Debate Heats Up on Global Warming
Some scientists say recent temperature measurements are either statistically insignificant or the result of cyclical factors that will "even out" over time.
An overall warming trend does seem clear, but interpretations of it vary. Current data on land and surface temperatures worldwide point to an overall trend toward planetary warming since the mid-20th century, according to scientists at NASA and the National Oceanic and Atmospheric Administration.
Scientists at NASA’s Goddard Institute for Space Studies (GISS) found that globally averaged temperatures last year were 0.99 degree Celsius, or 1.78 degrees Fahrenheit, above a mid-20th century baseline or average. The numbers mean that 2016 was the hottest year ever since regular temperature record-keeping began in 1880, the agency said.
The United Kingdom’s national meteorological service, Met Office, also agreed with 2016 being the hottest year, based on a separate analysis.
Skeptics who take a less sizzling view of 2016, however, tend to emphasize year-to-year changes rather than what are known as temperature anomalies – the difference between a selected year’s average global temperature and an average of temperature readings spanning many decades.
The Met Office numbers found that the 2016 average temperature was only 0.77 degree Celsius above an average for the years 1961 to 1990, but the meteorological service also reported that 2015 came in at 0.76 degree Celsius above the baseline average. So the difference between the two years is only 0.01 degree Celsius, which is far under the calculated error rate of 0.1 degree Celsius.
And there’s a similar insignificance between Met Office’s numbers for 2014 and 2013 – 0.07 degree Celsius, which again is well within the study’s margin of error.
Still, such year-to-year analyses are less important for NASA scientists than what they see as evidence of long-term trends.
“For climate studies, what matters are not the year-to-year fluctuations that are often impacted by unpredictable volcanic eruptions or ENSO (El Nino Southern Oscillations), but the long-term trends,” Reto Ruedy, a project manager at GISS, told AMI Newswire. “To measure and present those, you need a fixed base to which individual years can be compared.”
Year-to-year figures from NOAA seem to mirror the Met Office numbers for recent years. The difference between 2016 and 2015 is only 0.04 degree Celsius – again, a fraction of the margin of error of 0.1 degree Celsius. Such figures seem to add doubt to whether 2016 is truly the hottest year on record since the difference in the average global temperatures is statistically insignificant.
GISS’s analysis of global temperatures uses a baseline average of global temperatures recorded from 1951 to 1980. The NASA study found that 2016 was 0.12 degree Celsius warmer than 2015 and that 2015 was 0.13 degree Celsius warmer than 2014. These figures do surpass the 0.1 degree rate of error, but only by a relatively small amount.
And 2014 was found to be only 0.09 degree Celsius hotter than 2013 – a figure that’s, again, dwarfed by the error rate.
In addition, NASA officials concluded that the El Nino effect in 2016 boosted average global temperatures by 0.12 degree Celsius. That is the exact difference between the 2016 global average temperature and the 2015 number, as Dr. David Whitehouse of the Global Warming Policy Forum pointed out in a recent blog post.
So if you factor in El Nino, 2016 doesn’t look so piping hot, Whitehouse concluded.
But not so fast, says NASA’s Ruedy, who has studied past El Nino years. “2016 is also a record year in an adjusted time series from which the effects of volcanoes and ENSOs have been removed,” he said.
A key difference between NASA’s temperature numbers and those of NOAA and Met Office is that the latter two agencies provide surface temperatures only for areas where they have hard data, whereas GISS extrapolates its numbers to a larger domain – the Arctic in particular, according to Ruedy. Arctic temperatures in 2016 were much higher than usual, causing GISS’s numbers to differ more than usual with the other two agencies, he said.
Others see this sniping over data sets as missing the bigger picture.
“We can’t resolve whether 2016 was the hottest year with the instruments we have,” James Taylor, president of a policy institute called the Spark of Freedom Foundation, told AMI.
Humans are causing some warming on the planet, Taylor said, but he doesn’t think it’s as serious a problem as others do.
Relying more on nuclear power, natural gas and hydroelectric power is a common-sense option that those on the left and right could embrace to deal with perceived climate change issues, he said.
“If we are concerned about global warming, there are options available to reduce carbon dioxide emissions that make economic sense and would be supported by most skeptics and most conservatives,” Taylor said.
He also criticized how government scientists make adjustments to global temperature data, ostensibly to eliminate non-climatic factors such as equipment updates at weather stations.
“One takeaway from the (2016) temperature dispute is the need for a global network of surface temperature stations that don’t need to be adjusted by government officials, who often have an interest in viewing temperature one way or another,” Taylor said.
NASA scientists, however, remain cool to the skeptics’ arguments. “2016 is remarkably the third record year in a row in this series,” GISS Director Gavin Schmidt said in a prepared statement. “We don’t expect record years every year, but the ongoing long-term warming trend is clear.”