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Full-Text Articles in Physical Sciences and Mathematics
What Can We Learn From Past Warm Climates?, Raymond S. Bradley
What Can We Learn From Past Warm Climates?, Raymond S. Bradley
Raymond S Bradley
With limited political action to control fossil fuel use and associated greenhouse gas emissions, there is increasing emphasis on preparing for inevitable climate changes. But what changes should the world plan for? Model simulations provide some guidance about expected future climate scenarios, but we can also learn from past experience. Although there are no episodes in the past that are strictly comparable to the future, which is a world in which climate is modulated by human activities, there were warm periods in the past which resulted from other forcing factors. There are some lessons we can learn from paleoclimate records …
Natural Archives, Changing Climates, Raymond S. Bradley
Natural Archives, Changing Climates, Raymond S. Bradley
Raymond S Bradley
Climatic changes have occurred throughout human history, but instrumental measurements do not provide us with a very long perspective on climate variations. In many regions, instrumental records only extend back a century or two. To understand the longer-term variability of the climate system, we rely on natural archives— sediments, ice caps, peat bogs, cave deposits, banded corals and tree rings—in which a record of past changes in climate has been preserved. They are a treasure trove of the climatic and environmental history of the planet and provide information about factors that may have caused the climate to change, such as …
High-Resolution Paleoclimatology, Raymond S. Bradley
High-Resolution Paleoclimatology, Raymond S. Bradley
Raymond S Bradley
High resolution paleoclimatology involves studies of natural archives as proxies for past climate variations at a temporal scale that is comparable to that of instrumental data. In practice, this generally means annually resolved records, from tree rings, ice cores, banded corals, laminated speleothems and varved sediments. New analytical techniques offer many unexplored avenues of research in high resolution paleoclimatology. However, critical issues involving accuracy of the chronology, reproducibility of the record, frequency response to forcing and other factors, and calibration of the proxies remain. Studies of proxies at high resolution provide opportunities to examine the frequency and magnitude of extreme …
The Younger Dryas And The Sea Of Ancient Ice, Raymond S. Bradley, John H. England
The Younger Dryas And The Sea Of Ancient Ice, Raymond S. Bradley, John H. England
Raymond S Bradley
We propose that prior to the Younger Dryas period, the Arctic Ocean supported extremely thick multi-year fast ice overlain by superimposed ice and firn. We re-introduce the historical term paleocrystic ice to describe this. The ice was independent of continental (glacier) ice and formed a massive floating body trapped within the almost closed Arctic Basin, when sea-level was lower during the last glacial maximum. As sea-level rose and the Barents Sea Shelf became deglaciated, the volume of warm Atlantic water entering the Arctic Ocean increased, as did the corresponding egress, driving the paleocrystic ice towards Fram Strait. New evidence shows …