Abstract.A borehole temperature record from the Mill Island (East Antarctica) icecap reveals a large surface warming signal manifested as a 0.75 K temperature difference over the approximate 100 m depth in the zone of zero annual amplitude below the seasonally varying zone. The temperature profile shows a break in gradient around 49 m depth, which we model with inverse numerical simulations, indicating that surface warming started around the austral summer of 1980/81 AD ±5 yr. This warming of approximately 0.37 K per decade is consistent with trends seen in both instrumental and other reconstructions for Antarctica and, therefore, suggests that regional-rather than local-scale processes are largely responsible. Alteration of the surface energy budget arising from changes in radiation balances due to local cloud, the amount of liquid deposition and local air temperatures associated with altered air/sea exchanges also potentially plays a role at this location due to the proximity of the Shackleton Ice Shelf and sea-ice zone.
Refractory black carbon aerosols (rBC) emitted by biomass burning (fires) and fossil fuel combustion, affect global climate and atmospheric chemistry. In the Southern Hemisphere (SH), rBC is transported in the atmosphere from low latitudes to Antarctica and deposited to the polar ice sheet preserving a history of emissions and atmospheric transport. Here, we present two high-resolution Antarctic rBC ice core records drilled from the West Antarctic Ice Sheet divide and Law Dome on the periphery of the East Antarctic ice sheet. Separated by ~3500 km, the records span calendar years 1850–2001 and reflect the rBC distribution over the Indian and Pacific ocean sectors of the Southern Ocean. Highly correlated over the past 60 yr, the records show that coherent large-scale changes in SH rBC occurred at decadal to inter-annual time scales, notably in ENSO-like periodicities. Decadal trends in the records are similar to inventories of SH rBC emissions from grass fires and biofuels. The combined records suggest a large-scale reduction in rBC from 1950 to 1990 over the remote Southern Hemisphere
Abstract. Paleoclimate research indicates that the instrumental climate record (~100 years in Australia) does not cover the full range of hydroclimatic variability possible. To better understand the implications of this for catchment-scale water resources management, an annual rainfall reconstruction is produced for the Williams River catchment in coastal eastern Australia. No high resolution palaeoclimate proxies are located in the region and so a teleconnection between summer sea salt deposition recorded in ice cores from East Antarctica and rainfall variability in eastern Australia was exploited to reconstruct 1013 years of rainfall (AD 1000–2012). The reconstruction shows that significantly longer and more frequent wet and dry periods were experienced in the preinstrumental compared to the instrumental period. This suggests that existing drought and flood risk assessments underestimate the true risks due to the reliance on data and statistics obtained from only the instrumental record. This raises questions about the robustness of existing water security and flood protection measures and has serious implications for water resources management, infrastructure design, and catchment planning. The method used in this proof of concept study is transferable and enables similar insights into the true risk of flood/drought to be gained for other locations that are teleconnected to East Antarctica. This will lead to improved understanding and ability to deal with the impacts of multidecadal to centennial hydroclimatic variability.
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