Mercer (1969) considered breakup of an Arctic
Ocean ice sheet; this is cited as a likely explanation by Ruddiman and McIntyre (1981a), pp. 204ff.
Not exact matches
The world's
oceans are rapidly rising as waters warm and
ice sheets melt.
Additionally,
ice sheets are sometimes affected by increased
ocean temperatures that literally undermine the
ice sheets and melt them from below.
There are more, however, including the amount of sunlight an
ice sheet is able to reflect; the larger an
ice sheet, the more sunlight is reflected, but the smaller an
ice sheet, the more
ocean there is surrounding the
ice sheet to absorb the sunlight which in turn heats up the surrounding waters increasing the melt which decreases the size of the
ice sheet which in turn... and so goes the cycle.
Almost exactly a year ago, a 251 - square - kilometer
sheet of
ice broke from the Petermann Glacier in Greenland and started slowly drifting into the open
ocean.
Following the maxim of keeping everything as simple as possible, but not simpler, Will Steffen from the Australian National University and I drew up an Anthropocene equation by homing in on the rate of change of Earth's life support system: the atmosphere,
oceans, forests and wetlands, waterways and
ice sheets and fabulous diversity of life.
The Earth's climate system is characterised by complex interactions between the atmosphere,
oceans,
ice sheets, landmasses and the biosphere (parts of the world with plant and animal life).
«The widespread loss of Antarctic
ice shelves, driven by a warming
ocean or warming atmosphere, could spell disaster for our coastlines — and there is sound geological evidence that supports what the models are telling us,» said Robert M. DeConto of the University of Massachusetts Amherst, a co-author of the study and one of the developers of the
ice -
sheet model used.
Willis is leading a new mission to study the effects of warming
oceans on the melting of the Greenland
Ice Sheet.
Any parts of the bed this low are easily exposed to
ocean water, allowing the
ice sheet to weaken from below as the
ocean water warms.
That question is central to understanding the effects of
ice sheet melting on
ocean water properties, circulation, and biological systems, on scales from local to basinwide.
The deep grooves under the massive
ice sheet could facilitate flow into the
ocean, which suggests sea level rise estimates for this century need to be revised upwards
The precariously moored West Antarctic
ice sheet probably won't collapse into the
ocean all in one go as the climate warms.
The properties of the climate system include not just familiar concepts of averages of temperature, precipitation, and so on but also the state of the
ocean and the cryosphere (sea
ice, the great
ice sheets in Greenland and Antarctica, glaciers, snow, frozen ground, and
ice on lakes and rivers).
Today,
ice sheets are melting, sea level is rising,
oceans are warming, and weather events are becoming more extreme.
Scientists have suggested that
ice sheets covering the
ocean, or a hydrogen - sulfide haze, might have protected nascent life, but attempts to model these conditions have given ambiguous results.
In August 2015, University of Delaware oceanographer Andreas Muenchow and colleagues deployed the first UD
ocean sensors underneath Petermann Glacier in North Greenland, which connects the great Greenland
ice sheet directly with the
ocean.
They found that western Antarctica has recently seen warmer, saltier water being driven under the shelf — the part of the
ice sheet that sticks out over the
ocean (Science, doi.org/xkx).
The hope is that the cables could reveal secrets about what's happening underneath the
ice sheets, especially about melting at the so - called grounding line, the place where the bottom of an
ice sheet meets the slightly warmer
ocean.
The days were becoming rapidly shorter as winter approached, and I sat back and imagined the Arctic
Ocean, just outside the clinic windows, under a
sheet of
ice in just a few months.
From 500 feet up everything appeared in miniature except the giant
ice shelves — seemingly endless expanses of
ice, as thick as the length of several football fields, that float in the Southern
Ocean, fringing the
ice sheets that virtually cover the Antarctic landmass.
The warming
ocean and atmosphere that are already melting glaciers and
ice sheets produce a catastrophic rise in the
ocean.
The shelves act as a buttress to the «grounded»
ice, helping slow the flow of the
ice sheet's glaciers into the
ocean.
Perhaps extra carbon dioxide from a period of heightened seafloor eruptions eventually percolates through the
ocean and into the atmosphere, allowing warming that would deliver a coup de grâce to the massive
ice sheets.
The Antarctic
ice sheet, the thick layer of
ice covering much of the continent, is anchored in place by its floating fringe, shelves of
ice that jut out into the surrounding
ocean.
