Sentences with phrase «hemisphere ice sheets»

A prerequisite was the growth of very large Northern Hemisphere ice sheets, whose subsequent collapse created stadial conditions that disrupted global patterns of ocean and atmospheric circulation.

The glaciers atop Gondwana extended to at least 45 ° S latitude, similar to the latitude reached by Northern Hemisphere ice sheets during the Pleistocene.

«Even for a total of 500 Gt C cumulative emissions, which is only slightly above the present - day value, the evolution of the Northern Hemisphere ice sheets is affected over tens of thousands of years (Fig. 4).

The rapid increase in δ18O in the past few million years was associated with the appearance of Northern Hemisphere ice sheets, symbolized by the dark blue bar in figure 1a.

The Cenozoic record also reveals the amplification of climate change that occurs with growth or decay of ice sheets, as is apparent at about 34 Myr BP when the Earth became cool enough for large - scale glaciation of Antarctica and in the most recent 3 — 5 Myr with the growth of Northern Hemisphere ice sheets.

Heinrich events — abrupt periods of substantial iceberg discharge from the Northern Hemisphere ice sheets — occurred repeatedly throughout the last glacial period and had pronounced global effects on climate.

«Changes in the CO2 and CH4 content have played a significant part in the glacial - interglacial climate changes by amplifying, together with the growth and decay of the Northern Hemisphere ice sheets, the relatively weak orbital forcing»

But it was long suspected that «orbital factors» weren't the whole story, as the southern hemisphere ice sheets melted back at the same time as the northern ones.

«Matuyama 41,000 - Year Cycles: North Atlantic Ocean and Northern Hemisphere Ice Sheets.»

The cooling trend due to reduction of CO2 and changes in climate associated with changes in the geography eventually allowed Northern Hemisphere ice sheets to form, whereafter the strong amplification of Milankovic was possible.

worryingly Northern Hemisphere Ice sheets did not begin to form until 400 ppmv but I do not know when they became stable CO2 levels wise.

If so, the Southern Hemisphere ice sheets may once again exert dominant influence on climate cycles.

«The question is, will we push carbon dioxide high enough in the future that the Northern Hemisphere remains ice free and the advances and retreats begin again with the Southern Hemisphere ice sheets.»

Then in his Figure 1 Hansen shows Antarctic glaciation when deep ocean temperature was approx 3deg C and later the N. hemisphere ice sheet forming at say 2.5 deg C deep ocean temperature.

Not exact matches

Nie and Garzione suggest that the fluctuating Antarctic ice sheet in the late Miocene, at a time when there was minimal ice in the Northern Hemisphere, exerted the dominant control on the 100,000 year cycles observed in the Qaidam Basin record.

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.

«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.

And that if it did, the northern hemisphere would cool so much that that ice sheets would start to grow, creating a catastrophic new ice age.

The beginning of the last glacial period was characterized in the Northern hemisphere by significant accumulation of snow at high latitudes and the formation of a huge polar ice sheet.

The study, co-authored by Dr Thomas Stevens, from the Department of Geography at Royal Holloway, University of London, found a previously unknown mechanism by which the joining of North and South America changed the salinity of the Pacific Ocean and caused major ice sheet growth across the Northern Hemisphere.

This is often suggested to be the main factor influencing the decay of ice sheets in the northern hemisphere.

It appears the earth's climate is unstable when it cools a few degrees, as that starts the formation of the massive ice sheets in the Northern Hemisphere.

As the vast ice sheets that covered much of the northern hemisphere receded, human civilization blossomed, making the most of the relatively mild conditions that we still enjoy today.

Glaciologically, ice age implies the presence of extensive ice sheets in the northern and southern hemispheres; [1] by this definition we are still in an ice age (because the Greenland and Antarctic ice sheets still exist).

During the late Pliocene the spread of ice sheets in the Northern Hemisphere began.

The 8.2 kyr Holocene thermal maximum is thought to have been buffered by the presence of the Laurentide ice sheet in the northern hemisphere.

The LGM was a very different world than the present, involving considerable expansions of sea ice, massive Northern Hemisphere land ice sheets, geographically inhomogeneous dust radiative forcing, and a different ocean circulation.

``... without the CO2 feedback the climate change would be much more confined to the Northern Hemisphere extratropics, where the great ice sheets wax and wane.

However, without the CO2 feedback the climate change would be much more confined to the Northern Hemisphere extratropics, where the great ice sheets wax and wane.

