8 December 2016, The Conversation, Climate shenanigans at the ends of the Earth: why has sea ice gone haywire? There is no doubt that 2016 has been a record-breaking year for Earth’s climate. We will have to wait another couple of months for the final tally, but 2016 will be the hottest year in recorded history globally. Average temperatures are well above 1℃ warmer than a century ago. Global average temperatures, and “global warming”, often give the impression of a gradual change in Earth’s climate occurring uniformly across the planet. This is far from the truth – particularly at the ends of the Earth. The Arctic and Antarctic are behaving very differently from the global picture. One particular polar change that has caught the attention of scientists and the media this year has been the state of sea ice. The seasonal growth and decay of sea ice over the Arctic and Southern oceans is one of the most visible changes on Earth. But in the past few months its seasonal progression has stalled, plunging Earth’s sea ice cover off the charts to the lowest levels on record for November. Explaining what has caused this unexpectedly dramatic downturn in sea ice is a tale of two poles. Arctic amplifiers The northern polar region is an epicentre for change in our warming world. On average, the Arctic is warming at around twice the global average rate. This is due to several environmental processes in the Arctic that amplify the warming caused by rising atmospheric greenhouse gas levels. One of these amplifiers is the sea ice itself. …The southern story It’s a different story when we look at the ocean-dominated southern hemisphere. Antarctic climate records point to a delay in some of the effects of “global warming”. The reasons are still debated, partly because of the much shorter climate records that scientists have to work with in the Antarctic. But it is likely that the expansive Southern Ocean is an important climate change dampener that is able to “hide” some of the extra heat being absorbed by our planet beneath the ocean surface where we don’t feel it – yet. Read more here
Category Archives: The Science
7 December 2016, Climate Home, UN to extend freeze on climate change geoengineering. Draft documents suggest countries will agree to further ban on large-scale climate techno-fixes, warning risks of damage to biodiversity outweigh potential benefits. Countries should resist the urge to experiment with large scale planetary geoengineering until it’s clear what the consequences of meddling with the oceans or atmosphere may be. That’s the nub of a decision expected to be taken at the UN’s biannual biodiversity summit taking place in Cancun, Mexico this week, emphasising a “precautionary approach” to such projects. With greenhouse gas emissions closing in on levels that could guarantee warming of 1.5C above pre industrial levels and an El Nino-boosted 2016 likely to be the hottest year on record, some scientists are looking to emergency measures. But the UN is sticking to a familiar line: pumping the atmosphere with tiny mirrors to deflect sunlight, boosting the uptake of CO2 in oceans by stimulating plankton growth, or burning wood and pumping the emissions underground could be a bad idea. “We’re concerned that with any initiative regarding the use of geoengineering there needs to be an assessment,” UN biodiversity chief Braulio Ferreira de Souza Dias told Climate Home. “These can have unforeseen results and spin-offs. If you capture carbon in the oceans, this is effective through all the food chains.” Even national risk assessments on individual geoengineering projects would still form an “incomplete basis for global regulation” says the latest iteration of the UN draft decision, echoing previous Convention on Biological Diversity (CBD) decisions in 2010, 2012 and 2014. “More trans-disciplinary research and sharing of knowledge among appropriate institutions is needed,” it says, citing potential impacts on ecosystems and potential ethical issues. Read More here
4 December 2016, University of Melbourne – Pursuit, A long climatic affair. The first extensive retrospective of our climate history has traced the human fingerprint on record-breaking hot temperatures as far back as the 1930s. In recent years climate scientists have been examining what role climate change has played in unusual extreme weather events such as Australia’s hottest summer in 2012-13 and recent heatwaves. But before now, no-one had looked at how far back in time we could go and still link weird weather and record-breaking climate extremes to our influence. Our study, published in Geophysical Research Letters, addresses the question of when exactly climate change started altering the influence of record hot years and summers in a way we can detect. We looked at five regions of the world, as well as the whole globe. Human-made climate change has been influencing heat extremes for decades, with many past records directly attributable to the effect we have had on the climate. We found the last 16 record-breaking hot years globally up to 2014 were made more likely because of climate change (we didn’t include 2015 – the current holder of the hottest year record – because we performed our analysis before the end of last year). Read More here
29 November 2016, Carbon Brief, Guest post: Misleading media coverage of Antarctic sea ice paper. Dr Jonathan Day is a polar climate scientist at the University of Reading. His work focuses on understanding and predicting changes in sea ice in the Arctic and Antarctic. Last week, my colleague Tom Edinburgh and I published an article estimating the extent of Antarctic sea ice in the early 1900s, using sea ice observations recorded by explorers of the time. It received an overwhelming amount of coverage in the media. This was largely because it combined a human-interest story about the conditions faced by the early Antarctic explorers with an illuminating result regarding the thorny issue of Antarctic sea ice trends. Despite significant increases in global average temperature, sea ice in the Antarctic has been slightly increasing in extent over recent decades (1979 – present). Although much of the coverage was very well reported, there were other examples of the results being wrongfully interpreted, perhaps wilfully so. Some of the errors led to confusion, such as conflating sea ice with land ice. Others attempted to cast doubt on the link between greenhouse gases and global mean temperature, which was inappropriate and misleading. Read More here