11 July 2016, Carbon Brief, Shifting global cloud patterns could amplify warming, study says. A new study sheds light on one of the biggest uncertainties in predicting future changes to Earth’s climate: clouds. Clouds both warm the planet by insulating the Earth’s surface like a blanket, while simultaneously cooling it by reflecting away energy from the sun. Climate models predict that as the Earth warms in response to greenhouse gases, clouds will shift towards the poles and sit higher in the sky, further speeding up warming. But clouds are tricky to measure and until now, scientists haven’t been able to find direct evidence that these changes were actually happening in the real world. The new study published in Nature uses satellite data to identify how cloud patterns have changed in recent decades, confirming the pace of warming predicted by climate models. Satellite data Scientists use weather satellites to measure the extent, height and thickness of clouds. But these measurements suffer from several issues that can limit how useful they are for detecting long-term changes in cloudiness. Small discrepancies in the data are caused by satellite sensors degrading over time and being replaced by new, more precise instruments. Another issue is the gradual change in the orbit of satellites themselves, says the study’s lead author, Prof Joel Norris, professor of climate and atmospheric sciences at the Scripps Institution of Oceanography in San Diego. He explains to Carbon Brief: Read More here
Category Archives: The Science
20 May 2016, Renew Economy, Why we must ‘think global, act local’ on climate change. Many catchy slogans come and go: “Just do it”, “Carpe Diem”, “play hard.” But out of all of them, “think global, act local” is the one that resonates the most with me, and seems to apply best in this age when we are all connected but still have individual responsibilities.It’s a slogan that’s become more and more applicable in an era of distributed energy when every consumer that wants to, can make a difference at the local level. Disruptive technology typically depends on many individuals making small individual decisions that collectively have large impacts on corporate behaviour. In that spirit and as part of the “cognitive surplus” its seems worthwhile to pull together three articles that summarise some well known, and some slightly less well known, features of the global context that underlies the unfolding energy transformation in Australia. Article 1 today is a very brief and familiar summary of the global warming data and the primary contributors to CO2 emissions. Article 2 will summarise the global renewable energy picture; and Article 3 will look at some of the recent global data and analysis, including China and India coal-fired electricity generation and economics. Global temperature. I prefer to look at the global temperature in percentage terms. That’s because, in my experience, 1 degree doesn’t sound like something very important to the man in street, who is used to daily fluctuations of 10 degrees or more. Using percentages has its own problems, as Centigrade percentages will differ from Fahrenheit and, for the truly obsessed, Kelvin scales. Our primary data source is the National Oceanic and Atmospheric Administration (NOAA) and we like to use a 20-year moving average as the most smoothed form of data. The disadvantage of moving averages is that they are out of date and give equal weight to old observations This can be seen in the chart below. For that reason the ABS uses a “Henderson” trend for monthly and quarterly data, which gives more weight to the current observations and less weight to the older observations. Any stats-inclined people out there who want to calculate a 20-year Henderson weight, please get in touch. Here’s the chart then. The anomaly average for calendar 2016 year to date is 1.13°C, about 8 per cent above the 20th century average. GOOD SERIES OF GRAPHS IN ARTICLE. Read More here
11 May 2016, The Conversation, Antarctic ice shows Australia’s drought and flood risk is worse than thought. Australia is systematically underestimating its drought and flood risk because weather records do not capture the full extent of rainfall variability, according to our new research. Our study, published today in the journal Hydrology and Earth System Sciences, uses Antarctic ice core data to reconstruct rainfall for the past 1,000 years for catchments in eastern Australia. The results show that instrumental rainfall records – available for the past 100 years at best, depending on location – do not represent the full range of abnormally wet and dry periods that have occurred over the centuries. In other words, significantly longer and more frequent wet and dry periods were experienced in the pre-instrumental period (that is, before the 20th century) compared with the period over which records have been kept. Reconstructing prehistoric rainfall There is no direct indicator of rainfall patterns for Australia before weather observations began. But, strange as it may sound, there is a link between eastern Australian rainfall and the summer deposition of sea salt in Antarctic ice. This allowed us to deduce rainfall levels by studying ice cores drilled from Law Dome, a small coastal ice cap in East Antarctica. It might sound strange, but there’s a direct link between Antarctic ice and Australia’s rainfall patterns. Tas van Ommen, Author provided How can sea salt deposits in an Antarctic ice core possibly be related to rainfall thousands of kilometres away in Australia? It is because the processes associated with rainfall variability in eastern Australia – such as the El Niño/Southern Oscillation (ENSO), as well as other ocean cycles like the Interdecadal Pacific Oscillation (IPO) and the Southern Annular Mode (SAM) – are also responsible for variations in the wind and circulation patterns that cause sea salt to be deposited in East Antarctica (as outlined in our previous research). By studying an ice record spanning 1,013 years, our results reveal a clear story of wetter wet periods and drier dry periods than is evident in Australia’s much shorter instrumental weather record. Read More here
10 May 2016, New York Times, Global Warming Cited as Wildfires Increase in Fragile Boreal Forest. Scientists say the near-destruction of Fort McMurray last week by a wildfire is the latest indication that the vital boreal forest is at risk from climate change. Scientists have been warning for decades that climate change is a threat to the immense tracts of forest that ring the Northern Hemisphere, with rising temperatures, drying trees and earlier melting of snow contributing to a growing number of wildfires. The near-destruction of a Canadian city last week by a fire that sent almost 90,000 people fleeing for their lives is grim proof that the threat to these vast stands of spruce and other resinous trees, collectively known as the boreal forest, is real. And scientists say a large-scale loss of the forest could have profound consequences for efforts to limit the damage from climate change. In retrospect, it is clear that Fort McMurray, in northern Alberta, was particularly vulnerable as one of the largest human outposts in the boreal forest. But the destruction of patches of this forest by fire, as well as invasions by insects surviving warmer winters, has occurred throughout the hemisphere. In Russia, about 70 million acres burned in 2012, new statistics suggest, much of that in isolated areas of Siberia. Alaska, home to most of the boreal forest in the United States, had its second-largest fire season on record in 2015, with 768 fires burning more than five million acres. Global warming is suspected as a prime culprit in the rise of these fires. The warming is hitting northern regions especially hard: Temperatures are climbing faster there than for the Earth as a whole, snow cover is melting prematurely, and forests are drying out earlier than in the past. The excess heat may even be causing an increase in lightning, which often sets off the most devastating wildfires. Read More here