Sentences with phrase «for glaciation»

So we could be 8,000 years overdue already, or not due for another glaciation for another 12,000 years.

Glacio - epochs and the supercontinent cycle after ∼ 3.0 Ga: tectonic boundary conditions for glaciation.

Kent points out that according to the Milankovitch theory, we should be at the peak of a 20,000 - some year warming trend that ended the last glacial period; the Earth may eventually start cooling again over thousands of years, and possibly head for another glaciation.

That the dummies are off on a crusade against warmer winters could not possibly have been predicted in advance as we live in a world which for three and a half million years has had a marked tendency for glaciation creating the most pitiful of conditions.

Surprisingly, this raises the CO2 threshold for glaciation to a staggering 3000 ppmv or so.

The study Harris authored found that «the data... clearly shows the nominal 100KY cycle for glaciation and the interglacial phases and it shows that we have reached the end of the typical interglacial cycle and are due for a sudden cooling climate change.

As for the glaciation cycles of the current ice age, please see here.

Note that there is some hysteresis there; the thresholds for glaciation and deglaciation are not generally at the same point.

Going in and out of a snowball is a dramatic hysteresis; I think ice sheets may also exhibit hysteresis (threshold for glaciation not equal to threshold for deglaciation) though maybe I don't understand that correctly.

Jim Larsen # 30, I think Jim Hansen mentions the initial orbital forcing for glaciation - deglaciation to be less than 1 W / m2 averaged over the planet, maybe just a few tenths of a W / m2.

As astronomical cycles they are predictable into the future and will cause another ice age probably in around 50,000 years (that depends on where the threshold for glaciation is, and what future CO2 levels will be at that time), but there is no way the Milankovich cycles could explain the current global warming.

Jim Larsen # 30, I think Jim Hansen mentions the initial orbital forcing for glaciation - deglaciation to be less than 1 W / m2 averaged over the planet, maybe just a few tenths of a W / m2.

That would make Mars's giant mid-latitude mountains — Ascraeus Mons, Pavonis Mons and Arsia Mons — prime locations for glaciation around 210 million years ago.

After all, the mechanism for glaciations has not been fully explained.

Not exact matches

The next step will be to gather more ancient samples from before and after a major environmental change — the end of a glaciation, for example, or the arrival of humans in the New World — to see whether any epigenetic changes correlate with the environmental transition.

But when Nick Pyenson of the Smithsonian Institution in Washington DC modelled Pacific feeding grounds during peak glaciation, he found that very little of the north Pacific was shallow enough for feeding: sea levels were up to 120 metres lower than today and the Bering Sea was a land bridge.

So the fact that we have this very strong drying in the tropics during glaciation would argue for a strong feedback of water vapor concentration to the global climate during glacial - interglacial cycles.»

Because people arrived to the islands long after the end of the glaciation, starting some 6,000 years ago, the Caribbean islands provide an ideal laboratory for discovering the cause of these losses.

U-series dating is hardly new and has been used on corals before, but usually for the purpose of dating sea - level changes, glaciation, and world climate shifts over periods of 100,000 years.

The main trigger for the Quaternary glaciation was the continuing fall in the level of CO2 in the atmosphere due to the weathering of the Himalayas.

Records of sea surface temperature from oceanic sediment cores, for example, show that the magnitude of warming following several previous glaciations are well - correlated (www.ncdc.noaa.gov/paleo/recons.html).

In this case, the researchers combined records of ancient lake levels, location and extent of glaciation, variations in the composition of stalagmites in caves, and evidence for changes in vegetation and subsurface soil deposits associated with water table depth.

For example, closure of the Isthmus of Panama, and restriction of the Indonesian seaway, have been suggested as reasons for the onset of northern - hemisphere glaciation 3 million years ago (but that's 3 million, not 1 millioFor example, closure of the Isthmus of Panama, and restriction of the Indonesian seaway, have been suggested as reasons for the onset of northern - hemisphere glaciation 3 million years ago (but that's 3 million, not 1 milliofor the onset of northern - hemisphere glaciation 3 million years ago (but that's 3 million, not 1 million).

One of the extreme events, which has mystified scientists for long, took place 717 million years ago and is called «snowball Earth» — the largest glaciation event in history during which the planet was covered almost entirely in ice.

During glaciation, water was taken from the oceans to form the ice at high latitudes, thus global sea level drops by about 120 meters, exposing the continental shelves and forming land - bridges between land - masses for animals to migrate.

Ice ages can be further divided by location and time; for example, the names Riss (180,000 — 130,000 years bp) and Würm (70,000 — 10,000 years bp) refer specifically to glaciation in the Alpine region.

