Prehistoric changes in vegetation could predict future of Earth’s ecosystems
(31 August 2018)
Dramatic changes in the Earth’s vegetation at the end of the last ice age could be a sign of future climate driven changes if greenhouse gas emissions are not cut.
New research by an international team of scientists, including researchers at Durham University’s Department of Biosciences, found that the Earth’s vegetation underwent major changes as the last ice age came to an end 14,000 years ago and the planet warmed.
The researchers used their analysis of how vegetation changed after the last ice age to project how much current ecosystems could change in the 21st Century and beyond as global warming progresses.
They found that current warming from climate change might drive an equally dramatic change in vegetation within the next 100 to 150 years unless greenhouse-gas emissions are reduced.
Future climatic changes
The team analysed published reports for 594 sites from every continent except Antarctica, making it the most comprehensive compilation of vegetation and ecological data covering the period from the height of the ice ages 21,000 years ago to the pre-industrial era.
Durham University was responsible for the assessment of data from the European region.
Professor Brian Huntley, Emeritus Professor of Biosciences, Durham University, said: “Using data that reveal how vegetation responded to past climatic changes has provided valuable insights into the potential impacts of projected future climatic changes, and shows just how dramatic and far-reaching those impacts upon the natural world are likely to be.”
The regions of the world that had the biggest temperature increases since the ice ages had the greatest changes in vegetation, the research found.
Knowing the relationship between temperature change and the degree of vegetation change allowed the researchers to determine how ecosystems might change under various greenhouse-gas emissions models.
Risks for ecosystem change
Connor Nolan, a doctoral candidate in the University of Arizona’s Department of Geosciences, said: “We found that ecosystems all over the globe experienced big changes. About 70 percent of those sites experienced large changes in the species that were there and what the vegetation looked like.
“We used the results from the past to look at the risk of future ecosystem change.
“We find that as temperatures rise there are bigger and bigger risks for more ecosystem change.”
The Earth has warmed four to seven degrees Celsius (seven to 13 degrees Fahrenheit) since the last ice age. Climate change projections indicate the world will warm about that much “in the next 100-150 years if greenhouse gas emissions are not reduced substantially,” the authors wrote.
Changes in vegetation could threaten global biodiversity and derail vital services that nature provides to humanity, such as water security, carbon storage and recreation, according to study co-author Professor Jonathan Overpeck, dean of the School for Environment and Sustainability at the University of Michigan, USA.
Professor Overpeck added: “If we allow climate change to go unchecked, the vegetation of this planet is going to look completely different than it does today, and that means a huge risk to the diversity of the planet.”
The research was funded by The National Science Foundation, the US Department of the Interior Southwest Climate Adaptation Science Center, the Russian Academy of Sciences and the Russian Foundation for Fundamental Research funded the research.
The team used previously published research that calculated how the temperature changed from the ice ages to the pre-industrial era for sites throughout the globe.
For each of the sites, the authors enlisted experts to determine whether the degree of vegetation change since the last ice age was low, moderate or large.
The experts classified more than 67 percent of the vegetation changes as high and at least another 26 percent as moderate. The changes were especially pronounced in the mid-to-high latitudes in North America, Europe and South America -- regions that were most heavily glaciated and therefore had warmed the most since the ice ages.
Co-author Dr Stephen Jackson, director of the US Geological Survey’s Southwest Climate Adaptation Science Center, said comparisons in spatial patterns showing the size of ecological change and the size of temperature change matched up.
However, the warming projected for the 21st century and beyond would occur much, much faster, he said.
“We’re talking about the same amount of change in 10 to 20 thousand years that’s going to be crammed into a century or two,” Professor Jackson said. “Ecosystems are going to be scrambling to catch up.”