Journal ArticleDOI
Past Temperatures Directly from the Greenland Ice Sheet
Dorthe Dahl-Jensen,Klaus Mosegaard,Niels S. Gundestrup,Gary D. Clow,Sigfus J Johnsen,A. W. Hansen,Niels Balling +6 more
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TLDR
A Monte Carlo inverse method has been used on the temperature profiles measured down through the Greenland Ice Core Project (GRIP) borehole, at the summit of the Greenland ice Sheet, and the Dye 3 borehole 865 kilometers farther south, resulting in a 50, 000-year-long temperature history at GRIP and a 7000-year history at Dye3.Abstract:
A Monte Carlo inverse method has been used on the temperature profiles measured down through the Greenland Ice Core Project (GRIP) borehole, at the summit of the Greenland Ice Sheet, and the Dye 3 borehole 865 kilometers farther south. The result is a 50, 000-year-long temperature history at GRIP and a 7000-year history at Dye 3. The Last Glacial Maximum, the Climatic Optimum, the Medieval Warmth, the Little Ice Age, and a warm period at 1930 A.D. are resolved from the GRIP reconstruction with the amplitudes -23 kelvin, +2.5 kelvin, +1 kelvin, -1 kelvin, and +0.5 kelvin, respectively. The Dye 3 temperature is similar to the GRIP history but has an amplitude 1.5 times larger, indicating higher climatic variability there. The calculated terrestrial heat flow density from the GRIP inversion is 51.3 milliwatts per square meter.read more
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Numerical experiments on firn isotope diffusion with the Community Firn Model
Vasileios Gkinis,Christian Holme,Emma C. Kahle,Max C. Stevens,Eric J. Steig,Bo Møllesøe Vinther +5 more
TL;DR: In this paper, a tool for estimating firn-diffusion rates that builds on the Community Firn Model is presented. But the model requires two main inputs, temperature and accumulation, and it calculates the diffusion lengths for δ17O, δ18O and δD prior information on the precipitation is not a requirement.
Journal ArticleDOI
Recent changes in the climate: natural or forced by human activity?
TL;DR: Greenland ice core data yield well-dated information about climate over an extended period that indicates that large, probably global scale changes have occurred at numerous times in the past, and the warming during the past 100 y is not likely to be unique.
Journal ArticleDOI
Phase equilibrium for argon clathrate hydrate at the temperatures from 197.6 K to 274.1 K
TL;DR: The phase equilibrium conditions of clathrate hydrate of argon were measured by the isochoric procedure at the temperatures from 197.6 to 274.1 K as mentioned in this paper.
Journal ArticleDOI
1000 Years of climate change
TL;DR: In this paper, satellite observations of solar irradiance for the past two decades have allowed calibration of variations in solar activity proxies, and a number of attempts at reconstructing past climate variations via these proxies has shown that direct (irradiance) solar forcing can explain observed northern hemisphere temperatures from 1000 to 1900, but fails to account for most of the observed warming in the past 100 years, especially after 1975.
Journal ArticleDOI
30,000 Years of Ground Surface Temperature and Heat Flux Changes in Karelia Reconstructed from Borehole Temperature Data
TL;DR: In this article, the authors reconstructed past ground surface temperature and surface heat flux histories using data obtained from the 3.5-km-deep Onega borehole (Karelia, north-west Russia).
References
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Journal ArticleDOI
Decadal Trends in the North Atlantic Oscillation: Regional Temperatures and Precipitation
TL;DR: An evaluation of the atmospheric moisture budget reveals coherent large-scale changes since 1980 that are linked to recent dry conditions over southern Europe and the Mediterranean, whereas northern Europe and parts of Scandinavia have generally experienced wetter than normal conditions.
Journal ArticleDOI
Heat flow from the Earth's interior: Analysis of the global data set
TL;DR: In this paper, a new estimate of the Earth's heat loss based on a new global compilation of heat flow measurements comprising 24,774 observations at 20,201 sites is presented, which when areally weighted yield a global mean of 87 mW m -2 and a global heat loss of 44.2 x 10 2 W, an increase of some 4-8% over earlier estimates.
Journal ArticleDOI
Monte Carlo sampling of solutions to inverse problems
Klaus Mosegaard,Albert Tarantola +1 more
TL;DR: In inverse problems, obtaining a maximum likelihood model is usually not sucient, as the theory linking data with model parameters is nonlinear and the a posteriori probability in the model space may not be easy to describe.
Journal ArticleDOI
Arctic Environmental Change of the Last Four Centuries
Jonathan T. Overpeck,Konrad A Hughen,D. Hardy,Raymond S. Bradley,R. Case,M. A. Douglas,Bruce P. Finney,K. Gajewski,Gordon C. Jacoby,Anne E. Jennings,Scott F. Lamoureux,A. Lasca,Glen M. MacDonald,J.J. Moore,Michael Retelle,S. Smith,Alexander P. Wolfe,G. Zielinski +17 more
TL;DR: A compilation of paleoclimate records from lake sediments, trees, glaciers, and marine sediments provides a view of circum-Arctic environmental variability over the last 400 years.
Journal ArticleDOI
Climate instability during the last interglacial period recorded in the GRIP ice core
TL;DR: Isotope and chemical analyses of the GRIP ice core from Summit, central Greenland reveal that climate in Greenland during the last interglacial period was characterized by a series of severe cold periods, which began extremely rapidly and lasted from decades to centuries.