Friday, November 15, 2019

Serrano Glacier retreating. This is global warming, a climate emergency



A visit to Serrano Glacier in Bernardo O'Higgins National Park in Chile. The Glacier is retreating 10-20 metres per year, according to a Park Ranger when I asked about the current rate of glacial retreat. The Grey Glacier that discharges ice from the south Patagonian ice field is retreating at 5-10 metres per year.






According to NASA, the modern Patagonian icefields which span Argentina and Chile remain the largest expanse of ice in the Southern Hemisphere outside of Antarctica.

But rapid change is ongoing. “They are, in fact, melting away at some of the highest rates on the planet,” said Eric Rignot, a glaciologist at NASA’s Jet Propulsion Laboratory and the University of California-Irvine.

Here is how Davies and Glasser 2012 paper published in Journal of Glaciology summed up the trend, taken from Shrinking Patagonian Glaciers shortened version at Antarcticglaciers.org:

Satellite measurements of the Patagonian icefields suggest that they are currently rapidly receding and thinning, with a measureable contribution to eustatic sea level rise2. Many workers argue that the glaciers of the Patagonian Andes are now shrinking at an increased rate as a result of recent climate change3-5. However, these assessments of change are restricted by the availability of maps (last 60 years) and satellite images (last 40 years). In this study (from 40° to 56° South), we used geomorphological evidence of glacier extent during the LIA (~AD 1870) and satellite images to map glacier extent across the Andes over the last 140 years, in 1870, 1975, 1986, 2001 and 2011.

We have known of the trend in Patagonia's glaciers reducing and contributing to sea level rise for a substantial time. Greenpeace visited Chile with their ship Arctic Sunrise in 2004 and publicised the reduction in Patagonian glaciers.

Latest research highlighted in a Sydney Morning Herald article that sea levels have risen quite fast with changes in climate. The changes we are doing are much much greater than any previous natural changes.

"At its fastest – about 125,000 years ago when temperatures were about a degree warmer than now – sea levels rose as much as 3.4 metres per 100 years for several centuries to reach about 10 metres above current levels." writes Peter Hannam in Past Antarctic ice melt reveals potential for 'extreme sea-level rise' (november 6, 2019)

Lead author on the study, Eelco Rohling, writing at the Conversation, articulates the problem we have today in the final paragraph of his co-authored article: Scientists looked at sea levels 125,000 years in the past. The results are terrifying

Crucially, warming between the two poles in the last interglacial did not happen simultaneously. But under today’s greenhouse-gas-driven climate change, warming and ice loss are happening in both regions at the same time. This means that if climate change continues unabated, Earth’s past dramatic sea level rise could be a small taste of what’s to come.

Sea level rise in the IPCC reports, such as the recent Special Report on Ocean and Cryosphere, has long been a controversial topic, with some scientists saying estimates of sea level rise for the near future could be far too conservative. Traditionally these reports fail to adequately consider ice sheet mass collapse rates due to insufficient data and research. This research will help counter that view.






South Patagonian ice field losing ice mass

I also recently visited the Torres del Paine National Park and the Grey Glacier. The South Patagonian ice field is losing ice mass. The Grey Glacier is retreating at about 5 to 10 metres per year. Nearly all the Patagonian glaciers are in retreat, but at variable rates.




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