Sentences with phrase «isotopic records»

This may allow, for the first time, decoding of the factors that underlie temporal trends in bulk isotopic records, while simultaneosly monitoring changes at both the highest and lowest trophic levels.

Holocene climate variability in Antarctica based on 11 ice - core isotopic records.

Quite evident in the most recent several hundred years of the isotopic records is a seventy - year period of very low solar activity in the 17th and early 18th centuries — known as the Maunder Minimum — and following it, an unsteady, long - term rise to the present - day era of high sunspot numbers, called the Modern Maximum (Fig. 2 c, d).

The correlation of summer precipitation in the Southwestern U.S.A. with isotopic records of solar activity during the medieval warm period.

Sea - level and deep water temperature changes derived from benthic foraminifera isotopic records

As of March 2018, the beta version of the database contained 629 individual isotopic records from more than 432 global locations (Figure 1).

Marine climatic seasonality during early medieval times (10th to 12th centuries) based on isotopic records in Viking Age shells from Orkney, Scotland, Surge and Barret, 07/2012; read more here.

The fossil - coral oxygen isotopic records (δ18O) from Palmyra Island present similar, and climatologically consistent, changes to the Southwest PDSI variance over time, including decreased mean state of ENSO in the MCA (a cooler eastern equatorial Pacific) and more intense ENSO in the LIA, particularly during the mid-seventeenth century.

The sediments in Sky Pond in the Rocky Mountains show that around 1950 nitrogen began to flood the lake, an event unprecedented in at least 14,000 years and this isotopic record too could have a pretty precise start date: July 2, 1909 when Fritz Haber first demonstrated how to make ammonia from the air in Germany.

Because of these precise measurements, said Humayun, «we now have an isotopic record of how the atmosphere changed, with dates on it.»

(Though some have claimed in this thread that the balance of O2 generation may be related to the reduction of hydrogen by gravitational loss; most of the isotopic record still suggests that the balance of O2 appears to have a biologic influence and was not the result of planet wide respiration of H2.)

Once this had been done, they were able to subtract that information from the oxygen isotopic record.

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.

Not exact matches

The ratio of strontium to calcium in a given layer of coral reef — as well as the amount of a heavier isotope of oxygen in the carbonate itself — reflect the temperature in this historical record, but the isotopic information also reveals rainfall.

Dust found in the ice gives a record of what was in the air thousands of years ago, whether from volcanic eruptions or human activity, and the isotopic composition of the hydrogen and oxygen molecules in the snow give a record of the temperature of the earth at the time.

To create their new temperature record, which spans 3.5 million years at the end of the Cretaceous and the start of the Paleogene Period, the researchers analyzed the isotopic composition of 29 remarkably well - preserved shells of clam - like bivalves collected on Antarctica's Seymour Island.

Isotopic analysis of the guano pile in the M?gurici Cave resulted in a near annual record of winter precipitation for the region.

Two speakers from the Geological Society conference «Past Carbon Isotopic Events and Future Ecologies» came to the SMC to discuss climate clues from the geological record and what they can tell us about present and future changes to the climate.

First, I do think that there is a lot of work to be done in the interpretation of oxygen / hydrogen isotope values obtained at a site, and there's still plenty of disagreement in the paleo - community on how to best connect the isotopic signal in a record with climate.

Assessment of diffusive isotopic fractionation in polar firn, and application to ice core trace gas records.

To replicate the observed isotopic offset, the model requires that enhanced levels of organic - carbon and pyrite burial continued a few hundred thousand years after peak organic - carbon burial, but that their isotope records responded differently due to dramatically different residence times for dissolved inorganic carbon and sulfate in seawater.

A long lifetime for CO2 adjustment is also consistent with an isotopic event in the deep sea sedimentary record from 55 million years ago, the Paleocene / Eocene Thermal Maximum event.

Speaking of AGW and hurricanes and recent attempts to lenghthen the storm record with proxy data: I don't see how isotopic studies of the origin of rainfall waters in tree rings or sediment overwash studies can tell us accurately the past frequency or intensity of landfalling hurricanes.

First, I do think that there is a lot of work to be done in the interpretation of oxygen / hydrogen isotope values obtained at a site, and there's still plenty of disagreement in the paleo - community on how to best connect the isotopic signal in a record with climate.

[5] Linsley et al. (2006) reconstructed sea - surface temperature and sea surface salinity in the southwest Pacific starting circa 1600CE by measuring the oxygen isotopic composition of four Porites coral records from Rarotonga and two from Fiji.

Stevenson, S., B.S. Powell, M.A. Merrifield, K.M. Cobb, J. Nusbaumer, and D. Noone, 2015: Characterizing seawater oxygen isotopic variability in a regional ocean modeling framework: Implications for coral proxy records.

Here, we test a new proxy — the oxygen isotopic signature of individual benthic foraminifera — to detect rapid (i.e. monthly to decadal) variations in deep ocean temperature and salinity in the sedimentary record.

«THE stable carbon isotopic (13C / 12C) record of twentieth - century tree rings has been examined1 - 3 for evidence of the effects of the input of isotopically lighter fossil fuel CO2 (δ 13C ~ -25 ‰ relative to the primary PDB standard4), since the onset of major fossil fuel combustion during the mid-nineteenth century, on the 13C / 12C ratio of atmospheric CO2 (δ 13C ~ -7 ‰), which is assimilated by trees by photosynthesis.

Kandiano, E. S., Bauch, H. A. & Müller, A. Sea surface temperature variability in the North Atlantic during the last two glacial - interglacial cycles: comparison of faunal, oxygen isotopic, and Mg / Ca - derived records.

Changes in proxy records, either physical (such as the isotopic composition of various elements in ice) or biological (such as the width of a tree ring or the chemical composition of a growth band in coral), do not respond precisely or solely to changes in any specific climate parameter (such as mean temperature or total rainfall), or to the changes in that parameter as measured over a specific «season» (such as June - August or January - December).

(4) the historical temperature - record has relatively poor calibration (giving more weight to isotopic and borehole measures), and

How do water isotopic proxy records capture changes in tropical and extratropical modes of climate variability?

Kennedy, M.J., N. Christie - Blick, and L.E. Sohl, 2001: Are Proterozoic cap carbonates and isotopic excursions a record of gas hydrate destabilization following Earth's coldest intervals?

Until now, this view was based mainly on reanalysis of ca estimates from the isotopic composition of carbonates in paleosols, the only extensive proxy record to span most of the Phanerozoic.

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

Oakwood, the tragedy is not what's happening in science — things there are just as they should be: the field continues to develop new data and refined analyses, general conclusions have been reached that a very large majority support, based on well - established principles (properties of CO2, thermodynamics, effects of warmer air on evaporation...) and data (measures of CO2 levels, shifts in isotopic composition of atmospheric CO2, temperature records — instrumental and proxy,...).

Hyperthermals are recorded in carbonate sedimentary sequences by negative C - isotopic excursions, indicating a biogenic source for the gas emissions.

Changes in proxy records, either physical (such as the isotopic composition of various elements in ice) or biological (such as the width of a tree ring or the chemical composition of a growth band in coral), do not respond precisely or solely to changes in any specific climate parameter (such as mean temperature or total rainfall), or to the changes in that parameter as measured over a specific «season» (such as June to August or January to December).

So the isotopic spikes we do see in the geologic record may not be spiky enough to fit the Silurian hypothesis's bill.