5 July 2016, Washington Post, This new Antarctica study is bad news for climate change doubters. or a number of years now, climate change skeptics have argued that there’s a key part of the Earth’s climate system that upends our expectations about global warming, and that is showing trends that actually cut in the opposite direction. This supposed contrary indicator is the sea ice that rings the Antarctic continent, and that reached a new all-time record extent of 7.78 million square miles in September 2014 (see above). As that record suggests, this vast field of ice has been expanding in recent years, rather than shrinking. That means it’s doing the opposite of what is happening in the Arctic, where sea ice is declining rapidly — and also that it’s doing the opposite of what we might expect in a warming world. [Climate change skeptics may be about to lose one of their favorite arguments] Scientists don’t fully understand why Antarctic sea ice is growing — suggested explanations have posited more glacial melt dumping cold fresh water into the surrounding seas, or the way the Antarctic ozone hole has changed the circulation of winds around the continent. In a new study in Nature Geoscience, though, researchers with the National Center for Atmospheric Research (NCAR) in Boulder, Colo., along with colleagues from the University of Washington in Seattle and Australia, suggest that the phenomenon is simply the result of natural variability of the climate system — driven, in this case, by changes in the tropical Pacific Ocean that reverberate globally. Read more here
Category Archives: Impacts Observed & Projected
30 June 2016, NASA. Why a half-degree temperature rise is a big deal. The Paris Agreement, which delegates from 196 countries hammered out in December 2015, calls for holding the ongoing rise in global average temperature to “well below 2 °C above pre-industrial levels,” while “pursuing efforts to limit the temperature increase to 1.5 °C.” How much difference could that half-degree of wiggle room (or 0.9 degree on the Fahrenheit scale) possibly make in the real world? Quite a bit, it appears. The European Geosciences Union published a study in April 2016 that examined the impact of a 1.5 degree Celsius vs. a 2.0 C temperature increase by the end of the century, given what we know so far about how climate works. It found that the jump from 1.5 to 2 degrees—a third more of an increase—raises the impact by about that same fraction, very roughly, on most of the phenomena the study covered. Heat waves would last around a third longer, rain storms would be about a third more intense, the increase in sea level would be approximately that much higher and the percentage of tropical coral reefs at risk of severe degradation would be roughly that much greater. But in some cases, that extra increase in temperature makes things much more dire. At 1.5 C, the study found that tropical coral reefs stand a chance of adapting and reversing a portion of their die-off in the last half of the century. But at 2 C, the chance of recovery vanishes. Tropical corals are virtually wiped out by the year 2100. Read More here
29 June 2016, NASA, NASA maps California drought effects on Sierra trees. A new map created with measurements from an airborne instrument developed by NASA’s Jet Propulsion Laboratory, Pasadena, California, reveals the devastating effect of California’s ongoing drought on Sierra Nevada conifer forests. The map will be used to help the U.S. Forest Service assess and respond to the impacts of increased tree mortality caused by the drought, particularly where wildlands meet urban areas within the Sierra National Forest. After several years of extreme drought, the highly stressed conifers (trees that produce cones and are usually green year-round) of the Sierra Nevada are now more susceptible to bark beetles (Dendroctonus spp.). While bark beetles killing trees in the Sierra Nevada is a natural phenomenon, the scale of mortality in the last couple of years is far greater than previously observed. The U.S. Forest Service is using recent airborne spectroscopic measurements from NASA’s Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) instrument aboard NASA’s ER-2 aircraft, together with new advanced algorithms, to quantify this impact over this large region of rugged terrain. The high-altitude ER-2 aircraft is based at NASA’s Armstrong Flight Research Center, Edwards, California. Read More here
17 June 2016, The Guardian, What would a global warming increase of 1.5C be like? How ambitious is the world? The Paris climate conference last December astounded many by pledging not just to keep warming “well below two degrees celsius,” but also to “pursue efforts” to limit warming to 1.5C. That raised a hugely important question: What’s the difference between a two-degree world and a 1.5-degree world? Given we are already at one degree above pre-industrial levels, halting at 1.5C would look to be at least twice as hard as the two-degree option.So would it be worth it? And is it even remotely achievable? In Paris, delegates called on the UN’s Intergovernmental Panel on Climate Change (IPCC) to report on the implications of a 1.5C target. They want the job done by 2018, in time to inform renewed talks on toughening emissions targets beyond those agreed upon in Paris. But the truth is that scientists are only now getting out of the blocks to address what a 1.5C world would look like, because until recently it sounded like a political and technological impossibility. As a commentary published online in Nature Climate Change last week warned, there is “a paucity of scientific analysis” about the consequences of pursuing a 1.5C target. To remedy this, the paper’s researchers, led by Daniel Mitchell and others at Oxford University, called for a dedicated program of research to help inform what they described as “arguably one of the most momentous [decisions] to be made in the coming decade.” And they are on the case, with their own dedicated website and a major conference planned at Oxford in the fall. So what is at stake? There are two issues to address. First, what would be gained by going the extra mile for 1.5? And second, what would it take to deliver? Read More here