Melting mountain glaciers in South America are making sea levels rise faster now than at any time in the last 350 years, says BBC science news. Yet melting is less of a problem than warming.
Delen
The BBC reports on the research done by the universities of Aberystwyth, Exeter and Stockholm, published online last Sunday in Nature Geoscience. The researchers measured the melt rate of the 270 major glaciers in Chile and Argentina since the time of the Little Ice Age, which is defined as a period extending from the 16th to 19th century. The researchers discovered that the melting rate has accelerated dramatically over the last 30 years.
Dr Ernst Schrama (Aerospace Engineering) was involved in a similar publication (Science, 13 November 2009) concerning the accelerated melting of land ice in Greenland. He answered our questions by email.
The researchers say that the melting rate has accelerated ‘10 to 100 times’ in the last 30 years compared to the previous centuries. How did they establish that?
“They compared digital elevation models obtained from the space shuttle radar topography mission to earlier cartographic sources. This yields an insight into the mass loss rates of the last 30 years. To look further back in time, they studied, for instance, the moraines that glaciers left in the past.”
You have been working on data from the Grace gravity satellite on accelerated land ice loss in Greenland. Does Grace show accelerated glacier melt in South America as well?
“GRACE does show a negative mass balance over the Patagonian ice sheets. I cite from the article an observed rate of -27.9 +/- 11 cubic kilometres per year, which is about one-tenth of the Greenland value.”
After two hard winters in Western Europe, people seem to think global warming has come to a halt. What is your opinion?
“Weather and climate are really two different things. Two harsh winters in 2010 and 2011 is what we call a weather phenomenon, in my opinion. Also, during the most recent winter, it was unseasonably warm on the west coast of Greenland. Now, the global warming discussion is concerned with 10 to 30 year temperature trends. A graph of the year-average temperature in the Netherlands over the last century clearly shows a continuously rising trend. The extra degree centigrade since 1900 came from global warming.”
Do these latest findings significantly influence the estimates for sea level rise?
“Sea level rise is a small signal that used to stand at about 20 cm per century, since the start of the industrial revolution. Satellite radar data over the oceans has shown a rise of more like 34 cm per century. Greenland and West Antarctica contribute 350 gigatonnes per year, amounting to something like 10 cm per century. Patagonia adds another centimetre to that.
“The Delta committee forecasts up to 1.3 meters by the end of the century – three times more than the 34 cm – but why? The answer is that we did not account for the thermal expansion of seawater. About two thirds of the sea level rise signal is from volume expansion. I can’t make the message merrier than it is, but this is what people see in the data and what computer models forecast.”
N.F.Glasser et. al., Global sea-level contribution from the Patagonian Icefields since the Little Ice Age maximum, Nature Geoscience, 3 April 2011
Naam: Remco Advocaat (22, LR)
Dreamteam: DUT Racing (dutracing.nl)
Functie: Operational manager
“Dit is mijn auto, mijn trots” vertelt Remco Advocaat naast het fraai bestickerde bestelbusje van het Formula Student team. “Die raceauto zelf, daar weet ik niks van, ondanks dat ik fulltime deel uitmaak van het bestuur. Als operational manager ben ik namelijk voor alles verantwoordelijk wat niet met de raceauto te maken heeft. Zaken zoals dit busje, maar ook het eten, of onze eigen collegeblokken ter promotie, dat is wat ik doe. Af en toe werk ik weleens door tot een uur of drie ’s nachts. Een primeur, want voorheen deden alleen de techneuten van het team dat. Het is alleen qua tijd wel lastig te combineren met een vriendin. Misschien dat ik daarom de enige ben van het kernteam die er een vriendin op nahoudt.” Het toeval wil dat zijn huidige vriendin jaren geleden tijdens een TU-rondleiding met de middelbare school al eens op bezoek is geweest in de werkplaats. “Een vieze hal met allemaal enge mannetjes achter draaibanken, noemde ze dat toen”, aldus Advocaat. “Daar breng ik nu dus al mijn tijd door, heb ik haar gezegd. Zou ze daarom zo begripvol zijn?”
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