Norwegian scientists have studied the consequences of a 1°C rise on vegetation and fauna. They discovered that their life cycles, reproduction, and flowering have undergone a significant shift. Moreover, the greatest changes have occurred during periods of sharply rising temperatures.
The weatherweather affects the life cycle of speciesspecies, the number of individuals of a species and the distribution of species in a region. However, the same rise in temperature has different consequences on different aspects of life. It is precisely this impact that researchers from the Department of Natural History at the Norwegian University of Science and Technology (NTNU) are studying.
The idea is therefore to measure the impact of climate change at the local level: for this, the scientists analyzed hundreds of thousands of samples of plants, fungi, vertebratesvertebrates and invertebrates from the last 250 years from several museums. These “archives of life” allow us to compare the evolution of these species over the years.
Flowering delayed by three weeks in 250 years
These collections of animal and plant species have enabled researchers to understand how the global rise in temperatures affects their evolution in Norway.
For each additional degree, the researchers realized that:
- the number of zooplankton decreases by almost 7,700 individuals per square meter of water, according to studies carried out in the Jonsvatnet lake located in Trondheim;
- breeding birds lose an average of two breeding territories per square kilometer at Budalen in Trøndelag County;
- plants flower on average two days earlier in Trøndelag. For some plants, flowering occurs nine days earlier than a century ago. So that gives a lag of three weeks in 250 years when it comes to these plants.
Seen from a distance, these changes may seem minor, but the slightest decrease in a species, or the simple delay of a few days in flowering, has impacts on the entire life cycle of the species that depend on it.
Stable biological diversity despite global warming
Some aspects of the biodiversitybiodiversity however, did not change, despite the rise in temperatures, in the area studied in Norway: against all expectations, the diversity of species was not reduced, it remained stable, while the researchers thought that the number of species had decreased. Same observation for the geographical distribution of species.
However, the number of different species is a parameter that may be affected later by global warming: the latter can indeed have a rapid impact on the reproduction cycle of certain species, and a much later impact on others. other aspects of biological life.
The greatest changes have occurred during the greatest increases in temperature
How can we know if these changes are directly linked to climate change or to another natural evolution? Scientists have found a clear link between the times when the greatest biological changes occurred and the periods during which the climate underwent major upheavals: the rise in temperatures was greatest between 1900 and 1946, then between 1980 and 2020. Indeed, the period 1946-1979 was marked by a pause in the rise in temperatures. The greatest biological changes have occurred at the time of the greatest climatic changes.
