Nano- to Global-Scale Uncertainties in Terrestrial Enhanced Weathering.

Enhanced weathering (EW) is one of the most promising negative emissions technologies urgently needed to limit global warming to at least below 2 °C, a goal recently reaffirmed at the UN Global Climate Change conference (i.e., COP26). EW relies on the accelerated dissolution of crushed silicate rocks applied to soils and is considered a sustainable solution requiring limited technology. While EW has a high theoretical potential of sequestering CO2, research is still needed to provide accurate estimates of carbon (C) sequestration when applying different silicate materials across distinct climates and major soil types in combination with a variety of plants. Here we elaborate on fundamental advances that must be addressed before EW can be extensively adopted. These include identifying the most suitable environmental conditions, improving estimates of field dissolution rates and efficacy of CO2 removal, and identifying alternative sources of silicate materials to meet future EW demands. We conclude with considerations on the necessity of integrated modeling-experimental approaches to better coordinate future field experiments and measurements of CO2 removal, as well as on the importance of seamlessly coordinating EW with cropland and forest management.

The men of Nelson's navy: a comparative stable isotope dietary study of late 18th century and early 19th century servicemen from Royal Naval Hospital burial grounds at Plymouth and Gosport, England.

We present stable isotopic analyses of collagen from 80 servicemen excavated from the late 18th/early 19th century naval hospitals at Plymouth (50) and Haslar, Gosport (30) in southern England. Historical records suggest that, the diets of these two populations should be essentially identical. While δ(15) N of the rib collagen confirmed that naval servicemen were relatively well-catered for in terms of meat allowance (Plymouth average δ(15) N = 11.1‰, Gosport = 11.9‰), stable carbon isotope analysis produced average values for the two assemblages, which were significantly different (Plymouth average δ(13) C = -18.8‰, Gosport = -20.0‰). We postulate that these differences stem from divergent naval postings, with a greater proportion of Plymouth individuals serving in areas that entailed a greater input of C(4) foodstuffs. By comparison with published data from approximately contemporary burials at Snake Hill, Ontario, Canada and Chesapeake Bay, Virginia, we suggest that this area is the east coast of North America. For 15 of the 30 individuals from Gosport, we have data on ribs, femur, and dentine from the same skeleton, which appear to show that they came from a variety of locations in their preadolescence, but converged in dietary terms onto a "naval average," which is consistent with historical evidence for recruitment patterns into the Navy at the time. By comparison with published data from skeletons recovered from the wreck of the Mary Rose (sank 1545), we conclude that this naval diet was virtually unchanged from the 16th century to the end of the 18th century.