This chemical weathering process is too slow to damp out shorter - term fluctuations, and there are some complexities — glaciation can enhance the mechanical erosion that provides surface area for chemical weathering (some of which may be realized after a time delay — ie when the subsequent warming occurs — dramatically snow in a Snowball Earth scenario, where the frigid conditions essentially shut down all chemical weathering, allowing CO2 to build up to the point where it thaws the equatorial region, at which point runaway albedo feedback drives the Earth into a carbonic acid sauna, which ends via rapid carbonate rock formation), while lower sea level may increase the oxidation of organic C in sediments but also provide more land surface for erosion... etc..

Glacial troughs, excavated throughout maximum glaciations over the last 2 million years, provide a major route for Circumpolar Deep Water to access the ice shelves11.

Aaron Gronstal, in Astrobiology Magazine: «The interior of Yukon and Alaska was cold enough to support ice sheets but too dry for extensive glaciation.»

Beringia was by no means a tropical paradise for life, but the cold, wind - swept desert was an important ecological refuge for plants and animals when glaciation of the Earth was at its peak.»

They can be used for art classes, Geography looking at landscapes, glaciation and History of the people of Canada.

For use with mountain, geology, geography, ecology, habitats, glaciation, tectonics, and climate topics.

In all - wheel drive form, the Rogue manages to stay out of trouble when the white stuff starts blowing sideways at double - digit speeds, though for more prolonged glaciation periods we would have fitted it with snow tires.

For a while, it was thought that the glaciation of Antarctica may have significantly contributed to the cooling of the ocean, however, recent evidence tends to deny this.

It is to be noted here that there is no necessary contradiction between forecast expectations of (a) some renewed (or continuation of) slight cooling of world climate for a few decades to come, e.g., from volcanic or solar activity variations; (b) an abrupt warming due to the effect of increasing carbon dioxide, lasting some centuries until fossil fuels are exhausted and a while thereafter; and this followed in turn by (c) a glaciation lasting (like the previous ones) for many thousands of years.»

Without knowing the bigger picture (i.e having right global model of glaciations - deglaciations), the «local» responses may be misleading, especially for practical purposes.

The paper in Ambio (1997) shows in Fig 2 the entrance into glaciation starting now if CO2 is 210 ppmv, but the threshold in our model for entering into glaciation has been indicated many times to be 240 ppmv (see paper by Loutre and Berger cited by Tzedakis et al., and the papers Berger and Loutre in Science 2002, Berger et al. in Surveys in Geophysics 2003).

The earth has had significant Global Warming for some 20,000 years now... The only real argument is to the degree that mans activity has augmented that... We just came out of one - point - five - million years of continuous glaciation with sheets of two mile thick ice down past the 44th parallel... I will cheerfully deal with warming issues over that, any day...

The glaciological community has for decades harbored the widespread belief that the thermal evolution of the ice sheet, and the effect of this evolution on ice flow, are central in the ice - age cycling (not all communities agree, but there is plenty of literature on this from the land - ice crowd), so use of a temperature - independent rheology for the ice leaves out one favored explanation for termination of extensive glaciation.

There absolutely is climate change in accordance with the cycles of glaciation, orbital cycles, solar cycles and related for millions of years.

Or perhaps you could instead spend a few trillion (literally) dollars to alter the climate, and it doesn't work, the little bugger dies off anyhow, just in time for a new glaciation.

I think if it's handy to have a faux - factor for ocean heat gain % age then it's either from sea water melt / freeze temperature or the average ocean temperature during previous glaciation.

[The reason the Pliocene ended and made way for the Pleistocene increased polar glaciations could paradoxically also lie in this same strengthening of the MOC.

But a major problem exists for the standard orbital hypothesis of glaciation: Late Pliocene and early Pleistocene glacial cycles occur at intervals of 40 ky (8 — 11), matching the obliquity period, but have negligible 20 - ky variability.

Despite stating that there is no CO2 data near the time of the Devonian glaciation [there are values of 1000ppm and 1300ppm before and after the glaciation], and surmising that perhaps 2000ppm CO2 would be low enough to allow permanent ice to form the graph shows a value of below 500ppm for the late Devonian.

It was developed by scientists at CAGE — Centre for Arctic Gas Hydrate Environment and Climate, and shows that seafloor off Western Svalbard was covered by a large ice sheet during the last glaciation.

The period between was a period where oscillation of Climate was observed as variation of (much higher) sea levels rather than recurring glaciation events, for well over 200 Million years until the last ~ 3 Million.

Glaciers have been melting for 20,000 years, that is how the last Glaciation was reverted and this process is still proceeding.

Furthermore, the existence of some feedbacks leading to new states — classically the deglaciation / albedo runaway at the end of glaciations — can not be disputed, but is also accounted for with traditional approaches.

C: Datasets suggesting a drying environment at 2.5 Ma, shown by λ 18O from benthic foraminifera, a proxy for global temperature, smoothed with a Gaussian window of 200 ky; eustatic sea level; and magnetic susceptibility, a proxy for ice rafted debris and Northern Hemisphere glaciation.