Part II:
Many models coded before knowledge of the Pacific Decadal Oscillation become mainstream failed post-1998 because they did not account for the slowdown in warming. This has been discussed quite a bit in the scientific literature and the reasoning behind it has as well.
This is the first paper I have listed in my database on the subject. It states, basically, that there are perturbations in the long term trend but that doesn't necessarily mean that the long term trend has changed.
Is the climate warming or cooling? (Easterling et al, 2009) -
http://onlinelibrary.wiley.com/doi/1...9GL037810/full
And this paper which points to the ENSO and brings up the AMO, which they also states has not been a source of cooling over the past couple decades. (More on this later)
Overestimated global warming over the past 20 years (Fyfe et al, 2013) -
http://www.stat.washington.edu/peter...m/fyfeetal.pdf
Here is a paper stating that the models failed to capture the slowdown in warming beginning in the early 2000's but those models that capture the IPO/PDO cooling were able to adequately model trends.
Climate model simulations of the observed early-2000s hiatus of global warming (Meehl et al, 2014) -
http://fulltext.calis.edu.cn/nature/...limate2357.pdf
I'll list a few more papers on this subject before delving into the causes.
Well-estimated global surface warming in climate projections selected for ENSO phase (Risbey et al, 2014) -
http://www.marine.csiro.au/~ris009/p..._well_2014.pdf
Robust warming projections despite the recent hiatus (England et al, 2015) -
http://web.science.unsw.edu.au/~matt...cluding-SI.pdf
Quantifying the likelihood of a continued hiatus in global warming (Roberts et al, 2015) -https://www.researchgate.net/profile/Christopher_Roberts5/publication/273093564_Quantifying_the_likelihood_of_a_continued_hiatus_in_global_warming/links/54f6e39e0cf27d8ed71fa2f6.pdf
The causes of this slowdown has been looked into quite a bit. The Pacific Decadal Oscillation is the leading contender. The AMO runs counter to the PDO and the ENSO is a portion of the PDO. I will list all of their indexes here.
PDO Index:
http://research.jisao.washington.edu/pdo/
ENSO Index:
https://www.esrl.noaa.gov/psd/enso/mei/
AMO Index:
http://www.cgd.ucar.edu/cas/catalog/...AMO_fig123.gif
You can pretty much see that ENSO follows the phase of the PDO, of which ENSO is a part of, and the phase change of the PDO is approximately the same time as the phase change of the AMO only in opposite directions. This has lead to a whole lot of discussion and studies on the topic of how this relates to the 'hiatus' period and the constituents that make up the various oscillations and how they transport heat.
Recent global-warming hiatus tied to equatorial Pacific surface cooling (Kosaka et al, 2013) -
http://climate.fas.harvard.edu/files...ature_2013.pdf
Strengthening of ocean heat uptake efficiency associated with the recent climate hiatus (Watanabe et al, 2013) -
http://onlinelibrary.wiley.com/doi/1...grl.50541/full
Surface warming hiatus caused by increased heat uptake across multiple ocean basins (Drijfhout et al, 2014) -
http://www.ncaor.gov.in/files/Scienc...n-04-12-14.pdf
Now there have been studies in various aspects that make up the PDO. I'll list some here.
Recent intensification of wind-driven circulation in the Pacific and the ongoing warming hiatus (England et al, 2014) -
http://www.geo.cornell.edu/ocean/eas...irculation.pdf
Recent Walker circulation strengthening and Pacific cooling amplified by Atlantic warming (McGregor et al, 2014) -
http://citeseerx.ist.psu.edu/viewdoc...=rep1&type=pdf
And the following papers indicate how that heat is being transported.
Pacific origin of the abrupt increase in Indian Ocean heat content during the warming hiatus (Lee et al, 2015) -
http://sunburn.aoml.noaa.gov/phod/Lee_ngeo15.pdf
Role of Indian Ocean SST variability on the recent global warming hiatus (Arora et al, 2016) -
http://www.sciencedirect.com/science...21818115300412 (Abstract only)
I'll continue later tonight perhaps as life calls now.