Satellite measurements of Antarctic sea ice do not go back even 40 years. That’s not very much, especially when we consider that many natural climate cycles have periods of 60 years and more.
Luckily we have the field of climate reconstruction. Using historical documents and sediment cores, the development of ice cover can be estimated. In November, 2016, Tom Edinburg and Jonathan Day examined shipping log books from the time of Antarctic explorers and published on ice extent in The Cryosphere (…)
La découverte a été effectuée par des scientifiques français du CNRS, dans ce groupe qui vivait sur l’île de Petrels, en terre Adélie. Hormis les deux bébés manchots survivants, ils n’ont retrouvé que des corps d’animaux affamés et des oeufs non-éclos. Ces chercheurs, soutenus par le Fonds mondial pour la nature (WWF), observaient depuis 2010 cette colonie. Selon eux, l’étendue inhabituelle de la banquise a contraint les parents à aller plus loin chercher leur nourriture. Leur progéniture ont succombé à la faim.
A Russian team, however, has been active establishing a chronology of deuterium from snow-cores and -pits near the Vostok station (A.A. Ekaykin, et al., 2014). A summary (www.ncdc.noaa.gov/paleo/study/22532) with digital data became available in May, 2017. The data include annual measurements from 1654 to 2010, providing an overlap with the ice-core record that enables an assessment of present conditions from the perspective of ice-core record.
“It is tempting to say that the record low we are seeing this year is global warming finally catching up with Antarctica,” Meier said. “However, this might just be an extreme case of pushing the envelope of year-to-year variability. We’ll need to have several more years of data to be able to say there has been a significant change in the trend.”
The discovery of volcanoes under the Antarctic ice sheet may be old news, but now we have evidence that at least some of them have recently (geologically speaking) erupted…
Changes in the sources of nitrogen and the composition of the phytoplankton community are more likely to account for the differences seen in the isotope data, Huckstadt said. “It looks more like a shift at the base of the food web, probably related to the transition from the Little Ice Age to current conditions, causing changes in the phytoplankton community,” he said.
See also: “Here we present new data from the Ross Sea, Antarctica, that indicates surface temperatures were ~ 2 °C colder during the LIA, with colder sea surface temperatures in the Southern Ocean and/or increased sea-ice extent, stronger katabatic winds, and decreased snow accumulation.”
There are models that predict that the interior of the East Antarctic ice sheet wouldn’t change very much, even if the West Antarctic ice sheet was taken away,” Licht said. According to these models, even if the ice sheet’s perimeter retreats, its core remains stable.
by James E Kamis, August 23, in ClimateChangeDispatch
The now three-year-old Plate Climatology Theory is on the brink of total confirmation. This is the result of two just-released and very telling Antarctic research studies. Combining the results of these two studies with the massive amounts of pre-existing data it is possible to show with very high certainty that melting of West Antarctic glaciers is directly related to bedrock heat flow and chemically charged heated fluid flow from the 5,000-mile-long West Antarctic Rift System (see Figure 1).
“There are models that predict that the interior of the East Antarctic ice sheet wouldn’t change very much, even if the West Antarctic ice sheet was taken away,” Licht said. According to these models, even if the ice sheet’s perimeter retreats, its core remains stable.
Scientists announced today that a core drilled in Antarctica has yielded 2.7-million-year-old ice, an astonishing find 1.7 million years older than the previous record-holder
(…)
If the new result holds up, says Yige Zhang, a paleoclimatologist at Texas A&M University in College Station, the proxies will need to be recalibrated. “We have some work to do.”
The Edinburgh volcano survey, reported in the Geological Society’s special publications series, involved studying the underside of the west Antarctica ice sheet for hidden peaks of basalt rock similar to those produced by the region’s other volcanoes. Their tips actually lie above the ice and have been spotted by polar explorers over the past century.
Earlier studies had documented little change in the western Ross coastline prior to 1995, and the new study both confirmed the earlier work and extended the analysis to the present time.
This work underscores the complexity of Antarctic climate change and glacier response.
