Sentences with phrase «from past ice ages»

The different patterns can be used to hunt for now - disappeared glaciers from past ice ages.

Not exact matches

We present a synthesis of decadally resolved proxy temperature records from poleward of 60 ° N covering the past 2000 years, which indicates that a pervasive cooling in progress 2000 years ago continued through the Middle Ages and into the Little Ice Age.

On land, the capacity of animals to carry nutrients away from concentrated «hotspots,» the team writes, has plummeted to eight percent of what it was in the past — before the extinction of some 150 species of mammal «megafauna» at the end of the last ice age.

As Weir points out, it likely owes its survival as a species on being geographically isolated from its parental species at some point during a past ice age when rainforest coverage contracted, and wide rivers formed natural barriers.

Indeed, the main quandary faced by climate scientists is how to estimate climate sensitivity from the Little Ice Age or Medieval Warm Period, at all, given the relative small forcings over the past 1000 years, and the substantial uncertainties in both the forcings and the temperature changes.

Re 92 and 105: First I just want to reitterate more generally what 105 said — Milankovitch cycles have had climate signals, in ice ages or otherwise, — well probably ever since the Moon formed, although the signal from times past will not always reach us, but I've read of evidence of Milankovitch precession cycle forcing of monsoons in lakes in Pangea (PS over geologic time the periods of some of the Milankovitch cycles have changed as the Moon recedes from the Earth due to tides).

A sensitivity which is too low will be inconsistent with past climate changes - basically if there is some large negative feedback which makes the sensitivity too low, it would have prevented the planet from transitioning from ice ages to interglacial periods, for example.

The Past and Future Ocean Circulation from a Contemporary Perspective, in AGU Monograph, 173, A. Schmittner, J. Chiang and S. Hemming, Eds., 53 - 74, (pdf)» Wunsch's publications page is great food - for - thought, I particularly enjoyed his papers on Ice Age changes and the Milankovitch cycles.

Moreover, random interactions within the sun's magnetic field can flip the fluctuations from one cycle length to the other, matching the paleo - temperature record for ice ages on Earth for over the past 5.3 million years, when ice ages occurred occurred roughly every 41,000 years until about a million years ago when they switched to a roughly 100,000 - year cycle.

Although it was not a true ice age, the term was introduced It is not uncommon to read that ice cores from the polar regions contain records of climatic change from the distant past.

Visible from space, the hole is a relic of past ice ages and was made famous by the oceanographer Jacques - Yves Cousteau.

Discover the amazing ice age giants of Australia's past, the mega fauna, as revealed by the fossils and view the models recreated from the bones found in the Victoria Fossil Cave.

However, in periods in the past, say around 8,200 years ago, or during the last ice age, there is lots of evidence that this circulation was greatly reduced, possibly as a function of surface freshwater forcing from large lake collapses or from the ice sheets.

It is my understanding that the previous ice ages have ended in the past by a forcing from changes in tilt of the earth (i.e. Milankovitch cycles).

Mike's work, like that of previous award winners, is diverse, and includes pioneering and highly cited work in time series analysis (an elegant use of Thomson's multitaper spectral analysis approach to detect spatiotemporal oscillations in the climate record and methods for smoothing temporal data), decadal climate variability (the term «Atlantic Multidecadal Oscillation» or «AMO» was coined by Mike in an interview with Science's Richard Kerr about a paper he had published with Tom Delworth of GFDL showing evidence in both climate model simulations and observational data for a 50 - 70 year oscillation in the climate system; significantly Mike also published work with Kerry Emanuel in 2006 showing that the AMO concept has been overstated as regards its role in 20th century tropical Atlantic SST changes, a finding recently reaffirmed by a study published in Nature), in showing how changes in radiative forcing from volcanoes can affect ENSO, in examining the role of solar variations in explaining the pattern of the Medieval Climate Anomaly and Little Ice Age, the relationship between the climate changes of past centuries and phenomena such as Atlantic tropical cyclones and global sea level, and even a bit of work in atmospheric chemistry (an analysis of beryllium - 7 measurements).

Climate estimates compiled by geochemists from past periods with large changes (e.g. ice ages) show that the climate is a highly non-linear system, with thresholds and sudden dramatic changes.

