NASA'S EOSDIS Worldview: A new way to look closely at the Arctic sea ice

Check it out!  I am adding this link to the links in the left column of the this blog.

http://earthdata.nasa.gov/labs/worldview/?map=-2055840,311808,-745120,1232384&products=baselayers,MODIS_Terra_CorrectedReflectance_TrueColor~overlays,arctic_coastlines_3413&time=2013-07-26&switch=arctic

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"Increasing amount of Arctic Ocean deep waters in the Greenland Sea," by R. Somavilla, U. Schauer & G. Budéus, GRL (2013); doi: 10.1002/grl.50775

Geophysical Research Letters, (2013) in press; doi: 10.1002/grl.50775

Increasing amount of Arctic Ocean deep waters in the Greenland Sea

R. Somavilla, U. Schauer and G. Budéus

Abstract

In the last three decades, deep convection has come to a halt in the Greenland Sea. Hydrographic data reveal that during this period temperature and salinity in the deep Greenland Sea have increased at mean rates without precedent in the last 100 years, and these trends are among the highest in the global deep ocean. The origin of these changes is identified as the advection of Arctic Ocean deep waters and the necessary transports to explain them are calculated (0.440.09 Sv). Despite the fact that the deep Greenland Sea hardly covers 0.05% of the global surface, the resulting trends constitutes 0.3% of the World Ocean heat content increase per unit area of earth's surface and 0.1% of the global sea level rise. These results suggest that changes of the deep Arctic Mediterranean [see wikipedia link below for explanation of "mediterranean"] and their contribution to the global budgets need to be addressed.

http://onlinelibrary.wiley.com/doi/10.1002/grl.50775/abstract

http://en.wikipedia.org/wiki/Mediterranean_sea_%28oceanography%29

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Eemian interglacial period poor analog for current Arctic warming

Warm climate -- cold Arctic? The Eemian is a poor analogue for current climate change

by phys.org, June 14, 2012

The Eemian interglacial period that began some 125,000 years ago is often used as a model for contemporary climate change. In the international journal Geophysical Research Letters, scientists from Mainz, Kiel and Potsdam, Germany, now present evidence that the Eemian differed in essential details from modern climatic conditions.

To address the question about how climate may develop in the future, earth scientists direct their attention to the past. They look for epochs with similar conditions to today. The major identified climatic processes are then simulated with numerical models to further test possible reactions of the Earths' system. An epoch which is often regarded suitable for such an undertaking is the Eemian warm period, which began around 125,000 years ago following the Saalian ice age.

For about 10,000 years, average temperatures on Earth in the Eemian were rather enhanced – probably several degrees above today's level. This seems to be well documented in both ice cores as well as terrestrial records from land vegetation. Substantial parts of the Greenland ice had melted, and global sea level was higher than today. "Therefore, the Eemian time is suited apparently so well as a basis for the topical issue of climate change", says Dr Henning Bauch, who works for the Academy of the Sciences and the Literature Mainz (AdW Mainz) at GEOMAR | Helmholtz Centre for Ocean Research Kiel.

However, in a study which appears in the recent issue of the international journal Geophysical Research Letters Dr Bauch, Dr Evgeniya Kandiano of GEOMAR as well as Dr Jan Helmke of the Institute for Advanced Sustainability Studies in Potsdam now show that the Eemian warm period differed from the present day situation in one critical aspect – the development in the Arctic Ocean.

In our current warm period, also called Holocene, oceanic and atmospheric circulation delivers large amounts of heat northward into the high latitudes. The most well known heat conveyer is the Gulf Stream and its northern prolongation called the North Atlantic Drift. The currents provide not only the pleasant temperatures in Northern Europe, they also reach as far as the Arctic. Studies in the last years have shown that the oceanic heat transport to the Arctic has even increased, while the summer sea ice cover in the Arctic Ocean seems to be decreasing continuously. It has long been assumed that such conditions also prevailed 125,000 years ago. Accordingly, the Arctic should have been by and large ice-free in the Eemian summers.

Dr Bauch's group examined sediment cores from the seabed in which information about the climate history of the past 500,000 years is stored. These come from the Atlantic to the west of Ireland and from the central Nordic Seas to the east of the island of Jan Mayen. The sediments contain minute calcite tests of dead microorganisms (foraminifers). "The type of species assemblage in the respective layers as well as the isotopic composition of the calcitic tests give us information about temperature and other properties of the water in which they lived at that time", explains Dr Bauch.

The samples from the Atlantic delivered the higher-than-Holocene temperature signals so typical for the Eemian. The tests from the Nordic Seas, however, tell quite another story. "The found foraminifers of Eemian time indicate comparatively cold conditions." The isotope investigations of the tests, in combination with previous studies of the group, "indicate major contrasts between the ocean surfaces of these two regions ", according to Dr Bauch. "Obviously, the warm Atlantic surface current was weaker in the high latitude during the Eemian than today." His explanation: "The Saalian glaciation which preceded the Eemian was of much bigger extent in Northern Europe than during the Weichselian, the ice age period before our present warm interval. Therefore, more fresh water from the melting Saalian ice sheets poured into the Nordic Seas, and for a longer period of time. This situation had three consequences: The oceanic circulation in the north was reduced, and winter sea ice was more likely to form because of lower salinity. At the same time, this situation led to a kind of 'overheating' in the North Atlantic due to a continuing transfer of ocean heat from the south."

