Making sense of millennial-scale climate change

Author(s):  
R. B. Alley ◽  
P. U. Clark ◽  
L. D. Keigwin ◽  
R. S. Webb
2017 ◽  
Vol 13 (4) ◽  
pp. 345-358 ◽  
Author(s):  
Marília C. Campos ◽  
Cristiano M. Chiessi ◽  
Ines Voigt ◽  
Alberto R. Piola ◽  
Henning Kuhnert ◽  
...  

Abstract. Abrupt millennial-scale climate change events of the last deglaciation (i.e. Heinrich Stadial 1 and the Younger Dryas) were accompanied by marked increases in atmospheric CO2 (CO2atm) and decreases in its stable carbon isotopic ratios (δ13C), i.e. δ13CO2atm, presumably due to outgassing from the ocean. However, information on the preceding Heinrich Stadials during the last glacial period is scarce. Here we present δ13C records from two species of planktonic foraminifera from the western South Atlantic that reveal major decreases (up to 1 ‰) during Heinrich Stadials 3 and 2. These δ13C decreases are most likely related to millennial-scale periods of weakening of the Atlantic meridional overturning circulation and the consequent increase (decrease) in CO2atm (δ13CO2atm). We hypothesise two mechanisms that could account for the decreases observed in our records, namely strengthening of Southern Ocean deep-water ventilation and weakening of the biological pump. Additionally, we suggest that air–sea gas exchange could have contributed to the observed δ13C decreases. Together with other lines of evidence, our data are consistent with the hypothesis that the CO2 added to the atmosphere during abrupt millennial-scale climate change events of the last glacial period also originated in the ocean and reached the atmosphere by outgassing. The temporal evolution of δ13C during Heinrich Stadials 3 and 2 in our records is characterized by two relative minima separated by a relative maximum. This w structure is also found in North Atlantic and South American records, further suggesting that such a structure is a pervasive feature of Heinrich Stadial 2 and, possibly, also Heinrich Stadial 3.


2001 ◽  
Vol 16 (5) ◽  
pp. 535-543 ◽  
Author(s):  
Katherine Mc Intyre ◽  
Margaret L. Delaney ◽  
A. Christina Ravelo

Nature ◽  
2004 ◽  
Vol 432 (7013) ◽  
pp. 87-90 ◽  
Author(s):  
Jennifer L. Pierce ◽  
Grant A. Meyer ◽  
A. J. Timothy Jull

2013 ◽  
Vol 28 (1) ◽  
pp. 54-67 ◽  
Author(s):  
Shiloh A. Schlung ◽  
A. Christina Ravelo ◽  
Ivano W. Aiello ◽  
Dyke H. Andreasen ◽  
Mea S. Cook ◽  
...  

2021 ◽  
pp. 3-24
Author(s):  
John S. Dryzek

This chapter introduces the politics of the Earth, which has featured a large and ever-growing range of concerns, such as pollution, wilderness preservation, population growth, depletion of natural resources, climate change, biodiversity loss, and destabilization of the Earth system. It explains how the issues of Earth’s politics are interlaced with a range of questions about human livelihood, social justice, public attitudes, and proper relation to one other and other entities on the planet. It also discusses the consequences of discourses for politics and policies. The chapter clarifies how environmental issues like ecological limits, nature preservation, climate change, biodiversity, rainforest protection, environmental justice, and pollution are interconnected in all kinds of ways. It develops an environmental discourse analysis approach and shows how this approach will be applied in subsequent chapters, beginning with the positioning of environmental discourses in relation to the long dominant of discourse of industrialism.


2019 ◽  
Vol 5 (1) ◽  
pp. 1622485 ◽  
Author(s):  
Keith Phiri ◽  
Thulani Dube ◽  
Philani Moyo ◽  
Cornelias Ncube ◽  
Sibonokuhle Ndlovu

2016 ◽  
Vol 21 (4) ◽  
Author(s):  
Timothy Lynam ◽  
Iain Walker
Keyword(s):  

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