Australia’s warm-up ‘highly unusual’

The first large-scale temperature reconstruction for Australasia indicates there are no other warm periods in the last 1,000 years that match the warming since 1950. Researchers used a range of natural indicators, including tree rings, corals, and ice cores to study Australasian temperatures over the past millennium and compared them to climate model simulations. “Our study revealed that recent warming in a 1,000 year context is highly unusual and cannot be explained by natural factors alone, suggesting a strong influence of human-caused climate change in the Australasian region,” says lead researcher Joelle Gergis from the University of Melbourne. The study published in the Journal of Climate will form the Australasian region’s contribution to the 5th IPCC climate change assessment report chapter on past climate. Gergis says using what is known as “palaeoclimate,” or natural records, is fundamental in evaluating regional and global climate variability over centuries before direct temperature records started in 1910. Gergis collated these natural records provided by decades of work by more than 30 researchers from Australia, New Zealand, and around the world. The reconstruction was developed using 27 natural climate records calculated in 3,000 different ways to ensure the results were robust. Reconstructions of regional temperature not only provide a climate picture of the past, she says, but also a significant platform to reduce uncertainties associated with future climate variability. The study is part of a global collaboration, PAGES, Past Global Changes Regional 2K initiative, which is working to reconstruct the last 2,000 years of climate across every region in the world in order to reduce uncertainties associated with future climate change projections. Collaborators include the Climate Change Research Centre and the ARC Centre of Excellence for Climate System Science, University of New South Wales, where the climate modeling was conducted. The study was funded by the Australian Research Council, Federal Department of Climate Change and Energy Efficiency, and Past Global Changes (PAGES). from futurity