Problems, Philosophy and Politics of Climate Science by Guido Visconti

Author:Guido Visconti
Language: eng
Format: epub
Publisher: Springer International Publishing, Cham

5.4 Selection and Use of New Data

In the last few years, especially in connection with the CLARREO effort the climate community has become more and more aware of the necessity of a global climate observing system. This is actually the name of a WMO progam (GCOS) whose goal is to provide comprehensive information on the total, involving a multidisciplinary range of physical, chemical and biological properties, and atmospheric, oceanic, hydrological, cryospheric and terrestrial processes. On GCOS site you also read GCOS is intended to meet the full range of national and international requirements for climate and climate-related observations. As a system of climate-relevant observing systems, it constitutes, in aggregate, the climate observing component of the Global Earth Observation System of Systems (GEOSS). Being an intergovernmental organization, GCOS has somewhat limited capability, so that the community is rather moving in the direction of reproducing for the climate what in the past has been done for weather forecasting with the so called Observing Systems Simulation Experiments (OSSE) and which is described for example in (Arnold and Dey 1986). The experiments to which the acronym refer are actually sensitivity studies carried out with a computer simulation and are contrasted to the real data experiments. Simulations are mainly used as evaluations of proposed remote sensing system. It was quite natural that the same concept would be extended to climate but in this case the huge database of weather observations is missing. The new system was reported as COSSE, Climate Observing Systems Simulation Experiments. One of the principal advocates of COSSE is Bruce Wielicki of NASA Langley and he indicated the main objectives of COSSE as process observations besides long-term change observation while the observing system would include satellite, surface, in-situ and field experiment observation. The emphasis in designing COSSE is mostly on practical and achievable objectives. In one of the presentation of Bruce Wielicki this approach is summarized as “investigators seem to have settled for what is measurable instead of measuring what they really like to know”.

Based on that, COSSE studies reported some quantification of the science objectives which included for example, narrow the uncertainty in climate sensitivity by a factor of 2; determine the rate of change of sea-level rise to 0.2 mm/yr; measure the tropic expansion with a precision of 15 Km/decade; determine ocean heat storage to within 0.1 for 10 year average or 0.2 for annual average; determine Greenland and Antarctic ice sheet mass loss to within 0.1 mm/yr of sea level rise equivalent (that is how much ice loss produce the indicated sea-level rise). Some of the objectives are based on the CLARREO requirements. We have illustrated some of these effects already, except for the tropic expansion. Associated with global warming, an expansion of the tropical Hadley cell is expected with the consequence that the high pressure associated to the descending branch on the cell will affect the precipitation in that region negatively.

It is interesting to establish a correspondence between OSSE and COSSE. While for OSSE, the initial conditions for models are essential for COSSE is the decadal tendency.

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