This week’s “Daily Journal” guest columnist is Dr. Roy Cordato, John Locke Foundation Vice President for Research and Resident Scholar.
RALEIGH — For years all we heard from the news media were statements like, “over the last (fill in the number) of years temperatures have risen by (fill in the number) degrees.” But for the past few years, the reporting has changed. Now when new temperature data are released, from NASA or some other government agency, what we hear is that the most recent year was the second, fourth, eighth, or whatever warmest on record.
The change in emphasis, from reporting temperature trends over time to reporting the position of a particular year relative to others, is a misleading statistical sleight of hand that has been invoked by global warming alarmists. The reason is that temperature trends no longer support their claims. The planet has not been warming for at least the last 10 years, and according to some data records, the last 15 years.
Here’s what’s going on. Temperature records have been kept for about the last 110 years. Since the late 1800s, when these records began, there has been a reasonably steady climb in temperatures with two big spurts: from the early part of the 20th century to the 1940s, followed by a 30-year decline, and then from the mid-1970s to the late 1990s. On net, over the roughly 100 years, global average temperature increased.
This makes complete sense. During that period, the planet had been coming out of what was called the little ice age, which ended in the mid-1800s. Since the late 1990s, the last 15 or so years, the trend has plateaued. On average there has been no warming or cooling detected. Along this plateau, global average temperatures continue to go up and down year to year, just as they did when they were climbing during the years leading up to the plateau.
Along the plateau of the last 15 years, the average temperature is generally higher than for the years leading up to that plateau. The same is true for the year-to-year variations, i.e., peaks and troughs, in temperature that are occurring. In other words, it only makes sense, and one would expect, that the average global temperature in any year along the plateau would be higher than the vast majority of the 100 years or so leading up to the plateau.
This is why pointing to this year or last year or the year before and saying that it is the fifth, fourth, second, or even the warmest year on record is completely nonresponsive to the question: Is global warming occurring? It is in fact an irrelevant response meant to take the average person’s eye off the ball. That ball being average temperature trends over time, the only data that matters as evidence for global warming.
To put this in less abstract terms, imagine making the drive from Winston-Salem northwest on U.S. 421 into the mountains. As you drive the route, the elevation continues to climb as you head toward Boone. Right before you get to Boone, you begin to head south along the Blue Ridge Parkway. As you travel along the parkway, you are clearly in the mountains. As you drive along the mountains you go up long hills and down long hills. In other words, all along the parkway and through the mountain range the elevation goes up and down, but one thing is going to be true: The elevation along the Blue Ridge Parkway is higher than at the vast majority of the points along route 421 as you were making the climb up into the mountains.
Most of us realize that it would say nothing about the average elevation along the Blue Ridge Parkway or the trend in the average elevation along the Parkway to continuously point that out. The question of whether you are coming down out of the mountains or climbing further into them could never be answered using this method. Yet this is exactly what is going on when people compare the average temperature in a recent year to the total temperature record for the past 110 years, and my guess is that the alarmists who constantly do this know what they are doing. I do not think they are stupid.
As was revealed in the “Climategate” emails, the relevant climate data is well-known in the global warming alarmist community. Kevin Trenbirth of the National Center for Scientific Research and Intergovernmental Panel on Climate Change acknowledged in a particularly candid moment, “The fact is that we can’t account for the lack of warming since 1998, and it is a travesty that we can’t.” When those who claim to be concerned about the “state of the planet” ignore this fact, it is time to stop questioning their science or statistics and start questioning their motives.