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Since 65 million years ago (Ma), Earth's climate has undergone a significant and complex evolution, the finer details of which are now coming to light through investigations of deep-sea sediment cores. This evolution includes gradual trends of warming and cooling driven by tectonic processes on time scales of 10(5) to 10(7) years, rhythmic or periodic(More)
it is predicted that humans will have released about 5,000 gigatonnes of carbon (Gt C) to the atmosphere since the start of the industrial revolution if fossil-fuel emissions continue unabated and carbon-sequestration efforts remain at current levels 1. This anthropogenic carbon input, predominantly carbon dioxide (CO 2), would eventually return to the(More)
The relation between the partial pressure of atmospheric carbon dioxide (pCO2) and Paleogene climate is poorly resolved. We used stable carbon isotopic values of di-unsaturated alkenones extracted from deep sea cores to reconstruct pCO2 from the middle Eocene to the late Oligocene (approximately 45 to 25 million years ago). Our results demonstrate that pCO2(More)
Spectral analyses of an uninterrupted 5.5-million-year (My)-long chronology of late Oligocene-early Miocene climate and ocean carbon chemistry from two deep-sea cores recovered in the western equatorial Atlantic reveal variance concentrated at all Milankovitch frequencies. Exceptional spectral power in climate is recorded at the 406-thousand-year (ky)(More)
superior performance as gate dielectrics in organic thin-film transistors (5). For many organic semiconductors, device performance is constrained by the number of charge carriers rather than their mobility; the high capacitance of the ion gel boosts the carrier density in the semiconductor channel. Further, the high ionic mobility enables switching speeds(More)
The Palaeocene–Eocene Thermal Maximum (about 55 Myr ago) represents a possible analogue for the future and thus may provide insight into climate system sensitivity and feedbacks 1,2. The key feature of this event is the release of a large mass of 13 C-depleted carbon into the carbon reservoirs at the Earth's surface, although the source remains an open(More)
Relative to the present day, meridional temperature gradients in the Early Eocene age ( approximately 56-53 Myr ago) were unusually low, with slightly warmer equatorial regions but with much warmer subtropical Arctic and mid-latitude climates. By the end of the Eocene epoch ( approximately 34 Myr ago), the first major Antarctic ice sheets had appeared,(More)
The start of the Palaeocene/Eocene thermal maximum--a period of exceptional global warming about 55 million years ago--is marked by a prominent negative carbon isotope excursion that reflects a massive input of 13C-depleted ('light') carbon to the ocean-atmosphere system. It is often assumed that this carbon injection initiated the rapid increase in global(More)
The Paleocene-Eocene thermal maximum (PETM) has been attributed to the rapid release of approximately 2000 x 10(9) metric tons of carbon in the form of methane. In theory, oxidation and ocean absorption of this carbon should have lowered deep-sea pH, thereby triggering a rapid (<10,000-year) shoaling of the calcite compensation depth (CCD), followed by(More)
Paleoclimate d ata show that climate sensitivity is ~3°C for doubled CO 2 , including only fast feedback processes. Equilibrium sensitivity, including slower surface albedo feedbacks, i s ~6°C for doubled CO 2 fo r th e ran ge o f cl i-mate states between glacial conditions and ice-free Antarctica. Decreasing CO 2 was the main cause of a cooling trend that(More)