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
Category Archives: The Science
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
13 December 2015, Climate News Network, Cold water poured on warming pause. COP21: Scientists say pressure from climate sceptic voices may have led to credibility being given to the mistaken claim that there is evidence of a hiatus in global warming. The so-called, and much debated, hiatus in global warming may never have happened, according to new research The scientists say there is no substantive evidence for a recent flattening of the curve in the increase in global average temperatures: in other words, no pause, no slowdown in global warming. “We suggest,” they add, “that the use of those terms is therefore inaccurate.” But first, and briefly, the story so far. In the 1990s, planetary temperatures rose steadily, reaching a then all-time high in 1998. In the 21st century, temperatures on average continued to rise, but the rate of increase seemed to be lower. Even so, 13 of the 14 hottest years ever have happened this century, and 2014 was thehottest year ever. Denialists, sceptics and contrarians seized on the apparent slowdown and claimed that global warming had stopped. And teams of climate scientists were drawn, like moths to a flame, again and again to the question of whether there really was a slowdown − and, if so, why. Unexplained data They kept doing so because that is how science works: researchers worry away at unexplained data. They evaluate each other’s hypotheses, try to kick them to death, and then propose an alternative. So, in the course of the last three years, scientists have variously accepted that global warming was never going to proceed at a steady, inexorable rate, that some Atlantic Ocean cycle might be at play to damp atmospheric temperatures, or that the heat might have disappeared into the Pacific depths. They have also proposed that an increase in volcanic activity may have masked solar radiation, and that extremes of temperature were on the increase even if the average appeared not to be rising intemperately. Read More here
11 December 2015, The Conversation, Climate and the rise and fall of civilizations: a lesson from the past. 2015 will likely be the hottest year on record, beating the previous record set only in 2014. It is also likely to be the first year the global average temperature reaches 1℃ above pre-industrial temperatures (measured from 1880-1899). Global warming is raising temperatures, and this year’s El Niño has pushed temperatures higher still. Although 2015 is unusually hot, 1℃ symbolically marks the halfway point to 2℃, widely considered to be the threshold of “dangerous” climate change. In fact an additional 0.5-1℃ is actually masked by sulphur aerosols which we have added to the atmosphere alongside greenhouse gases. A temperature level of 1℃ (above pre-industrial levels) is similar to or warmer than the peak temperatures of the early Holocene epoch approximately 8,000-7,200 years ago. Studies of the early Holocene provide clues to what was such a world like. The climate roller-coaster The last ice age (or Last Glacial Maximum) peaked around 26,000 years ago. The earth warmed over the coming millennia, driven by an increase in radiation from the sun due to changes in the earth’s orbit (the Milankovic cycles) amplified by CO₂ released from warming water, which further warmed the atmosphere. But even as the earth warmed it was interrupted by cooler periods known as “stadials”. These were caused by melt water from melting ice sheets which cool large regions of the ocean. Marked climate variability and extreme weather events during the early Holocene retarded development of sustainable agriculture. Sparse human settlements existed about 12,000 – 11,000 years ago. The flourishing of human civilisation from about 10,000 years ago, and in particular from 7,000 years ago, critically depended on stabilisation of climate conditions which allowed planting and harvesting of seed and growing of crops, facilitating growth of villages and towns and thereby of civilisation. Read More here