Has the Climate Worm Turned?

by Bill Chameides | July 17th, 2009
posted by Erica Rowell (Editor)

Permalink | 3 comments

Buoys like this one measure ocean temperature at varying depths and give forewarning of El Nino or La Nina events. With the June onset of El Nino, the warm phase of the ENSO phenomenon, global temperatures have risen. (NOAA)

Some say that global cooling — maybe even another ice age — is around the corner. A report just out from the U.S. National Climate Data Center suggests otherwise.

Since the record high of 1998, global temperatures have moderated. With the exception of 2005, which either tied 1998 as the warmest year on record or slightly exceeded it, depending upon which analysis you choose, globally averaged land and sea temperatures have remained flat or even decreased somewhat. (See my previous post for details.)

Some have pronounced global warming dead — “Get out your parkas,” they advise, ”another ice age is only years away.” But short-term temperature variations do not a global climate trend make. Why? Because year-to-year fluctuations in global temperatures can be caused by any number of factors in addition to greenhouse gases. Over the short-term these factors can mask the long-term warming effect of greenhouse gases, but eventually the longer-term warming trend wins out.

Take a look at the global temperature record over the past 100 years or so.

We see a number of periods when global temperatures exhibited a short-term cooling. People might have concluded from that short-term trend that a long-term cooling was upon us (as some folks did in the 1960s), but they would have been wrong. Clearly, the long-term trend has been one of warming.

Which brings us to the present.

The recent cool temperatures are not inconsistent with our understanding of how the climate system works. Two of the factors that can influence short-term variations in global temperatures — the solar cycle and the El Niño/Southern Oscillation (or ENSO) — have both been in phases that favor cool temperatures.

But things have changed. The Sun broke out of an extended solar minimum in activity as 2008 came to a close. And in June, El Niño, the warm phase of ENSO, appeared in the Southern Pacific.

And now we hear from the National Oceanic and Atmospheric Administration’s National Climate Data Center (NCDC) that, almost like clockwork, with the onset of El Niño, global temperatures have responded with a vengeance. In other words warm.

  • Globally averaged land and sea surface temperatures during June, 2009, were the second warmest on record for the month of June. The sea surface temperatures were the warmest of any June on record.
  • Globally averaged land and sea surface temperatures from January to June 2009 were tied with 2004 as the fifth warmest 6-month period (January-June) on record.

The NCDC goes so far as to predict that if “El Niño conditions continue to mature as projected by NOAA, … global temperatures are likely to continue to threaten previous record highs.”

As I said, a short-term record does not make a long-term climate trend, so we should not over-interpret the significance of these recent measurements. Nevertheless, what’s good for the goose is good for the gander. Those folks who have pointed to the last few years as evidence of global cooling may have some “’splainin’ to do.”

filed under: climate change, El Nino, El Nino-Southern Oscillation, ENSO, faculty, temperatures
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  1. Dan K.
    Jul 20, 2009

    Interesting blog. I found this today, which shows a potential effect of climate change on the planet. Fascinating!

  2. hoot
    Jul 17, 2009

    Some say, some say, some say? Who? Certainly not climate scientists.

    • Bill Chameides
      Jul 21, 2009

      Hoot – sometimes I decide to let my readers figure things out for themselves. It’s the frustrated mystery writer in me. My bad. You are correct: I would not characterize these “some” as climate scientists. They might disagree.

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