Cruz has been taking some heat — pun intended — lately over his global warming comments. While the recent focus has been on his interview on “Late Night with Seth Meyers,” Cruz made similar comments in the past, as shown in the CNN interview in February 2014.
Our friends at PolitiFact and our colleagues at Energy & Environment and The Fix have debunked Cruz’s “Late Night” comments. But readers of The Fact Checker also asked us to take a look, so we did. Cruz, as the first official presidential candidate, has received a lot of attention for his remarks. And global warming likely will be a topic of interest as the election season gears up.
Is Cruz correct that there has been “zero warming” or “no recorded warming” in the last 15 to 17 years?
After initial criticism of his interview, Cruz seemed to back away a bit from his comment about “zero” and “no recorded” global warming. In a March 24, 2015, interview with Texas Tribune, Cruz changed the statement to “no significant warming”: “I’m a big believer that we should follow the science, and follow the evidence. If you look at global warming alarmists, they don’t like to look at the actual facts and the data. The satellite data demonstrate that there has been no significant warming whatsoever for 17 years.”
Cruz’s spokesman Phil Novack told The Fact Checker that Cruz is using data showing global warming trends have been flat since 1998. Novack pointed us to several sources.
First, the reference to satellite data comes from these two analyses of global temperatures. The tables show that temperature levels have not reached the peak warm level in 1998. This is usually the starting point for skeptics who argue there has been no global warming in recent years; that year was particularly warm, due to an El Niño weather pattern.
In response to criticisms that Cruz only looked at satellite data, Novack also sent us other tables using various data points. The global temperatures data set looks like this:
The bottom graph is the relevant one here. The red and blue lines are two versions of satellite data. The black line is the weather balloon data. The green line is the actual surface level data. From 1998 to 2012, the last year in that data set, the red satellite data found a decrease in temperatures, at -0.043 degrees centigrade per decade. The rest found modest growth, ranging from 0.061 degrees to 0.072 degrees centigrade per decade.
But Carl Mears, senior scientist at Remote Sensing Systems who created the data set underlying the red satellite line, said temperature trends depend on the year chosen as the starting point. If you go back to 1993, for example, then all four lines show an increase in temperatures.
“You can look at the data since 1980, and it’s pretty clear that there’s an ascending trend there. But if you look at any 15-year period, it’s a lot less clear that the trend line that you drive might actually mean something,” Mears said.
Novack also sent us this graphic, which appears to show that temperatures have gone up since the late 1990s, though not significantly after 2000.
Researchers largely have agreed that the rate of global warming has slowed in recent years. The Intergovernmental Panel on Climate Change has acknowledged that the rate of warming since the 1998 El Niño has been smaller than the rate calculated since 1951.
Global warming skeptics have latched on to this finding to assert there is no scientific evidence to show that global warming is still a concern. Yet the IPCC and other researchers have found that this trend is reflective of short-term natural variability, and that global warming is still a long-term concern.
There are many ways to measure global temperature. This study by Berkeley Earth, an independent nonprofit that studies land temperature data for climate science, looked at the various measures to understand this “pause” in global warming. Land/ocean temperatures (which is land temperature stations with sea surface data from ships and buoys) showed flat temperatures since 2001, though a long-term increase since 1970. Looking only at land temperatures, there was an increase since 2001. Ocean temperatures cooled slightly, and other measures still showed some increase in temperatures since 2001.
The range of data available, including ocean heat content, data about glaciers receding, sea level height data and others, all point to continued global warming even after 1998, Mears said.
When it comes to the climate and such realms of time as, say, the planet, a decade or two are short-term periods. Indeed, the variety of measurements of global temperatures show a general upward trend since at least 1970. Consider this graphic from Berkeley Earth, which combined 105 temperature models:
One of the main theories for this “pause” in global warming is that the oceans are in a decades-long heating and cooling variation. The pause does not prove a reduction in total energy received by the planet, according to the U.K. Met Office. Rather, some researchers say it has been affected by the ocean heat content.
Michael Mann, Penn State meteorology professor who also published a paper in the journal Science about the effect of ocean heating and cooling on recent warming levels, said 17 years is a short period for evaluating global temperature trends. Based on the historical pattern of oscillations in ocean temperatures, the Pacific Ocean trend is close to “bottoming out,” he said. “It is current as low as it’s been for the past century, so we expect that it will return to more neutral and then positive values as the cycle continues,” he said.
Novack said such explanations of current global warming trends goes directly to Cruz’s point that major policy decisions should not be made on scientific theories that are based on flawed models. They should be based on data, and the temperature plateau shows the models that previously were used projecting continued rise were incorrect, Novack said. Cruz is not denying temperatures are warmer now than they were 50 years ago, Novack said, noting that Cruz voted for an amendment in January stating climate change is real.
The Pinocchio Test
Cruz’s claims that there has been “zero warming” or “no recorded warming” since 1998 is not correct. Cruz may be able to make such statements based on particular measurements, but the range of data that are used to record global temperatures do not support that claim and show there have been slight increases in global temperatures since then. His subsequent comment that there has not been significant warming since 1998 is more on point, and researchers largely agree that the rate of global warming has slowed down in recent years.
The notion that concerns over global warming is no longer backed by science is not an accurate portrayal of the issue. Even the non-satellite data that Cruz’s spokesman provided show that temperature levels have risen in the past 15 years, just not at the level of 1998 temperatures, which was an anomaly because of the strong El Niño. It is a highly misleading statement to the average viewer or reader, because of the starting point of Cruz’s calculation. And to place the context of global temperatures in 15- or 17-year increments doesn’t mean much in a debate where a decade or two are short periods of time.
There is a reason why Cruz uses this particular year, and that reason is what makes this claim misleading. Cruz’s most recent statement, that “no significant” warming has taken place in the past 17 years, is more accurate, which makes this claim not quite worthy of Four Pinocchios.
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