Details of Award
NERC Reference : NE/S002324/1
RECONSTRUCTING LATITUDINAL TERRESTRIAL TEMPERATURE GRADIENTS AT THE CRETACEOUS-PALAEOGENE BOUNDARY: TESTING THE "EQUABLE EARTH" HYPOTHESIS
Grant Award
- Principal Investigator:
- Dr R Jerrett, The University of Manchester, Earth Atmospheric and Env Sciences
- Co-Investigator:
- Professor BE van Dongen, The University of Manchester, Earth Atmospheric and Env Sciences
- Co-Investigator:
- Professor G Price, University of Plymouth, Sch of Geog Earth & Environ Sciences
- Co-Investigator:
- Dr S K Lengger, University of Plymouth, Sch of Geog Earth & Environ Sciences
- Grant held at:
- The University of Manchester, Earth Atmospheric and Env Sciences
- Science Area:
- Atmospheric
- Earth
- Terrestrial
- Overall Classification:
- Panel A
- ENRIs:
- Global Change
- Science Topics:
- Analytical Science
- Climate & Climate Change
- Cenozoic climate change
- Mass extinctions
- Mesozoic climate change
- Palaeo proxies
- Palaeoclimatology
- Palaeoenvironments
- Isotopic analysis
- Sediment/Sedimentary Processes
- Earth Surface Processes
- Peatlands
- Abstract:
- As anthropogenic atmospheric warming is forecasted to exceed 2C above preindustrial temperatures by 2100, a key uncertainty in predicting the impact of this change is the quantitative understanding of how this warming will be distributed in the oceans and atmosphere. One means of assessing this is to look to the geological past, especially the late Cretaceous to Eocene (100-34 Ma ago), when atmospheric pCO2 levels were last as high as the 700 ppmv forecasted for 2100, and global mean annual temperatures (MAT) were up to 8C warmer than today (the so-called "Greenhouse World"). Fossil data suggest that temperature-sensitive organisms, such as reptilians, were living in the Arctic-circle during this period, and led to the emergence of the "Equable Earth" hypothesis - a scenario that invokes near total collapse of the meridional, equator-to-pole temperature gradient at this time. This indicates a climate system that operated in a fundamentally different way to the modern "Icehouse World", with a different/enhanced means of transporting heat from the tropics to the poles. A fundamental problem for scientists aiming to predict future climate change, is that state-of-the-art models are not able to reproduce the degree of collapse of the global meridional temperature gradient suggested by fossil data, reflecting a problem with either the "Equable Earth" hypothesis, or with climate modelling. Either way, this uncertainty impedes our ability to confidently predict the impact of future climate change with far-reaching implications. This research will be the first robust test of the "Equable Earth" hypothesis. We will reconstruct meridional variation in land surface MAT in a transect along the North American Continent, spanning mid- to high-palaeolatitude for several discrete time-equivalent instantaneous time-slices spanning the Cretaceous-Palaeogene (K-Pg) boundary - an interval in the middle of the "Greenhouse World". The MATs will be reconstructed using the brGDGT palaeotemperature proxy from collected coal samples. brGDGTs are lipids produced by bacteria thriving in terrestrial environments, whose distribution is a function of land surface MAT and can be used to reconstruct land surface MATs. We have identified ten separate sites, spanning 47-75N of palaeolatitude, where coals (fossil peats) were demonstrably accumulating coevally, by the occurrence within each of the coals of the globally synchronous Iridium (Ir)-enriched layer that settled from the atmosphere after the impact of a meteorite at the K-Pg boundary. In addition to the Ir-enriched layer, the coals contain datable tephra horizons, which will constrain vertical rates of change of MAT from time-slice to time-slice. They also contain distinctive carbon isotopic events before, during and after the Ir- enriched layer, which provide additional correlatable time lines between all locations. Combined, this provides an unique opportunity to generate serial time-slice reconstructions of meridional land surface MAT gradients, spaced at sub-orbital durations, at this critical period in Earth history. This will provide us with the opportunity to critically test the "Equable Earth" hypothesis, by placing numerical bounds on meridional MAT gradients for a series of time slices in continental interiors at this time. By generating meridional MAT gradients for multiple intervals, and by generating a tephrochronologically-based time-series through the succession, it will be possible to place bounds on the rates of change of MAT in time, from mid- to high- latitude. This will also reveal, for the first time, the dynamics in space and time of the "Greenhouse Earth" climate system, and will also allow us to assess MAT in the aftermath of meteorite impact at the K-Pg boundary, giving insight into the response of the climate system to catastrophic change, and allowing us to test competing hypotheses of climate change as the driver for the mass extinction at the K-Pg boundary.
- NERC Reference:
- NE/S002324/1
- Grant Stage:
- Completed
- Scheme:
- Standard Grant FEC
- Grant Status:
- Closed
- Programme:
- Standard Grant - NI
This grant award has a total value of £582,024
FDAB - Financial Details (Award breakdown by headings)
| DI - Other Costs | Indirect - Indirect Costs | DA - Investigators | DI - Equipment | DI - Staff | DA - Estate Costs | DI - T&S | DA - Other Directly Allocated |
|---|---|---|---|---|---|---|---|
| £103,645 | £131,579 | £54,457 | £9,360 | £109,788 | £54,949 | £56,062 | £62,183 |
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