There has recently been much huffing and puffing about an apparent slowdown in the rate of global warming, with a recent article in The Economist on the matter getting lots of attention, http://www.economist.com/news/science-and-technology/21574461-climate-may-be-heating-up-less-response-greenhouse-gas-emissions . The supposed "reduced climate sensitivity" (to CO2 concentration changes) has gotten all the usual suspects very excited, from longtime more or less respectable scientific "skeptics" (most of whom accept that there is warming but just say it is not as great as most others say) through literate innumerates such as George Will who recently asserted that there had not been a year warmer than 1998 since then (2010 was and is currently the record-holder), on through to the completely irresponsible political hacks ranting about hoaxes such as Sen. Inhofe (Lunatic-OK) and Virginia AG Ken Cuccinelli, now running for Governor of my state, who sued the University of Virginia to get ahold of the emails of climatologist Michael Mann where surely he would find the smoking gun to show the hoaxing conspiracy (!!!). In any case, there does appear to have been some slowing of the rate of increase in average global temperature in the last few years, with this spring being the coldest in the US since 1975 punctuating the point, even though "weather is not climate." So, what is up?
According to recent research by Balmaseda et al appearing in Geophysical Research Letters and some other outlets, as linked to at Real Climate, http://www.realclimate.org/index.php/archives/2013/04/the-answer-is-blowing-in-the-wind-the-warming-went-into-the-deep-end/ , indeed the answer is blowing in ocean winds that have reduced the warming effect in the atmosphere in the near term. However, while the air may not have gotten as much warmer as the main models predicted, the planet is still warming. The main recent locus of this warming has been in the ocean at depths greater than 700 meters, "the deep end." This fulfills a warning made by many that indeed the global climate is very hard to model, with lots of nonlinear dynamics and complexities and sub-parts that react and interact with all kinds of thresholds. A piece of this is that at some point down the road the warming will again move towards the surface and back into the atmosphere, so we could get a rather sharp and sudden increase down the road at some point (and also El Nino and some other such phenomena are playing roles). I have a few further observations.
One is to anyone who wants to argue that the claim that global warming may have slowed down (or possibly even reversed slightly) cannot be right because the glaciers are still retreating and the Arctic ice sheet reached an all time minimum in late 2012. I note that once the average global temperature gets above a certain point, the glaciers can retreat and the Arctic ice can continue to shrink at a constant level of temperature without any further increases happening. So, these real phenomena do not prove that the average global temperature is continuing to increase.
Also, there is the fact that there are substantial regional variations in temperature trends. This was used by some skeptics to argue against global warming some years ago when it was noted that certain parts of the globe were indeed cooling. However, in connection with the last paragraph, the part of the world that has seen the most warming all along has been the Arctic zone, something I had forecast to me decades ago by Patrick Michaels, a prominent warming skeptic (although one of those who says that warming is happening). So, it could well be that there continues to be a rising temperature in the Arctic zone, even if the global average were to be falling slightly, or at least constant.
A more general point is one that many people are unaware of, that the probability distribution of likely outcomes is almost certainly highly kurtotic, quite likely a Paretian power law, with fat tails, and very unlikely to be Gaussian normal. As it is most of the IPCC reports have plugged in assumptions of the latter, but Martin Weitzman has in several places argued that the power law outcome is much likelier, with the ubiquity of nonlinear positive feedback effects of various sorts in the system responsible for this (albedo, methane in Siberia, etc.). This means that the probability both of a seriously catastrophic increase in temperature and also of a reversal and decline in temperature are much higher if Weitzmann is right and the IPCC is wrong. By his calculation, if the distribution is Paretian power law, the probability of a seriously catastrophic 12 degrees C temperature increase could be as high as 1% ("Fat-Tailed Uncertainty in the Economics of Climate Change," Review of Environmental Economics and Policy, 2011, vol. 5, pp. 275-292).
Regarding the possibility of a temporary stallout or reversal of global temperature, it should be kept in mind that between about 1940 and 1975 global average temperature in fact declined somewhat, even as CO2 concentrations were mounting. It remains both unmodeled and unclear why that happened, and indeed in the early 1970s there were more climatologists than is now admitted who were forecasting either a new ice age or at least an unclear outcome between warming and cooling tendencies (that had flipped around to a mostly pro-warming stance by 1975). A possible candidate for cooling was higher rates of emissions of sulfur-laden aerosols from coal burning, which came under regulation in the leading industrial countries starting in the early 1970s. Indeed, the only letter I ever had published in the Washington Post was on precisely this issue back in 1977 (yes, I have been involved with climate modeling off and on for 40 years). And while the dates are propitious and telling, this matter is not really resolved even now.
In any case, it does look like global warming is still proceeding, but at somewhat deep levels in the oceans (yes, there is data supporting this, not just modeling), which at some point will surface to become more clearly manifest. The hacks and innumerates should be more careful about their spoutings, although I have no doubt that this will not slow them down or quiet them.
PS, Addendum: For anybody wanting to look at the global temperature average series by month and half year since 1880, please see http://data.giss.nasa.gov/gistemp/tabledata_v3/GLB.Ts+dSST.txt .