Atmospheric mineral dust aerosols affect Earth’s radiative balance and are an important climate forcing and feedback mechanism. Dust is argued to have played an important role in past natural climate changes through glacial cycles, yet temporal and spatial dust variability remain poorly constrained, with scientific understanding of uncertainties associated with radiative perturbations due to mineral dust classified as “very low”. To advance understanding of the dust cycle, we present a high-resolution dust record from the Red Sea, sourced principally from Arabia, with a precise chronology relative to global sea level/ice volume variability. Our record correlates well with a high-resolution Asian dust record from the Chinese Loess Plateau. Importing our age model from the Red Sea to the Chinese Loess Plateau provides a first detailed millennial-scale age model for the Chinese loess, which has been notoriously difficult to date at this resolution and provides a basis for inter-regional correlation of Chinese dust records. We observe a high baseline of dust emissions from Arabia and China, even through interglacials, with strong superimposed millennial-scale variability. Conversely, the distal EPICA Dome C Antarctic ice core record, which is widely used to calculate the radiative impact of dust variations, appears biased to sharply delineated glacial/interglacial contrasts. Calculations based on this Antarctic dust record will therefore overestimate the radiative contrast of atmospheric dust loadings on glacial/interglacial timescales. Additional differences between Arabian/Asian and circum-Saharan records reveal that climate models could be improved by avoiding ‘global mean’ dust considerations and instead including large-scale regions with different dust source variability. 相似文献
A series of Monomethyl branched alkanes compounds were detected between nC14–nC36, in immature and low maturity Jurassic humic coal, Junggar basin. 2-methyl alkanes and 3-methyl alkanes accounted for the vast majority of the compounds. It is worth noting that the 2-methyl alkanes in the humic coal samples show an obvious distribution of even carbon predominances rarely reported in the literature. The results show that with the increase of Pr/Ph (pristane/phytane), the even carbon dominance of 2-methyl alkanes is more obvious, while the odd carbon number distribution of 3-methyl alkanes is weakened. As Pr/Ph increases in the humic coal, the relative content of the hopanes increased, while the relative content of 2-methyl alkanes and 3-methyl alkanes increases first and then decreases.