Sentences with phrase «ice over thousands of years»

But that's an Antarctica average based on air samples that were each gradually trapped in the ice over thousands of years.

Within the disk, tiny dust grains accumulate layers of ice over thousands of years.

The ice sheet is made up of annual layers of snow that never melted and became compacted into ice over thousands of years.

Not exact matches

Over hundreds or thousands of years, vast ice sheets can melt away, further decreasing the planet's reflectivity.

Over hundreds of thousands of years, the Neandertal lineage developed successfully in western Eurasia and survived severe fluctuations between colder and warmer climactic cycles of the Ice Age.

John Stewart said, «During the Ice Age just over 40 thousand years ago in the north of England Neanderthals were living in an environment which included extinct animals like woolly mammoths, woolly rhinos and cave hyenas as well as the more familiar horses and reindeer.

The bottom few feet of ice is probably cluttered with such debris, picked up by the glacier as it slid over the hidden face of Antarctica for thousands of years.

This may also help explain the cyclical rise and fall of ice ages over hundreds of thousands of years.

Humanity has now raised global CO2 levels by more than the rise from roughly 180 to 260 ppm at the end of the last ice age, albeit in a few hundred years rather than over more than a few thousand years.

Ice keeps a record of environmental changes as it accumulates over thousands of years, so the longer the core, the better.

As the region warms due to increased greenhouse - gas emissions, ice melts, reducing Antarctica's elevation over centuries or thousands of years.

Researchers also think it's possible that over thousands of years, the diamonds slowly sink through the planets» ice layers and assemble into a thick layer around the core.

What they found was that local destabilization of the Amundsen Sea region of West Antarctica ultimately causes the entire ice sheet to fall into the ocean over several centuries to several thousands of years, gradually adding 3 meters to global sea levels, they report online today in the Proceedings of the National Academy of Sciences.

Earth's climate naturally varies between times of warming and periods of extreme cooling (ice ages) over thousands of years.

Although that is unlikely to happen for many thousands of years, the ice sheet has increasingly lost mass over the last two decades, and the glaciers that serve as its outlet to the sea are accelerating.

Romania's Scarisoara Ice Cave holds the world's oldest cave glacier, built up by water dripping into the cavern over thousands of years.

The team suspects that some of the pockets in these gullies might have held water in various forms in the recent past, over the last few hundreds of thousands of years, periodically harboring snow and ice when the conditions were right.

Severinghaus discovered that xenon and krypton are well preserved in ice cores, which provides the temperature information that can then be used by scientists studying many other aspects of the earth's oceans and atmosphere over hundreds of thousands of years.

These attempted to determine how ice thicknesses, temperatures and gas - hydrate stability likely changed over tens of thousands of years.

Every year that it snows in Antarctica, the new snow layer weighs on the previous layer, compacting over hundreds or thousands of years to eventually form layers of ice.

Meanwhile, over thousands of years feedback and re-feedback CO2 enters the atmosphere, and we're at a supercharged version of emerging from an ice age.

That estimate was based in part on the fact that sea level is now rising 3.2 mm / yr (3.2 m / millennium)[57], an order of magnitude faster than the rate during the prior several thousand years, with rapid change of ice sheet mass balance over the past few decades [23] and Greenland and Antarctica now losing mass at accelerating rates [23]--[24].

Living on the Chukotka Peninsulafor over a thousand years (on the Western most edge of Siberia; where the Russian side of the ice bridge that once linked Asia and North America lies), the Chukchi found the Husky useful as sled - dogs, watch dogs and for herding reindeer.

«As the ice sheet in Greenland melts over thousands of years and becomes lower, the temperature will increase because of the elevation loss.

However, atmospheric CO2 content plays an important internal feedback role.Orbital - scale variability in CO2 concentrations over the last several hundred thousand years covaries (Figure 5.3) with variability in proxy records including reconstructions of global ice volume (Lisiecki and Raymo, 2005), climatic conditions in central Asia (Prokopenko et al., 2006), tropical (Herbert et al., 2010) and Southern Ocean SST (Pahnke et al., 2003; Lang and Wolff, 2011), Antarctic temperature (Parrenin et al., 2013), deep - ocean temperature (Elder eld et al., 2010), biogeochemical conditions in the Northet al., 2008).

It features some of the most dramatic and rapid climate shifts in Earth's history, as well as tenacious scientists braving the hostile ice and snows of Greenland and Antarctica for years on end to bring home that most precious material: kilometre - long cores of ancient ice, dating back over a hundred thousand years.

