To begin with the last statement, the idea that global warming has stopped is a common misunderstanding, based on
confusing short term variability with the long term underlying trend.
Please explain how you accounted for
short term variability in your over effort at verification here (other than to say they don't mater when looking at trends):
The main point is that just as surface temperatures has experienced periods of short term cooling during long term global warming, similarly the ocean
shows short term variability during a long term warming trend.
This means in the Arctic region, GISS data is relatively coarse grained, as individual grid cells above 80N may include station data interpolated out to as much as 1200 km, and are likely to show the
higher short term variability which is characteristic of data from individual Polar stations.
The more they keep emphasizing that the model can't be proven wrong
by short term variability, the more they emphasise that we have to wait a long time before we know whether their models are right.
* The variability shown in the uptick from 1900 looks unusual only because an instrumental temperature record - which captures variability - is now used, whereas the long term paleo reconstruction proxies previously used, do not have this ability to
capture short term variability and thereby present an impression of a «stable» climate.
You distinguish between within day variability, within season variability and
short term variability due to e.g. large scale weather systems.
In fact, if you plug an artificial data series with a long - term trend in it, that trend gets wiped out completely, leaving
just shorter term variability behind.
Forecasts can only be tested against future temperatures over time scales sufficiently long to be largely outside the range of
shorter term variability.
Your first differencing removes the trends for the large part and so restricts you to
short term variability — much of which is related to hidden variables in your analysis (i.e. ENSO, volcanic AOD etc.), thus causality is going to be tricky.
The changes in latent in sensible and latent heat flux from ocean to atmosphere that occur during El Nino (greater flux) and La Nina (lower flux) are of course key to understanding
the short term variability in tropospheric temperatures.
Im mostly interested in
shorter term variability (daily / intraseasonal / interannual), so I don't need a deep ocean circulation.
You can easily see
the short term variability, but also the long term downward trend is quite clear.