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Posts tagged Ice

Arctic Ice by Canada and Greenland

80.8N 71.4W

June 24th, 2013 Category: Climate Change MODISTerra

Canada and Greenland – June 22nd, 2013

This image shows glacial ice and sea ice in the Arctic, between Canada and Greenland. Effects of Arctic climate change include a marked decrease in Arctic sea ice; thawing permafrost, leading to the release of methane, a potent greenhouse gas; the release of methane from clathrates, leading to longer time-scale methane release; the observed increase in melt on the Greenland Ice Sheet in recent years; and potential changes in patterns of ocean circulation.

Scientists worry that some of these effects may cause positive feedbacks which could accelerate the rate of global warming. The sea ice in the Arctic region is in itself important in maintaining global climate due to its albedo (reflectivity). Melting of this sea ice will therefore exacerbate global warming due to positive feedback effects, where warming creates more warming by increased solar absorption.

Sediments and Melting Ice in James Bay, Canada – June 24th, 2013

52.6N 80.1W

June 24th, 2013 Category: Image of the day, Sediments MODISTerra

Canada – June 22nd, 2013

James Bay and Hudson Bay constitute a large, shallow, inland sea connected to the Atlantic Ocean by Hudson Strait and the Labrador Sea, and to the Arctic Ocean by the Foxe Basin, and Fury and Hecla Strait. Currents are strongly affected by influxes of fresh water from rivers and, during the open-water season, by wind stress. Cold saline water enters Hudson Bay and James Bay from the northwest. Less saline surface outflows occur along the eastern shores of James Bay and Hudson Bay north to Hudson Strait.

These two “bays” are the largest bodies of water in the world that seasonally freeze over each winter and become ice-free each summer. In Hudson Bay, the ice cover starts to form in northern areas by late October and continues to grow until a maximum cover is reached at he end of April. Polynya (open water leads in the ice which are known to be important biologically throughout the Arctic) are found predominantly along the north-west and east coasts of Hudson Bay, both coasts of James Bay, and in the vicinity of the Belcher Islands. In James Bay, the ice cover begins to decay in late May, and the area becomes ice-free by the end of July.

The watershed of Hudson Bay and James Bay covers well over one-third of Canada, from southern Alberta to central Ontario to Baffin Island, as well as parts of North Dakota and Minnesota in the United States. The rivers flowing into Hudson Bay and James Bay discharge more than twice the flow of either the Mackenzie or St. Lawrence rivers. The seasonal timing of this freshwater discharge is a major factor governing the productivity and JSC of the region. Hydro developments that change the timing and rate of flow of fresh water may cause changes in the nature and duration of ice-cover; habitats of marine mammals, fish, and migratory birds; currents into and out of Hudson Bay/James Bay; seasonal and annual loads of sediments and nutrients to marine ecosystems (likely leading to lower biological productivity of estuaries and coastal areas); and anadromous fish populations (click here for more information).

Greenland Ice Sheet and Climate Change

71.5N 31.4W

June 20th, 2013 Category: Climate Change VIIRSSuomi-NPP

Greenland – June 19th, 2013

The Greenland ice sheet is a vast body of ice covering 1,710,000 square kilometres (660,235 sq mi), roughly 80% of the surface of Greenland. It is the second largest ice body in the world, after the Antarctic Ice Sheet.

The ice sheet is almost 2,400 kilometres (1,500 mi) long in a north-south direction, and its greatest width is 1,100 kilometres (680 mi) at a latitude of 77°N, near its northern margin. The mean altitude of the ice is 2,135 metres (7,005 ft). The thickness is generally more than 2 km (1.24 mi) and over 3 km (1.86 mi) at its thickest point.

Some scientists predict that climate change may be near a “tipping point” where the entire ice sheet will melt in about 2000 years. If the entire 2,850,000 cubic kilometres (683,751 cu mi) of ice were to melt, it would lead to a global sea level rise of 7.2 m (23.6 ft).

Arctic Sea Ice by Russia and Climate Change Issues

69.8N 163.3E

June 18th, 2013 Category: Climate Change MODISTerra

Russia – June 18th, 2013

Since 1979 the Arctic region has been extensively monitored by satellites. They detect the ice surface area, the extent of the area covered with ice and also the total amount or volume of ice. The results of these observations are startling. For example, sea ice area and the amount of perennial (multi-year) ice has decreased dramatically over the past 3 decades. In 2012, the September average ice extent dipped below 4 million km², which is about half of what it was in 1979. Ice volume shows a comparable rapid decrease (click here for more information).

Greenland’s Ice and Climate Change

71.0N 39.1W

June 17th, 2013 Category: Climate Change AVHRRMetOp

Greenland – June 16th, 2013

New research suggests that Greenland’s vast ice sheet isn’t as fragile as some climate scientists feared. The work indicates the majority of ice on Greenland could remain intact for hundreds of years even if the planet warms considerably. The real risks may lie in Antarctica, which may be more unstable than scientists have thought.

The study used ice cores to study conditions during a period of natural global warming that occurred between 115,000 and 130,000 years ago, when temperatures were about 14.5 Fahrenheit degrees higher than they are today. This was known as the Eemian period.

During this inter-glacial time about 75 percent of Greenland’s ice sheet remained intact. Accordingly, the study also indicates that Antarctica, which has much more ice, must have contributed significantly more to a sea levels that were 25 feet above what they are today.

Nevertheless this paper will likely muddy the already very muddy waters of the interface scientists have with the public and their perception of this issue. The concerns about recent trends on Greenland’s giant ice mass have been warranted, given signs of extensive surface melting and the possibility, explored here, that meltwater gushing to the ice sheet’s base through natural “drain pipes” called moulins could accelerate the flow of ice to the sea (click here for more information).

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