Marcel Crok | De staat van het klimaat Lezing KNAW klimaatbrochure Seminar | Maandag 12 december | Nieuwspoort Den Haag
Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations. Hoofdconclusie IPCC 2007
The observed patterns of warming, including greater warming over land than over the ocean, and their changes over time, are only simulated by models that include anthropogenic forcing. Hoofdstuk 9, IPCC 2007
“Clearly, the changes are not linear and can also be characterized as level prior to about 1915, a warming to about 1945, leveling out or even a slight decrease until the 1970s, and a fairly linear upward trend since then (Figure 3.6 and FAQ 3.1).” IPCC 2007
“Modelling studies are also in moderately good agreement with observations during the first half of the 20th century when both anthropogenic and natural forcings are considered…” IPCC 2007, pag. 686
…although assessments of which forcings are important differ, with some studies finding that solar forcing is more important (Meehl et al., 2004) while other studies find that volcanic forcing (Broccoli et al., 2003) or internal variability (Delworth and Knutson, 2000) could be more important.”…” IPCC 2007
Modellen en observaties komen goed overeen in deze periode maar is dat om de juiste reden?
Von Neumann: With four parameters I can fit an elephant, and with five I can make him wiggle his trunk
Kiehl 2007
Aanname achter ‘het bewijs’ is dat modellen in staat zijn het klimaat goed te simuleren Maar is dat zo?
Dit is geen toename van maar een herverdeling van energie!
Modellen overschatten opwarming oceanen
Modellen overschatten opwarming atmosfeer
En spectaculair sinds 2001…
Energie oceanen blijft achter bij verwachtingen
Conclusie: Modellen vertonen nog grote gebreken. Schijnbare overeenkomst tussen 1970 en 2000 zien als bewijs dat CO 2 de hoofdoorzaak is, is op zijn zachtst gezegd voorbarig