Nitrogen and the terrestrial carbon cycle

Nitrogen is a key component of the terrestrial carbon cycle, and the latest versions of vegetation models in land surface models include nitrogen. After being part of the team that implemented nitrogen into JULES, I am currently working on extending this nitrogen component to account for mycorrhizal fungi.

GCM canopy interception capacity parameterisation

How much water can the vegetation canopy hold and how should models parameterise this? It sounds like a simple question, but nothing could be further from the truth. In models, the representation of the canopy interception capacity varies quite a bit from the measured values in the literature – by as much as a factor …

Modelling terrestrial biodiversity in the past

How has terrestrial biodiversity changed over time? Previous modelling studies of vegetation have generally used a small number of plant functional types to understand how the terrestrial biosphere responds to climate changes. Whilst being useful for understanding first order climate feedbacks, this climate-envelope approach makes a lot of assumptions about past vegetation being very similar …

When carbon is irrelevant – vegetation and the glacial cycle

The net impact of the terrestrial biosphere on climate over the glacial-interglacial cycle has been speculated upon and modeled at low resolution (e.g. with only 51° longitude). Given the spatial heterogeneity of biogeophysical (e.g. albedo) effects, it is important to consider finer spatial scales and distinguish between biogeophysical and biogeochemical effects to fully understand the …

Afforestation and future climate

Afforestation and future climate; should we be re-evaluating its role in climate change mitigation policy? Global land use change and its interaction with the climate system is recognised as an important component of the IPCC future climate scenarios. The full effects of carbon and non-carbon impacts of land use change in the representative concentration pathways …

Natural vs Anthropogenic Land cover change

Our latest paper, Quantifying the relative importance of land cover change from climate and land use in the representative concentration pathways, is published in Global Biogeochemical Cycles. The link to the official publishers version is here. You can find the abstract listed there. In this paper, we disassemble the contributions of LULCC, CILCC and accumulation …

Biogeophysical changes to the land surface

I’m generally (though not exclusively) interested in biogeophysical changes to the land surface. What does this mean? Well, there are two ways that the land surface can affect the climate. One is the biogeochemical, the other is biogeophysical. The difference is this: Biogeochemical generally means changes in greenhouse gases (e.g. carbon dioxide, methane, nitrous oxide …

Cooling with Crops: Context and Assessment

This paper is published in Philosophical Transactions A and provides a full explanation of the concept of crop albedo bio-geoengineering, as well as how it compares to other geoengineering proposals. See the full paper, Singarayer and Davies-Barnard 2012. The intention of this review is to place crop albedo biogeoengineering in the wider picture of climate …

Regional climate change mitigation with Crops

The risk of climate change has stimulated research into a range of geoengineering ideas (the intentional manipulation of the climate to counteract global warming) to mitigate surface warming. Bio-geoengineering is the suggestion that the reflectance of incoming solar radiation by crops could be increased, thereby providing regional summer-time cooling of up to one degree Celsius …

Land Use Change from Zero Agricultural Productivity Growth

Future land cover will have a significant impact on climate and is strongly influenced by the extent of agricultural land-use. Differing assumptions of crop yield increase and carbon pricing mitigation strategies affect projected expansion of agricultural land in future scenarios. In the CMIP5 Representative Concentration Pathway RCP4.5, the biogeochemical (greenhouse gas emissions etc.) effects of these land …