This new post on the indispensable SkepticalScience website has an indispensable graphic for anyone who is ever doing presentations on climate science. It is based on the recent Berkeley study funded by the right-wing Koch brothers that confirmed (once again) that the temperature record is indeed showing a warming trend.
One of climate skeptics favourite argument which I myself have had to deal with is that “warming has stopped since year x” or to take a snowy winter or cool summer as “proof” that warming is not happening. What these people misunderstand – or consciously ignore – is that weather is not climate. The term “climate” refers to the long-term average over at least 30 years. And obviously greenhouse gases are not the only factor influencing temperature.
There are also a number of effects which can have a large impact on short-term temperatures, such as oceanic cycles like the El Niño Southern Oscillation or the 11-year solar cycle. Sometimes these dampen global warming, and sometimes they amplify it. However, they’re called “oscillations” and “cycles” for a reason – they alternate between positive and negative states and don’t have long-term effects on the Earth’s temperature.
Right now we’re in the midst of a period where most short-term effects are acting in the cooling direction, dampening global warming. Many climate “skeptics” are trying to capitalize on this dampening, trying to argue that this time global warming has stopped, even though it didn’t stop after the global warming “pauses” in 1973 to 1980, 1980 to 1988, 1988 to 1995, 1995 to 2001, or 1998 to 2005 (Figure 1).
As Figure 1 shows, over the last 37 years one can identify overlapping short windows of time when climate “skeptics” could have argued (and often did, i.e. here and here and here) that global warming had stopped. And yet over the entire period question containing these six cooling trends, the underlying trend is one of rapid global warming (0.27°C per decade, according to the new Berkeley Earth Surface Temperature [BEST] dataset). And while the global warming trend spans many decades, the longest cooling trend over this period is 10 years, which proves that each was caused by short-term noise dampening the long-term trend.
In short, those arguing that global warming has stopped are missing the forest for the trees, focusing on short-term noise while ignoring the long-term global warming signal. Since the release of the BEST data which confirmed the global warming observed by all other global temperature measurements, climate “skeptics” have been scrambling for a way to continue denying that global warming is a problem, and focusing on the short-term noise has become their preferred go-to excuse.
And actually there are not really any temporary cooling trends. You get them only if you carefully select specific starting and end years. Almost any choice of starting and end years yields a warming trend. Saying that warming has stopped since year x is like looking at GDP figures from before and during a recession and concluding that economic growth has stopped.