11 May 2016, The Conversation, Antarctic ice shows Australia’s drought and flood risk is worse than thought. Australia is systematically underestimating its drought and flood risk because weather records do not capture the full extent of rainfall variability, according to our new research. Our study, published today in the journal Hydrology and Earth System Sciences, uses Antarctic ice core data to reconstruct rainfall for the past 1,000 years for catchments in eastern Australia. The results show that instrumental rainfall records – available for the past 100 years at best, depending on location – do not represent the full range of abnormally wet and dry periods that have occurred over the centuries. In other words, significantly longer and more frequent wet and dry periods were experienced in the pre-instrumental period (that is, before the 20th century) compared with the period over which records have been kept. Reconstructing prehistoric rainfall There is no direct indicator of rainfall patterns for Australia before weather observations began. But, strange as it may sound, there is a link between eastern Australian rainfall and the summer deposition of sea salt in Antarctic ice. This allowed us to deduce rainfall levels by studying ice cores drilled from Law Dome, a small coastal ice cap in East Antarctica. It might sound strange, but there’s a direct link between Antarctic ice and Australia’s rainfall patterns. Tas van Ommen, Author provided How can sea salt deposits in an Antarctic ice core possibly be related to rainfall thousands of kilometres away in Australia? It is because the processes associated with rainfall variability in eastern Australia – such as the El Niño/Southern Oscillation (ENSO), as well as other ocean cycles like the Interdecadal Pacific Oscillation (IPO) and the Southern Annular Mode (SAM) – are also responsible for variations in the wind and circulation patterns that cause sea salt to be deposited in East Antarctica (as outlined in our previous research). By studying an ice record spanning 1,013 years, our results reveal a clear story of wetter wet periods and drier dry periods than is evident in Australia’s much shorter instrumental weather record. Read More here
14 April 2016, The Guardian, World’s scientists to join forces on major 1.5C climate change report. Special UN report will offer comprehensive assessment of impacts of a 1.5C rise in global warming on sea level, coral bleaching and biodiversity. Scientists from around the world will contribute to a major UN report on how global temperatures can be held to a rise of 1.5C and what the impact might be on sea level rises, the bleaching of corals and biodiversity. The special report, from the Intergovernmental Panel on Climate Change (IPCC), will assess all the available peer-reviewed science along with other special reports on how land and oceans are being affected by climate change. These will look at the melting of ice in polar and mountain regions, as well as the impact of climate change on cities and food supplies. “We now have a roadmap for the next comprehensive assessment which will be published in 2022, in good time for the global stocktake by governments in 2023,” said Hoesung Lee, chair of the panel, in Nairobi. The 1.5C report was requested by governments meeting at the Paris climate talks in December where countries unexpectedly agreed to “pursue efforts” to limit warming to 1.5C above pre-industrial levels. 1.5C marks the point, say many scientists, where there is a real danger of serious “tipping points” in the world’s climate. Temperatures have already risen 1C and show little sign of slowing. “Before the Paris meeting governments were focussing on [a rise of ] 2C. The latest assessment by the IPCC showed that some serious risks to corals and sea-level rise emerge at 1.5C. But there was not much available [science] on these topics. There is a lot we need to find out about 1.5C. We are ready to embark on this,” said Lee. “Limiting warming to 1.5C will be a significant challenge,” said Myles Allen, Professor of Geosystem Science at Oxford university’s Environmental Change Institute (ECI). “In a nutshell, it means we have to reduce emissions twice as fast as we would have done to limit warming to 2C – and that was already looking challenging. Inevitably, people are already starting to ask if it is worth it. These are big tough questions, and we haven’t much time to answer them, so the academic community needs to step up.” Read More here