The paper also finds that several significant past climate fluctuations — including a warm spell that peaked around 1100 A.D. called the medieval warm period and the so - called little ice age from the 1400s through the 1700s — were global in scope.

Indeed, the main quandary faced by climate scientists is how to estimate climate sensitivity from the Little Ice Age or Medieval Warm Period, at all, given the relative small forcings over the past 1000 years, and the substantial uncertainties in both the forcings and the temperature changes.

We all tend to cherry - pick to some degree to support our conclusions, but one factor that seems to be routinely ignored is the fact that the planet has been steadily emerging from an Ice Age for the past 11,000 + / - years.

There is still some discussion about how exactly this starts and ends ice ages, but many studies suggest that the amount of summer sunshine on northern continents is crucial: if it drops below a critical value, snow from the past winter does not melt away in summer and an ice sheet starts to grow as more and more snow accumulates.

Seafloor sediments show that during past ice ages, more iron - rich dust blew from chilly, barren landmasses into the oceans, apparently producing more algae in these areas and, presumably, a natural cooling effect.

«The extent of the ice in the Nordic Seas... has decreased by ≈ 33 % over the past 135 years... The time series indicates that we are in a state of continued recovery from the cooling effects of the Little Ice Age.&raqice in the Nordic Seas... has decreased by ≈ 33 % over the past 135 years... The time series indicates that we are in a state of continued recovery from the cooling effects of the Little Ice Age.&raqIce Age.»

We are using the same approach as last year: applying the survival fraction of ice of different ages determined from past seasons to the observed distribution of ice ages at the beginning of the melt season.

«The authors write that «the Mediterranean region is one of the world's most vulnerable areas with respect to global warming,»... they thus consider it to be extremely important to determine what impact further temperature increases might have on the storminess of the region... produced a high - resolution record of paleostorm events along the French Mediterranean coast over the past 7000 years... from the sediment bed of Pierre Blanche Lagoon [near Montpellier, France]... nine French scientists, as they describe it, «recorded seven periods of increased storm activity at 6300 - 6100, 5650 - 5400, 4400 - 4050, 3650 - 3200, 2800 - 2600, 1950 - 1400, and 400 - 50 cal yr BP,» the latter of which intervals they associate with the Little Ice Age.

Although the I.P.C.C. allowed for the possibility that variations in sunlight could have ended the «Little Ice Age,» a period of cooling from the 14th century to about 1850, our data argues strongly that the temperature rise of the past 250 years can not be attributed to solar changes.

Recent mild warming over the past 150 years merely represents a recovery from the Little Ice Age which was the catastrophic cooling phase that followed the MWP.

For roughly the past 10,000 years, since the end of the last Ice Age, human beings have enjoyed a relatively stable, comfortable «interglacial» period, during which they've invented everything from agriculture to moon rockets.

Such oceanic temperature as now subsists would probably be a historical inheritance from a long past state possibly at the end of the last ice age when it was reset by a combination of changed energy throughput from the sun plus the resistor effect of the oceans and air combined with the then state of the air circulation.

Corresponding to the recovery from the Little Ice Age, sea level has risen about eight inches in the past 130 years.

Well; if a statement regarding atmospheric cooling is taking place, and we know from past experience (climate history) that if this cooling continues and the build up of ice continues in Antartica like it is; then it is possible that the planet may very well be headed back into an ice age - and when this «atmospheric cooling» trend is mentioned on the GISS [NASA] Webpage, and by one of the GISS scientists (Kate Marvel, a climatologist at GISS and the paper's lead author) then i would have to conclude that the are embracing the science revealing evidence that such mechanics are, taking place, and I view their statemnt as an endorsement and ot their recognition, of global cooling.

The hockey stick pattern also shows up in the following papers: «Medieval Warm Period, Little Ice Age and 20th century temperature variability from Chesapeake Bay» «Inter-hemispheric temperature variability over the past millennium»

To curiosity - driven scientist Dan Lunt, understanding the past climate of our Earth (from the scorching greenhouse of the mid-Cretaceous, to the frozen wastes of the last ice age) is of fundamental interest.

According to the report, which follows a series of comprehensive reports from the IPCC in the past year on climate science and impacts, temperatures already have increased by 0.85 degrees Celsius since 1880, a more rapid shift in the climate than that which heralded the end of the last ice age about 10,000 years ago.

