Learn how plants respond to higher atmospheric CO2 concentrations

How does rising atmospheric CO2 affect marine organisms?

Click to locate material archived on our website by topic

Recent Arctic Temperatures: Unusual or Nothing Special?
Volume 8, Number 2: 12 January 2005

A long succession of climate models has consistently suggested that CO2-induced global warming should be significantly amplified in earth's polar regions, and that the first signs of man's predicted impact on the world's weather should be manifest there. In the words of Meadows (2001), "the place to watch for global warming - the sensitive point, the canary in the coal mine - is the Arctic." So let's check it out and see just what level of warmth the Arctic has achieved over the past two decades, a period of time during which climate alarmists claim the earth attained a mean temperature that is unprecedented over the past one to two millennia.

Working with the Jones et al. and Global Historical Climatology Network (GHCN) databases of the World Temperatures section of our website, we have calculated the difference between the ten-year mean maximum temperature of each 10-degree latitude band of the Northern Hemisphere that occurred somewhere between the late 1930s and early 1950s (mid-century Tmax) and the most recent ten-year mean maximum temperature (end-century Tmax) that occurred exclusively over the most recent ten years of the available records (1994-2003). The figure below depicts our results in the form of a graph of mid-century Tmax minus end-century Tmax vs. latitude, where the plotted data points are averages of the Jones et al. and GHCN results, except for the 80-90N latitude belt, where there were insufficient data to obtain a result from the GHCN database.

As can be seen from this figure, the warmth of the last ten years (1994-2003) was indeed greater than that of the mid-20th century maximum everywhere from the equator to 70N. In the Arctic, however, from 70N to the pole, the earlier maximum was greater, and by a relatively large amount.

These instrumental temperature measurements create major problems for the world's climate alarmists. The real-world data either totally destroy their contention that "the place to watch for global warming - the sensitive point, the canary in the coal mine - is the Arctic," or, if this statement is true, they totally destroy their more basic premise, i.e., that CO2-induced global warming is occurring, for they reveal a significant cooling of the Arctic between 1940 and 1998 (the mean midpoints of the ten-year periods used to define the mid-century and end-century mean maximum temperatures of the Arctic), a stretch of time that witnessed the greatest increase in atmospheric CO2 concentration of the entire industrial era: a rise of 60 ppm, which constitutes close to 70% of the entire increase in atmospheric CO2 experienced from the inception of the Industrial Revolution through 1998.

Consequently, in response to the question posed in the title of our Editorial - Recent Arctic Temperatures: Unusual or Nothing Special? - we are forced to conclude they have indeed been nothing special. In addition, it should be obvious to even the most casual of observers that this finding argues strongly against the existence of a CO2-induced greenhouse effect that is anywhere near the magnitude of what is claimed by the world's climate alarmists, as that hypothesized phenomenon appears to be totally overpowered by natural decadal variations of the type that produced the warmer temperatures of the late 1930s to early 1950s and the cooler temperatures of the 1960s and 70s, from which the Arctic has yet to fully recover.

Sherwood, Keith and Craig Idso

Meadows, D.H. 2001. Polar bears and 3-year-olds on thin ice. AlterNet.org. Posted 6 February 2001.