Pliocene climate extremities: understanding the range of climates in Earth’s last warm period
This PhD will use climate models to understand the range of climates during one of the last periods of global warmth in Earth history, the mid-Pliocene.
Background
The mid-Pliocene Warm Period has long been an important palaeoclimate for understanding warm climates with similar to present-day atmospheric carbon dioxide. As such, it has appeared in multiple Intergovernmental Panel on Climate Change (IPCC) reports and the Palaeoclimate Model Intercomparison Project (PMIP). The main timeslice used within the Pliocene is marine isotope stage KM5c, as a time with elevated greenhouse gases and very similar to modern orbital forcing (Haywood et al., 2013). This is the focus of the PlioMIP international climate model intercomparison project (Haywood et al., 2024). However, this timeslice is only a comparatively stable moment in time during the transition from a relatively large glacial period (M2) to a time of maximum sea level (KM3). These cold and warm Pliocene climate extremities are more enigmatic and less well known, but have potentially important consequences for both our understanding of the Pliocene, the functioning of climate in warmer than modern palaeoclimates and our PlioMIP simulations.
Figure 1 | Benthic oxygen isotopes from the Lisiecki and Raymo (2005) stack (LR04). This shows warming (up plot) and cooling episodes (down plot) from 3.6Ma (million years ago) to 2.6Ma (timescale at top is in kyrs). This time incorporates the start of the intensification of Northern Hemisphere glaciation (NHG) and the mid-Pliocene or mid-Piacenzian warm period (mPWP; shaded), which extends from the Mammoth to the Kaena magnetic reversals. The two or three character alphanumeric designation around the mPWP refer to individual glacial or interglacial episodes and the dashed line shows modern benthic δ18O (Dolan et al., 2015).
This project will use both an existing ensemble of simulations from different climate models of KM5c from around the world as part of the PlioMIP project and new climate model simulations of the M2 glacial and the KM3 interglacial to investigate the Earth system of the Pliocene and climate extremities of this glacial-interglacial transition. This will give the student experience of analysing large datasets, manipulating climate model outputs and running climate model simulations. There is also the opportunity to tailor the project to the interests and skills of the successful candidate. Among the many options of further science areas that could be examined are Pliocene ice sheets, vegetation changes through the Pliocene or the impacts of palaeogeographic change on ocean circulation.
Figure 2 | Mean annual temperature changes between standard PlioMIP timeslice, KM5c, and the simulated pre-industrial climate (right, labelled d), from a previous iteration of the Pliocene Model Intercomparison Project (PlioMIP). Difference between the KM3 and KM5c climates purely due to changes in the orbital forcing, ignoring other potential changes, such as greenhouse gases (Prescott et al., 2018).
Training and Research Environment
The student will be trained in the analysis of large climate datasets and will have the opportunity to gain skills in the setting up, running and development of a variety of models. Being based in the Institute for Climate and Atmospheric Science (ICAS) and the Physical Climate and Cryosphere and Palaeo@Leeds research clusters, gives the student access to a wealth of palaeoclimate and climate change expertise. The project will also work with the PlioMIP project members from climate modelling institutes from across the world. As part of the YES-DTN, there will be many opportunities to develop new skills. The student will be expected to attend and present at national and international scientific meetings. There is also the opportunity for at least one research trip to a climate modelling or palaeclimate research group in either Europe or the USA, as part of the international network researching the Pliocene.
Student Profile
No applicant will have all the required skills and knowledge prior to starting this PhD and the strong interdisciplinary nature of the research means that it is suitable for a broad range of academic backgrounds. These include, but are not limited to physics, maths, environmental science, geography, oceanography, computer science etc. Numeracy, computing and programming skills would be an advantage, but are not essential.