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About The Cover

Cover image expansion

ONLINE COVER To determine how North Africa's climate has evolved over the past millions of years, experts have studied dust flux records from marine sediments. These long-term records are based largely on fluxes calculated using age model-based mass accumulation rates (MARs). However, this method suffers from many potential biases, including limited resolution. The paleoclimate community has recently diverted from the MAR approach and has started to use constant flux proxies, such as excess 230Th from seawater that can be used to determine sediment accumulation rates. Relying on 230Th from marine sediment cores to more reliably calculate fluxes, Skonieczny et al. present the first Saharan dust record than spans many glacial cycles. They discovered that in the Sahara Desert, dust emissions over the last 240,000 years have varied in accordance with Northern Hemisphere summer monsoons rather than glacial-interglacial changes as had been previously assumed. These results question the use of existing Pleistocene dust records to examine the connections between climate and hominid evolution. CREDIT: GIDEON MENDEL/CORBIS VIA GETTY IMAGES