10 May 2017, Climate News Network, Ocean oxygen decline greater than predicted. Circulation changes caused by warming waters and melting polar ice are the most probable explanations for the rapidly falling levels of oxygen in the ocean. US scientists who have been warning that warmer oceans are more likely to be poorer in dissolved oxygen have now sounded the alarm: ocean oxygen levels are indeed falling, and seemingly falling faster than the corresponding rise in water temperature. That colder water can hold more dissolved gas than warmer water is a commonplace of physics: it is one reason why polar seas are teeming with marine life and tropical oceans are blue, clear and often relatively impoverished. In 2013, an international consortium of marine scientists warned that oxygen levels in the oceans could fall by between 1% and 7% by the century’s end. And this could, other scientists predicted, lead to what they politely called “respiratory stress” for some marine life. Ocean warming Ocean ecologists in the US and Germany warned last year that parts of the deep oceans were already showing signs of oxygen deprivation with corresponding dead zones. Earlier this year, another research group looked at the computer simulations for the years 1920 to 2100 and predicted that the hazards were likely to increasewith warming. Now the team have returned to the issue. They report in Geophysical Research Letters that they looked at data for the last 50 years and found the oxygen levels started dropping in the 1980s, as ocean temperatures began to climb – and falling unexpectedly rapidly. The trend of oxygen falling is about two to three times faster than what we predicted from the decrease of solubility associated with ocean warming,” says Takamitsu Ito, of the School of Earth and Atmospheric Sciences at the Georgia Institute of Technology, who led the study. “This is most likely due to the changes in ocean circulation and mixing associated with the heating of the near-surface waters and the melting of polar ice.” Read More here
Category Archives: Ecosystem Stress
5 April 2017, ECOS, Before the storm. It’s a catastrophe in anyone’s book, not least those of insurance companies anticipating the tens of thousands of claims likely to be lodged.As the floods surged south in the days after Cyclone Debbie hit landfall near Bowen in north Queensland on March 28, a natural disaster was declared in five major centres in northern New South Wales.Citing the chairman of the Insurance Council of Australia, the Australian Financial Review said “in insurance terms, a catastrophe means a disaster that causes a significant number of claims in a region” and for Cyclone Debbie that could be claims over $1 billion. CSIRO’s Dr Chi-Hsiang Wang and colleagues have been researching the cost implications of extreme weather events but with a focus at the other end – predicting the likely cost before the storms. Counting the cost of extreme events Deloitte Access Economics last year delivered a report on building resilient infrastructure which estimated that, between 2002-03 and 2010-11, an annual average of more than $450 million was spent by Australian governments on restoring essential public infrastructure following extreme weather. If it’s business-as-usual, the report said, $17 billion is expected to be spent on direct replacement costs of essential infrastructure due to natural disasters between 2015 and 2050. These estimates don’t factor in the impacts of climate change. In the case of Cyclone Debbie, the wind intensity exceeded the limitations of the building specifications. “It’s not a surprise that we see considerable damage because the intensity is so high,” says Dr Wang. Until now, a cyclone with the force of Debbie was considered a once in a 2,000 year event by Australian design standard for wind actions (AS/NZS 1170.2:2011). That may change. “There’s a consensus among scientists, although not as strong as the consensus around rising global temperatures, that for some tropical cyclone basins around the world they are likely to see events of increased intensity,” he adds. What’s missing? Dr Wang says the current practice for wind impact assessment of physical infrastructure uses only wind intensity (in terms of wind gust) to gauge the damage potential of windstorms. “This ignores other threats brought upon by the accompanying rainfall and storm surge,” he says. Read More here
4 April 2017, Climate News Network, Brazil monkey deaths signal spread of viruses. Climate change and deforestation in Brazil help mosquitoes spread viruses to humans and endangered species of monkeys. Scientists in Brazil believe that global warming and climate change have created conditions that favour the reproduction of the mosquitoes that transmit viruses such as yellow fever, now spreading through previously immune regions of Brazil. The Intergovernmental Panel on Climate Change suggests that an increase of 4°C in mean annual temperatures is possible in these south and central regions because of warming caused by carbon dioxide concentrations. The yellow fever virus can be transmitted to humans and to monkeys, and thousands of monkeys − some from endangered species − have died in the last four months. Most of the deaths have been caused by the virus, but some monkeys have been shot or clubbed to death by Brazilians who erroneously believe that they, and not the mosquitoes, are responsible for transmitting the virus to humans. The woolly spider monkey (muriqui), and the brown howler monkey (bugio) are the species most affected. Sérgio Lucena, a primatologist and zoology professor at the Federal University of Espírito Santo, says that, in fact, monkeys are sentinels because they die before humans. “If the virus begins to propagate in a determined area, the death of monkeys sends us a warning.” Encourage viruses Since January, the yellow fever virus has claimed nearly 2,000 human victims, 300 of them fatal, in a region of Brazil where it had been eliminated in the 1940s. The epidemic began in the state of Minas Gerais last December, and since then it has spread to the neighbouring states of Espirito Santo, Rio, São Paulo and Bahia. Vaccination campaigns are now under way. The virus, which is transmitted by the haemagogus mosquito, is normally confined to the tropical regions in the north of Brazil. Read More here
24 March 2017, Climate News Network, World’s reefs damaged beyond repair. Australia’s Great Barrier Reef and reefs in the Maldives have been dangerously weakened by coral bleaching caused by global warming and El Niño events. The Great Barrier Reef, one of the wonders of the Pacific Ocean, may never fully recover from the combined effects of global warming and an El Niño year, according to a new study in one of the world’s leading science journals. And a second study, in a second journal, warns that increased sea surface temperatures have also caused both a major die-off of corals and the collapse of reef growth rates in the Maldives, in the Indian Ocean. Corals are very sensitive to ocean temperatures, and in unusually hot years – and these have recurred naturally and cyclically since long before humans started burning coal, oil and gas, to accelerate the build-up of greenhouse gases in the atmosphere – the corals react to stress by bleaching. That is, they eject the photosynthesising algae that live with them in symbiosis, to the advantage of both creatures. Hotter oceans But the world’s oceans are becoming hotter anyway, because of global warming driven by greenhouse gas concentrations in the atmosphere. The seas are becoming ever more acidic as atmospheric carbon dioxide reacts with the water. And the periodic return of a blister of oceanic heat in the eastern Pacific called El Niño – Spanish for “The Child”, because it becomes most visible around Christmastime – has begun to put the world’s reefs at risk. The El Niño of 2015-16 triggered a massive episode of bleaching throughout the tropics. And, Australian researchers say in Nature, the bleaching continues. “We’re hoping that the next two to three weeks will cool off quickly, and this year’s bleaching won’t be anything like last year. The severity of the 2016 bleaching was off the chart,” says Terry Hughes, of Australia’s Centre of Excellence for Coral Reef Studies, at James Cook University in Queensland. “It was the third major bleaching to affect the Great Barrier Reef, following earlier heatwaves in 1998 and 2002. Now we’re gearing up to study a potential number four. “We have now assessed whether past exposure to bleaching in 1998 and 2002 made reefs any more tolerant in 2016. Sadly, we found no evidence that past bleaching makes the corals any tougher.” Read More here