Migratory birds that no longer migrate in winter. Species thriving in regions where only a decade ago they had never been observed. The leaves of some tree species shrinking in size. All signs of the impact of climate change on biodiversity - a significant impact, even for our own human species.
Climate change, one factor among others
Climate change, fragmentation and destruction of habitats, pollution, overexploitation of resources and biological invasions are all factors that contribute to the worldwide changes that are wreaking havoc on biodiversity. Each of these acts at a different level, from global to local, over the short or long term. Climate change is a global phenomenon with lasting effects. Each species, each ecosystem is affected differently by these factors and it is sometimes difficult to pinpoint the precise cause of any given change observed. Nevertheless, the impact of climate change is now clearly establishment. Its effects are felt all the more in southern regions and in specialized species. The greater the warming, the more species will find it difficult to adapt.
A few examples of climate change impacts on biodiversity
- 28,000 greylag geese wintered in France in 2011, compared with 10 in 1968.
- In just a few years, the Quino checkerspot, a Mexican butterfly that was feared on the brink of extinction, migrated to higher altitudes and changed its feeding habits.
- On 1 January 2015, 368 species of plant were in bloom in the UK, compared with only 20 species fifty years ago.
- The average weight of the Alpine chamois has dropped by 25% since 1980, an adaptation probably due to higher mountain temperatures.
- In Australia, the leaves of the broad-leaf hopbush have shrunk to adapt to an increase in temperature of 1.5% between 1950 and 2005.
Climate change impact on biodiversity: the challenge for humans
Denis Couvet, professor of ecology specialized in the relationship between biodiversity and human societies :
Essential aspects of human life depend on how biodiversity will respond to climate change. This issue is rarely discussed in the public sphere because it’s difficult to bring tangible scientific evidence to the table. A typical example is that of pollination. In China, pollinating insects have completely died out in some regions. But we don’t have the empirical and scientific knowledge to explain why. That shouldn’t stop us, however, from taking measures that we already know to be favourable to pollinators (regulating the use of pesticides, etc.).
With the changes worldwide, the functions of some ecosystems won’t be able to keep up. We know that, faced with these difficulties, humans respond more or less well, particularly in terms of social cohesion. For instance, despite attempts to adapt, the Sumerian and Mayan civilizations died out due to climate variations and over-farming. The effects of today’s climate change on our societies is probably already being felt. The civil war in Syria began after an unprecedented drought prompted many farmers to migrate to the cities.
So for human societies, the impact of climate change on biodiversity is anything but banal. One of the issues for the MNHN is to demonstrate and remind people of the dynamics that exist between biodiversity and society.