This gradual removal of CO2 from the atmosphere reduces the overall greenhouse effect and thus slowly draws the entire planet into an ice age, driving further ice sheet expansion over tens of thousands of years (a complete ice age cycle is around 100,000 years)

The postulated and very likely cause of the ice ages are variations of the earths orbit around the sun, and variations of the inclination of the earth's axis in relation to this orbit, which cause variations of the sun's heating of different parts of the earth at different times of the year (mainly the northern hemisphere) over long periods of time (tens of thousands of years).

Over all, the loss of the West Antarctic ice from warming is appearing «more likely a definite thing to worry about on a thousand - year time scale but not a hundred years,» Dr. Pollard said.

Over tens of thousands of years, Milankovich cycles have increased and decreased seasonality, leading to periods of greater ice cover which in turn reflect away sunlight, cooling the planet.

An ice core - formed by compaction of previous snowfalls - constitutes a historical record of the local climate and atmosphere stretching back over thousands of years.

Glacial cycles (ice ages) are set in motion by (1) periodic wobbles in the tilt of the Earth's rotation, (2) changes in the tilt of its axis, and (3) the shape of its orbit occurring over tens of thousands of years.

Over thousands of years, the layers of snow build up, forming a flowing sheet of ice thousands of feet thick and tens to thousands of miles across.

Over thousands of years, the layers of snow pile up into thick masses of ice, growing thicker and denser as the weight of new snow and ice layers compresses the older layers.

If we hindcast them a couple tens of thousands of years do they show us a mile of ice over the Great Lakes?

The differences are (1) that you can not afford spatio - temporal resolution of weather models to simulate thousand years forward, and (2) in weather model you don't care if your prediction will blow up in 100 years yielding Venus condition or Ice Ball, you just stop the computer after a week of simulated time, and start over.

They know that the highly regular ice ages are caused primarily not by CO2 increases and decreases in the atmosphere but by well known wobbles in the earth's rotation — over tens of thousands of years.

A process that occurs over thousands of years after the ice melts.

Thousands of years ago, during the height of the ancient Greek and Roman empires, lead emissions from sources such as the mining and smelting of lead - silver ores in Europe drifted with the winds over the ocean to Greenland — a distance of more than 2800 miles (4600 km)- and settled onto the ice.

That estimate was based in part on the fact that sea level is now rising 3.2 mm / yr (3.2 m / millennium)[57], an order of magnitude faster than the rate during the prior several thousand years, with rapid change of ice sheet mass balance over the past few decades [23] and Greenland and Antarctica now losing mass at accelerating rates [23]--[24].

This can be inferred from ice core measurements, which show a near constant atmospheric concentration of CO2 over the last several thousand years prior to the Industrial Era.

64) Michael Mann of Penn State University has actually shown that the Medieval Warm Period and the Little Ice Age did in fact exist, which contrasts with his earlier work which produced the «hockey stick graph» which showed a constant temperature over the past thousand years or so followed by a recent dramatic upturn.

(71) If the conventional beliefs had been the same in 1993 as in 1953 — that significant climate change always takes many thousands of years — scientists would have passed over the decade - scale fluctuations in ice cores as meaningless noise.

Ice - flow corrections allow reconstruction of snow accumulation rates over tens of thousands of years with little additional uncertainty.

This small thickening, sustained over thousands of years and spread over the vast expanse of these sectors of Antarctica, corresponds to a very large gain of ice - enough to outweigh the losses from fast - flowing glaciers in other parts of the continent and reduce global sea level rise.

Second, a quick reality check shows that Greenland's ice cap is hundreds of thousands of years old and covers over 80 % of the island.

While sea level has varied greatly in the past, it has generally changed slowly, over many thousands of years — except when ice sheets collapse.

Of course, the simplest explanation is that the ice core measurements are unreliable, and I suspect that is likely enough, given that there is no way to actually confirm the model for how CO2 is trapped and held over centuries, much less many thousands of years, in an end - to - end fashioOf course, the simplest explanation is that the ice core measurements are unreliable, and I suspect that is likely enough, given that there is no way to actually confirm the model for how CO2 is trapped and held over centuries, much less many thousands of years, in an end - to - end fashioof years, in an end - to - end fashion.

When scientists later used ice cores to tease out the pattern of temperature and CO2 changes over the past few hundred thousand years, they got the sort of pattern you'd expect from the 1990 hypothesis (here's another graph).

All these changes take place over tens of thousands of years, but they can change the amount of sunlight that the Earth gets in the Northern or Southern Hemisphere, and these changes in the distribution of the sun's heat are closely tied to the rise and fall of ice ages.