Dr Phil Holden

pbhResearch Investment Fellow: Integrated Earth System Modelling

 Email: Philip.Holden-8AT8-open.ac.uk

Phone: +44 (0) 7095 351 332


My research centres upon the evaluation of Earth system model uncertainty through the statistical analysis of large numbers (“ensembles”) of model simulations, with applications in both past and future climate change, especially global carbon-cycle dynamics and climate change impacts. I performed a suit of ~50 climate-carbon cycle ensemble experiments with GENIE for contribution to Working Group I of the IPCC Fifth Assessment Report (AR5).

My work uses both GENIE (a state of the art intermediate complexity carbon-cycle model with a moderately complex representation of the physics and biology of the ocean, but a simple representation of the atmosphere) and PLASIM (a substantially more complex model of the atmosphere for use in climate projections, but lacking the complexity of GENIE in the ocean). I am presently coupling GENIE and PLASIM together to produce a model with the full complexities of both, opening up a range of possible future applications.

Recent published research topics include:

Development of an emulator of the future climate change projections of PLASIM. An emulator is a statistical description of a model that produces a fast approximation to the model’s output, enabling applications that would not be possible with the model itself. Ongoing work has coupled this emulator to impact models to evaluate climate change impacts on crops, human health, energy demands for heating and cooling, and hydro-electric power potential.

Design of a model of land use change (a representation of land used for agriculture) that I have incorporated into GENIE. I applied the resulting model to derive a probabilistic quantification of the terrestrial carbon cycle response to fossil fuel emissions and also to build an emulator of the global carbon cycle. This emulator will provide a substantial upgrade for the carbon-cycle component of integrated assessment models, models that quantify fossil fuel emissions but lack a detailed description of what happens to the CO2 and how long it stays in the atmosphere.

Design of a large ensemble of coupled climate-carbon cycle configurations of GENIE that I have applied to investigate the uncertainty in oceanic uptake of CO2 and its isotopes. Work is ongoing to apply this ensemble to transient glacial-interglacial carbon cycle simulations.

A probabilistic calibration of the uncertainty of the simulated future Earth system response (climate, vegetation, ocean circulation and sea ice) to changes in atmospheric CO2, using ensembles of GENIE simulations constrained by Last Glacial Maximum climate.

GENIE ensembles of simulations of glacial climate to address i) the role of de-glacial melt-water forcing and, potentially, WAIS retreat in explaining the behaviour of Antarctic climate observed in the EPICA ice-core record and ii) the role of orbital changes in the glacial-interglacial variability of tropical vegetation. An on-going project is applying these simulations, together with emulations of PLASIM, to address the evolution of species diversity in South America over the last million years.

Recent publications