23 January 2016, Carbon Brief, Arctic and Med face hotspot worries. Uneven heating of the Earth’s surface as a result of climate change could see some regions facing seriously high rises in average temperatures. Forget the notion of a 2˚C global average temperature rise. In parts of the Arctic, regional average warming passed that limit 15 years ago. New research suggests that if the world really does warm to an average of 2˚C, then mean temperatures in the Mediterranean region could be 3.4˚C warmer than in pre-industrial times. And in some parts of the Arctic, 2˚C average warmingcould translate as a 6˚C rise. Sonia Seneviratne, head of the land-climate dynamics group at Switzerland’sInstitute for Atmospheric and Climate Science (ETH Zurich), and colleaguesreport in Nature journal that they have been thinking about the meaning of a 2˚C global average warming. Because it is an average, some regions will inevitably be hotter than this average. So she and her fellow researchers have been trying to calculate what further emissions of greenhouse gases in the atmosphere – the exhausts from fossil fuel combustion that drive global warming – will mean for the people who live in specific parts of the planet. Average warming They focused on what climate models could tell them about extremes of temperature and precipitation in selected regions on the global map. The answer is disconcerting: to limit average temperature rises for the Mediterranean to 2˚C, the world will have to sharply reduce its fossil fuel combustion and contain the global average warming to 1.4˚C. Since the planet is already on average 1˚C warmer than it was in pre-industrial times, this puts the challenge of climate change in an ever more urgent context. Professor Seneviratne pointed out two years ago that extremes might be more significant in climate change than global averages.” We could potentially see even greater regional variation than these findings show” And she is not the only researcher to look for the significance of local climate change implicit in a shift in planetary averages. A team of oceanographers in 2013 examined much the same pattern of variation and predicted that, for some regions,real and enduring climate change could arrive by 2020. Read More here
Category Archives: The Science
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
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