Climate Sensitivity

Global Temperature: What Do You Want It to Be?

New study suggests "hiatus" could last 30 more years.



Most of you will recognize the old joke referenced in the headline variously attributed to statisticians, economists and, my favorite version, accountants:

Finally, the businessman interviewed an accountant. When he asked him what two plus two was, the accountant got up from his chair, went over to the door, closed it, came back and sat down. Leaning across the desk, he said in a low voice, "How much do you want it to be?"

I am not accusing climate scientists of engaging such behavior, but for a "settled" science there's plenty to argue about. For example, just three months ago I reported a study published in Nature Climate Change that predicted that the globe would warm at rates unprecedented for at least the past 1,000 years by 2020.

Yet, earlier this week another study published in Nature based on cooling ocean temperature trends in the North Atlantic concluded that the current 18-year hiatus in the increase of average global temperature could extend for several more decades. From

A new study, by scientists from the University of Southampton and National Oceanography Centre (NOC), implies that the global climate is on the verge of broad-scale change that could last for a number of decades.

The change to the new set of climatic conditions is associated with a cooling of the Atlantic, and is likely to bring drier summers in Britain and Ireland, accelerated sea-level rise along the northeast coast of the United States, and drought in the developing countries of the Sahel region. Since this new climatic phase could be half a degree cooler, it may well offer a brief reprise from the rise of global temperatures, as well as resulting in fewer hurricanes hitting the United States.

By "brief reprise," the authors note that fluctuations in the Atlantic Multi-decadal Oscillation impacts climate on timescales of 20-30 years. Of course, other researchers blame the hiatus on the Pacific Ocean. So climate change warriors on both sides can pick (and I do not mean "cherrypick") studies to back their views of how much global average temperature is likely to increase.