About half of the CO2 emitted by man gets absorbed by the oceans and so does not stay in the atmosphere. Here there are certain areas of the ocean that are especially efficient CO2 sinks, while others do not absorb so well. What follows is a look of the newest literature on the subject.
A commentary appearing here at the Swiss Baseler Zeitung (BAZ) slams a recently published British paper on moss growth in Antarctica that gave the impression the south polar continent was greening up due to climate change.
The BAZ writes that the paper is an example of “how today science is manipulated and used for political purposes“.
I thought I’d take a moment from my R&R to write about all the hullabaloo surrounding the calving of the large iceberg off the Larsen C ice shelf in Antarctica. First, a few of the headlines:
Progressive bottom melting and break-up of West Antarctica’s seafloor hugging Larsen Ice Shelf is fueled by heat and heated fluid flow from numerous very active geological features, and not climate change.
When considering the scale of temperature changes that alarmists anticipate because of Man-made Global Warming and their view of the disastrous effects of additional Man-made Carbon Dioxide emissions in this century, it is useful to look at climate change from a longer term, century by century and even on a millennial perspective.
by James Kamis, July 4, 2017 in ClimateChangeDispatch
Geological heat flow is fueling bottom melting and associated cracks across West Antarctica’s Larsen Ice Shelf, having little to do with man-made global warming. Significant amounts of high-quality data and relevant geological observations support this revelation, given historical and current geological mapping efforts done in Antarctica.
In a new study, scientists puzzled by the sudden ice loss matched satellite images of Antarctica with weather data from the second half of 2016 to figure out what caused so much of the ice to melt. They found that a series of remarkable storms during September, October and November brought warm air and strong winds from the north that melted 75,000 square kilometers (30,000 square miles) of ice per day. That’s like losing a South Carolina-sized chunk of ice every 24 hours.
In a new study, scientists puzzled by the sudden ice loss matched satellite images of Antarctica with weather data from the second half of 2016 to figure out what caused so much of the ice to melt. They found that a series of remarkable storms during September, October and November brought warm air and strong winds from the north that melted 75,000 square kilometers (30,000 square miles) of ice per day. That’s like losing a South Carolina-sized chunk of ice every 24 hours.
The levels of microplastic particles accumulating in the Antarctic are much worse than expected, a team of experts has warned.
The continent is considered to be a pristine wilderness compared to other regions and was thought to be relatively free from plastic pollution. However new findings by scientists from University of Hull and British Antarctic Survey (BAS) have revealed that recorded levels of microplastics are five times higher than you would expect to find from local sources such as research stations and ships
In their seminal paper on the Vostok Ice Core, Petit et al (1999) [1] note that CO2 lags temperature during the onset of glaciations by several thousand years but offer no explanation. They also observe that CH4 and CO2 are not perfectly aligned with each other but offer no explanation. The significance of these observations are therefore ignored. At the onset of glaciations temperature drops to glacial values before CO2 begins to fall suggesting that CO2 has little influence on temperature modulation at these times.
The West Antarctic Ice Sheet, a landbound mass of ice larger than Mexico, experienced substantial surface melt through the austral summer of 2015-2016 during one of the largest El Niño events of the past 50 years, according to scientists who had been conducting the first comprehensive atmospheric measurements in the region since the 1960s.
A new NASA study says that an increase in Antarctic snow accumulation that began 10,000 years ago is currently adding enough ice to the continent to outweigh the increased losses from its thinning glaciers.
The research challenges the conclusions of other studies, including the Intergovernmental Panel on Climate Change’s (IPCC) 2013 report, which says that Antarctica is overall losing land ice.
According to the new analysis of satellite data, the Antarctic ice sheet showed a net gain of 112 billion tons of ice a year from 1992 to 2001. That net gain slowed to 82 billion tons of ice per year between 2003 and 2008.
As we did in the previous two posts, we will examine each proxy and reject any that have an average time step greater than 130 years or if it does not cover at least part of the Little Ice Age (LIA) and the Holocene Climatic Optimum (HCO). We are looking for coverage from 9000 BP to 500 BP or very close to these values. Only simple statistical techniques that are easy to explain will be used.
La géologie, une science plus que passionnante … et diverse
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