Professor Tim Lenton
Chair in Climate Change/Earth Systems Science

Key publications | Publications by category | Publications by year

Key publications

Lenton TM, Boyle RA, Poulton SW, Shields-Zhou GA, Butterfield NJ (2014). Co-evolution of eukaryotes and ocean oxygenation in the Neoproterozoic era. Nature Geoscience, 7(4), 257-265.

Co-evolution of eukaryotes and ocean oxygenation in the Neoproterozoic era

The Neoproterozoic era (about 1,000 to 54' million years ago) was a time of turbulent environmental change. Large fluctuations in the carbon cycle were associated with at least two severe-possible Snowball Earth-glaciations. There were also massive changes in the redox state of the oceans, culminating in the oxygenation of much of the deep oceans. Amid this environmental change, increasingly complex life forms evolved. The traditional view is that a rise in atmospheric oxygen concentrations led to the oxygenation of the ocean, thus triggering the evolution of animals. We argue instead that the evolution of increasingly complex eukaryotes, including the first animals, could have oxygenated the ocean without requiring an increase in atmospheric oxygen. We propose that large eukaryotic particles sank quickly through the water column and reduced the consumption of oxygen in the surface waters. Combined with the advent of benthic filter feeding, this shifted oxygen demand away from the surface to greater depths and into sediments, allowing oxygen to reach deeper waters. The decline in bottom-water anoxia would hinder the release of phosphorus from sediments, potentially triggering a potent positive feedback: phosphorus removal from the ocean reduced global productivity and ocean-wide oxygen demand, resulting in oxygenation of the deep ocean. That, in turn, would have further reinforced eukaryote evolution, phosphorus removal and ocean oxygenation. (C) '014 Macmillan Publishers Limited. All rights reserved.
Daines SJ, Clark JR, Lenton TM (2014). Multiple environmental controls on phytoplankton growth strategies determine adaptive responses of the N:P ratio. Ecology Letters, 17(4), 414-425.

Multiple environmental controls on phytoplankton growth strategies determine adaptive responses of the N:P ratio

The controls on the 'Redfield' N : P stoichiometry of marine phytoplankton and hence the N : P ratio of the deep ocean remain incompletely understood. Here, we use a model for phytoplankton ecophysiology and growth, based on functional traits and resource-allocation trade-offs, to show how environmental filtering, biotic interactions, and element cycling in a global ecosystem model determine phytoplankton biogeography, growth strategies and macromolecular composition. Emergent growth strategies capture major observed patterns in marine biomes. Using a new synthesis of experimental RNA and protein measurements to constrain per-ribosome translation rates, we determine a spatially variable lower limit on adaptive rRNA:protein allocation and hence on the relationship between the largest cellular P and N pools. Comparison with the lowest observed phytoplankton N : P ratios and N : P export fluxes in the Southern Ocean suggests that additional contributions from phospholipid and phosphorus storage compounds play a fundamental role in determining the marine biogeochemical cycling of these elements. (C) '014 John Wiley and Sons Ltd/CNRS.
Lenton TM, Crouch M, Johnson M, Pires N, Dolan L (2012). First plants cooled the Ordovician. Nature Geoscience, 5(2), 86-89. Author URL
Lenton TM (2011). Early warning of climate tipping points. Nature Climate Change, 1, 201-209.
Rockstrom J, Steffen W, Noone K, Persson A, Chapin FS, Lambin EF, Lenton TM, Scheffer M, Folke C, Schellnhuber HJ, et al (2009). A safe operating space for humanity. Nature, 461(7263), 472-475. Author URL
Lenton TM, Held H, Kriegler E, Hall JW, Lucht W, Rahmstorf S, Schellnhuber HJ (2008). Tipping elements in the Earth's climate system. Proc Natl Acad Sci U S A, 105(6), 1786-1793.

Tipping elements in the Earth's climate system.

The term "tipping point" commonly refers to a critical threshold at which a tiny perturbation can qualitatively alter the state or development of a system. Here we introduce the term "tipping element" to describe large-scale components of the Earth system that may pass a tipping point. We critically evaluate potential policy-relevant tipping elements in the climate system under anthropogenic forcing, drawing on the pertinent literature and a recent international workshop to compile a short list, and we assess where their tipping points lie. An expert elicitation is used to help rank their sensitivity to global warming and the uncertainty about the underlying physical mechanisms. Then we explain how, in principle, early warning systems could be established to detect the proximity of some tipping points.
 Abstract.  Author URL

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