Climate change can have a significant impact on the life cycle of species, the number of individuals of a species, the overall number of species, and the composition and distribution of species in an area.
However, understanding the specific effects of climate change on different species can be difficult.
Researchers often investigate many different questions in a large geographical area, using various methods that make results from different surveys difficult to compare. This makes it difficult or impossible to measure a local effect of climate change. Additionally, publication bias can skew our overall understanding of the effects of climate change, as studies that show no effect or the opposite effect than expected are often not published.
To study the effects of climate change on specific species in a specific area, researchers from several institutions, including the Norwegian University of Science and Technology’s (NTNU) University Museum, came together to devise a helpful method: using museum collections that have been built up over 250 years. By examining these collections, which are archives of the life in an area over a long period of time, researchers can measure the ecological response to climate change in central Norway. They looked at a number of species, including vertebrates, invertebrates, plants and fungi, and found that even small changes in temperature can have a big impact.
For example, for each degree the temperature rises, researchers found that the number of zooplankton decreases by almost 7700 individuals per cubic metre of water in Jonsvatnet, a lake in Trondheim. Similarly, the number of nesting birds is decreasing by two fewer breeding territories per square kilometre in Budalen in Trøndelag county. Additionally, flowering plants bloom earlier throughout Trøndelag, on average two days earlier per degree warmer. These changes can also have a cascading effect on other species, such as those that eat zooplankton, birds or plants.
“We can see a clear, regional connection with the climate,” says James D. M. Speed, a professor in the Department of Natural History at the NTNU University Museum. He adds, “It’s really interesting to be able to show that we can use the museum collections in new and innovative ways.”