28 January 2016, Climate Home, Scientists pour cold water on ocean geoengineering idea. One keenly-argued possible way of moderating the build-up of carbon dioxide in the atmosphere may not work, scientists have concluded. They say there is evidence that seeding the oceans with iron so that the algae that live there will multiply and devour more CO2 − thus preventing it reaching the atmosphere and intensifying the human contribution to global warming – is not as promising a solution as its supporters hope. The extra iron can certainly stimulate the algae to grow more vigorously, but at a cost. More algae in one part of the oceans may mean there will be fewer in other areas, the researchers say. Report: Scientists warn against geoengineering as short-term climate fix. They report in Nature journal that the depths of the central Pacific Ocean contain ancient sediments that cast doubt on iron’s ability to slow the Earth’s steady temperature rise. In parts of the oceans that lack the iron that plants need, algae are scarce. Experiments have shown that dumping iron into these areas can encourage algal growth, so large-scale fertilisation could theoretically reduce atmospheric CO2. The seafloor sediments the team studied show that, during past ice ages, more iron-rich dust blew from cold and barren landmasses into the oceans, apparently producing more algae in these areas and, presumably, a creating natural cooling effect. But the researchers say increased algal growth in one area can inhibit growth elsewhere, because ocean waters are always on the move and algae also need other nutrients, such as nitrates and phosphates. Read More here
25 January 2016, The Guardian. Sea level rise from ocean warming underestimated, scientists say. Thermal expansion of the oceans as they warm is likely to be twice as large as previously thought, according to German researchers. The amount of sea level rise that comes from the oceans warming and expanding has been underestimated, and could be about twice as much as previously calculated, German researchers have said. The findings in the Proceedings of the National Academy of Sciences, a peer-reviewed US journal, suggest that increasingly severe storm surges could be anticipated as a result. Sea level can mount due to two factors – melting ice and the thermal expansion of water as it warms. Until now, researchers have believed the oceans rose between 0.7 to 1mm per year due to thermal expansion. But a fresh look at the latest satellite data from 2002 to 2014 shows the seas are expanding about 1.4mm a year, said the study. “To date, we have underestimated how much the heat-related expansion of the water mass in the oceans contributes to a global rise in sea level,” said co-author Jurgen Kusche, a professor at the University of Bonn. The overall sea level rise rate is about 2.74mm per year, combining both thermal expansion and melting ice. Read More here