pmip3:wg:p2f:papers
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pmip3:wg:p2f:papers [2017/02/13 17:18] jules [How well do simulated last glacial maximum tropical temperatures constrain equilibrium climate sensitivity?] |
pmip3:wg:p2f:papers [2017/06/07 09:08] (current) jules [Future climate forcing potentially without precedent in the last 420 million years] |
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| + | ==== Future climate forcing potentially without precedent in the last 420 million years ==== | ||
| + | Foster, G. L., Royer, D. L., & Lunt, D. J., (2017). Future climate forcing potentially without precedent in the last 420 million years. Nature Communications, 8, 1–8. http://doi.org/10.1038/ncomms14845 | ||
| + | https://www.nature.com/articles/ncomms14845 | ||
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| + | Abstract: ''The evolution of Earth’s climate on geological timescales is largely driven by variations in the magnitude of total solar irradiance (TSI) and changes in the greenhouse gas content of the atmosphere. Here we show that the slow B50 Wm 2 increase in TSI over the last B420 million years (an increase of B9 Wm 2 of radiative forcing) was almost completely negated by a long-term decline in atmospheric CO2. This was likely due to the silicate weathering- negative feedback and the expansion of land plants that together ensured Earth’s long-term habitability. Humanity’s fossil-fuel use, if unabated, risks taking us, by the middle of the twenty-first century, to values of CO2 not seen since the early Eocene (50 million years ago). If CO2 continues to rise further into the twenty-third century, then the associated large increase in radiative forcing, and how the Earth system would respond, would likely be without geological precedent in the last half a billion years.'' | ||
| ==== The University of Victoria Cloud Feedback Emulator (UVic-CFE): cloud radiative feedbacks in an intermediate complexity model ==== | ==== The University of Victoria Cloud Feedback Emulator (UVic-CFE): cloud radiative feedbacks in an intermediate complexity model ==== | ||
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| From the abstract: ''HadGEM2-A simulates extreme cooling over northern continents and nearly complete die back of vegetation in Asia, giving a poor representation of the LGM environment compared with reconstructions of surface temperatures and biome distributions. The model also performs significantly worse for the LGM in comparison with its precursor AR4 model HadCM3M2. Detailed analysis shows that the major factor behind the vegetation die off in HadGEM2-A is a subtle change to the temperature dependence of leaf mortality within the phenology model of HadGEM2. This impacts on both snow-vegetation albedo and vegetation dynamics. A new set of parameters is tested for both the pre-industrial and LGM, showing much improved coverage of vegetation in both time periods, including an improved representation of the needle-leaf forest coverage in Siberia for the pre-industrial. The new parameters and the resulting changes in global vegetation distribution strongly impact the simulated loading of mineral dust, an important aerosol for the LGM. The climate response in an abrupt 4× pre-industrial CO2 simulation is also analysed and shows modest regional impacts on surface temperatures across the Boreal zone.'' | From the abstract: ''HadGEM2-A simulates extreme cooling over northern continents and nearly complete die back of vegetation in Asia, giving a poor representation of the LGM environment compared with reconstructions of surface temperatures and biome distributions. The model also performs significantly worse for the LGM in comparison with its precursor AR4 model HadCM3M2. Detailed analysis shows that the major factor behind the vegetation die off in HadGEM2-A is a subtle change to the temperature dependence of leaf mortality within the phenology model of HadGEM2. This impacts on both snow-vegetation albedo and vegetation dynamics. A new set of parameters is tested for both the pre-industrial and LGM, showing much improved coverage of vegetation in both time periods, including an improved representation of the needle-leaf forest coverage in Siberia for the pre-industrial. The new parameters and the resulting changes in global vegetation distribution strongly impact the simulated loading of mineral dust, an important aerosol for the LGM. The climate response in an abrupt 4× pre-industrial CO2 simulation is also analysed and shows modest regional impacts on surface temperatures across the Boreal zone.'' | ||
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| + | ==== Tropical cyclone genesis potential across palaeoclimates ==== | ||
| + | Koh, J. H. and Brierley, C. M., Clim. Past, 11, 1433-1451, doi:10.5194/cp-11-1433-2015, 2015. http://www.clim-past.net/11/1433/2015/ (open access) | ||
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| + | ''The favourability of the mid-Pliocene, Last Glacial Maximum (LGM) and mid-Holocene for tropical cyclone formation is investigated in five climate models. During the mid-Pliocene and LGM, changes in carbon dioxide led to sea surface temperature changes throughout the tropics, yet the potential intensity is calculated to be relatively insensitive to these changes. Changes in tropical cyclone genesis potential during the mid-Holocene are found to be asymmetric about the Equator: being reduced in the Northern Hemisphere but enhanced in the Southern Hemisphere. This is clearly driven by the altered seasonal insolation. Nonetheless, the enhanced seasonality drove localised changes in genesis potential, by altering the strength of monsoons and shifting the intertropical convergence zone. Trends in future tropical cyclone genesis potential are consistent neither between the five models studied nor with the palaeoclimate results. It is not clear why this should be the case.'' | ||
| ==== Evaluation of CMIP5 palaeo-simulations to improve climate projections. ==== | ==== Evaluation of CMIP5 palaeo-simulations to improve climate projections. ==== | ||
pmip3/wg/p2f/papers.1487006316.txt.gz · Last modified: 2017/02/13 17:18 by jules
