JON CARTWRIGHT

A study of more than 30 watersheds across the western US has cast doubt on the idea that an epidemic of bark beetles has been affecting water supplies.

Researchers at the Colorado School of Mines, US, found no evidence that outbreaks of the mountain pine beetle have affected peak or average daily streamflows in seven western US states. Instead, the authors believe that changes in streamflow patterns are caused by climatic variability.

“When we did not find a consistent pattern of change in the watersheds impacted [by the mountain pine beetle], we decided to dig a little deeper to see if we could explain why some watersheds were significantly impacted while others weren’t,” said Kimberly Slinski. “This study doesn’t provide conclusive proof that rainfall and temperature patterns are driving the streamflow patterns, but the data clearly show that [they] are related.” […]

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The artificial alkalinization of seawater could protect coral reefs from some of the harm from ocean acidification due to rising carbon dioxide emissions, a study by researchers in Germany has concluded.

The study shows that alkalinization – which could be achieved by distributing lime or other alkaline substances in the ocean – could prevent coral dissolving, although it may have harmful side effects.

“We show that the artificial alkalinization of seawater could be one of several strategies that may be needed in conjunction to protect coral reefs from climate change,” said Andreas Oschlies of the GEOMAR Helmholtz Centre for Ocean Research, Germany. […]

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Rising greenhouse-gas emissions could not only lead to climate change, but also boost stratospheric ozone outside the tropics beyond historic levels, according to scientists in the US and the UK.

A study that explored the prospects for stratospheric ozone under different greenhouse-gas emissions scenarios found that the continued emission of carbon dioxide could over-compensate for lost stratospheric ozone towards the end of this century, leading to less transmission of ultraviolet (UV) radiation.

The consequences are unknown, but could affect ecosystems and levels of vitamin D uptake in humans, the scientists say.

“Stratospheric ozone depletion is generally considered to pose more problems than benefits for human health,” said Amy Butler of the US National Oceanic and Atmospheric Administration. “But having higher stratospheric ozone levels than historically experienced also has implications for surface UV.” […]

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Deforestation has increased the occurrence of flooding in Indonesian Borneo over the past 30 years, according to researchers in Australia and Indonesia.

Based on interviews with local villagers and articles from local media sources, the study shows that, in just three years, upwards of 750,000 people from hundreds of settlements were displaced by flooding. Those affected are more likely to have come from regions deforested for mining and oil-palm plantations, the researchers say.

“The relationship between land cover and flooding occurrence in the tropics remains unclear, primarily because the data to study these relationships are difficult to obtain for large geographic scales,” said Erik Meijaard of the University of Queensland. “Our study shows that deforestation does increase the frequency of flood events – and this is important in broader sustainable development planning, where often the benefits of deforestation are quite well known but not the costs.” […]

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The South Atlantic may have been one of the first regions to experience a dramatic shift in atmospheric circulation due to anthropogenic climate change, according to an international study.

The research – which combined computer modelling with proxy records dating back 6000 years – suggests that a low-pressure system to the west of the Antarctic Peninsula has had a rising influence over circulation patterns in the South Atlantic since the 1940s, driving southerly air masses over the Falkland Islands and South Georgia.

The circulation pattern had not previously existed for millennia, the scientists believe, implying its emergence was an anthropogenic phenomenon – although they insist more evidence is needed before making any definite claims. […]

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Published in ERW, 10 Aug 2016

Lessons could be learnt from the way that the Chinese economy responded to climate changes in the 17th to 19th centuries, according to a statistical study by researchers in China and Switzerland.

The team found that when China was ruled by its final imperial dynasty, a general cooling of the climate induced long-term fluctuations in the economy. It also discovered that the population acted primarily as consumers rather than producers, leaving it all the more vulnerable to these economic fluctuations.

“To improve current plans of adaptation or mitigation, we need to know about these past interactions between climate change and human societies,” said Qing Pei of the Education University of Hong Kong. “Economy is usually the pillar of a society. Therefore, lessons on climate change and the economy could be [beneficial in understanding] the future of human beings when facing unprecedented global warming.” […]

The rest of this article is available here.

Published in ERW, 9 Aug 2016

The application of surplus nitrogen fertilizer to cellulosic biofuels can reduce the climate benefit of the crop nearly two-fold, according to a study by US scientists.

The study, which focused on the biofuel crop switchgrass, has shown that increasing application of nitrogen fertilizer leads to an exponential rise in nitrogen leaching and in the emission of the greenhouse gas nitrous oxide. Beyond a small level of fertilizer application, however, the benefit to the crop itself was minimal.

“We are not saying ‘Do not fertilize’,” said Philip Robertson of Michigan State University, US. “If the crop is responsive to nitrogen fertilizer, then it makes good sense to fertilize at rates that result in greater crop growth – but no more than that.” […]

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