Temps de lecture :2 minutes
Before human beings even became aware of it, animals and plants felt the first effects of climate change. Spring came earlier and a milder climate allowed species to enter spaces they had not been able to access before. The time and space of the living world had changed.
To find the conditions they are used to, living things migrate towards cooler areas, high up in the mountains or towards the poles. In North America, vegetation and tundra are thus slowly being replaced by conifers and taiga plants. Every year, the boundary between the two ecosystems moves northwards by an average of 12 km. Insects everywhere take advantage of the milder winters to widen their proliferation area. This is the case of the pine processionary, a caterpillar in France and the mountain pine beetle, a beetle that is threatening millions of hectares in Canada.
Even life in the ocean is affected: plankton in the Atlantic Ocean have moved 10 degrees in latitude northwards – that is to say by 1 000 km – over forty years! Man has also been affected: the change in plankton communities has severely reduced the number of cod in the North Sea. This fish is an important resource for fisheries.
But certain species cannot escape. This is the case of the polar bear. It uses the ice floe as a platform to hunt and thus store fat before the summer fast. It has nowhere to go and the spring thaw moves forward 8 days every decade. The polar bear’s hunting season is therefore getting shorter whilst its fast is getting longer. In Canada’s Hudson Bay, the number of polar bears has decreased by 22 % since 1987. The bears have become thinner: on average, the females weigh 70 kg less than 30 years ago. If the Arctic ice cover melts, polar bears will disappear. They have become the unwilling symbols of global warming and its risks.