Climate sensitivity

The last published report of the IPCC acknowledges that the single largest uncertainty in determining the climate sensitivity to either natural or anthropogenic changes are clouds and their effects on radiation and their role in the hydrological cycle. .. At the present time, weaknesses in the parameterization of cloud formation and dissipation are probably the main impediment to improvements in the simulation of cloud effects on climate (IPCC, 1995, p. 346). 

In such diverse and sophisticated gas-using economies, security of supply and the efficient employment of producing assets depend upon an extensive network of pipelines that interconnect regions with diverse climates and diverse consumption patterns winter-peaking and summer-peaking demand that is climate-sensitive, business cycle-sensitive, and price-sensitive customers who place a high premium on continuity of supply, and those who are relatively insensitive to risk of interruption. These parties depend to a different degree, and place... 

Many climatically sensitive feedback processes could be described in addition to those outlined above. We have restricted our attention to processes that have potentially large effects. A large effect is defined as one that could change the current rate of atmospheric CO2 increase by at least 50% ( 1 Pg C-yr"" ). 

Hansen, J., Lacis, A., Rind, D. et al. (1984). Climate sensitivity analysis of feedback mechanisms. Geophys. Monogr. 20, pp. 130-163. Am. Geophys. Union, Washington DC. 

Hoffert, M. I. and Covey, C. (1992). Deriving global climate sensitivity from paleoclimate reconstructions. Nature 360,573-576. 

Lorius, C., Jouzel, J., Raynaud, D. et al. (1990). The ice-core record climate sensitivity and future greenhouse warming. Nature 347,139-145. 

Tipper ET, Bickle MJ, Galy A, West AJ, PomiFs C, Chapman HJ (2006) The short term climatic sensitivity of carbonate and silicate weathering fluxes insight from seasonal variations in river chemistry. Geochim Cosmochim Acta 70(ll) 2737-2754... 

The main tools used to provide global projections of future climate are general circulation models (GCMs). These are mathematical models based on fundamental physical laws and thus constitute dynamical representations of the climate system. Computational constraints impose a limitation on the resolution that it is possible to realise with such models, and so some unresolved processes are parameterised within the models. This includes many key processes that control climate sensitivity such as clouds, vegetation and oceanic convection [19] of which scientific understanding is still incomplete. 

Easy translation to emission targets, thus not including climate sensitivity in cost calculations. 

Large uncertainty in required emission reductions as result of the uncertainty in climate sensitivity and thus costs. 

Anthropogenic addition to radiative forcing at stabilisation (W/m2) Stabilisation level for C02 only (ppm C02) Multi-gas concentration level (ppm C02-eq.) Global mean temperature °C increase above pre-industrial at equilibrium," using best estimate climate sensitivity of 3°C Peaking year for C02 emissions Change in C02 emissions in 2050 (% of 2000 emissions) ... 

K. Caldeira, A.K. Jain, M.I. Hoffert, Climate sensitivity uncertainty and the need for energy without C02 emission, Science 299 (2003) 2052-2054. 

High atmospheric COj leads to fester evapotranspiration rates, providing another mechanism by which water vapor levels increase. This is singularly important as water vapor changes are now recognized by the IPCC as the largest feedback affecting climate sensitivity. 

Anbar, A. D., Y. L. Yung, and F. P. Chavez, Methyl Bromide Ocean Sources, Ocean Sinks, and Climate Sensitivity, Global Biogeochem. Cycles, 10, 175-190(1996). 

Lacis, A. A., and M. I. Mishchenko, Climate Forcing, Climate Sensitivity, and Climate Response A Radiative Modeling Perspective on Atmospheric Aerosols, in Aerosol Forcing of Climate (R. J. Charlson and J. Heintzenberg, Eds.), Wiley, New York, 1995. 

Previous modeling studies with GCMs have suggested that large-scale changes in Amazonia land surface cover may affect the regional climate. Sensitivity studies with these models have shown that realistic descriptions of the land surface are critical to these results. For example, the predicted climatic effects of large-scale deforestation... 

Zeng, N. 1998 "Understanding climate sensitivity to tropical deforestation in a mechanistic model." Journal of Climate 11 1969-1975. 

Henderson-Sellers a.. Climate sensitivity variations in vegetated land surface albedos. In Proc. 6th Annual Climate Diagnostic Workshop, Columbia University , 155, 144 (October 14-16, 1981). 

Walter and Heimann (2000) report application of a one-dimensional process-based climate-sensitive model simulating processes leading to CH4 emission from natural wetlands. The model treats three CH4 transport mechanisms— diffusion, plant transport, and ebullition explicitly—and is forced with daily values of temperature, water table, net primary productivity, and thaw depth at permafrost sites. Their objective was to provide a model that could be applied to simulating CH4 emissions in various regions as a function of the prevailing climate that could also be used on a global scale. The model was tested with time-series data from five different wetland sites. Soil temperature and water-table position explained seasonal variations, but the authors emphasized that the absence of a simple relationship between controlling factors and CH4 emission requires the process-based approach. 

Walter B. and Heimann M. (2000) A process-based, climate-sensitive model to derive methane emissions from natural wetlands application to five wetland sites, sensitivity to model parameters, and climate. Global Biogeochem. Cycles 14, 745-765. 

Dansgaard W., Johnsen S., Clausen H. B., Dahl-Jensen D., Gundestrup N., Hammer C. U., and Oeschger H. (1984) North Atlantic climatic oscillations revealed by deep Greenland ice cores. In Climate Processes and Climate Sensitivity (eds. J. E. Hansen and T. Takahashi). American Geophysical Union, Washington, DC, pp. 288-298. 

Yarincik K. M., Murray R. W., and Peterson L. C. (2000b) Climatically sensitive eolian and hemipelagic deposition in the Cariaco Basin, Venezuela, over the past 578,0(X) years results from Al/Ti and K/Al. Paleoceanography 15, 210-228. 

---