Organisms are effected by their environment and climate in fundamental ways that interact with their physiology and shape their form. Many of these adaptations and physical manifestations of those impacts can preserve as part of their remains. While very special conditions are required for long-term preservation, within any one fossil locality multiple techniques using the physical, chemical, and/or taxonomic characteristics of the organisms and sediments, can be combined to understand the environment and answer questions about ecological and climatic phenomena in deep time.
I investigate past terrestrial environments to inform research on climate and ecological processes across grand timescales. I use a broad base in biological sciences and the drive to find the connections between seemingly distinct lines of evidence, to understand systems and uncover mechanisms in the environments of the distant past.
While reconstructing ancient environments is a fascinating pursuit in itself, there is much more that can be achieved using these ecological and climatic archives. My current work will be pursuing a method for reconstructing patterns of cloud in deep time. Although cloud is the greatest source of uncertainty in climate models, we have no way to test cloud-model performance under the climate conditions of our near future. Palaeoclimate models and data can act as such a test bed for our nearest analogue for future climate, the Pliocene, but only if we can reconstruct cloud.
My previous postdoctoral research has focused on the interactions between climate, vegetation and fire, as feedbacks to the amplification of polar temperatures in the Pliocene High Arctic, ~3.6 million years ago. Investigating these feedbacks and the mechanisms that drive them in the Pliocene has an advantage over modern studies in that our modern environment is not in equilibrium with the current level of CO2 radiative forcing. Models of Pliocene climate that comprise the Pliocene Model Intercomparison Project – the largest synoptic modelling effort for the Pliocene - underestimate polar temperatures by between a few and 20°C compared to proxy estimates, undermining their predictive ability, and suggesting we have not understood and incorporated all of the important short and long term feedbacks in the climate system into the models. Improving our understanding of the mechanisms that drive these climate feedbacks will contribute to improving our understanding of the drivers of the climate system more generally, and thus impact near-future climate prediction efforts.
I am interested in continuing to investigate polar amplification, both during the Pliocene and during other past periods of global warmth such as the Eocene, when Antarctica was also host to a diverse ecosystem including forests. Current studies suggest a different shape to the temperature amplification-latitude curve for the southern poles, and as our atmospheric CO2 levels are set to exceed those of the Pliocene, understanding of periods with higher radiative forcing from CO2 becomes critical.
In tandem with palaeoclimate. I intend to pursue a better understanding of how and when diversity changes in relation to these patterns. The latitudinal biodiversity gradient is a fascinating and controversial phenomena in modern ecology. Using deep time as a laboratory of ‘different worlds’ in which we can study environments unlike any on Earth at this time, is one of the best strengths of paleoecology. I posit that using palaeoecological methods, we could disentangle some of the relationships between latitude, climate stability, climate values, and energy inputs, with speciation, extinction, migration and emigration.
Stepping forward from Deep Time, palaeoecology and palaeoclimatology can inform us about our own past. Patterns of migration, collapse of civilizations, and drivers of success are often linked to the climate an environment. In turn, our patterns of land use influence the climate and environment around us. The same techniques used to study polar amplification in past global warm periods, or reconstruct the environment where dinosaurs roamed, can be employed at high resolution in Holocene sediments and offer the opportunity for interdisciplinary collaboration.
Plants – The majority of the techniques I use and the majority of terrestrial fossils preserved are plant parts. This includes pollen, spores, fruits, cones, wood and leaves. Each of these components can tell us about different scales of processes. For example, pollen tends to reflect a broad regional signal as the wind pollinated plants have evolved to travel long distances by air. In contrast, wood, and particularly stump wood, usually provides a very local snap-shot of the environment. Where the two preserve together, taxonomic analysis can reveal heterogeneity of a landscape. Many physical characteristics of plants reflect their environment because behavioural avoidance is not possible. As a result, plant parts as proxies have been a focus for development of hindcasting climates of the past. For example, the taxonomic composition of a region may be determined from the pollen and and/or fruiting bodies and the most likely climate range derived from modern observations of those taxa. Other environmental information is also available; for example, pollen records the palaeo-elevation of a site through the effect of UV-B on the composition of the pollen walls.
Animals –Although animals use behavioural modifications to avoid environmental stresses they do not escape all the effects on the body. The isotopic signal of meteoric water may record temperature and becomes integrated into the tooth enamel and bone of the animals that consume it or shell of animals that live within it. The microstructure of the bones of animals records periods of physiologic stress such as long distance migrations and periods of low metabolism such as torpor or hibernation, in the type and rate of deposition of bone. In some groups this can form patterns in bone quite like tree rings, with concentric patterns of faster, less dense growth and slower, denser growth, cessation and even resorption.
The archives of past environments preserved in our landscapes provide a laboratory in which many techniques can be used to understand ecological and climatic phenomena in the Earth System. I use a broad set of these techniques and collaborate widely with geologists, biogeochemists, palaeobotanists, vertebrate and invertebrate palaeontologists, and climate modelers, to use the specimens preserved to their full potential. By doing so, I create a more complete picture of past environments and their interactions, to contribute to both pressing questions about climate and enduring questions in modern ecology.