Archives par mot-clé : Ice

Novel hypothesis goes underground to predict future of Greenland ice sheet

by Penn State, February 2,  2019 in ScienceDaily


Paleoclimatic records indicate that most of Greenland was ice-free within the last 1.1 million years even though temperatures then were not much warmer than conditions today. To explain this, the researchers point to there being more heat beneath the ice sheet in the past than today.

Data show that when the Iceland hot spot — the heat source that feeds volcanoes on Iceland — passed under north-central Greenland 80 to 35 million years ago, it left molten rock deep underground but did not break through the upper mantle and crust to form volcanoes as it had in the west and east. The Earth’s climate then was too warm for Greenland to have an ice sheet, but once it cooled the ice sheet formed, growing and shrinking successive with ice ages.

Antarctic Losing Tiny Amounts Of Ice (Or Maybe It’s Gaining Ice, NASA Is Not Sure!)

by P. Homewood, January 15, 2019 in NotaLotofPeopleKnowThat


Antarctica is shedding ice at a staggering rate.

Scientists have discovered global warming has caused the melting of the ice on the continent to increase sixfold since 1979.

This phenomenal rate of melting has seen global sea levels rise by more than half an inch – and experts predict it will get worse. 

Scientists have predicted a ‘multi-meter sea level rise from Antarctica in the coming centuries’ as a result of the vast loss of ice.

Researchers discovered that, between 1970 and 1990, the continent was shedding an average of 40 gigatons of ice mass annually.

This jumped to an average of 252 gigatons a year between 2009 and 2017.

https://www.dailymail.co.uk/sciencetech/article-6590841/Antarctica-losing-SIX-TIMES-ice-year-1970s.html#newcomment

 

You may of course recall that it was only three years ago that the same NASA, who are behind this latest scare story, were telling us that the ice cap was actually growing in Antarctica. But more of that in a minute.

There are several aspects to this latest story that need closer examination.

Arctic Sea Ice Extent Higher Than 2006 Last Month

by P. Homewood, January 9, 2019 in NotaLotofPeopleKnowThat


Just last March, the Guardian was trying to panic us about record lows in Arctic sea ice during last winter.

Back in the real world, DMI confirm that average Arctic sea ice extent in December was higher last month than in 2006. In reality, there has been very little change at all since 2005.

http://ocean.dmi.dk/arctic/icethickness/txt/IceVol.txt

 

“Terrifying Sea-Level Prediction Now Looks Far Less Likely”… But “marine ice-cliff instability” is “just common sense”

by David Middleton, January 5, 2019 in WUWT


Marine ice cliff instability (MICI) “has not been observed, not at such a scale,” “might simply be a product of running a computer model of ice physics at a too-low resolution,” ignores post glacial rebound, couldn’t occur before ” until 2250 or 2300″… Yet “the idea is cinematic,” “it’s just common sense that Antarctic glaciers will develop problematic ice cliffs” and something we should plan for…

“Our results support growing evidence that calving glaciers are particularly sensitive to climate change.”  Greenland’s climate is always changing… Always has and always will change… And the climate changes observed over the last few decades are not unprecedented. The Greenland ice sheet is no more disappearing this year than it was last year and it is physically impossible for the ice sheet to “collapse” into the ocean.

Figure 6. Jakobshavn Isbrae. (Wikipedia and Google Earth)

Late Summer Arctic Ice Volume Has Been Growing Since 2007…Contradicts Earlier Climate Predictions

by Kirye, December 12, 2018 in NoTricksZone


The media, alarmist scientists and many leading policymakers often tell the public “the Arctic is rapidly melting”. And if a poll were done today, a vast majority of the people in Japan and elsewhere would say this is true. Unfortunately they have become the victims of “fake news”.

Luckily we have some hard data from the Arctic. And if one looks at them, it is true that sea ice has seen a declining trend – if we go back 40 years.

Yet, if we look at the past 12 years, we see that the trend for minimum has stopped, and one could argue even reversed:

Record Cold Hits North America, Arctic Sea Ice Stable As Solar Activity Reaches Near 200-Year Low

by P. Gosselin, November 26, 2018 in NoTricksZone


Winter has arrived much earlier than normal this year, particularly across North America, where cold records have been shattered.

This Thanksgiving is in fact going down as one of the coldest ever on record across the Northeast. The Washington Post here, for example, reports that Thanksgiving and Black Friday 2018 will be remembered for a record-shattering cold snap across the Northeast United States.”

