The impacts of climate change on crop productivity are often assessed using simulations from a numerical climate model as an input to a crop simulation model. The precision of these predictions reflects the uncertainty in both models. We examined how uncertainty in a climate (HadAM3) and crop General Large-Area Model (GLAM) for annual crops model affects the mean and standard deviation of crop yield simulations in present and doubled carbon dioxide (CO2) climates by perturbation of parameters in each model. The climate sensitivity parameter (gamma, the equilibrium response of global mean surface temperature to doubled CO2) was used to define the control climate. Observed 1966-1989 mean yields of groundnut (Arachis hypogaea L.) in India were simulated well by the crop model using the control climate and climates with values of gamma near the control value. The simulations were used to measure the contribution to uncertainty of key crop and climate model parameters. The standard deviation of yield was more affected by perturbation of climate parameters than crop model parameters in both the present-day and doubled CO2 climates. Climate uncertainty was higher in the doubled CO2 climate than in the present-day climate. Crop transpiration efficiency was key to crop model uncertainty in both present-day and doubled CO2 climates. The response of crop development to mean temperature contributed little uncertainty in the present-day simulations but was among the largest contributors under doubled CO2. The ensemble methods used here to quantify physical and biological uncertainty offer a method to improve model estimates of the impacts of climate change.
We introduce a new generic tool
Relating the resulting min-entropy to the original one, and apply it to several
Settings of interest, including sampling of subsystems and measuring in a
Randomly chosen basis. The sampling results lead to new upper bounds on quantum
Random access codes, and imply the...
Abelian and non-Abelian gauge theories are of central importance in many
areas of physics. In condensed matter physics, Abelian U(1) lattice gauge
theories arise in the description of certain quantum spin liquids. In quantum
information theory, Kitaev's toric code is a Z(2) lattice gauge theory. In...
Pubget Updates sends you emails when Pubget finds new papers that match your search. Use Pubget Updates to get the latest articles for your specialty, written by a colleague, or published by your favorite journals.