PLIOTRANS · PLIOcene TRANSient Climate Modelling: Towards a global consensus between ice volume, temperature and relative sea level for the Late Pliocene

PLIOcene TRANSient Climate Modelling: Towards a global consensus between ice volume, temperature and relative sea level for the Late Pliocene

The Antarctic and Greenland ice sheets will be significant contributors to sea-level rise during and beyond this century. An increase in sea level will have considerable impact on ecosystems, the vulnerability of the coast and on society. It will increase the risk of flooding, accelerate coastal retreat and erosion and damage coastal infrastructures around the globe. A better understanding of the responses of the ice sheets to a warming climate is evidently needed to make more rigorous predictions of the impact of regional sea-level variations. The Late Pliocene (3.264 to 3.025 million years before present) was a warm interval in the history of the Earth that can be used to gain a better understanding of the response of the ice sheets to a warming climate with CO2 levels close to or higher than present. For this project we performed experiments with ice-sheet models forced with multiple snapshot experiments of the HadCM3 climate mode. The climate model simulations used Pliocene boundary conditions such as topography and an atmospheric CO2 level set to 405 ppm, similar to that what it is today. For these simulation, we specifically focused on two short warm intervals of each 40,000 years duing the Late Pliocene, for which each period a set of climate model simulations were performed varying the orbital parameters, leading to differences in received warmth from the Sun (Prescott et al, 2014). For these 40,000 yr simulations the ice-sheet models for Antarctica and Greenland where run simultaneously forced by temperature and precipitation from the climate model. Our simulations indicate that for one particular interval the response is rather stable, in line with the small variations in received warmth from the sun. On the other hand, the other interval shows a much stronger and opposite change in Solar warmth over Antarctica and Greenland. Hence the ice sheets show a strong asynchronous response to the same climate. This response is shown to be a key factor for interpretting the global change in sea level. In particular, simply summing the maximum individual contribution of the Greenland and Antarctic ice sheets to sea-level rise is shown to be larger that then actual synchronous sum of the sea-level contributions. References: Prescott, C. L., Haywood, A. M., Dolan, A. M., Hunter, S. J., Pope, J. O., Pickering, S. J., Assessing orbitally-forced interglacial climate variability during the mid-Pliocene Warm Period, Earth and Planetary Science Letters, 400, 261-271, 2014.

Data: CORDIS, © European Union