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Quantifying Uncertainty in Climate Projections including Biogeochemical Feedbacks

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More accurate models of climate change

Global climate change is one of the most pressing challenges of the 21st century. Scientists have significantly advanced models by including previously missing biogeochemical processes and mathematically estimating uncertain parameters.

Climate Change and Environment

Contemporary climate models that predict future impact must balance accuracy against the level of detail and included processes. Given the increasing complexity of such models, the computational load can become prohibitive. In addition, as more and more detail is added about uncertain processes, subjective albeit expert assumptions about parameters can impact on the accuracy of predictions. The EU-funded project 'Quantifying uncertainty in climate projections including biogeochemical feedbacks' (CLIMB) explored the potential importance of coupled carbon-nitrogen-phosphorus-sulphur (C-N-P-S) cycle processes together with first-order physical processes. Studies have shown amplification of carbon cycle feedback by C-N-P-S cycles. Scientists explored whether or not including these processes reduces uncertainty in the past and present global carbon budget. They also addressed the degree to which the C-N-P-S feedback cycles impact future global warming and whether or not they affect related uncertainty. Importantly, researchers included explicit descriptions of rivers and the global coastal zone, essential to the global biogeochemical cycle but missing from current Earth system models. In addition, they constrained uncertain parameters using an inverse estimation process based on geophysical observations during the past millennium. CLIMB research led to modifications of the coupled carbon-nitrogen-phosphorus biogeochemical cycle model known as Terrestrial-Ocean-aTmosphere Ecosystem Model version 2 (TOTEM2) and an associated publication. Mathematical parameterisation of carbon cycle factors is expected to have major impact on more accurate predictions, leading to informed global climate policy development. Overall, CLIMB has advanced Earth observation models of global climate change with careful and scientific consideration of C-N-P-S cycle processes. Additional papers are in various stages of the publication process.

Keywords

Climate change, biogeochemical processes, climate models, climate projections, C-N-P-S cycle, carbon cycle feedback, carbon budget, global warming, rivers, coastal zone, biogeochemical cycle, geophysical, TOTEM2, climate policy, Earth observation

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