20 January 2016, Science Daily, Impact of human activity on local climate mapped. Earth’s temperature has increased by 1°C over the past century, and most of this warming has been caused by carbon dioxide emissions. But what does that mean locally? A new study published in Nature Climate Change pinpoints the temperature increases caused by CO2 emissions in different regions around the world. Using simulation results from 12 global climate models, Damon Matthews, a professor in Concordia’s Department of Geography, Planning and Environment, along with post-doctoral researcher Martin Leduc, produced a map that shows how the climate changes in response to cumulative carbon emissions around the world. They found that temperature increases in most parts of the world respond linearly to cumulative emissions. “This provides a simple and powerful link between total global emissions of carbon dioxide and local climate warming,” says Matthews. “This approach can be used to show how much human emissions are to blame for local changes.” Read More here
Category Archives: The Science
19 January 2016, Carbon Brief, Heat absorbed by oceans has doubled since 1997. The ocean is taking up twice as much heat now as it was just two decades ago, relative to pre-industrial times. According to new research, a third of that heat – and rising – is finding its way into the deep ocean below 700m, temporarily slowing warming at Earth’s surface. That the oceans are warming isn’t a surprise to scientists – it’s what we would expect from rising greenhouse gases. The more surprising part is the speed at which it is taking place. The new study, published today in Nature Climate Change, says as much heat entered the oceans in the last 18 years as in the previous 130 years. The new findings add to a growing body of research on the unseen impact of human activity on the oceans and the role they play in moderating the temperature we feel on Earth’s surface, say scientists not involved in the study. A brief history The oceans take up more than 90% of the heat trapped by greenhouse gases. It follows, then, that we would look to the oceans in seeking the fingerprint of human-caused climate change. Read more here
16 January 2016, Climate News Network, Giant boost for south polar waters. Massive icebergs more than 18km long are feeding vital nutrients into the Southern Ocean and helping to increase its carbon storage capacity. British scientists have identified the monsters that fertilise the Southern Ocean and help remove carbon dioxide from the atmosphere. Giant icebergs drifting northwards could be responsible for storing up to a fifth of all the carbon that sinks into the south polar waters. Geographers at the University of Sheffield report in Nature Geoscience journal that they analysed 175 satellite images of ocean colour – an indicator ofphytoplankton activity. They learned that each huge iceberg, as it breaks off the ice shelf and begins to float away, also begins to cascade iron and other vital mineral nutrients in its melting waters. This is enough to stimulate ferocious plankton productivity for up to a month in its wake. The icebergs are not small − the researchers define “giant” as at least 18 kilometres in length − and nor can they be very frequent. Area of influence “We detected substantially enhanced chlorophyll levels, typically over a radius of at least four to 10 times the iceberg’s length,” says Grant Bigg, Professor in Earth Systems Science, who led the research. “The evidence suggests that carbon export increases by a factor of five to 10 over the area of influence, and up to a fifth of the Southern Ocean’s downward carbon flux originates with giant iceberg fertilisation. “If giant iceberg calving increases this century, as expected, this negative feedback on the carbon cycle may become more important than we previously thought.” The guess is that the Southern Ocean accounts for perhaps 10% of the ocean’s absorption of carbon dioxide from the atmosphere. Research such as this is part of the global process of understanding all theintricacies of the carbon cycle − in turn, an important part of modelling future climate change as a consequence of rising levels of greenhouse gas in the atmosphere, driven by human combustion of fossil fuels. Read More here
14 January 2016, Yale Connections, Experts Fault Reliance on Satellite Data Alone. Over-reliance on satellite data to the exclusion of other data can amount to ‘confirmation bias,’ say scientists urging analysis of numerous different data sets. This month’s “This is Not Cool” video focuses on an ongoing, and again festering, climate science controversy, the value and reliability of satellite-derived global temperatures. And of that data at the exclusion of – or as a surrogate for – other data. Independent videographer Peter Sinclair sought reactions of leading climate scientists to points made in a recent hearing of the Senate Commerce, Science and Transportation Committee, chaired by Texas Republican Senator and presidential nominee hopeful Ted Cruz. “According to the satellite data, there has been no significant global warming for the past 18 years,” the senator said.In the hearing, Senator Cruz emphasized that “The satellite data are the best data we have,” an often-echoed point made by those generally scornful of much of the so-called consensus climate science. Climate scientists Michael Mann, Kevin Trenberth, Andrew Dessler, Carl Mears, and Ben Santer, David Titley, and others voice what they see as limitations or shortcomings of the satellite data. They point to a history of documented errors and mistakes that have often caused satellites to underestimate climate warming.Among these errors are a failure to account for “orbital decay,” changes measuring in the diurnal cycle, and faulty calibration of satellite sensors. Most of all, they discourage over-reliance on any single set of data and instead urge consideration of numerous authoritative data sets. Remote Sensing Systems scientist Carl Mears points to inherent problems in reviewing data only from a particular point in time, especially the often-chosen 1998 starting point, which was characterized by a strong El Niño. “If you start driving at the top of a hill, you’re going to go down, at least at the beginning,” says Mears. Andrew Dessler of Texas A&M says he sees in all this an example of “confirmation bias,” with climate contrarians often looking only at data that “tells them what they want to hear.” Read More here