05/18/2010 04:58 pm ET | Updated May 25, 2011

Letter From Earth: We're Getting Warmer

2010 is shaping up to be the warmest year on record.

The U.S. National Climatic Data Center (NCDC) has released its preliminary analysis of global temperatures for the month of April: it was a hot one.

NCDC reports that April's globally averaged surface temperature is the warmest on record. Also the warmest on record are the first four months of 2010 (January through April).

January-April 2010 Land & Ocean Surface Mean Temperature Anomalies

Temperature measurements for the first four months of 2010 show record-breaking warmth. (Source: NCDC/NOAA)

This April's temperatures beat out 1998's, the previous record-holder for the warmest April. Global temperatures during April 2010, according to NCDC, averaged 58.1 degrees Fahrenheit, which is some 1.37 degrees above the 20th century average, NCDC's baseline. In April 1998, global temperatures averaged about 1.28 degrees Fahrenheit above the baseline.

The comparison between 2010 and 1998 is interesting. NCDC ranks 1998 as the second warmest year on record, right behind 2005. Two things probably contributed to 1998's record warmth -- a strong El Niño in the South Pacific, which favors the transfer of heat from the ocean to the atmosphere, and a so-called solar maximum, in which a little extra energy in the form of solar radiation hits Earth.

Interestingly, after a long period of either La Niña (i.e., anti-El Niño) or neutral conditions, the South Pacific returned to El Niño in mid-2009 and there it has stayed at least through last month.

However, the current El Niño is not nearly as strong as the one in 1998, and the current Sun, much less active than it was in 1998 when it was just shy of its peak, has just recently started to dig out of a very deep and long solar minimum.

So, with this year's weaker El Niño and much weaker solar activity, another explanation for 2010's warmth is needed. What could that possibly be? Gee, hey, gee ... it's a gas to try to solve such a conundrum.

United States Playing It Cool, but Mark My Words, Elsewhere It's Been Hot

While most of the rest of the world is heating up, U.S. temperatures have remained fairly unremarkable, even on the cool side for the most part (see graphic below). This continues a trend seen last winter, when much of the United States shivered while most other parts of the globe saw record warmth.

January-April 2010 Contiguous U.S. Temps

(Source: NCDC/NOAA)

The discouraging part of this temperature pattern is that while conditions remain stable over the contiguous United States, temperatures in Alaska and north of the border in Canada and over Greenland -- some of the world's most climate-sensitive regions -- are way up. At the very least those warmer conditions will mean more melting permafrost and more melting of the Greenland ice sheet.

So what's at the bottom of the recent absence of a U.S. warming trend? Some would point to changes in the jet stream and the polar front. But more visionary folks might see this as validation of that New Age philosophy that if you just believe something hard enough, it will happen. Under this scenario, as long as Americans remain in denial about global warming, they will be able to stay "cool" so to speak? This kind of takes to an extreme Mark Twain's quip that "it's your human environment that makes your climate." But, with all due respect to Mr. Twain, I just can't accept that much human-induced climate change. You might say I am a skeptic. And speaking of skeptics ...

January-April 2010 Contiguous U.S. Temps

(Source: NCDC/NOAA)

If You're Skeptical -- When in Doubt, Tell the Truth

It has been my experience that there are folks out there who are skeptical of these temperature records.

A frequent complaint from such skeptics: You can't believe temperature records from surface networks, because the data are skewed by effects such as urban heat islands and station creep and questionable statistical manipulations to remove such artifacts. It's all "lies, damned lies, and statistics," I guess.

Well, I don't agree, but OK, let's throw out all the land data and just look at the data from the ocean.

Average Temperatures Over the Ocean Surface

  • During the month of April ocean temperatures were the warmest on record; and
  • Over the first four months of 2010 they were the second warmest.

The last time I checked: urban heat islands weren't really a factor over the ocean.

Satellite-basedTemperature Record from University of Alabama

Some skeptics go even further, claiming you can't believe any of those
surface measurements or the government scientists who analyze them. They
prefer mid-atmospheric temperatures analyzed by scientists from the
University of Alabama (UAH) using satellite data.

Again I don't agree, but take a gander at the temperature trends from UAH. Not quite at the 1998 level but clearly warmer than any other year on the UAH record.

The bottom line: anyway you cut it, 2010 is shaping up to be a very warm year.

UAH Globally Averaged Satllite-Based Temperature of the Lower Atmosphere (Jan 1979-Apr 2010)

(Source: UAH)

The Bigger Picture

The 21st century's opening decade, although the warmest on record, saw little rise in global temperatures from year to year. That stasis in global temperatures prompted some to declare that global warming was over, even that an ice age was coming. Using such a short temperature record to prognosticate might make good PR, but scientifically it's silly. Likewise, we shouldn't make too much of the recent jump in global temperatures. Let's wait and see. But harking back to an earlier quotation: reports of global warming's death are exaggerated.

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