Judith Curry met citaat

Met enige regelmaat wordt onderbouwing verlangd van de aanname dat variatie in weer en klimaat grotendeels dan wel geheel valt binnen de natuurlijke variatie en dat deze derhalve niet behoeft worden toegeschreven aan menselijke klimaatbeïnvloeding. Nu is al vaker gesteld dat het verwerpen van de nulhypothese de taak is van degenen die een alternatieve hypothesis willen opdringen, zoals de ‘anthropogenic global warming’. Daarmee is de bewijslast ten onrechte omgekeerd. Dat is echter niet erg, want hier volgt een overzicht van een aantal recente studies die aantonen dat natuurlijke variaties het klimaat domineren.

Hier laten we voorlopig even bij. Er is nog wel meer. Maar mocht u worden uitgedaagd om dominante natuurlijke variatie te onderbouwen boven een eventueel ‘anthropogenic global warming’ signaal, dan kunt u uitgebreid winkelen op deze pagina.

Gagné et al., 2017 demonstreren dat zee-ijs minima in de Noordelijke IJszee rond 1950 vergelijkbaar waren met de huidige waarden en dat minimum was niet veroorzaakt door ‘global warming’.

“ … This would imply that the Arctic sea ice recession observed in recent decades is well within the range of natural variability, or within the range of what has occurred without human interference or high rates of anthropogenic CO2 emissions ….”

Lachniet et al., 2017 tonen aan dat variatie in de moesson in Midden-Amerika geheel verklaard kan worden door natuurlijke cycli en gebeurtenissen.

“… This observation suggests that if anthropogenic forcing has impacted the Mesoamerican monsoon, the signal has yet to be detected above the level of natural climate variability …”

Conroy et al., 2017 ontdekken dat de variatie in de Tibetaanse neerslag de voorspelde intensiveringstrend negeert en dat het geheel valt binnen de natuurlijke variatie van de afgelopen 4100 jaar.

“20th century precipitation variability in southern Tibet falls within the range of natural variability in the last 4100 yr, and does not show a clear trend of increasing precipitation as projected by models.”

Bianchette et al., 2017 constateren dat variatie in zeeniveau aan de westelijke oceaankust van Mexico in de laatste 3200 jaar is toe te schrijven aan de El Niño/La Niña cycli en dus niet aan ‘global warming’.

“Seven periods of increased water level, varying in duration, occurred during the backbarrier period, with El Niño-Southern Oscillation (ENSO) likely the main climatic mechanism causing these periodic shifts in the paleo-precipitation levels. We suggest that the deepest water levels detected over the last ~3200 years correlate with periods of increased ENSO activity.”

Clarke et al., 2017 concluderen dat het neerslagpatroon in California wordt bepaald door de ‘El Niño Southern Oscillation’ en dus niet door ‘global warming’.

“Corresponding ~4-8 year periodicities identified from Wavelet analysis of particle size data from Pescadero Marsh in Central Coast California and rainfall data from San Francisco reflect established ENSO periodicity, as further evidenced in the Multivariate ENSO Index (MEI), and thus confirms an important ENSO control on both precipitation and barrier regime variability.”

Valdés-Pineda et al., 2017 merken op dat de neerslagcycli in Chili sterk samenhangen met de ‘Pacific Decadal Oscillation’ en de ‘Atlantic Multi-decadal Oscillation’ en dus niet met ‘global warming’.

“This study analyzes these low-frequency patterns of precipitation in Chile (>30 years), and their relationship to global Sea Surface Temperatures (SSTs), with special focus on associations with the Pacific Decadal Oscillation (PDO) and the Atlantic Multi-decadal Oscillation (AMO) indices. … We conclude that a significant multi-decadal precipitation cycle between 40 and 60 years is evident at the rain gauges located in the subtropical and extratropical regions of Chile. This low-frequency variability seems to be largely linked to PDO and AMO modulation.”

Shi et al., 2017 ontdekken dat het neerslagpatroon in Oost-China samenhangt met een ‘North South bipodale swing’ en interne variabiliteit en dus niet met ‘global warming’.

“Five of the six coupled ocean-atmosphere climate models of the Paleoclimate Modeling Intercomparison Project Phase III (PMIP3), can reproduce the south-north dipole mode of precipitation in eastern China, and its likely link with ENSO. However, there is mismatch in terms of their time development. This is consistent with an important role of the internal variability in the precipitation field changes over the past 500 years.”

He et al., 2017 constateren dat de gestrengheid van de Euro-aziatische winters sterk samenhangt met de ‘Arctic Oscillation/North Atlantic Oscillation’ en mogelijk met de 11-jarige zonnecyclus en dus niet met ‘global warming’.

