CC3 -- Why I believe that a third option is needed for climate change

Nabber wrote: »

In laymans terms. Scientists provide the data. IPPC administrators cherry pick the data they want.
IPPC is not looking for the truth, just to reinforce the belief.


It's not a stretch to assume a political body and the MSM have not done this before. Not so long ago we were treated to pictures of missile silos, launch pads and chemical labs. Things that never existed

Gaoth Laidir wrote: »

Funny you should mention that, as the graph I posted above (which you didn't comment on, I see) show a perfect natural correlation with the AMO for that period (quoted in bold). Here it is again for you in case you missed it.

Our premise, first of all, is that if a truly oscillatory AMO or PDO signal exists, there must be a coherent large-scale pattern of variability in the climate system that may or may not cancel in a hemispheric mean, and possesses a narrow-band signature in the frequency domain that is statistically significant against the null hypothesis of coloured noise (including as a special case, the typical null hypothesis of simple red noise). Moreover, given the level of sophistication of the current generation of climate models, as indicated, for example, by their ability to capture the coupled ocean–atmosphere dynamics underlying the interannual oscillatory ENSO phenomenon, we should expect evidence for the signal across a suite of state-of-the-art climate model simulations. We must, however, allow for the possibility that the precise spatial patterns and timescales of the signal might vary from model to model, while recognising the limitations that still exist in some models when it comes to the representation of ocean–atmosphere processes relevant to decadal internal variability55,56,57. An additional caveat is that oscillatory interdecadal signals could be intermittent, excited episodically by stochastic forcing27,58 but otherwise quiescent over time intervals lasting a century or more. Control simulations should ideally therefore span ~150 years or longer for more confident inferences regarding the nature of such variability.
https://www.nature.com/articles/s41467-019-13823-w

The above results were compared (Fig. 3) to an AMO study by Mann et al.26 that examined the performance of competing methods of defining the AMO from observations. Mann et al.26 show that a commonly used approach for estimating the AMO—linear detrending followed by a low-pass filter—leaves behind residual low-frequency (anthropogenic and natural) forced variability that masquerades as an apparent internal AMO oscillation. The study showed that a more rigorous approach that uses the CMIP5 multimodel ensemble mean to estimate and then remove the forced signal yields an entirely different and lower-amplitude AMO series. They showed that the detrended AMO approach yields an inflated apparent AMO signal with precisely the features mentioned above: positive peaks near 1940 and 2000 and negative peak near 1980. Those features were shown to be largely an artifact of the substantial 1950s–1970s aerosol surface cooling trend masquerading as part of an AMO oscillation. Mann and Emanuel44 came to a similar conclusion.

It is worth noting that some individual models do indeed exhibit an AMO-like multidecadal signal in the control simulations. Consider for example GFDL ESM-2G, which exhibits a distinct spectral peak centred at ~40 year period that is significant at the p < 0.01 level, with a spatiotemporal pattern that is indicative of an AMO-like signal (Fig. 4). These models are nonetheless the exception to the rule, with, as noted earlier, fewer than 7 out of 43 models breaching the p = 0.1 significance level (we would expect at least 4 based on chance alone).
Based on the available observational and modelling evidence, the most plausible explanation for the multidecadal peak seen in modern climate observations is that it reflects the response to a combination of natural and anthropogenic forcing during the historical era. Moreover, there is no compelling evidence from control simulations for any robust interdecadal or multidecadal climate oscillations, with the only signals that are distinct from coloured noise found within the interannual ENSO frequency band. While this does not prove that physically-based interdecadal and multidecadal modes of variability do not exist, it does call into question whether they can be classified as an oscillation (i.e. a narrowband signal).

This finding has a number of important implications. The lack of evidence for bidecadal or multidecadal oscillations that are distinct from red noise calls into question prospects for skilful initial value decadal forecasts based on the assumption of predictable internal variability. Some recent work suggests that apparent predictability in these forecasts arises mostly or entirely from the specification of forcing (e.g. the predictable warming following large volcanic eruptions in 1982 and 1991)48. Our findings, moreover, call into question the past attribution to interdecadal and multidecadal climate cycles of a variety of climate trends including recent increases in North Atlantic sea surface temperatures and Atlantic hurricane activity44. Our findings also motivate a re-evaluation of evidence21,24 for low-frequency climate oscillations in paleoclimate proxy data. Such apparent oscillations could reflect either internal or externally forced low-frequency climate variability. Parallel analyses of CMIP Last Millennium simulations and long-term paleoclimate proxy data, which might shed further light on this matter, constitute the subject of potential future study.
https://www.nature.com/articles/s41467-019-13823-w

Oneiric 3 wrote: »

It is increasingly obvious now that 'science', at least certain branches of it, has become extremely politicised, and this 'listen to the scientists' mantra that has emerged in the realm of politics lately is really nothing more than a fundamentalist call to prayer, and to disagree, even slightly, is akin to blasphemy. Sorry, but I'll listen to whomever I see fit and to my own instincts, thanks.