A Neoproterozoic Snowball Earth

Abstract

Negative carbon isotope anomalies in carbonate rocks bracketing Neoproterozoic glacial deposits in Namibia, combined with estimates of thermal subsidence history, suggest that biological productivity in the surface ocean collapsed for millions of years. This collapse can be explained by a global glaciation (that is, a snowball Earth), which ended abruptly when subaerial volcanic outgassing raised atmospheric carbon dioxide to about 350 times the modern level. The rapid termination would have resulted in a warming of the snowball Earth to extreme greenhouse conditions. The transfer of atmospheric carbon dioxide to the ocean would result in the rapid precipitation of calcium carbonate in warm surface waters, producing the cap carbonate rocks observed globally.

What price ‘prestige’ in publishing?

“…These numbers can be the origin of funny calculations 2 . A colleague and I published a squib in which, using paragraphs from the biblical books of Isaiah and Revelation, the temperatures of heaven and hell were calculated as 504.5 and 716.6 K respectively 3 .…”

Inorganic carbon addition stimulates snow algae primary productivity

“…We demonstrate that snow algae primary productivity is stimulated by the addition of inorganic carbon. Our results indicate a positive feedback between increasing CO 2 and snow algal primary productivity, underscoring the need for robust climate models of past and present glacial/interglacial oscillations to include feedbacks between supraglacial primary productivity, albedo, and atmospheric CO 2 .Earth has experienced intervals of glacial and interglacial periods in its history including Snowball Earth events [1,2]. Today, glaciers and ice sheets are integral to the Earth's climate and hydrological system-they influence regional and global climate, are sensitive to climate change, and are the largest freshwater reservoir on Earth [3,4].…”

“…Earth has experienced intervals of glacial and interglacial periods in its history including Snowball Earth events [1,2]. Today, glaciers and ice sheets are integral to the Earth's climate and hydrological system-they influence regional and global climate, are sensitive to climate change, and are the largest freshwater reservoir on Earth [3,4].…”

C, O, and Sr isotopic variations in Neoproterozoic-Cambrian carbonate rocks from Sete Lagoas Formation (Bambuí Group), in the Southern São Francisco Basin, Brazil

“…During the Cryogenian, the Sturtian (~720 Ma) and Marinoan (~635 Ma) low-latitude global glaciations (Halverson et al, 2005, Hoffman & Li, 2009) isolated the atmosphere of oceans, thus creating low bio-productivity of photosynthetic marine organisms, and also generated 12 C accumulation in the oceans, as proposed in the "Snowball Earth" hypothesis (Kirschvink, 1992;Hoffman et al, 1998). After the retreat of glaciers and marine transgression by global warming, carbonates deposited immediately after glaciations recorded negative excursions in the δ 13 C values.…”

“…Neoproterozoic carbonate sequences overlying glacial deposits, also known as cap carbonates, have been widely used as regional and global chemostratigraphic correlation tools due to their characteristic negative carbon isotopic signature and lack of reliable biostratigraphy (Kennedy, 1996;Kaufman et al, 1997;Hoffman et al, 1998;Jacobsen & Kaufman, 1999;Hoffman & Schrag, 2002). During the Cryogenian, the Sturtian (~720 Ma) and Marinoan (~635 Ma) low-latitude global glaciations (Halverson et al, 2005, Hoffman & Li, 2009) isolated the atmosphere of oceans, thus creating low bio-productivity of photosynthetic marine organisms, and also generated 12 C accumulation in the oceans, as proposed in the "Snowball Earth" hypothesis (Kirschvink, 1992;Hoffman et al, 1998).…”