“… Numerous atmospheric scientists have documented that the AO could impact significantly the climate over Europe and Far East. … It is evident that a positive winter AO causes warmer winters over East Asia through enhancing Polar westerly jet which prevents cold Arctic air from invading low latitudes.”

Muñoz et al., 2017 signaleren dat de globale temperatuur in het stabiele holoceen in de laatste elf duizend jaar varieerde tussen 2,5 graden lager en 3,5 graden hoger dan vandaag de dag. De ‘global warming’ heeft dus nog een eind te gaan voordat het uit deze grenzen loopt.

“Temperature and humidity display rapid and significant changes over the Holocene. The rapid transition from a cold (mean annual temperature (MAT) 3.5°C lower than today) and wet Younger Dryas to a warm and dry early Holocene is dated at 11,410 cal yr BP. During the Holocene, MAT [mean annual temperature] varied from ca. 2.5°C below to 3.5°C above present-day temperature.”

Park et al., 2017 observeren dat het Mexicaanse klimaat sinds het begin van de twintigste eeuw hoofdzakelijk wordt gecontroleerd door de ‘Pacific Decadal Oscillation’ en dus niet door ‘global warming’.

“According to our results, the central Mexican climate has been predominantly controlled by the combined influence of the 20-year Pacific Decadal Oscillation (PDO) and the 70-year Atlantic Multidecadal Oscillation (AMO). However, the AMO probably lost much of its influence in central Mexico in the early 20th century and the PDO has mostly driven climate change since.”

Fan en Yang, 2017 merken op dat de Noordelijke wintertemperaturen hoofdzakelijk worden bepaald door de ‘Pacific Decadal Oscillation’ wellicht versterkt door broeikaseffect van wolken en waterdamp (CO2 is niet genoemd) en dus niet door ‘global warming’.

“The wintertime Arctic temperature decreased from 1979 to 1997 and increased rapidly from 1998 to 2012, in contrast to the global mean surface air temperature [which] increased between 1979 and 1997,  followed by a hiatus … A recent study suggests a possible role of the Pacific Ocean decadal oscillation in regulating wintertime climate in the Arctic (Screen and Francis 2016). … The ‘‘greenhouse effect’’ of water vapor and clouds may amplify the effect of winds on Arctic winter climate. … In summary, the correlation analyses presented in this paper shows a natural mode of Arctic winter variability …”

Reynolds et al., 2017 onderkennen in een studie van het atlantische klimaat vele oorzaken voor fluctuaties in het klimaat maar noemen nergens ‘global warming’.

“Evidence derived from instrumental observations suggest that Atlantic variability, associated with changes in SSTs and fluctuations in the strength of the Atlantic Meridional Overturning Circulation (AMOC), is directly linked with broader scale climate variability, including Brazilian and Sahel precipitation (Folland et al., 1986 and Folland et al., 2001), Atlantic hurricanes and storm tracks (Goldenberg et al., 2001 and Emanuel, 2005), and North American and European temperatures (Sutton and Hodson, 2005, Knight et al., 2006 and Mann et al., 2009). Furthermore, evidence derived from palaeoceanographic records suggests that a reduction in the meridional heat transport through the surface components of the AMOC was in part responsible for the reductions in temperatures associated with the Medieval Climate Anomaly (MCA; 1000–1450) to Little Ice Age (LIA; 1450–1850) transition (Lund et al., 2006, Trouet et al., 2009, Trouet et al., 2012, Wanamaker et al., 2012 and Moffa-Sánchez et al., 2014).”

Hao en He, 2017 vinden een link tussen de winters in Azie en de ‘El Niño Southerly Oscillation’ en de ‘Atlantic Multidecadal Oscillation’, maar noemen geen rol voor ‘global warming’.

“… this study found that the Atlantic Multidecadal Oscillation (AMO) affects the influence of ENSO-like sea surface temperature anomalies …Warmer-than-normal winters occurred across East Asia when the ENSO-like and AMO were positively in-phase, with a significantly weakened Siberian High and anomalous anticyclones over the western North Pacific. The opposite patterns occurred under negatively in-phase conditions.”

Reischelmann et al., 2017 kunnen de neerslag in Noord Duitsland oorzakelijk verbinden aan de ‘North Atlantic Oscillation’ en niet aan ‘global warming’.

“We document that long-term patterns in temperature and precipitation are recorded in dripwater patterns of Bunker Cave and that these are linked to the North Atlantic Oscillation (NAO).”

Zaitchik, 2017 ziet dat de tropische ‘Madden-Julian Oscillation’ voor regenval een duidelijke interactie heeft met de ‘El Niño Southerly Oscillation’ en de ‘Indische Oceaan Dipool’. Er wordt geen gewag gemaakt van een relatie met ‘global warming’.

