28 August 2017, Climate Home, Link between Hurricane Harvey and climate change is unclear. Reports the devastating storm was made worse by humanity’s carbon emissions fail to grasp climate change is not just about warming. The unprecedented amount of rainfall accompanying Hurricane Harvey immediately raised the question whether and to what extent climate change is to blame. In a warming world the vapour capacity of the atmosphere increases, and more extreme rainfall, like Texas is witnessing right now, is to be expected as a result. This leads many to conclude that climate change exacerbated the impacts of hurricane Harvey. It is very appropriate to highlight that this is the kind of event we expect to see more of in a warming world. However, to apply this argument directly and attribute (and quantify) the impacts from Harvey itself to human-induced climate change, neglects that climate change is not just about warming. In a changing climate, two effects come together: not only does the atmosphere warm up (thermodynamic effect) but the atmospheric circulation, which determine where, when, and how weather systems develop, can change as well (dynamic effect). Changes in the atmospheric circulation can increase the thermodynamic effect (as we saw during floods Louisiana in 2016) or act in the opposite direction to the thermodynamic effect, leading to locally decreasing the risk of extreme rainfall or canceling the effect of the warming alone (examples here). Dynamical factors and thermodynamic aspects of climate change can interact in complex ways and there are many examples where the circulation is as important as the thermodynamics. Read More here
Category Archives: The Science
14 August 2017, ECOS, Mapping fire-prone areas before the fires. Two months after Portugal’s deadliest fire season in recent record, thousands of firefighters have again been deployed in the last few days to battle new wildfires. It’s a crisis Australia knows well from its own bushfire history which paints an equally bleak and devastating picture. Events such as Ash Wednesday in Victoria and South Australia in the 1980s, Black Saturday in Victoria in 2009 and the enduring 2001 Black Christmas in NSW, resulted in hundreds of lives lost and close to 5,000 homes destroyed. These are just three examples of a long list of major Australian bushfire events. As we head towards 2050, climate change is predicted to cause fire seasons to start earlier, end later and involve more frequent extremes of weather that support major loss events. More than ever before, planning and preparation is playing a significant role in mitigating major bushfires and their effects on lives, properties and infrastructure. Following a state-wide project that saw CSIRO develop mapping technology that identified bushfire prone areas in Queensland down to a 25 metre square area, our researchers have now stepped onto the international stage by mapping regions all over the world that have conditions susceptible to fire events. This latest global tool is a valuable resource for hazard analysts, financers, developers and even the general public, seeking bushfire information online. Read More here
14 August 2017, Climate News Network, Climate warms the Earth, not chance. Recent record year temperatures show how climate warms the Earth. Without global warming, such a sequence would have been highly improbable.Each of the last three years has seen record temperatures worldwide, further evidence that climate warms the Earth, not mere chance. Each has been named the warmest year since records began. The chance of this being pure co-incidence is little more than one in a thousand, unless human-induced or anthropogenic climate change is factored in. The chance of 2016 reaching the temperature it did, when it did, would have been one in a million, unless climate change was counted as a contributor. And if anthropogenic global warming, driven by the profligate combustion of fossil fuels over the last two centuries, is fed into the calculations, then the probability becomes quite high: in fact there would be a 50% chance of three consecutive record-breaking years at any time since the beginning of the century, according to a new study in the journal Geophysical Research Letters. Calculating the odds Michael Mann, the distinguished climate scientist at Pennsylvania State University, is at it again. He and colleagues have been calculating the odds on the recent run of high temperatures to see if they can be explained by any factors other than climate change. He has done this before: at the beginning of the year he calculated the chance that 13 of the warmest 15 years ever had all occurred in the first 15 years of this century. The probabilities at their highest worked out at one chance in 5,000, unless climate change was taken into account. At their lowest, the probability was one in 170,000. Read More here
9 August 2017, The Conversation, Southeast Europe swelters through another heatwave with a human fingerprint. Parts of Europe are having a devastatingly hot summer. Already we’ve seen heat records topple in western Europe in June, and now a heatwave nicknamed “Lucifer” is bringing stifling conditions to areas of southern and eastern Europe. Several countries are grappling with the effects of this extreme heat, which include wildfires and water restrictions. Temperatures have soared past 40℃ in parts of Italy, Greece and the Balkans, with the extreme heat spreading north into the Czech Republic and southern Poland. Some areas are having their hottest temperatures since 2007 when severe heat also brought dangerous conditions to the southeast of the continent. The heat is associated with a high pressure system over southeast Europe, while the jet stream guides weather systems over Britain and northern Europe. In 2007 this type of split weather pattern across Europe persisted for weeks, bringing heavy rains and flooding to England with scorching temperatures for Greece and the Balkans. Read More here