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Comprehensive global climate models are the only tools that account for the complex set of processes which will determine future climate change at both a global and regional level. Planners are typically faced with a wide range of predicted changes from different models of unknown relative quality, owing to large but unquantified uncertainties in the(More)
At its recent meeting (September 2008) involving 20 climate modeling groups from around the world (i.e., most of the major groups performing climate change research today), the WCRP's Working Group on Coupled Modelling (WGCM), with input from IGBP's AIMES, agreed on a new set of coordinated climate model experiments, to be known as phase five of the Coupled(More)
Processes in the climate system that can either amplify or dampen the climate response to an external perturbation are referred to as climate feedbacks. Climate sensitivity estimates depend critically on radia-tive feedbacks associated with water vapor, lapse rate, clouds, snow, and sea ice, and global estimates of these feedbacks differ among general(More)
The equilibrium climate sensitivity (ECS) of the two perturbed physics ensembles (PPE) generated using structurally different GCMs, MIROC3.2 and HadSM3, is investigated. We develop a method to quantify the SW cloud feedback by clouds with different cloud top pressure. We find that the difference in the ensemble means of the ECS between the two ensembles is(More)
The performance of several state-of-the-art climate model ensembles, including two multi-model ensembles (MMEs) and four structurally different (perturbed parameter) single model ensembles (SMEs), are investigated for the first time using the rank histogram approach. In this method, the reliability of a model ensemble is evaluated from the point of view of(More)
Cloud feedbacks and rapid adjustments to an abrupt quadrupling of CO 2 are diagnosed in five CMIP5 models using cloud radiative kernels in combination with cloud top pressure-and optical depth-partitioned cloud fractions. Upon CO 2 quadrupling, clouds exhibit a rapid reduction in fractional coverage, cloud top pressure, and optical depth, each contributing(More)
1. Synopsis Cloud-radiative effects are expected to control many aspects of the current and future climates, ranging from the large-scale circulation of the atmosphere and intra-seasonal variability to climate sensitivity and precipitation projections. However, investigations so far have been carried out using individual models and various methodologies. To(More)
In addition to influencing climatic conditions directly through radiative forcing, increasing carbon dioxide concentration influences the climate system through its effects on plant physiology. Plant stomata generally open less widely under increased carbon dioxide concentration, which reduces transpiration and thus leaves more water at the land surface.(More)
An extended cloud-clustering method to assess the seasonal variation of clouds is applied to five CMIP5 models. The seasonal variation of the total cloud radiative effect (CRE) is dominated by variations in the relative frequency of occurrence of the different cloud regimes. Seasonal variations of the CRE within the individual regimes contribute much less.(More)