Wissenschaftliche Basis des Pariser Klimavertrages auf dem Prüfstand

Vor kurzem erschien im International Journal of Climate Change Strategies and Management ein Paper von Antero Ollila (Ollila 2018), in dem die wissenschaftliche Basis des Pariser Klimavertrags diskutiert wird (kostenfreies pdf hier):

Challenging the scientific basis of the Paris climate agreement

Purpose: The purpose of this paper is to analyze the scientific basis of the Paris climate agreement.

Design/methodology/approach: The analyses are based on the IPCC’s own reports, the observed temperatures versus the IPCC model-calculated temperatures and the warming effects of greenhouse gases based on the critical studies of climate sensitivity (CS).

Findings: The future emission and temperature trends are calculated according to a baseline scenario by the IPCC, which is the worst-case scenario RCP8.5. The selection of RCP8.5 can be criticized because the present CO2 growth rate 2.2 ppmy−1 should be 2.8 times greater, meaning a CO2 increase from 402 to 936 ppm. The emission target scenario of COP21 is 40 GtCO2 equivalent, and the results of this study confirm that the temperature increase stays below 2°C by 2100 per the IPCC calculations. The IPCC-calculated temperature for 2016 is 1.27°C, 49 per cent higher than the observed average of 0.85°C in 2000.

Originality/value: Two explanations have been identified for this significant difference in the IPCC’s calculations: The model is too sensitive for CO2 increase, and the positive water feedback does not exist. The CS of 0.6°C found in some critical research studies means that the temperature increase would stay below the 2°C target, even though the emissions would follow the baseline scenario. This is highly unlikely because the estimated conventional oil and gas reserves would be exhausted around the 2060s if the present consumption rate continues.

Auf WUWT erläuterte der Autor sein Paper in einem gesonderten Beitrag. Bereits einige Monate zuvor hatten Sebastian Lüning und Fritz Vahrenholt die Basisannahmen des Pariser Klimavertrages in einem eigenen Paper in Frontiers in Earth Science hinterfragt:

Paleoclimatological Context and Reference Level of the 2°C and 1.5°C Paris Agreement Long-Term Temperature Limits
The Paris Agreement adopted in December 2015 during the COP21 conference stipulates that the increase in the global average temperature is to be kept well below 2°C above “pre-industrial levels” and that efforts are pursued to limit the temperature increase to 1.5°C above “pre-industrial levels.” In order to further increase public acceptance of these limits it is important to transparently place the target levels and their baselines in a paleoclimatic context of the past 150,000 years (Last Interglacial, LIG) and in particular of the last 10,000 years (Holocene; Present Interglacial, PIG). Intense paleoclimatological research of the past decade has firmed up that pre-industrial temperatures have been highly variable which needs to be reflected in the pre-industrial climate baseline definitions. The currently used reference level 1850–1900 represents the end of the Little Ice Age (LIA). The LIA represents the coldest phase of the last 10,000 years when mean temperatures deviated strongly negatively from the Holocene average and which therefore are hard to justify as a representative pre-industrial baseline. The temperature level reached during the interval 1940–1970 may serve as a better reference level as it appears to roughly correspond to the average pre-industrial temperature of the past two millennia. Placing the climate limits in an enlarged paleoclimatic context will help to demonstrate that the chosen climate targets are valid and represent dangerous extremes of the known natural range of Holocene temperature variability.

Das pdf der Arbeit von Lüning & Vahrenholt ist kostenfrei hier herunterladbar.