Wednesday, 22 January 2014

The Anthropocene

Image from this web site:

William F. Ruddiman

The start of the period of large-scale human effects on this planet (the Anthropocene) is debated. The industrial view holds that most significant impacts have occurred since the early industrial era (1850), whereas the early-anthropogenic view recognizes large impacts thousands of years earlier. This review focuses on three indices of global-scale human influence: forest clearance (and related land use), emissions of greenhouse gases (CO2 and CH4), and effects on global temperature. Because reliable, systematic land-use surveys are rare prior to 1950, most reconstructions for early-industrial centuries and prior millennia are hind casts that assume humans have used roughly the same amount of land per person for 7,000 years. But this assumption is incorrect. Historical data and new archeological databases reveal much greater per-capita land use in preindustrial than in recent centuries. This early forest clearance caused much greater preindustrial greenhouse-gas emissions and global temperature changes than those proposed within the industrial paradigm.

Authors and affiliations:
William F. Ruddiman

Monday, 20 January 2014

Amazon River carbon dioxide outgassing fuelled by wetlands

Black river (Rio Negro). Amazon jungle. Original file

Gwenaël Abril, Jean-Michel Martinez, L. Felipe Artigas, Patricia Moreira-Turcq, Marc F. Benedetti, Luciana Vidal, Tarik Meziane, Jung-Hyun Kim, Marcelo C. Bernardes, Nicolas Savoye, Jonathan Deborde, Edivaldo Lima Souza, Patrick Albéric, Marcelo F. Landim de Souza & Fabio Roland

River systems connect the terrestrial biosphere, the atmosphere and the ocean in the global carbon cycle. A recent estimate suggests that up to 3 petagrams of carbon per year could be emitted as carbon dioxide (CO2) from global inland waters, offsetting the carbon uptake by terrestrial ecosystems. It is generally assumed that inland waters emit carbon that has been previously fixed upstream by land plant photosynthesis, then transferred to soils, and subsequently transported downstream in run-off. But at the scale of entire drainage basins, the lateral carbon fluxes carried by small rivers upstream do not account for all of the CO2 emitted from inundated areas downstream. Three-quarters of the world’s flooded land consists of temporary wetlands, but the contribution of these productive ecosystems to the inland water carbon budget has been largely overlooked. Here we show that wetlands pump large amounts of atmospheric CO2 into river waters in the floodplains of the central Amazon. Flooded forests and floating vegetation export large amounts of carbon to river waters and the dissolved CO2 can be transported dozens to hundreds of kilometres downstream before being emitted. We estimate that Amazonian wetlands export half of their gross primary production to river waters as dissolved CO2 and organic carbon, compared with only a few per cent of gross primary production exported in upland (not flooded) ecosystems. Moreover, we suggest that wetland carbon export is potentially large enough to account for at least the 0.21 petagrams of carbon emitted per year as CO2 from the central Amazon River and its floodplains. Global carbon budgets should explicitly address temporary or vegetated flooded areas, because these ecosystems combine high aerial primary production with large, fast carbon export, potentially supporting a substantial fraction of CO2 evasion from inland waters.

More information about the article: Nature 505,395–398(16 January 2014)

Authors and affiliations:
Laboratoire Environnements et Paléoenvironnements Océaniques et Continentaux (EPOC), CNRS, Université Bordeaux 1, Avenue des Facultés, 33405 Talence, France
Gwenaël Abril,
Nicolas Savoye &
Jonathan Deborde
Laboratoire Géosciences et Environnement de Toulouse, Institut de Recherche pour le Développement, Université Paul Sabatier, 14 avenue Edouard Belin, 31400 Toulouse, France
Gwenaël Abril,
Jean-Michel Martinez &
Patricia Moreira-Turcq
Laboratoire d’Océanologie et Géosciences, CNRS, Université du Littoral Côte d’Opale, 32 avenue Foch, 62930 Wimereux, France
L. Felipe Artigas
Equipe Géochimie des Eaux, Institut de Physique du Globe de Paris, Université Paris Diderot, Sorbonne Paris Cité, 35 rue Hélène Brion, 75205 Paris Cedex 13, France
Marc F. Benedetti
Laboratório de Ecologia Aquática, Departamento de Biologia, Universidade Federal de Juiz de Fora, Rua José Lourenço Kelmer, MG 36036-900 Juiz de Fora, Brazil
Luciana Vidal &
Fabio Roland
Laboratoire Biologie des Organismes et Ecosystèmes Aquatiques (BOREA), Muséum National d’Histoire Naturelle, CNRS, IRD, UPMC, 61 rue Buffon, 75005, Paris, France
Tarik Meziane
NIOZ (Royal Netherlands Institute for Sea Research), Department of Marine Organic Biogeochemistry, Texel, 1790 AB Den Burg, The Netherlands
Jung-Hyun Kim
Programa de Geoquímica, Universidade Federal Fluminense, Outeiro São João Batista, RJ 24020015 Niterói, Brazil
Marcelo C. Bernardes
Instituto de Geociências, Universidade de Brasília, Campus Universitário Darcy Ribeiro, DF 70.910-900 Brasília, Brazil
Edivaldo Lima Souza
Institut des Sciences de la Terre d’Orléans, 1A rue de la Férollerie, 45071 Orléans Cedex 2, France
Patrick Albéric
Laboratório de Oceanografia Química, Universidade Estadual de Santa Cruz, Rodovia Ilhéus-Itabuna, 45662-900 Ilhéus, Bahia, Brazil
Marcelo F. Landim de Souza 

Tuesday, 10 December 2013

A volcanic activity alert-level system for aviation: review of its development and application in Alaska

Tungurahua volcano in Ecuador
An ash cloud from an eruption of the Tungurahua volcano in Ecuador and the peak of the dormant Chimborazo volcano project through cloud cover in this photo taken from NASA's C-20A flying at 41,000 feet (12,500 meters) altitude about 100 miles (160 kilometers) northeast of Guayaquil, Ecuador on March 17, 2013. (c) NASA

In the the issue of the journal Natural Hazards published in December 2013 an article concerning the volcanic activity alert-level system for aviation. The authors are Marianne Guffanti and Thomas P. Miller from US Geological Survey. Here below the abstract.

An alert-level system for communicating volcano hazard information to the aviation industry was devised by the Alaska Volcano Observatory (AVO) during the 1989–1990 eruption of Redoubt Volcano. The system uses a simple, color-coded ranking that focuses on volcanic ash emissions: Green—normal background; Yellow—signs of unrest; Orange—precursory unrest or minor ash eruption; Red—major ash eruption imminent or underway. The color code has been successfully applied on a regional scale in Alaska for a sustained period. During 2002–2011, elevated color codes were assigned by AVO to 13 volcanoes, eight of which erupted; for that decade, one or more Alaskan volcanoes were at Yellow on 67 % of days and at Orange or Red on 12 % of days. As evidence of its utility, the color code system is integrated into procedures of agencies responsible for air-traffic management and aviation meteorology in Alaska. Furthermore, it is endorsed as a key part of globally coordinated protocols established by the International Civil Aviation Organization to provide warnings of ash hazards to aviation worldwide. The color code and accompanying structured message (called a Volcano Observatory Notice for Aviation) comprise an effective early-warning message system according to the United Nations International Strategy for Disaster Reduction. The aviation color code system currently is used in the United States, Russia, New Zealand, Iceland, and partially in the Philippines, Papua New Guinea, and Indonesia. Although there are some barriers to implementation, with continued education and outreach to Volcano Observatories worldwide, greater use of the aviation color code system is achievable.

Authors and affiliations:
Marianne Guffanti, Thomas P. Miller