On the one hand, the study introduces new views on the Eemian climate. On the other hand, the new results have consequences for climatology in general: "Obviously, some decisive processes in the Eemian ran off differently, like the transfer of ocean warmth towards the Arctic. Models should take this into consideration if they want to forecast the future climate development on the basis of past analogues like the Eemian ", says Dr. Bauch.

http://phys.org/news/2012-06-climate-cold-arctic-eemian.html

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"The impact of radiosonde data over the ice-free Arctic Ocean on the atmospheric circulation in the Northern Hemisphere," by Jun Inoue et al., GRL 40 (2013); doi:10.1002/grl.50207

Geophysical Research Letters, 40(5) (16 March 2013) 864-869; doi:10.1002/grl.50207

The impact of radiosonde data over the ice-free Arctic Ocean on the atmospheric circulation in the Northern Hemisphere

1. Jun Inoue^1,2,3,*, 
2. Takeshi Enomoto^1,4 and 
3. Masatake E. Hori^1,2

Abstract

We investigated the impact of radiosonde data from the ice-free Arctic Ocean obtained by the Japanese R/V Mirai during a cruise in the fall of 2010 on the AFES-LETKF experimental ensemble reanalysis version 2 (ALERA2) data set. The reanalysis used radiosonde data over the ice-free region. Compared with observations, it captured Arctic cyclogenesis along the marginal ice zone, including a tropopause fold, very well. Without the observations, a 5 K cold bias in air temperature was found, suggesting that radiosondes over the Arctic Ocean are vital for reproducing the change in tropopause variability. As a consequence of including the Arctic radiosondes, a tropopause height difference formed and persisted after cyclogenesis, increasing the subpolar jet in ALERA2 by 3% at 65–70° N. The air temperature in the whole troposphere north of 70° N showed a cooling in the 2 weeks after cyclogenesis, whereas a warming was observed in the lower stratosphere, reflecting the regional impact of the intensive radiosonde observations. A remote response of the radiosondes over the Arctic Ocean to the midlatitudes was discussed by focusing on the density of observing network and seasonal march of atmospheric circulations. Our results demonstrated that the high-temporal radiosonde observations over the Arctic Ocean can help reduce uncertainty in reanalyses and numerical weather predictions throughout the northern half of the Northern Hemisphere for weeks afterwards.

http://0-onlinelibrary.wiley.com.library.hct.ac.ae/doi/10.1002/grl.50207/abstract

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BBC: Arctic Ocean 'acidifying rapidly'

By Roger HarrabinEnvironment analyst, BBC News, May 6, 2013

Continue reading the main story

Related Stories

• Canadian glaciers face 'big losses'
• Cryosat observes big Arctic ice loss
• The 'big melt' at the roof of the world

The Arctic seas are being made rapidly more acidic by carbon-dioxide emissions, according to a new report.

Scientists from the Arctic Monitoring and Assessment Programme (AMAP) monitored widespread changes in ocean chemistry in the region.

They say even if CO2 emissions stopped now, it would take tens of thousands of years for Arctic Ocean chemistry to revert to pre-industrial levels.

Many creatures, including commercially valuable fish, could be affected.

They forecast major changes in the marine ecosystem, but say there is huge uncertainty over what those changes will be.

It is well known that CO2 warms the planet, but less well-known that it also makes the alkaline seas more acidic when it is absorbed from the air.

Continue reading the main story

The Arctic

• The Arctic region contains a vast ice-covered ocean roughly centred on the Earth's geographic North Pole
• The Sun doesn't rise at all on the shortest day of the year within the Arctic Circle
• Humans have inhabited the Arctic region for thousands of years, and the current population is four million
• Geologists estimate the Arctic may hold up to 25% of the world's remaining oil and natural gas

• Watch the dramatic retreat of some of the world's largest glaciers

Absorption is particularly fast in cold water so the Arctic is especially susceptible, and the recent decreases in summer sea ice have exposed more sea surface to atmospheric CO2.

The Arctic's vulnerability is exacerbated by increasing flows of freshwater from rivers and melting land ice, as freshwater is less effective at chemically neutralising the acidifying effects of CO2.

The researchers say the Nordic Seas are acidifying over a wide range of depths - most quickly in surface waters and more slowly in deep waters.

The report’s chairman, Richard Bellerby from the Norwegian Institute for Water Research, told BBC News that they had mapped a mosaic of different levels of pH across the region, with the scale of change largely determined by the local intake of freshwater.

“Large rivers flow into the Arctic, which has an enormous catchment for its size,” he said.

“There’s slow mixing so in effect we get a sort of freshwater lens on the top of the sea in some places, and freshwater lowers the concentration of ions that buffers pH change. The sea ice has been a lid on the Arctic, so the loss of ice is allowing fast uptake of CO2.”

This is being made worse, he said, by organic carbon running off the land – a secondary effect of regional warming.

“Continued rapid change is a certainty,” he said.

“We have already passed critical thresholds. Even if we stop emissions now, acidification will last tens of thousands of years. It is a very big experiment.”

The research team monitored decreases in seawater pH of about 0.02 per decade since the late 1960s in the Iceland and Barents seas.

Chemical effects related to acidification have also been encountered in surface waters of the Bering Strait and the Canada Basin of the central Arctic Ocean.

Scientists estimate that the average acidity of surface ocean waters worldwide is now about 30% higher than before the Industrial Revolution.

The researchers say there is likely to be major change to the Arctic marine ecosystem as a result. Some key prey species like sea butterflies may be harmed. Other species may thrive. Adult fish look likely to be fairly resilient but the development of fish eggs might be harmed. It is too soon to tell.

http://www.bbc.co.uk/news/science-environment-22408341

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