“… On longer time scales, there is evidence that MJO activity both modulates and is modulated by the El Niño Southern Oscillation and the Indian Ocean Dipole. The implications of these interactions for MJO connections to Africa require further research, as does the potential for trends in MJO behavior and impacts on Africa under global climate change.”

Wu et al., 2017 hebben uitgevogeld dat de ongebruikelijke opwarming van de Oost-Chinese kust samenhangt met een onbalans tussen meer El Niño’s en minder La Niña’s en niet door ‘global warming’.

“… We suggest that the rapid warming during winter is a result of the asymmetry in the El Niño–Southern Oscillation teleconnection, through which El Niño events induce significant warming over the ECCW at its peak, whereas La Niña events fail to do the opposite that would completely reverse the trends; in addition, there were more El Niño than La Niña events during the recent decades. All these contribute to the winter warming during 1982–1998.”

Parekh et al., 2017 signaleren dat de zeespiegelstijging in de Arabische zee wordt gemoduleerd door natuurlijke variatie van de diverse cycli en dus niet door ‘global warming’.

“The rate of sea level rise over the Arabian Sea is about 0.5–3 mm/year, whereas over the Bay of Bengal, it is 0.75–6 mm/year. Major contributors to these changes in the Indian Ocean are steric effect and short-term climate variability such as El Niño–Southern Oscillation (ENSO) and the Indian Ocean Dipole. This affirms that sea level trends over north Indian Ocean get modulated by inter-annual and decadal scale natural climate variability. The inter-annual variability is stronger than decadal variability, which in turn is stronger than the long-term sea level trend. Sea level change in the Indian Ocean is about 1.5 mm/year in the past sixty years or so, whereas the global sea level trends are a bit higher [1.7 mm/yr].”

McAneney et al., 2017 onderzochten de zeespiegelstijging maar slaagden er niet in om daarvoor een antropogene oorzaak te ontdekken.

“Global averaged sea-level rise is estimated at about 1.7 ± 0.2 mm year−1 (Rhein et al. 2013), however, this global average rise ignores any local land movements …. In short, we have been unable to detect any influence of global warming at this tropical location on either the frequency, or the height of major flooding other than that due to its influence on sea-level rise.”

Hu et al., 2017 concluderen dat de oceaan oppervlaktetemperaturen buiten de tropen hoofdzakelijk worden bepaald door toevallige processen en niet door ‘global warming’, deze worden daarbij niet genoemd.

“[I]t was a challenge to predict the evolution of this warm event, especially for its growth. That is consistent with the fact that [sea surface temperature anomalies] in extratropical oceans are largely a consequence of unpredictable atmospheric variability. [T]he marked differences in both the spatial distribution and amplitude between Figs. 4 and 3 suggest that maybe only a fraction of the observed variability in NEPO was forced by the SSTA while a large amount of the observed variability may have been a consequence of the atmospheric internal variability (noise). That is consistent with the conclusion from some recent works in examining the climate variability in mid- and high latitudes of the Northern Hemisphere, such as Baxter and Nigam (2015), Hartmann (2015), Lee et al. (2015), Seager et al. (2015), Watson et al. (2016), and Jha et al. (2016). … The remarkable amplitude differences between the observations (Fig. 3) and the simulations (Fig. 4) plus the large fluctuation of the pattern correlation (Figs. 5a, 6a), are indicative of the importance of the atmospheric internal variability (noise) in driving the observed anomalies in NEPO [northeastern Pacific Ocean]. [I]t was a challenge to predict the persistent SST anomalies in the northeastern Pacific because the SST anomaly in NEPO [northeastern Pacific Ocean] is largely controlled by unpredictable stochastic [random] atmosphere variability.”

Reid, 2017 komt tot de slotsom dat de geringe temperatuurstijging van de afgelopen 166 jaar slechts insignificante ‘red noise’ variatie is.

“The small increase in global average temperature observed over the last 166 years is the random variation of a centrally biased random walk. It is a red noise fluctuation. It is not significant, it is not a trend and it is not likely to continue.”

Stegall and Kunkel, 2017 menen dat natuurlijke variatie in het klimaat van dezelfde orde van grootte is dan een eventueel antropogeen signaal, hetgeen tot grote onzekerheden leidt.

“These results indicate that there is potential skill in use of GCMs [climate models] to provide projections of hot and cold extremes on the 30-yr timescale. However, it is important to note that natural variability is comparable to the forced signal on this timescale and thus introduces uncertainty.”

Bron (met dank aan Kenneth Richard).

Print Friendly, PDF & Email