Stable isotopes and Antarctic moss banks: plants and soil microbes respond to recent warming on the Antarctic Peninsula [abstract only]

The Antarctic Peninsula is one of the most rapidly warming regions on Earth, with air temperature increases of as much as 3°C recorded since the 1950s. However, the longer-term context of this change is limited and existing records, largely relying on ice core data, are not suitably located to be able to trace the spatial signature of change over time. We are working on a project exploiting stable isotope records preserved in moss peat banks spanning 10 degrees of latitude along the Antarctic Peninsula as an archive of late Holocene climate variability. Here we present a unique time series of past moss growth and soil microbial activity that has been produced from a 150 year old moss bank at Lazarev Bay, Alexander Island (69°S), a site at the southern limit of significant plant growth in the Antarctic Peninsula region. These moss banks are ideal archives for palaeoclimate research as they are well-preserved by freezing, generally monospecific, easily dated by radiocarbon techniques, and have sufficiently high accumulation rates to permit decadal resolution. We use accumulation rates, cellulose δ13C and fossil testate amoebae to show that growth rates, assimilation and microbial productivity rose rapidly in the 1960s, consistent with temperature change, although recently may have stalled, concurrent with other evidence. The increase in biological activity is unprecedented in the last 150 years. Along with work completed on Signy Island (60°S), in the South Orkney Islands, in which we used carbon isotope evidence to show recent climate-related enhancement of CO2 assimilation and peat accumulation rates in Antarctica, the observed relationships between moss growth, microbial activity and climate suggests that moss bank records have the potential to test the regional expression of temperature variability shown by instrumental data on the Antarctic Peninsula over centennial to millennial timescales, by providing long-term records of summer growth conditions, complementing the more distant and widely dispersed ice core records. We will conclude by placing the records into the wider context of the latest progress of analysis of moss bank cores obtained along the length of the Antarctic Peninsula and Scotia arc. Royles, J., M. J. Amesbury, P. Convey, H. Griffiths, D. A. Hodgson, M. J. Leng and D. J. Charman (2013). Plants and soil microbes respond to recent warming on the Antarctic Peninsula. Current Biology 23(17): 1702-1706. Royles, J., J. Ogée, L. Wingate, D. A. Hodgson, P. Convey and H. Griffiths (2012). Carbon isotope evidence for recent climate-related enhancement of CO2 assimilation and peat accumulation rates in Antarctica. Global Change Biology 18(10): 3112-3124

Moss stable isotopes (carbon-13, oxygen-18) and testate amoebae reflect environmental inputs and microclimate along a latitudinal gradient on the Antarctic Peninsula.

The stable isotope compositions of moss tissue water (δ(2)H and δ(18)O) and cellulose (δ(13)C and δ(18)O), and testate amoebae populations were sampled from 61 contemporary surface samples along a 600-km latitudinal gradient of the Antarctic Peninsula (AP) to provide a spatial record of environmental change. The isotopic composition of moss tissue water represented an annually integrated precipitation signal with the expected isotopic depletion with increasing latitude. There was a weak, but significant, relationship between cellulose δ(18)O and latitude, with predicted source water inputs isotopically enriched compared to measured precipitation. Cellulose δ(13)C values were dependent on moss species and water content, and may reflect site exposure to strong winds. Testate amoebae assemblages were characterised by low concentrations and taxonomic diversity, with Corythion dubium and Microcorycia radiata types the most cosmopolitan taxa. The similarity between the intra- and inter-site ranges measured in all proxies suggests that microclimate and micro-topographical conditions around the moss surface were important determinants of proxy values. Isotope and testate amoebae analyses have proven value as palaeoclimatic, temporal proxies of climate change, whereas this study demonstrates that variations in isotopic and amoeboid proxies between microsites can be beyond the bounds of the current spatial variability in AP climate.The research was funded by the Natural Environment Research Council Antarctic Funding Initiative grant NE/H014896/ to DJC, PC, DAH and HG. PC, DAH and JR contribute to the BAS ‘Polar Science for Planet Earth’ research programme. Carbon isotope analyses were undertaken by Chris Kendrick at the NERC Isotope Geosciences Laboratory. Sample collection was supported by HMS Protector and HMS Endurance. Thanks to Iain Rudkin and Ashly Fusiarski for fieldwork support, to Adrian Dahood for water sample collection and to Sue Rouillard in the University of Exeter Geography drawing office for Figure 1.This is the final version of the article. It first appeared from Springer via https://doi.org/10.1007/s00442-016-3608-

Heating up the Holocene

With direct meteorological data on the Antarctic Peninsula only dating back to the 1950s, scientists must search elsewhere for climate change records of the distant past. A series of expeditions to analyse ancient moss are poised to provide a longer-term perspective on the region’s warming pattern

The Oral History Metadata Synchronizer (OHMS) Proposal

Dan Royles proposal for a pedagogical project that connects students to unique primary sources from the past an

"DON'T WE DIE TOO?": THE POLITICAL CULTURE OF AFRICAN AMERICAN AIDS ACTIVISM

This project reveals the untold story of African Americans AIDS activists' fight against HIV and AIDS in black communities. I describe the ways that, from 1985 to 2003, the both challenged public and private granting agencies to provide funds for HIV prevention efforts aimed specifically at black communities, and challenged homophobic attitudes among African Americans that, they believed, perpetuated the spread of the disease through stigma and silence. At the same time, they connected the epidemic among African Americans to racism and inequality within the United States, as well as to the pandemic raging throughout the African Diaspora and in the developing world. In this way, I argue, they contested and renegotiated the social and spatial boundaries of black community in the context of a devastating epidemic. At the same time, I also argue, they borrowed political strategies from earlier moments of black political organizing, as they brought key questions of diversity, equality, and public welfare to bear on HIV and AIDS. As they fought for resources with which to stop HIV and AIDS from spreading within their communities, they struggled over the place of blackness amid the shifting politics of race, class, and health in post-Civil Rights America. Adding their story to the emerging narrative of the history of the epidemic thus yields a more expansive and radical picture of AIDS activism in the United States.Histor

To Make the Wounded Whole

In the decades since it was identified in 1981, HIV/AIDS has devastated African American communities. Members of those communities mobilized to fight the epidemic and its consequences from the beginning of the AIDS activist movement. They struggled not only to overcome the stigma and denial surrounding a “white gay disease” in Black America, but also to bring resources to struggling communities that were often dismissed as too “hard to reach.” To Make the Wounded Whole offers the first history of African American AIDS activism in all of its depth and breadth. Dan Royles introduces a diverse constellation of activists, including medical professionals, Black gay intellectuals, church pastors, Nation of Islam leaders, recovering drug users, and Black feminists who pursued a wide array of grassroots approaches to slow the epidemic's spread and address its impacts. Through interlinked stories from Philadelphia and Atlanta to South Africa and back again, Royles documents the diverse, creative, and global work of African American activists in the decades-long battle against HIV/AIDS.</p