1,890 research outputs found

    Climate change: where is the hockey stick? evidence from millennial-scale reconstructed and updated temperature time series.

    Get PDF
    The goal of this paper is to test on a millennial scale the magnitude of the recent warmth period, known as the “hockey-stick”, and the relevance of the causative anthropogenic climate change hypothesis advanced by several academics and worldwide institutions. A select batch of ten long-term climate proxies, included in the NOAA 92 PCN dataset all of which running well into the nineties, is updated to the year 2011 by means of a Time-Varying Parameter Kalman Filter SISO model for state prediction. This procedure is applied by appropriately selecting as observable one out of the HADSST2 and of the HADCRUT3 series of instrumental temperature anomalies available since the year 1850. The updated proxy series are thereafter individually tested for the values and time location of their four maximum non-neighboring attained temperatures. The results are at best inconclusive, since three of the updated series, including Michael Mann’s celebrated and controversial tree-ring reconstructions, do not refute the hypothesis, while the others quite significantly point to different dates of maximum temperature achievements into the past centuries, in particular those associated to the Medieval Warm Period.Climate Change; Hockey Stick Controversy; Time Series; Kalman Filter

    Application of Paleoclimatology to Coral Reef Monitoring and Management

    Get PDF
    The skeletons of reef-building corals are valuable archives of climatic and environmental information. Paleoclimatic data chiefly have been generated in areas most sensitive to global or regional climatic variability. However, these records also provide valuable information on anthropogenic influences – guidance of value to resource managers. NOAA’s Coral Reef Watch targets observations of current and past coral reef health in or near marine protected areas through satellites, in situ sensor platforms, and paleoclimatic analyses. Paleoclimatic data provide retrospective monitoring through multi-century environmental reconstructions that improve our understanding of past stress to coral reefs. Two sites in the Florida Keys National Marine Sanctuary were the first to benefit from Coral Reef Watch Program paleoenvironmental analyses. Coral cores yielded direct measurements of δ18O, δ13C, Sr/Ca, and coral skeletal growth (extension, density, and calcification) and reconstructions of reef temperatures. Temperature reconstructions were compared with instrumental data from nearby stations and global data sets, while skeletal growth was used to infer responses to changing climatic and environmental conditions. Differences between paleoclimatic data and gridded datasets demonstrated that paleodata provide more accurate estimates of reef temperatures as they sample subsurface temperatures where the corals live. Because of relatively high thermal variability, at least 12 samples per year are needed at these sites. Further work will extend these records back in time, to new locations, and expand on the data reconstructed from the skeletal archives

    Reviews of Science for Science Librarians: Drought in the Agricultural and Geosciences Literature

    Get PDF
    Drought is a hot topic, given the climatic events of summer 2012 in the United States. This article provides a fundamental understanding of drought—its definitions, classifications, ratings, and impact on agriculture. Also included are introductions to drought-related research areas in the geosciences—specifically geology, hydrology, and atmospheric sciences—as well as pointers to reliable sources of information about drought from the agricultural and geosciences literature

    Multi-Periodic Climate Dynamics: Spectral Analysis of Instrumental, Short- and Long-length Proxy Temperature Records

    Get PDF
    Analyzing 26 short-length (less than 3000 years) instrumental and proxy temperature records and five long-length (greater than 3000 years) proxy temperature records using Discrete Fourier Transform has shown that as the length of significant periods increase in the time domain then so does the power at which the period is observed. A t-test verifies that a positive correlation exist between the length of the significant periods and the power with a confidence level of ∝ \u3e0.05. Significant frequencies with period greater than 30 years are confirmed using Monte Carlo simulations, which were created using a nonlinear approach known as fractional Brownian motion (FBM). While completing the spectral analysis it was observed in the spectral analysis is an absence of significant periods between about 1000 years and 20,000 years. Also, wavelet analysis of all short-length temperature records turned up no significant findings
    • …
    corecore