Related: ABC radio - The World Today: Early butterflies linked to climate change
The University of Melbourne led study found that over a 65 year period, the mean emergence date for adults of the Common Brown butterfly (Heteronympha merope) has shifted 1.6 days earlier per decade in Melbourne, Australia. The findings are unique because the early emergence is causally linked with a simultaneous increase in air temperatures around Melbourne of approximately 0.14°C per decade, and this warming is shown to be human-induced (anthropogenic).
Lead author of the study Dr Michael Kearney from the Department of Zoology, University of Melbourne said the findings could help our ability to forecast future impacts of climate change on biodiversity. "Shifts in these seasonal life cycle events represent a challenge to species, altering the food and competition present at the time of hatching. Studies such as ours will allow better forecasting of these shifts and help us understand more about their consequences," says Dr Kearney.
The research was conducted by Dr Kearney and PhD student Natalie Briscoe. Professor David Karoly from the School of Earth Sciences, University of Melbourne contributed the climate modeling work. Co-authors include Dr Warren Porter (University of Wisconsin) and Drs Melanie Norgate and Paul Sunnucks from Monash University. The study, funded by an Australian Research Council grant to Monash, Melbourne and Wisconsin Universities, was published in Biology Letters, a prestigious international journal of the Royal Society.
"Scientists have previously observed that biological events are happening progressively earlier in spring over the past few decades. This new work has tied the earlier emergence of butterflies directly to a regional temperature increase, and has tied the temperature increase very strongly to increases in greenhouse gas concentrations caused by humans," said Professor Karoly.
Science has filled in the lines between the dots, but our politicians are still to take the necessary actions in regard to controlling greenhouse gas emissions.
- Melbourne University Media release, March 17, 2010 - First study to link earlier butterfly emergence with climate change
- Biology Letters - Study Abstract