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. Read More here
Tag Archives: Extreme Events
21 March 2017, The Guardian, Record-breaking climate change pushes world into ‘uncharted territory’ Earth is a planet in upheaval, say scientists, as the World Meteorological Organisation publishes analysis of recent heat highs and ice lows. The record-breaking heat that made 2016 the hottest year ever recorded has continued into 2017, pushing the world into “truly uncharted territory”, according to the World Meteorological Organisation. The WMO’s assessment of the climate in 2016, published on Tuesday, reports unprecedented heat across the globe, exceptionally low ice at both poles and surging sea-level rise. Global warming is largely being driven by emissions from human activities, but a strong El Niño – a natural climate cycle – added to the heat in 2016. The El Niño is now waning, but the extremes continue to be seen, with temperature records tumbling in the US in February and polar heatwaves pushing ice cover to new lows. “Even without a strong El Niño in 2017, we are seeing other remarkable changes across the planet that are challenging the limits of our understanding of the climate system. We are now in truly uncharted territory,” said David Carlson, director of the WMO’s world climate research programme. “Earth is a planet in upheaval due to human-caused changes in the atmosphere,” said Jeffrey Kargel, a glaciologist at the University of Arizona in the US. “In general, drastically changing conditions do not help civilisation, which thrives on stability.” The WMO report was “startling”, said Prof David Reay, an emissions expert at the University of Edinburgh: “The need for concerted action on climate change has never been so stark nor the stakes so high.” The new WMO assessment also prompted some scientists to criticise Donald Trump. “While the data show an ever increasing impact of human activities on the climate system, the Trump administration and senior Republicans in Congress continue to bury their heads in the sand,” said Prof Sir Robert Watson, a distinguished climate scientist at the UK’s University of East Anglia and a former head of the UN’s climate science panel. Read More here
1 March 2017, The Conversation, As global food demand rises, climate change is hitting our staple crops. While increases in population and wealth will lift global demand for food by up to 70% by 2050, agriculture is already feeling the effects of climate change. This is expected to continue in coming decades. Scientists and farmers will need to act on multiple fronts to counter falling crop yields and feed more people. As with previous agricultural revolutions, we need a new set of plant characteristics to meet the challenge. When it comes to the staple crops – wheat, rice, maize, soybean, barley and sorghum – research has found changes in rainfall and temperature explain about 30% of the yearly variation in agricultural yields. All six crops responded negatively to increasing temperatures – most likely associated with increases in crop development rates and water stress. In particular, wheat, maize and barley show a negative response to increased temperatures. But, overall, rainfall trends had only minor effects on crop yields in these studies. Since 1950, average global temperatures have risen by roughly 0.13°C per decade. An even faster rate of roughly 0.2°C of warming per decade is expected over the next few decades. As temperatures rise, rainfall patterns change. Increased heat also leads to greater evaporation and surface drying, which further intensifies and prolongs droughts. A warmer atmosphere can also hold more water – about 7% more water vapour for every 1°C increase in temperature. This ultimately results in storms with more intense rainfall. A review of rainfall patterns shows changes in the amount of rainfall everywhere. Read More here
28 February 2017, Climate News Network, Inequalities fuel human impacts on climate. For the second time this year, a group of climate scientists has called for a new approach to climate change research to produce a better and more precise idea of how the world will change as global average temperatures rise. The call comes only weeks after a distinguished international team reminded researchers that some details of the planetary climate machine are still unresolved – such as what happens to all the carbon released by fossil fuel combustion, and how rainfall patterns will change in the decades to follow. Neither group is challenging the general climate models, which broadly predict that, unless action is taken, global average temperatures could rise by 4°C and global sea levels by a metre or so. What each wants is more detailed answers. The latest call comes from a team of US and Japanese scientists, who argue in their report in National Science Review journal that the human dimension is missing. What people do over the next decades will feed back into the mechanics of climate change. Missing dimensions The missing dimensions of the human impacts and contribution, they say, are threefold: the economic inequalities that stoke conflict and drive migration; the levels and patterns of consumption of resources that fuel these inequalities; and the numbers of people consuming these resources and demanding energy to improve their lives over the next two generations. For instance, the scientists say, human choices make a difference. The rate of atmospheric concentrations of the greenhouse gases carbon dioxide, methane and nitrous oxide increased 700-fold, 1,000-fold and 300-fold respectively after the “green revolution” of the 1960s, compared with pre-industrial levels. Population growth was a factor. So was economic growth. And this corresponded to a doubling of human impacts every 17 years. “The doubling of this impact is shockingly rapid,” says the study leader, Safa Motesharri, a systems scientist at the University of Maryland’s National Socio-Environmental Synthesis Centre. Read More here