EarthTalks at GEOCENTER Denmark

April 23, 2021By Tais W DahlUncategorized

The Section for Geobiology at GLOBE has helped organizing the spring season of EarthTalks 2021, and we welcome interested students and researchers to participate over Zoom (link below). The talks will not be recorded. Earth Talks Lecture Series – Spring 2021 Friday afternoons 14:00-15:00 DK time (sharp) 23/4 – Prof. Sigur∂ur Gislason, University of Iceland The … Read More

Did land plants alter erosion rates on Earth?

March 28, 2021By Tais W DahlUncategorized

A discussion arises from the recent review article in Chemical Geology, where Tais W. Dahl and Susanne Arens concluded that land plants did not forever increase the physical weathering rates of the continental crust. This conclusion was reached from the records of preserved sediment rock volume and the timing of plant-assisted weathering as recorded in … Read More

The Carlsberg foundation supports field work in Siberia

January 27, 2021By Tais W DahlUncategorized

The Carlsberg Foundation is sponsoring field work led by Tais W. Dahl to Arctic Siberia, where an important climate catastrophe is recorded in marine sedimentary rocks. The expedition will bring back data and samples deposited in the oceans during a climate event that caused sulfidic anoxia to suddenly expand in warming oceans and wipe out … Read More

Press release: Early animals had a shorter day

October 12, 2020By Tais W DahlUncategorized

In a brief story published in Danish on Videnskab.dk, Aske L. Sørensen and Tais W. Dahl explain one of the consequences of their latest EPSL paper: Earth was spinning faster 500 million years ago. The scientific paper entitled “Astronomically forced climate change in the Late Cambrian” documents Milankovitch-cycles in two drill cores through the Alum … Read More

Tracing global ocean oxygenation from calcitic brachiopods

August 4, 2020By Tais W DahlPublication, Research, Students and postdocs

The uranium isotope composition of seawater provide insights to how much sediment burial occurs globally in anoxia settings. Therefore, it is desirable to measure uranium isotopes to track the oxygenation state of the oceans through geological time. However, there is currently no geological archive that can reliably record the composition of ancient seawater. Calcitic brachiopods … Read More

New paper: The impact of land plant evolution on Earth’s climate and oxygenation state

May 14, 2020By Tais W DahlPublication, Research

The colonization of land by plantss, fungi and animals has had a profound impact on Earth’s climate and oxygenation state. In a comprehensive review paper, we have summarize the current state of knowledge and compiled available evidence in support that terrestrial life has caused: Atmospheric CO2 decline and climatic cooling (permanent transition) Atmospheric O2 rise … Read More

New GCA paper: Volcanic eruptions triggered repeated marine anoxia and reveal global-scale feedbacks during the Permian-Triassic mass extinction 250 million yeers ago

April 18, 2020By Tais W DahlPublication, Research, Students and postdocs, Uncategorized

The largest animal extinction event in recorded history occurred 251 Ma at the Permian-Triassic boundary coinciding with expansive marine anoxia. In a new study, led by postdoc Feifei Zhang, of a greatly expanded dolomite section from the Carnic Alps, Austria, marine anoxia is found to have expanded in two pulses separated by ~100,000 years. Global … Read More

Expansive ocean anoxia during the Late Devonian Hangenberg event

March 1, 2020By Tais W DahlPublication, Research, Students and postdocs

Marine animal extinction events have occurred episodically over the past 550 million years with expansive marine anoxia as the proximate kill mechanism. New evidence from a carbonate section in South China (Long’an) shows that the Late Devonian Hangenberg event should be counted as one such events. Postdoc Feifei Zhang have analyzed uranium isotopes in a … Read More