Description: Assessments of climate sensitivity to projected greenhouse gas concentrations underpin environmental policy decisions, with such assessments often based on model simulations of climate during recent centuries and millennia1, 2, 3. These simulations depend critically on accurate records of past aerosol forcing from global-scale volcanic eruptions, reconstructed from measurements of sulphate deposition in ice cores4, 5, 6. Non-uniform transport and deposition of volcanic fallout mean that multiple records from a wide array of ice cores must be combined to create accurate reconstructions. Here we re-evaluated the record of volcanic sulphate deposition using a much more extensive array of Antarctic ice cores. In our new reconstruction, many additional records have been added and dating of previously published records corrected through precise synchronization to the annually dated West Antarctic Ice Sheet Divide ice core7, improving and extending the record throughout the Common Era. Whereas agreement with existing reconstructions is excellent after 1500, we found a substantially different history of volcanic aerosol deposition before 1500; for example, global aerosol forcing values from some of the largest eruptions (for example, 1257 and 1458) previously were overestimated by 20–30% and others underestimated by 20–50%.

Description: © The Author(s), 2014. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Scientific Reports 4 (2014): 5848, doi:10.1038/srep05848.

Description: Interior Antarctica is among the most remote places on Earth and was thought to be beyond the reach of human impacts when Amundsen and Scott raced to the South Pole in 1911. Here we show detailed measurements from an extensive array of 16 ice cores quantifying substantial toxic heavy metal lead pollution at South Pole and throughout Antarctica by 1889 – beating polar explorers by more than 22 years. Unlike the Arctic where lead pollution peaked in the 1970s, lead pollution in Antarctica was as high in the early 20th century as at any time since industrialization. The similar timing and magnitude of changes in lead deposition across Antarctica, as well as the characteristic isotopic signature of Broken Hill lead found throughout the continent, suggest that this single emission source in southern Australia was responsible for the introduction of lead pollution into Antarctica at the end of the 19th century and remains a significant source today. An estimated 660 t of industrial lead have been deposited over Antarctica during the past 130 years as a result of mid-latitude industrial emissions, with regional-to-global scale circulation likely modulating aerosol concentrations. Despite abatement efforts, significant lead pollution in Antarctica persists into the 21st century.

Description: This work primarily was supported by the U.S. National Science Foundation Division of Polar Programs (research grants 9903744, 0538427, 0538416, 0968391, 1142166, 0632031; instrument grants 0216552, 0421412).

Description: The authors would like to make the following corrections to the published article [1]. In Section 1, fourth paragraph: In the sentence “Proxy Proxy data, such as glacio-chemical data from firn and ice cores, may partly compensate for the lack of direct observations.” the word “Proxy” should be deleted as it occurs twice. The sentence should have read: “Proxy data, such as glacio-chemical data from firn and ice cores, may partly compensate for the lack of direct observations.”. In Section 3.4, second paragraph: In the sentence “The slope of the δ18O–δD relationship (7.94) is close to that of the Global Meteoric Water Line (GMWL) [49] and is of the same order of magnitude as the slope of the site-specific LMWL (m = 7.76).” the “m =” should be deleted before “7.76” and “, 8” should be inserted after “GMWL”. The sentence should have read: “The slope of the δ18O–δD relationship (7.94) is close to that of the Global Meteoric Water Line (GMWL, 8) [49] and is of the same order of magnitude as the slope of the site-specific LMWL (7.76).”. In Section 4.5, first paragraph: In the sentence “Figure 8c,e visualise the anti-correlation between MLT and SIE in both the Bellingshausen-Amundsen Sea and the Weddell Sea (r 〉 −0.6, p = 0; Table 5).” the “〉” in the parenthesis should be replaced by “=”. The sentence should have read: “Figure 8c,e visualise the anti-correlation between MLT and SIE in both the Bellingshausen-Amundsen Sea and the Weddell Sea (r = −0.6, p = 0; Table 5).”. In the original publication, there was a mistake in Table 1 [1]. The order of the values in the column “Accumulation Rate (kg m−2 a−1)” was reversed for the years 2012 to 2015. The authors state that the scientific results for the accumulation rates in Table 1, which are presented and discussed in Sections 3.2 and 4.2 of the original publication, are not affected by this mistake, as all values were used correctly there. The corrected Table 1 is as follows: Annual accumulation rates calculated for the OH-12 drill site for the period 2012–2015. In the original publication, there was a mistake in Figure 6 [1]. The intercept in the equation for the δ18O−δD relationship of firn core OH-12 should be +6.01 and not −6.01. The corrected equation is δD = 7.94 × δ18O + 6.01. A correction was also made to the second paragraph in Section 3.4, where in the sentence “However, intercepts differ significantly (OH-12: −6.01; LMWL: −1.52; GMWL: +10), which is also reflected by the position of the OH-12 samples in the δ18O–δD plot (Figure 6a).” the intercept of the δ18O−δD relationship of firn core OH-12 should accordingly be +6.01 and not −6.01. In addition, in the same sentence the word “the” should be inserted before the word “intercepts”. The sentence should have read: ”However, the intercepts differ significantly (OH-12: +6.01; LMWL: −1.52; GMWL: +10), which is also reflected by the position of the OH-12 samples in the δ18O–δD plot (Figure 6a).”. The updated Figure 6 is as follows: (a) δ18O–δD relationship of all considered precipitation samples collected at Bernardo O’Higgins station (OH) between 2008 and 2017 (n = 294; coloured dots) compared to the δ18O–δD relationship of firn core OH-12 (n = 414; white dots). The Global Meteoric Water Line (GMWL) is indicated in blue. The Local Meteoric Water Line (LMWL) established for the study site by Fernandoy et al. [31,32] is shown as a dashed red line and the LMWL derived in this study as a solid red line. For each δ18O–δD relationship, the equation, the coefficient of determination (R2) and the p-value (p) are given. (b) Time series of δ18O, δD and d excess of OH-12 constructed based on the weighted age scale. High-resolution data are shown as light-coloured lines and monthly means as bold lines. The authors apologize for any inconvenience these mistakes may have caused the readers. The authors state that the scientific conclusions are unaffected. This correction was approved by the Academic Editor. The original publication has also been updated.