Broadly speaking, we can use the temperature change from the instrumental record (the past 150 years or so), or complex computer models of the climate, or temperature changes we've deduced for climates in the distant past (such as the last ice age 20,000 years ago, or the warm Pliocene 3 to 5 million years ago).

«He (Salby) suggests that its warmth which tends to produce more CO2, rather than vice versa — which, incidentally is the story of the past recoveries from ice ages.»

This theory promised, moreover, to give the timing of past changes precisely from basic physical principles, and to predict future ice ages.

Proxies such as these provide most knowledge of past climate fluctuations, such as the Medieval Warm Period from about 800 to 1300 and the Little Ice Age, centred on the year 1700.

He suggests that its warmth which tends to produce more CO2, rather than vice versa — which, incidentally is the story of the past recoveries from ice ages.

Related Volcanoes, Tree Rings, and Climate Models: This is how science works Fossil Focus: Using Plant Fossils to Understand Past Climates and Environments Atmospheric oxygen over Phanerozoic time Coupled carbon isotopic and sedimentological records from the Permian system of eastern Australia reveal the response of atmospheric carbon dioxide to glacial growth and decay during the late Palaeozoic Ice Age

Over the past two centuries, our planet finally began to emerge from the Little Ice Age that had cooled the Earth and driven Viking settlers out of Greenland.

They call it a 50 km ride, but it is really a 25 km slog uphill as we ride up from the lake past the shores of ancient Lake Algonquin (the waters edge after the ice age) and stop for a break at the high point;

(c) There is a debate about the attribution (causes) of past warming — which probably varied over time — between natural drivers (e.g., rebound from the Little Ice Age, solar influences) and anthropogenic drivers (eg, CO2, aerosols, land use changes).

The models heavily relied upon by the Intergovernmental Panel on Climate Change (IPCC) had not projected this multidecadal stasis in «global warming»; nor (until trained ex post facto) the fall in TS from 1940 - 1975; nor 50 years» cooling in Antarctica (Doran et al., 2002) and the Arctic (Soon, 2005); nor the absence of ocean warming since 2003 (Lyman et al., 2006; Gouretski & Koltermann, 2007); nor the onset, duration, or intensity of the Madden - Julian intraseasonal oscillation, the Quasi-Biennial Oscillation in the tropical stratosphere, El Nino / La Nina oscillations, the Atlantic Multidecadal Oscillation, or the Pacific Decadal Oscillation that has recently transited from its warming to its cooling phase (oceanic oscillations which, on their own, may account for all of the observed warmings and coolings over the past half - century: Tsoniset al., 2007); nor the magnitude nor duration of multi-century events such as the Mediaeval Warm Period or the Little Ice Age; nor the cessation since 2000 of the previously - observed growth in atmospheric methane concentration (IPCC, 2007); nor the active 2004 hurricane season; nor the inactive subsequent seasons; nor the UK flooding of 2007 (the Met Office had forecast a summer of prolonged droughts only six weeks previously); nor the solar Grand Maximum of the past 70 years, during which the Sun was more active, for longer, than at almost any similar period in the past 11,400 years (Hathaway, 2004; Solankiet al., 2005); nor the consequent surface «global warming» on Mars, Jupiter, Neptune's largest moon, and even distant Pluto; nor the eerily - continuing 2006 solar minimum; nor the consequent, precipitate decline of ~ 0.8 °C in TS from January 2007 to May 2008 that has canceled out almost all of the observed warming of the 20th century.

Relevant information regarding its value comes from observations of past climates (including the ice age period) and from model simulations.

On the one side, we know that the level of carbon dioxide in the atmosphere was much lower during past ice - ages than during warm periods, so it is reasonable to expect that an artificially high level of carbon dioxide might stop an ice - age from beginning.

Dr. Habibullo Abdussamatov, who heads Russia's prestigious Pulkovo Observatory in St. Petersburg, predicts that: «after the maximum of solar Cycle - 24, from approximately 2014, we can expect the start of the next bicentennial cycle of deep cooling with a Little Ice Age in 2055 plus or minus 11 years» (the 19th to occur in the past 7,500 years).

It is also in line with past temperatures showing recovery from cold periods such as the Little Ice Age that we are still recoveing from and we are still not as warm as Roman Warm Period and perhaps approaching the temperatures of the Medieval Warm Period.