10 November 2015, Science Daily, Geophysics could slow Antarctic ice retreat. Gravitational effects, variations in Earth structure could damp rise in global sea levels. The anticipated melting of the massive West Antarctic Ice Sheet could be slowed by two big factors that are largely overlooked in current computer models, according to a new study. The findings, published online in Nature Communications, suggest that the impact on global sea levels from the retreating ice sheet could be less drastic — or at least more gradual — than recent computer simulations have indicated. Over the past year, numerous studies have warned that parts of the West Antarctic Ice Sheet are on the verge of a runaway retreat. Just last week a high-profile research paper forecast that this could lead eventually to a rise in global sea levels of as much as three metres. The authors of the new Nature Communications paper, however, focus on two geophysical elements that they say aren’t adequately reflected in computer simulations for this region: the surprisingly powerful gravitational pull of the immense ice sheet on surrounding water, and the unusually fluid nature of the mantle beneath the bedrock that the ice sits on. “The fate of the polar ice sheets in a warming world is a major concern for policy makers — and attention is rightly focused on the importance of restraining CO2 emissions and preparing for rising sea levels,” says lead author Natalya Gomez, an assistant professor of Earth and Planetary Sciences at McGill University in Montreal. “But our study shows that for Antarctica, in particular, computer models also need to take into account how gravitational effects and variations in Earth structure could affect the pace of future ice-sheet loss.” Read More here
Category Archives: The Science
10 November 2015, The Conversation, Ocean acidification: the forgotten piece of the carbon puzzle. Ocean acidification – the rise in ocean acidity due to the increased absorption of carbon dioxide (CO₂) – is often thought of as consequence of climate change. However, it is actually a separate, albeit very closely-related problem. Ocean acidification is often referred to as “the other CO₂ problem” because, like climate change, it is primarily a result of the increased emissions of this gas. Despite their common driver, though, the processes and impacts of ocean acidification and climate change are distinct. It should not be assumed that policies intended to deal with the climate will simultaneously benefit the oceans. The current emphasis of global climate policies on a warming target is a case in point. A narrow focus on temperature stabilisation, for example, opens the door for policy interventions that prioritise the reduction of greenhouse gases other than carbon dioxide. This is because non-CO₂ greenhouse gases — like methane and nitrous oxide, which can arise from agricultural and industrial processes — typically have a higher global warming potential and might even be less costly than CO₂ to reduce. In addition, several geoengineering schemes have been proposed to reduce the impacts of a warming climate. Yet such schemes often do nothing to address emissions, and may even exacerbate carbon absorption in the oceans. Read More here
9 November 2015, Science News, The past shows how abrupt climate shifts affect Earth. New research shows how past abrupt climatic changes in the North Atlantic propagated globally. The study, led by researchers from Centre for Ice and Climate at the University of Copenhagen’s Niels Bohr Institute, shows how interaction between heat transport in the ocean and the atmosphere caused the climatic changes to be expressed in different ways across the Southern Hemisphere. The results shows how forcing the climate system into a different state can trigger climate variations that spread globally and have very different impacts in different regions of Earth. This is important now, where rising atmospheric CO2 levels lead to global warming and may trigger abrupt climatic changes. The results have been published in the scientific journal Nature Geoscience. The history of climate on Earth is stored in tiny variations in kilometer-thick ice cores, sediments from lakes and oceans, and other natural archives that are layered down over thousands of years and works as archives of past temperatures. By recovering and deciphering these archives, researchers can reveal how and why the climate changed in the past, and in this way learn how the climate system may react in the future as the planet warms and the ice sheets melt. Read more here
9 November 2015, Carbon Brief, Global temperature rise set to hit 1C of warming this year, Met Office says. Scientists expect 2015 to be the first year where global annual average temperature passes 1C above pre-industrial levels. As of the end of September, global temperature is sitting at 1.02C above the 1850-1900 average, and is “expected to hold” for the rest of the year, a short Met Office report says. This is another piece of evidence of “systematic warming” of the Earth’s climate, saysDr Peter Stott, head of the climate monitoring and attribution at the Met Office Hadley Centre. The news generated some media interest, including headlines in the BBC and Guardian. It comes on the same day as the World Meteorological Organisation announced that the global average concentration of carbon dioxide surpassed 400 parts per million in spring 2015, notes the Independent. ‘Important marker’ Each year, major meteorological organisations around the world calculate the global average surface temperature. It’s just one measure of how the world is changing in response to human-caused greenhouse gas emissions. These provisional figures for 2015 come from HadCRUT4, a dataset of observed global temperatures jointly put together by the UK Met Office and the Climatic Research Unit (CRU) at the University of East Anglia. The data suggests that 2015 will reach, and surpass, 1C above pre-industrial temperatures for the first time in human history. The cross in the top right-hand corner of the chart below shows where the 2015 temperature currently sits compared to the last 150 years. Read more here