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Just one degree of warming can change a species

It only takes one degree of warming to change a species, according to a new study led by the Norwegian University of Science and Technology. The researchers looked at the climate responses of individual species by analyzing natural history collections, which they say are an underexploited resource for long-term ecological research.

“Natural history collections can provide unique insight into a wide range of ecological responses over a period of time that is much greater than what most ecological monitoring programs manage. So the collections are an essential and invaluable source for ecological research over time,” said study lead author Professor James D. M. Speed.

All of life on Earth is affected by the surrounding environment, so it is clear that climate change has an impact on species around the world. What is not as clear, however, is how each individual species will respond to specific changes in temperature.

“The climate affects 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,” said Professor Speed.

To investigate how the climate affects individual species, the team set out to examine how plants and animals have been affected by temperature changes in Norway over a long period of time.

“We used museum collections that have been built up over 250 years to measure the ecological response to climate change in central Norway,” said Professor Speed. “We looked at a number of species, including vertebrates, invertebrates, plants and fungi.”

Animal and plant specimens preserved in museum collections hold valuable insight into how we can expect climate change to progressively affect our world today. 

“What these data and the objects in the museum collections have in common is that studying climate change was not one of their purposes when they were collected. Only now are we seeing that the collections are relevant and that we can use them for such a purpose,” said study co-author Tommy Prestø “It’s really interesting to be able to show that we can use the museum collections in new and innovative ways.”

The results of the analysis clearly indicate that even a single degree of warming can induce major changes. The researchers found that:

  • The number of zooplankton decreases by almost 7,700 individuals per cubic meter of water per degree warmer in Jonsvatnet, a lake in Trondheim.
  • The number of nesting birds is decreasing by two fewer breeding territories per square kilometre per degree warmer in Budalen in Trøndelag county.
  • Flowering plants bloom earlier throughout Trøndelag, on average two days earlier per degree warmer.

The researchers also determined that when some species change, the life cycle of other species can change as well. “We can see a clear, regional connection with the climate,” said Professor Speed.

“For certain plant species, we’ve found that they’re flowering on average nine days earlier per century,” said Presto. “This means that some of our plant species bloom three weeks earlier now than they did 250 years ago.”

“But not everything changes with the climate. Some aspects of nature are more resilient. Overall, the distribution of species and species diversity stays stable over time. That surprised us,” said Professor Speed.

Fluctuations in the number of animals and species composition do not directly follow fluctuations in temperature, noted the researchers. A time period of 250 years can have both periods of warming and a stable climate, which means that species could have delayed responses to climate change. 

The greatest immediate threat to plants and animals may be land-use changes such as deforestation. The International Nature Panel IPBES reports that land-use changes have had the largest relative negative impact on nature since 1970.

The study is published in the journal Ecology and Evolution.

By Chrissy Sexton, Editor

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