Dramatic vegetation changes in the past offer clues for future

Friday 31 August 2018

We're already starting to see warning signs of big changes in vegetation across Australia, with declines in the Mountain Ash forests in Victoria and the Pencil Pine forests in Tasmania that are occurring, in large part, due to climate change.

Dramatic vegetation changes in the past hint at dire future

A study on dramatic changes to Earth's vegetation as it emerged from the last ice age and temperatures rose has offered clues on the kinds of transformations that will occur to landscapes with similar increases in temperature anticipated over just the next 150 years.

ANU was part of the international research team that found two-thirds of the world's vegetation underwent significant changes from 21,000 years ago until the pre-industrial era, when the Earth warmed by 4-7 degrees Celsius.

Knowing the relationship between temperature change and the degree of vegetation change allowed the researchers to determine how ecosystems might be transformed under various greenhouse gas emissions models for this new study published in Science.  

One of the ANU researchers, Professor Simon Haberle, said the team used the results from past changes to vegetation at 594 sites including every continent except Antarctica to assess the risk of future changes to ecosystems globally.    

"We're already starting to see warning signs of big changes in vegetation across Australia, with declines in the Mountain Ash forests in Victoria and the Pencil Pine forests in Tasmania that are occurring, in large part, due to climate change," said Professor Haberle from the ANU Department of Archaeology and Natural History.

"Widespread and rapid changes to ecosystems are likely to have major knock-on effects for nationally important ecosystem services such as biodiversity, carbon storage and recreation."

Dr Janelle Stevenson from the ANU School of Culture, History, and Language was a co-author on the new Science paper, which was led by the University of Arizona and involved a team of 42 authors from around the world.

"The palaeoecological data that was used for this study can be viewed as natural experiments exploring the response of ecosystems to drivers of change over time scales that can't be captured by instrumental or historical records," Dr Stevenson said.

ANU contributed and analysed datasets, based on ancient pollen records, for a large number of the sites from Australia and across the Pacific and South East Asia that had been compiled over decades.

"Pollen reflects the changes in landscape and vegetation cover, and the beauty of these ancient pollen records is that they allow us to see these changes over thousands to millions of years," Dr Stevenson said.  

"The parts of Earth that had the biggest temperature increases over the time period analysed also had the most substantial changes in vegetation.

"Our study provides yet another wake-up call that we need to act now to move rapidly towards an emission-free global economy."

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