Arctic sea ice, snow and ice cover rebound

Arctic sea ice volume has rebounded and is near normal levels. The sea ice trend has remained stable over the past decade and thus defy all the climate alarmist predictions of an Arctic meltdown.

 

Chart made by Kirye. Data Source: Danish Meteorological Institute.

 

Carottes de glace, CO2 et micro-organismes

by Paul Berth, 22 novembre 2018, in ScienceClimatEnergie


Les microbulles de gaz emprisonnées dans les carottes de glace sont fréquemment utilisées pour estimer le taux de CO2 de l’atmosphère du passé. Il s’agit de méthodes de mesure indirectes. Par exemple la carotte de glace EPICA Dome C en Antarctique nous suggère que le CO2 de l’atmosphère a varié entre 180 et 300 ppmv pendant les derniers 650 000 ans (Brook 2005). Cependant, le taux de CO2 observé dans ces carottes de glace représente-il vraiment l’atmosphère du passé? Nous allons montrer ici qu’un paramètre est souvent négligé par les glaciologues, et que ce paramètre pourrait avoir un effet considérable sur le résultat des analyses : il s’agit de la présence de micro-organismes dans la glace et les microbulles.

Arctic sea ice: Simulation versus observation

by U.  of California – Santa Barbara, Nov 13, 2018 in ScienceDaily


As an indicator of the impacts of climate change, Arctic sea ice is hard to beat. Scientists have observed the frozen polar ocean advance and retreat at this most sensitive region of the Earth over decades for insight on the potential ripple effects on assorted natural systems: global ocean circulation, surrounding habitats and ecosystems, food sources, sea levels and more.

“We’re mostly interested in the period from the early 2000s to the present day, where we see such strong melting,” said graduate student Ian Baxter, who also works with Ding. It’s known, he added, that the effects of changes in the Arctic are no longer confined to the region and in fact spread to the mid-latitudes — often in the form of cold weather outbreaks. The group is interested in how effects in the tropics could spread beyond that region and affect the Arctic.

How the Greenland ice sheet fared in 2018

by R. Mottram et al.  (DMI), October 27, 2018 in ScienceNordic


The end of August traditionally marks the end of the melt season for the Greenland ice sheet as it shifts from mostly melting to mostly gaining snow.

As usual, this is the time when the scientists at DMI and our partners in the Polar Portal assess the state of the ice sheet after a year of snowfall and ice melt. Using daily output from a weather forecasting model combined with a model that calculates melt of snow and ice, we calculate the “surface mass budget” (SMB) of the ice sheet.

This budget takes into account the balance between snow that is added to the ice sheet and melting snow and glacier ice that runs off into the ocean. The ice sheet also loses ice by the breaking off, or “calving”, of icebergs from its edge, but that is not included in this type of budget. As a result, the SMB will always be positive – that is, the ice sheet gains more snow than the ice it loses.

For this year, we calculated a total SMB of 517bn tonnes, which is almost 150bn tonnes above the average for 1981-2010, ranking just behind the 2016-17 season as sixth highest on record.

By contrast, the lowest SMB in the record was 2011-2012 with just 38bn tonnes, which shows how variable SMB can be from one year to another.

Maps show the difference between the annual SMB in 2017 (left) and 2018 (right) compared with the 1981-2010 period (in mm of ice melt). Blue shows more ice gain than average and red shows more ice loss than average. (Credit: DMI Polar Portal)

19th century glacier retreat in the Alps preceded the emergence of industrial black carbon deposition on high-alpine glaciers

by M. Sigl et al., October 16, 2018 in TheCryosphere


Abstract. Light absorbing aerosols in the atmosphere and cryosphere play an important role in the climate system. Their presence in ambient air and snow changes the radiative properties of these systems, thus contributing to increased atmospheric warming and snowmelt. High spatio-temporal variability of aerosol concentrations and a shortage of long-term observations contribute to large uncertainties in properly assigning the climate effects of aerosols through time.

Starting around AD1860, many glaciers in the European Alps began to retreat from their maximum mid-19th century terminus positions, thereby visualizing the end of the Little Ice Age in Europe. Radiative forcing by increasing deposition of industrial black carbon to snow has been suggested as the main driver of the abrupt glacier retreats in the Alps. The basis for this hypothesis was model simulations using elemental carbon concentrations at low temporal resolution from two ice cores in the Alps.