14 July 2017, Nature Communications, The unprecedented 2015/16 Tasman Sea marine heatwave. The Tasman Sea off southeast Australia exhibited its longest and most intense marine heatwave ever recorded in 2015/16. Here we report on several inter-related aspects of this event: observed characteristics, physical drivers, ecological impacts and the role of climate change. This marine heatwave lasted for 251 days reaching a maximum intensity of 2.9 °C above climatology. The anomalous warming is dominated by anomalous convergence of heat linked to the southward flowing East Australian Current. Ecosystem impacts range from new disease outbreaks in farmed shellfish, mortality of wild molluscs and out-of-range species observations. Global climate models indicate it is very likely to be that the occurrence of an extreme warming event of this duration or intensity in this region is respectively ≥330 times and ≥6.8 times as likely to be due to the influence of anthropogenic climate change. Climate projections indicate that event likelihoods will increase in the future, due to increasing anthropogenic influences. Read More here
Category Archives: Impacts Observed & Projected
13 July 2017, Climate Central, Greenhouse Gases Are Rapidly Changing the Atmosphere. Humanity’s grand experiment in the atmosphere continues, and a new report documents just how far it’s gone. On Tuesday, the National Oceanic and Atmospheric Administration released its annual index of 20 key greenhouse gases. It shows that their direct influence on the climate has risen 140 percent since 1750, with 40 percent of that rise coming in just the past 26 years. That increase is almost entirely due to human activities and has caused the planet to warm 1.8°F (1°C) above pre-industrial temperatures. The index takes greenhouse gas measurements from about 80 ships and observatories around the world — gathered in all their parts per million and parts per billion glory — and boils them down into a simple numerical index, which defines the rise from 1700-1990 as 100 percent or simply 1. This year’s number: 1.4. It’s a simple number that contains multitudes. For example, carbon dioxide’s influence on the climate has increased 54 percent overall since 1990. The four other major greenhouse gases in the index, which include nitrous oxide, methane and two types of chlorofluorocarbons, are responsible for 42 percent of the increase with 15 minor greenhouse gases accounting for the missing 4 percent. Carbon dioxide has risen rapidly in the atmosphere, with 2016 marking the second-largest annual increase ever observed at the Mauna Loa Observatory, the world’s main measuring station. This May, monthly carbon dioxide peaked at 409.65 parts per million. That’s a record high and a mark unseen in human history. If emissions continue on their current trend, the atmosphere will hit a state unseen in 50 million years. A bright spot in the report is the decline of chlorofluorocarbons’ warming influence on the planet. The chemicals were commonly used as refrigerants until the Montreal Protocol banned them in 1989. The treaty came about because they deplete the protective ozone layer, but phasing them out has also helped reduce their warming impact on the climate. Read More here
6 July 2017, The Guardian, Hopes of mild climate change dashed by new research. Planet could heat up far more than hoped as new work shows temperature rises measured over recent decades don’t fully reflect global warming already in the pipeline. Hopes that the world’s huge carbon emissions might not drive temperatures up to dangerous levels have been dashed by new research. The work shows that temperature rises measured over recent decades do not fully reflect the global warming already in the pipeline and that the ultimate heating of the planet could be even worse than feared. How much global temperatures rise for a certain level of carbon emissions is called climate sensitivity and is seen as the single most important measure of climate change. Computer models have long indicated a high level of sensitivity, up to 4.5C for a doubling of CO2 in the atmosphere. However in recent years estimates of climate sensitivity based on historical temperature records from the past century or so have suggested the response might be no more than 3C. This would mean the planet could be kept safe with lower cuts in emissions, which are easier to achieve. But the new work, using both models and paleoclimate data from warming periods in the Earth’s past, shows that the historical temperature measurements do not reveal the slow heating of the planet’s oceans that takes place for decades or centuries after CO2 has been added to the atmosphere. “The hope was that climate sensitivity was lower and the Earth is not going to warm as much,” said Cristian Proistosescu, at Harvard University in the US, who led the new research. “There was this wave of optimism.” The new research, published in the journal Science Advances, has ended that. “The worrisome part is that all the models show there is an amplification of the amount of warming in the future,” he said. The situation might be even worse, as Proistosescu’s work shows climate sensitivity could be as high as 6C. Read More here
28 June 2017, Climate Home, Even Boeing-747 tanker jets can’t win our total war on fires. The more effectively we suppress fires, the worse they become. As climate change makes the world more combustible, we need a new approach. In 1910 Ed Pulaski, a US Forest Service ranger, rounded up his men who were fighting a forest fire in dense conifer forests in northern Idaho and forced them, some at gunpoint, to take refuge in an abandoned mine shaft. The Pulaski tunnel (now a tourist site) represents the dramatic historical moment when ad-hoc approaches to controlling wildfire were shown to be utterly inadequate – this heroic failure provided the impetuous for the US Forest Service to declare total war on fire. Nearly all of Pulaski’s men survived the conflagration, one of thousands of fires that burnt across Idaho during an extremely hot and dry summer, an event now known at the ‘Big Burn’. The sheer ferocity, geographic scale and destructive power of the 1910 Idaho fires shifted the focus of the US Forest Service (USFS) from forestry toward fire fighting. This led to the development of networks of fire towers to identify wildland ignitions. They would be extinguished by teams of trained forest fire fighters, many of whom use a combined ax and mattock invented by, and named after, Ed Pulaski.The iconic mascot Smokey Bear was created by the US advertising industry to promote forest fire awareness. The USFS fire fighting policy evolved to a mandated extinguishment of any new forest fire ignition by 10am the following day, with some managers demanding that the fire size was kept below 10 acres. This total war on fire also drove innovation. In the early 1960 the USFS established Fire Lab at Missoula where an aeronautic engineer, redeployed after the defence department project he was working on was cancelled, developed the first mathematical description of fire, creating the foundation for predictive fire behaviour modelling….But there is a very big catch. The US approach is proving to be ecologically and economically unsustainable – especially in an era of increasing fire threat due to climate change.1 Total fire suppression has created the ‘fire suppression paradox’: the more effective suppression is the worse fires become. Fuel that would historically have been burnt by lightning or indigenous people builds up, resulting in catastrophic fires that are uncontainable regardless of the available technology. The fire suppression paradox also has another unintended and counterproductive consequences: communities come to believe flammable landscapes are safe, resulting in increasing urban sprawl into wildlands that are primed to burn. This massively increases the risk of loss of life and property and the inevitable, tragic loss drives further investment into aerial fire fighting. Climate change is turbo-charging this feedback – fire seasons are worsening, fire disasters are becoming more destructive, and hence demands for more investment in aggressive fire fighting are growing worldwide. Collectively this is creating a dangerous and economically and ecologically unsustainable fire-suppression spiral. Read More here