Nonetheless, the LGM climate remained cold due to the presence of large ice sheets in the Northern Hemisphere (Peltier, 1994, 2004) and reduced atmospheric CO2 concentration (185 ppm according to recent ice core estimates, see Monnin et al., 2001).

If the West Antarctic Ice Sheet collapses, sea level will fall close to the Antarctic and will rise much more than the expected estimate in the northern hemisphere because of this gravitational effect;

Such close linkages between CO2 concentration and climate variability are consistent with modelling results suggesting with high confidence that glacial — interglacial variations of CO2 and other greenhouse gases [CH4, N2O] explain a considerable fraction of glacial — interglacial climate variability in regions not directly affected by the northern hemisphere continental ice sheets (Timmermann et al., 2009; Shakun et al., 2012).

Yet the Pliocene world was very different today, with a much warmer Northern hemisphere, a deglaciated Greenland, episodic deglaciation of the West Antarctic Ice Sheet, and considerably warmer tropical temperatures.

Other forcings, including the growth and decay of massive Northern Hemisphere continental ice sheets, changes in atmospheric dust, and changes in the ocean circulation, are not likely to have the same kind of effect in a future warming scenario as they did at glacial times.

The 8.2 kyr Holocene thermal maximum is thought to have been buffered by the presence of the Laurentide ice sheet in the northern hemisphere.

While temperatures in the Northern Hemisphere were warmer than average during the summers, the tropics and areas of the Southern Hemisphere were colder than average which comprised an average global temperature still overall lower than present day temperatures Northwestern North America had peak warmth first, from 11,000 to 9,000 years ago, while the Laurentide ice sheet still chilled the continent.

The Last Glacial Maximum is a period when ice sheets during the last northern hemisphere ice age were at their highest extent.

Unlike the formerly - glaciated regions of the Northern Hemisphere, 98 % of Antarctic bedrock remains covered by ice and the ice sheet edge is fringed by extensive ice shelves; this hampers the collection of data on ice history and introduces substantial uncertainty in reconstructions.

The majority of the warming in the last 150 years has been in high latitudes of the Northern hemisphere with the most amount of warming occurring on the Greenland ice sheet which is the same pattern of warming that occurred in past D - O cycles.

Although ice sheets covered much of the Northern Hemisphere during a series of Pleistocene Ice Ages, the Earth now has just two major ice sheets, one on Greenland and one on Antarctiice sheets covered much of the Northern Hemisphere during a series of Pleistocene Ice Ages, the Earth now has just two major ice sheets, one on Greenland and one on AntarctiIce Ages, the Earth now has just two major ice sheets, one on Greenland and one on Antarctiice sheets, one on Greenland and one on Antarctica.

In the Southern Hemisphere, GRACE measurements indicated a significant ice loss in the Antarctic Ice Sheet from 2002 to 20ice loss in the Antarctic Ice Sheet from 2002 to 20Ice Sheet from 2002 to 2005.

The best - studied case so far is the abrupt warming in the Northern Hemisphere about 15,000 years ago that started the ice sheets to melting.

The miles - thick ice - sheets of Antarctica continue to surprise scientists, as they attempt to prise out the secrets from deep within the southern hemisphere's giant ice locker.

It's not confirmed, but is believed that this established the Gulf Stream leading to the Northern Hemisphere glaciation (NHG), the build - up of the Laurentide and Scandinavian ice - sheets.

Over the last two decades, the Greenland and Antarctic ice sheets have been losing mass, glaciers have continued to shrink almost worldwide, and Arctic sea ice and Northern Hemisphere spring snow cover have continued to decrease in extent.

Temperatures are rising across the globe, but scientists say that the warmth in the Arctic has been especially profound, as they report exceptionally low snow cover in the Northern Hemisphere and premature seasonal melting of sea ice along with the Greenland ice sheet.

«The positive ice - albedo feedback acts to amplify the climate change as a consequence of the melting of sea ice and ice sheets in the Northern Hemisphere.

More summer sunlight began falling on the northern hemisphere, melting those massive ice sheets and sending icebergs and fresh water into the North Atlantic Ocean.

In 2011, annual snow cover extent over Northern Hemisphere continents (including the Greenland ice sheet) averaged 24.7 million square kilometers, which is 0.3 million square kilometers less than the long - term average.

Peter U. Clark, Richard B. Alley, and David Pollard, «Northern Hemisphere ice - sheet influences on global climate change,» Science 286: 1104 - 1111 (5 November 1999).