947, Jean Combes began a titanic collection of data. The then 20-year-old amateur scientist began recording the date on which the first leaves appeared in various trees in the south-east of the United Kingdom. Seventy-five years later, not a year has gone by.

For Tim Sparks, a professor of environmental science at Cambridge University, this data is a gold mine. “In the 1950s and 1960s, trees had their first leaves almost always in mid-April,” he reports. The dates have been gradually evolving and are now three weeks ahead. »

Professor Sparks joined colleagues at European universities to assess whether this trend was widespread around the world. His article was recently published in the journal Nature Climate Change makes a clear observation: global warming is accelerating the arrival of leaves and flowers on trees.


Tulips on display in the snow at the Montreal Botanical Garden

The researchers analyzed the oldest series of annual data on trees collected from countries in Europe and Asia. In all these series, the leaf and flowering occurred, on average, before 1985 than before 1950, with a difference ranging from 6 to 30 days.

Kyoto cherries are the centerpiece of researchers. “This tree is associated with festivals in Japan, which allows us to have data from 1,200 years ago,” says Tim Sparks. Last year saw the earliest flowering ever recorded.

In the animal kingdom

The first springs are also felt beyond the vegetable kingdom. “There’s a lot of animal testing,” says Tim Sparks. We see it especially in the migrations of insects, amphibians and birds. »

Several species of birds are laying their eggs a month earlier than a century ago, according to a University of Chicago study.

Canada is no exception, says Shawn Leroux. Memorial University of Newfoundland biologist is closely monitoring the impacts of climate change on local species. “Virtually all the spring events we observe arrive in the country earlier: the melting of ice in the lakes, the arrival of butterflies, the flowering of flowers, etc. he says.

species at risk

Is the early awakening of these ecosystems good news? Not necessarily, according to Tim Sparks. “I think the biggest risk is the lack of synchrony between species,” he explains.

For example, as soon as spring arrives, the chicks feed their chicks with caterpillars, which themselves feed on young leaves of still tender trees. However, global warming is not accelerating the development of these three interdependent species at the same rate.

Species are under-resourced. They can move to find food if they are able to migrate and they can feed on other foods if they are able to adapt. If they don’t, they die.

Shawn Leroux, a biologist at Newfoundland Memorial University

Michel Labrecque, head of the scientific research and development division at the Montreal Botanical Garden, is more concerned about weather disruptions caused by climate change.

The snowfall of April 19 is proof of this. “What we are seeing most seriously right now is mostly warming for a few days in March, followed by a return to much colder temperatures,” he notes.


Michel Labrecque, head of the scientific research and development division of the Montreal Botanical Garden

Plants that bloom too soon are at risk of frost. “It can destroy the shoots,” says the botanist. Some fruit trees can’t even produce. »

Of science and beliefs

Tim Sparks now hopes his research will raise awareness about the effects of global warming.

“People can’t see what a tenth of a degree increase means. On the other hand, if we say that spring will come weeks earlier, it will be concrete, ”explains the Cambridge University professor of environmental sciences.

Every year for 20 years, the teacher has photographed the same landscapes of the United Kingdom. His sample is not yet significant, but the images could be a goldmine for future generations of researchers.

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