Sentences with phrase «oxygen isotope ratios»

A study by Thomas, Dennis et al 2009 [8] derived a high resolution temperature proxy record from oxygen isotope ratios from the ice core.

The team used records of oxygen isotope ratios (which provide a record of ancient water temperature) from microscopic plankton fossils recovered from the Mediterranean Sea, spanning the last 5.3 million years.

To date, we have a full complement of analyses for about three years of growth for one tusk from the Taimir Peninsula of Siberia (the Jarkov mammoth; ca. 20,300 rybp) and growth increment and tusk apatite carbon and oxygen isotope ratios for two to three years of growth from two tusks from Wrangel Island (4,400 and 4,120 year bp).

Stable oxygen isotope ratios contained in the shell can be used to infer past water temperatures.

In addition, Valley and his group measured oxygen isotope ratios, which give evidence of early homogenization and later cooling of the Earth.

To better understand the cycle of magma production, the researchers analyzed oxygen isotope ratios in quartz and zircon, water - and heat - resistant minerals, from volcanic rocks in the Yellowstone caldera.

Because of the rapid growth rate of the snails, which are a widespread invasive species in India, moisture - sensitive oxygen isotope ratios in growth bands in the animals» shells preserve week - to - week rainfall rates, the researchers found.

In this study, we used oxygen isotope ratios, which is a commonly used palaeothermometer.

When the jet stream got loopy In order to track the jet stream's behavior thousands of years ago, Bowen and his fellow researchers looked at oxygen isotope ratios from lake cores and cave formations in the eastern and western United States.

He realized that the skewed oxygen isotope ratios could be explained if the rock had been exposed to martian air or water for a long period.

The glaciation was favored by an interval when the Earth's orbit favored cool summers but Oxygen isotope ratio cycle marker changes were too large to be explained by Antarctic ice - sheet growth alone indicating an ice age of some size.

Veizer, the geochemist, was studying oxygen isotope ratios in fossil crustaceans dating back more than 500 million years, a temperature proxy for equatorial oceans during the entire eon of visible life on earth.

Looking at the isotopic record from the PETM, scientists see both carbon and oxygen isotope ratios spiking in exactly the way we expect to see in the Anthropocene record.

Like the data used right through 0.02 to 66 My, the Freidrich et al collection comprises stable oxygen isotope ratios from the shells of tiny bottom - dwelling, deep - water marine organisms (benthic foraminifera).

Because of the rapid growth rate of the snails, which are a widespread invasive species in India, moisture - sensitive oxygen isotope ratios in growth bands in the animals» shells preserve week - to - week rainfall rates, the researchers found.

When the researchers analyzed the oxygen isotope ratios over the past 8,000 years, they found that the jet stream became wavier — with colder Eastern winter weather and warmer Western winter weather — on about a 4,000 - year cycle.

They found that the oxygen isotope ratio in Yonderup dripwater was 2 ‰ (2 parts per thousand) higher than expected.

They then compared the oxygen isotope ratio in Yonderup dripwater with that predicted by a model (which simulated the dripwater δ18O based on measurements of rainwater δ18O), as well as that measured at a different cave in the region.

But the team's measurements of the oxygen isotope ratios in the creatures» teeth, a sensitive paleo - thermometer, suggest that the climate where these dinosaurs lived probably averaged about 10 ° Celsius over the course of a year — substantially colder than most of the dinosaur era, and in fact close to that seen in northeastern China today, Xu notes.

But the oxygen isotope ratios were puzzlingly different from those in all other martian meteorites.

Subsequent analyses of the cores» oxygen isotope ratios, magnetic values, calcium carbonate concentrations and fossilized diatoms (microscopic, silica - encased algae) indicated that the lake's environs were wet both during the last Ice Age and during later cold periods in the North Atlantic Ocean region.

Oxygen isotope ratios in carbonate sediments are correlated with the ratio of precipitation to evaporation and thus indicate aridity.

This proxy, known as the δ18O stable oxygen isotope ratio, varies in proportion to the ambient moisture.

Then the team restricted evidence to just three measurements that can be obtained from shell samples in sediment cores: cadmium concentration and carbon and oxygen isotope ratios in the calcium carbonate shells.

They limited data sources to locations around the world in which paleoceanographic data also exist, using seven variables: salinity; potential temperature; oxygen isotope ratios in water; carbon isotope ratios in dissolved inorganic carbon; and concentrations of phosphate, nitrate, and dissolved oxygen.

One group of students has been drilling modern and fossil teeth to obtain samples that will be analyzed to examine stable carbon and oxygen isotope ratios.

That seems a way more satisfactory approach than the crude estimate in Hansen et al (2013) that I've been using, which relies on an interpretive leap from a deep water temperature proxy (oxygen isotope ratios from the microscopic shells of bottom - dwelling marine critters).

Temperature is often the easiest thing to measure, thanks to the oxygen isotope ratio correlating with air temperature, but it is not necessarily the most relevant.

The group highlighted the added value of measuring paired coral strontium / calcium ratios (Sr / Ca) and oxygen isotope ratios (δ18O), two key proxies for sea surface temperature that are often referred to as paleothermometers (δ18O also reflects sea surface salinity).

Rainfall from cyclones contains relatively little heavy oxygen so analysing the oxygen isotope ratio of calcite in stalagmites can reveal the extent of cyclone activity.

The team then compared the oxygen isotope ratio for each year's wet season from 1990 to 2010 with a cyclone activity index of the average accumulated energy expended, based on factors such as number of cyclones, cyclone strength, size and time on storm track.

... Until recently, it was thought that past temperature changes were no more rapid than 1 degree Celsius... per millennium, but recent information from both Greenland and Antarctica, which goes back approximately 400,000 years, indicates that there have been many intervals of very rapid temperature change, as judged by shifts in oxygen isotope ratios.

This proxy, known as the δ18O stable oxygen isotope ratio, varies in proportion to the ambient moisture.

We use fossil tetraether lipids derived from soil bacteria, oxygen isotope ratios (δ18O) and annual ring widths in fossil wood, as well as the composition of paleovegetation (see the Appendix) from the Beaver Pond site on Ellesmere Island (78 ° N, 82 ° W, and 378 masl; see Fig.

Carbon and oxygen isotope ratios both shift at the same boundary; the former shows disruption of the carbon cycle, while the latter shows an abrupt warming of about 6 degrees.

Global, cyclic, decadal, climate patterns can be traced over the past millennium in glacier fluctuations, oxygen isotope ratios in ice cores, sea surface temperatures, and historic observations.