This could have significant implications for Antarctica's
ice shelves and
ice sheets, with previous research showing that even small increases in
ocean temperatures can substantially increase melt rates around the Peninsula.
«If the West Antarctic
ice sheet were to disappear, sea level would rise almost 19 feet; the
ice in the Greenland
ice sheet could add 24 feet to that; and the East Antarctic
ice sheet could add yet another 170 feet to the level of the world's
oceans: more than 213 feet in all.»
These coastal glaciers hold back inland glaciers, so their collapse would set off a chain reaction ending with the West Antarctic
Ice Sheet pouring into the Southern
Ocean.
It's known that when
ice sheets start to melt, cooling the air in that region, the winds over the Southern
Ocean strengthen, Toggweiler says.
The Arctic took another 3,000 - 4,000 years to warm this much, primarily because of the fact that the Northern Hemisphere had huge
ice sheets to buffer warming, and the fact that changes in
ocean currents and Earth's orbital configuration accelerated warming in the south.
Many of the glaciers that jut out into the
ocean are thinning, but whether the
ice sheet itself has remained stable and intact, even during warm interglacial periods, is a matter of considerable debate.
• In Antarctica, Greenland and other places where big
ice sheets are surrounded by the
ocean, sometimes big chunks of
ice fall into the
ocean after they have started to melt.
«Very old
ice probably exists in small isolated patches at the base of the
ice sheet that have not yet been identified, but in many places it has probably melted and flowed out into the
ocean.»
The paper also describes an atmosphere -
ocean modeling study of feedback loops caused by
ice sheet melting under 2 °C conditions.
As the
ice sheets melt, there will not only be more water in the
oceans, but the positions of those hills and valleys will shift.
A new study says that climate - induced feedback loops could lead to a change in
ocean stratification and the more rapid melting of
ice sheets.
The
ice sheet reflects energy into space, and as that bright reflective surface is lost, more heat is trapped in the
ocean.
That might include draining away the water that lubricates the bottom of an
ice sheet, speeding its progress to the sea, or installing barriers to prevent warming
ocean waters from hitting the bottom of such glaciers and hastening meltdown.
«It could be in the form of an
ice sheet, or an aquifer, or a piece of
ocean.
«It's hard to discern an
ice sheet's cycles on land because it destroys the evidence,» she says, «but it dumps that evidence in the
oceans, archived in layers on the bottom.»
Analyzing and dating these rocks, they found that
ocean water began to appear on the ridge's land - facing side in 1945, even as the
ice sheet remained grounded on the ridge's summit, scientists report online today in Nature.
«We argue that it was the establishment of the modern deep
ocean circulation — the
ocean conveyor — about 2.7 million years ago, and not a major change in carbon dioxide concentration in the atmosphere that triggered an expansion of the
ice sheets in the northern hemisphere,» says Stella Woodard, lead author and a post-doctoral researcher in the Department of Marine and Coastal Sciences.
Massive
ice sheets grew across the Antarctic continent, major animal groups shifted, and
ocean temperatures decreased by as much as 5 degrees.
If there's anything more complicated than the global forces of thermal expansion,
ice sheet melt and
ocean circulation that contribute to worldwide sea - level rise, it might be the forces of real estate speculation and the race - based historical housing patterns that color present - day gentrification in Miami.
Enkelmann appreciates the challenge of collecting samples here because this range has the highest peaks of any coastal mountain range and is only 20 kilometers from the Pacific
Ocean, but she points out that it is a tough area to study because of the big
ice sheets.
«The strong impact of
ocean onto Antarctic
ice sheet dynamics, or the knowledge that we have about it, is reinforced by our study,» said lead study author Hannes Konrad of the University of Leeds in an interview with E&E News.
Massive reorganizations of the
ocean - atmosphere system, the authors argue, are the key events that link cyclic changes in the earth's orbit to the advance and retreat of
ice sheets
The study fuels a growing concern among scientists about the factors affecting the Antarctic
ice sheet — namely, that warm
ocean waters are helping to melt glaciers and drive greater levels of
ice loss, particularly in West Antarctica.
Antarctica's great
ice sheet is losing ground as it is eroded by warm
ocean water circulating beneath its floating edge, a new study has found.
But because the surrounding
ocean would have been warmer, and stabilizing sea
ice less abundant, the massive East Antarctic
ice sheet may have contributed to higher sea levels by flowing more quickly towards the
ocean.