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: The Science
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
5 July 2017, The Guardian, Climate Change Authority loses last climate scientist. Imagine, if you will, a government board to champion Australian arts without any artists on it, or an agency to advise on medical research without any medical researchers. Or perhaps even, imagine a government authority set up to provide expertise on climate policy without any actual climate scientists. Well you don’t have to imagine that last one, because that’s what we now have – the government’s Climate Change Authority is now sans climate scientist. Prof David Karoly, of the University of Melbourne, has just finished his term on the authority’s board – the only member to stick it out for the full five years. Karoly says without someone to replace him, the authority will struggle to fulfil its legal mandate. He told me: I think that it is critically important that at least one member of the Climate Change Authority is an expert and experienced climate change scientist. Such a member is needed to provide information and interpretation on the latest climate change science publications and data. In my view, it can only do that with a climate change scientist as a member, to provide expert assessment of the effectiveness of proposed greenhouse gas emission reductions nationally and globally, and the projected impacts on Australia from current and future climate change. The Climate Change Authority Act 2011 states that, in conducting a review, the authority must have regard to environmental effectiveness among a number of other matters. I asked the Department of the Environment and Energy if there were any plans to replace Karoly with another climate scientist. The department said: Government appointments to the CCA are a matter for the Government under the CCA’s legislation. The Chief Scientist is an ex officio Member of the Authority and can assist on scientific matters and in providing access to the scientific community, including climate scientists. So in other words, it won’t replace Karoly and will instead just rely on the chief scientist, Alan Finkel, to act as a go-between, which of course is much more efficient and logical than actually having a climate scientist right there in the room. That would be silly, right? Read More here