Butterflies herald global warming for Melbourne in Landmark research

So the common brown butterfly flaps its wings in Melbourne creating ripples around the globe through it's central role in a new study that shows a causal link between human induced global warming and a natural event. The Common Brown butterfly has become an important harbinger of changing climate for Melbourne and Australia. A landmark research project discovered a causal link between increasing greenhouse gases, regional warming and the change in timing of Butterflies emerging in spring over 10 days earlier than they did 65 years ago, a shift that has been linked by the study to regional human-induced climate change.

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.

Sources

• Melbourne University Media release, March 17, 2010 - First study to link earlier butterfly emergence with climate change


• Biology Letters - Study Abstract