The National Oceanic and Atmospheric Administration’s (NOAA) press release headline January 18 was blunt: “NOAA: 2017 was 3rd warmest year on record for the globe.” The tagline that followed made the inference obligatory for all climate alarmists: “NOAA, NASA scientists confirm Earth’s long-term warming trend continues” (emphasis added).
The New York Times trumpeted, “2017 Was One of the Hottest Years on Record,” adding, “Scientists at NASA on Thursday ranked last year as the second-warmest year since reliable record-keeping began in 1880, trailing only 2016. The National Oceanic and Atmospheric Administration, which uses a different analytical method, ranked it third, behind 2016 and 2015.”
The UK Guardian likewise proclaimed, “2017 was the hottest year on record without an El Niño, thanks to global warming.”
Similar headlines appeared around the world.
Even notorious “climate skeptics” Roy W. Spencer (a Cornwall Alliance Senior Fellow) and John R. Christy, at the University of Alabama, who archive temperature data from satellites for NASA, reported, “2017 Third Warmest in the 39-Year Satellite Record.”
So, the debate over dangerous manmade global warming is over, and the alarmists have won.
At least, that’s what the alarmists want you to believe.
But that’s what they’ve been claiming for nearly 30 years, and the debate continues. One wonders whether the facts can really bear the weight alarmists put on them.
The first thing to note is that the differences in “global average temperature” are way too small to have any significant impact on any ecosystem, let alone the welfare of human beings, who are far better than most other life forms at adapting to their environment and—much more importantly—modifying it to suit their needs.
Take a good look at this graph of the UAH satellite monthly data from 1979–2017:
The blue circles represent the departure from the 1981–2010 global lower troposphere (largest part of the atmosphere and supposedly most susceptible to CO2-driven warming) average temperature for every month from December 1979–December 2017. The red line represents the running, centered 13-month average.
Take careful note of the scale on the vertical axis—running from -0.7˚C to +0.9˚C, a total span of 1.6˚C (~2.9˚F). Over the 39 years, the greatest negative departure from the 1981–2010 average was one month in 1985, at about 0.51˚C below, while the greatest positive departure was one month in 2016, at about 0.88˚C above, for a total spread of about 1.39˚C.
Now peer at that red line a bit—the one showing the running, centered 13-month average. The biggest difference is between one month in 1983, at about 0.35˚C below average, and one month in 2016, at about +0.5˚C above average—a spread of about 0.85˚C (about 1.1˚F).
The raw data behind that graph, which Spencer provided to me, show that 1985 was the coolest year, at 0.36˚C below the 1981–2010 average, while 2016 was the warmest, at 0.511˚C above it. That’s a total spread of 0.871˚C (~1.57˚F).
Now consider this graph, by retired atmospheric physicist and MIT Professor of Meteorology Richard Lindzen, showing actual low and high temperatures (in ˚F) for Boston, MA for each day from February 9 to March 11, 2013 (blue bars), the climatological range of temperatures for that date (dark gray bars), and the record low to record high temperatures for that date (light gray bars).
As you can see, the actual temperature spread in Boston on any given day in that period of 2013 ranged from perhaps 2˚ (February 27) to about 25˚ (February 11), and an eyeball-estimated average spread would seem to be around 10˚ to 15˚. For the last day shown, March 11, 2013, the record low was 9˚ (in 1939) and the record high 67˚ (in 1990). And the record low for the whole 31-day period over the past 175 years was about -18˚, while the record high was about 72˚.
What should immediately jump out at you is that the smallest low-to-high spread for a single day, about 2˚F (1.11˚C) is about one-fourth larger, and the average low-to-high spread for a single day (~5.6˚C to ~8.3˚C) is about 6 to 10 times larger, than the total spread between the warmest and coolest years for the globe (0.871˚C).
Oh, and what about that red line in Lindzen’s graph? Its thickness depicts the total increase in global average temperature over the past 175 years—roughly equal to the smallest one-day temperature differential in Boston from February 9–March 11, 2013, about one-fifth to one-eighth of the average one-day differential, and about one twenty-fifth of the largest.
Yet Bostonians survive.
But does the fact that, according to the UAH satellite data, 16 out of the 20 warmest years in the satellite record (which, remember, goes back only to 1979) have occurred in the last 17 years? Doesn’t that show that, as NOAA put it, “Earth’s long-term warming trend continues”?
Not at all. Look again at the red line in the UAH graph. It’s clear that there has been no significant warming trend since 1998. As Lindzen put it:
The emphasis on “warmest years on record” appears to have been a response to the observation that the warming episode from about 1978 to 1998 appeared to have ceased and temperatures have remained almost constant since 1998. Of course, if 1998 was the hottest year on record, all the subsequent years will also be among the hottest years on record, since the temperature leveled off at that year and continued into the subsequent years—all of which are now as hot as the record year of 1998. None of this contradicts the fact that the warming (i.e., the increase of temperature) has ceased.
Another thing: according to Christy (personal communication through Spencer), the margin of error for the estimates of annual global average temperature for the satellite estimates is 0.1˚C.
With that in mind, the difference between any given year and the next-warmest in the satellite record exceeded the margin of error in only one case: 1998 (second-warmest in the record) was 0.107˚C warmer than 2017 (third-warmest).
The difference between 2016 (the warmest year) and 1998 was only 0.028˚C, or about three-tenths of the margin of error. In other words, we don’t know whether 2016 or 1998 was warmer. The fourth- and fifth-warmest years (2010 and 2015) are also within the margin of error from each other.
One has to go from the sixth-warmest year (2002) to the twelfth-warmest (2001) to get a gap that exceeds the margin of error again; i.e., we don’t know which of 2002, 2005, 2003, 2014, 2007, 2013, or 2001 was actually the sixth—or the twelfth—warmest year, or anything in between.
All that makes it pretty clear that global temperature has plateaued over the last twenty years. We simply don’t know whether “Earth’s long-term warming trend” stopped in 1998, will resume sometime, or will reverse and turn into a cooling trend.
This isn’t even to broach the question of what caused the warming from 1880 the present—or, rather, as shown in this graph by NOAA of global land and ocean surface temperature anomalies (which, unlike satellite data, are subject to great doubt because of spatial distribution, measuring station dropouts, homogenization methods, and other problems), the cooling from about 1880–1910, the warming from about 1910–1945, the cooling from about 1945–1975, the warming from about 1975–1998, and the plateau from about 1998–2015. (We do have a pretty good idea what caused the warming of 2015–2016 and into 2017: an extraordinarily strong El Niño, similar to the one that made 1998 so warm.)
Climate alarmists routinely attribute the warming to increasing atmospheric CO2 concentration, as suggested in this graph from Climate Central:
At first glance, the CO2/temperature anomaly fit seems pretty good. But closer examination, especially if you look back again to the UAH graph above, recognizes that CO2 was rising while temperature fell from about 1880–
2010 1910 and from about 1945–1975 and rose even faster during the plateau from about 1998–2015. That suggests that CO2 is at least not the sole driver, and possibly not the main driver, of the net warming over the 137-year period.
And as it happens, research by John Christy, Joseph D’Aleo, and James Wallace found that solar, volcanic, and ocean current variations could explain all the observed global temperature variations, leaving none to attribute to CO2.
So don’t be frightened by the headlines. Look behind them, and you’ll see something quite different.