20th-Century doubling in dust archived in an Antarctic Peninsula ice core parallels climate change and desertification in South America

Abstract

Crustal dust in the atmosphere impacts Earth's radiative forcing directly by modifying the radiation budget and affecting cloud nucleation and optical properties, and indirectly through ocean fertilization, which alters carbon sequestration. Increased dust in the atmosphere has been linked to decreased global air temperature in past ice core studies of glacial to interglacial transitions. We present a continuous ice core record of aluminum deposition during recent centuries in the northern Antarctic Peninsula, the most rapidly warming region of the Southern Hemisphere; such a record has not been reported previously. This record shows that aluminosilicate dust deposition more than doubled during the 20th century, coincident with the Ϸ1°C Southern Hemisphere warming: a pattern in parallel with increasing air temperatures, decreasing relative humidity, and widespread desertification in Patagonia and northern Argentina. These results have far-reaching implications for understanding the forces driving dust generation and impacts of changing dust levels on climate both in the recent past and future.aluminosilicate dust ͉ global warming ͉ human impacts ͉ Patagonia ͉ radiative transfer C rustal dust in the atmosphere has a direct impact on climate forcing in two significant ways: modifying the radiation balance and affecting cloud nucleation and optical properties (1, 2). Atmospheric crustal dust also supplies iron, an essential nutrient for phytoplankton, to ocean surface waters and may indirectly affect climate by modulating the biological export of carbon to the deep ocean (3). Impacts of atmospheric dust on regional radiation budgets are similar in magnitude to those from sulfate and biomass burning aerosols (4) but can be either negative or positive (1). Estimates of the optical properties of dust have been revised recently as a result of improved in situ and remote sensing measurements (5, 6), but warming has been predicted across areas of high albedo (7, 8) such as snow-and ice-covered regions of the Antarctic Peninsula where recent warming has been pronounced (9). Although atmospheric dustiness has been linked to large-amplitude, large-scale temperature changes in past ice core studies of glacial to interglacial transitions (10, 11), it is unclear whether projected climate warming in coming decades to centuries will result in more or less atmospheric dust (12). Decadal changes in dust flux have been reported for ice cores from the Antarctic Peninsula (13, 14), but reliable, high-time-resolution records of changes in dust levels during recent decades and centuries are sparse (15).Ice core records offer the possibility of reconstructing past changes in dust concentration (10,11,(13)(14)(15)(16)(17)(18)(19)(20). Most previous high-resolution ice core studies used as proxies of atmospheric dust the non-sea-salt component of soluble calcium (nssCa) or magnesium (nssMg) that are computed by using estimated elemental ratios in sea salt aerosols (11,19). At many ice core sites, particularly coastal locations, the nssCa ...

Fallout and distribution of volcanic ash over Argentina following the May 2008 explosive eruption of Chaitén, Chile

“…Eruptions of this magnitude are potentially recorded in Argentine shelf sediments, and are periodic contributors to the Antarctic and Southern Ocean dust budget [McConnell et al, 2007]. Comparison with Patagonian dust (Figure 6), for which Andean volcanic ash of the more common andesitic composition forms an important component [Gaiero et al, 2007], shows that rarer rhyolitic ash, such as that from Chaitén, is a minor dust component.…”

Biological consequences of earlier snowmelt from desert dust deposition in alpine landscapes

“…While this process has occurred historically, the increasing area of arid lands and the utilization of these lands by expanding human populations have increased dust loads (4)(5)(6). For example, during settlement of the western U.S., the intensification of human activities such as agriculture, grazing, and resource exploration in semiarid landscapes led to 500% greater dust deposition in the adjacent mountains (7).…”

An ice‐core proxy for northerly air mass incursions into West Antarctica

“…A separate study of dust concentrations from a northern Antarctic Peninsula ice core (McConnell et al, 2007) suggests dust concentrations starting to rise around 1900, coincident with Patagonian warming. However, this increase occurs ∼60 years before any such rise in the NAMI proxy.…”