While on the campaign trail in New Hampshire, Republican presidential candidate Ted Cruz gave a speech to local residents that contained inaccurate and misleading claims about climate science and its terminology:

Cruz claimed “none of the alarmists say ‘global warming’ anymore — now it’s ‘climate change.’ ” That’s inaccurate. Scientists still use both terms, but tend to use “climate change” more often because, in addition to warming, it refers to phenomena such as sea-level rise and changes in precipitation patterns.

Cruz also said “climate change is the perfect pseudoscientific theory because it can never, ever, ever be disproven.” This is false. It could be, but the chances are slim. Climate change rests on the veracity of the greenhouse effect, a theory which has been repeatedly verified since it was first proposed in 1824.

Cruz says “if it gets hotter or colder, wetter or drier — the climate has always changed since the beginning of time.” That’s misleading. The climate fluctuates due to natural causes, but it’s unlikely that these phenomena alone account for some more recent changes. The models do not predict uniform warming or cooling. Some places may be cooler, but overall warming is expected.

Cruz made his remarks in Conway, New Hampshire, on Jan. 19, the day before the National Oceanic and Atmospheric Administration and NASA released findings that strongly suggest 2015 was the hottest year on record by a long shot.

Cruz, Jan. 19: Has anyone noticed in the past couple of years, the theory has magically changed a third time? Now none of the alarmists say ‘global warming’ anymore — now it’s ‘climate change.’ … If you are a big government politician, if you want more power, climate change is the perfect pseudoscientific theory. How many of y’all remember high school biology? Remember the scientific method? You start with a hypothesis and then you use evidence to try to disprove the hypothesis, to test it to see if it’s true. Climate change is the perfect pseudoscientific theory because it can never, ever, ever be disproven. If it gets hotter or colder, wetter or drier — the climate has always changed since the beginning of time. It will continue to change till the end of time.

This isn’t the first time during the presidential campaign that Cruz has called climate change “pseudoscientific.”

On Dec. 8 2015, Cruz, in an NPR interview, said: “Climate change is the perfect pseudoscientific theory for a big government politician who wants more power. Why? Because it is a theory that can never be disproven.”

Climate Change vs. Global Warming

First of all, since “alarmists” include scientists, Cruz’s claim that “none of the alarmists say ‘global warming’ anymore — now it’s ‘climate change’ ” is inaccurate. Scientists still use both terms. “Climate change” has also been around in the scientific literature longer than “global warming,” though it didn’t always refer to both anthropogenic and natural climate change as it does today.

According to NASA and NOAA, “climate change,” “global warming” and the related term “greenhouse effect” can refer to both natural and human influences on the planet. Scientists at these organizations and others, such as the Intergovernmental Panel on Climate Change, tend to tack on adjectives like anthropogenic or enhanced when referring specifically to human-influenced atmospheric and climatic changes. But for the sake of simplicity, instances of these three terms will refer to human-related changes here, unless stated otherwise.

Michael Mann, a climatologist and geophysicist at Pennsylvania State University, also told us by phone that, to scientists, “climate change,” “global warming” and the “greenhouse effect,” refer to different, albeit closely-related, phenomena. As a result, scientists use all of these terms (and many more) to explain the phenomena they observe.

However, Mann did say (as does NASA — see entry for “climate change”) that scientists prefer the term “climate change” because it encompasses global warming as well as other phenomena, like sea-level rise and changes in precipitation patterns.

There is general consensus in the scientific community regarding the definitions of these three terms (compare NASA and NOAA‘s definitions, for example). The “greenhouse effect” is the process by which gases including carbon dioxide and methane act as a blanket over the planet, trapping the sun’s radiation, or heat. “Global warming” refers to an increase in the Earth’s average surface temperature because of rising greenhouse gas levels in the atmosphere from the burning of fossil fuels. Global warming then leads to other changes in the global climate, including those related to precipitation, the seasons and sea levels — a collection of phenomena, which, among others, fall under the title “climate change.”

In a nutshell, says Mann, the greenhouse effect facilitates global warming, which leads to climate change.

In a phone interview, Erik Conway, a historian at NASA since 1998, told us that the first usage of the term “global warming” in the scientific literature most likely occurred in 1975, when the journal Science published the geochemist Wallace Broecker’s paper “Climatic Change: Are We on the Brink of a Pronounced Global Warming?”

“Climate change,” on the other hand, probably dates back to the 19th century, said Conway, but for decades scientists used it to refer to natural changes in the climate, like ice ages. For this reason, pinpointing when the exact term was first used in an anthropogenic sense is tricky, he said.

However, the physicist Gilbert N. Plass did use the term “climatic change” — similar to “climate change” — in an anthropogenic sense in his 1956 paper titled “The Carbon Dioxide Theory of Climatic Change.” Plass’ paper discusses how the “extra CO 2 released into the atmosphere by industrial processes and other human activities may have caused the temperature rise during the present century.”

For most of the 1970s, scientific publications regularly used the phrase “inadvertent climate modification” to describe human impact on the climate, Conway wrote on NASA’s website in 2008. At the time, scientists weren’t sure how increased greenhouse gases in the atmosphere would affect the global climate, so they used this more neutral term to describe their findings.

But in the 1979 document often called the Charney Report for its chairman, Jule Charney, the phrase “inadvertent climate modification” was dropped for the terms “global warming” and “climate change.” “When referring to surface temperature change, Charney used ‘global warming.’ When discussing the many other changes that would be induced by increasing carbon dioxide, Charney used ‘climate change,’ ” much like scientists use the terms today, explains Conway.

Conway also writes that the usage of “global warming” “exploded” in the popular media in June 1988 when James E. Hansen, a prominent NASA scientist, used the term during testimony to Congress about the subject. Hansen said, for example: “Global warming has reached a level such that we can ascribe with a high degree of confidence a cause and effect relationship between the greenhouse effect and the observed warming.”

In emails to us, both Anthony Leiserowitz, director of the Yale Program on Climate Change Communication, and Harvard historian Naomi Oreskes said Republican strategist Frank Luntz popularized the phrase “climate change” — at least among some politicians.

Prior to the 2002 midterm elections, Luntz wrote a then-confidential memo to the Bush administration urging it to avoid the “frightening” phrase “global warming,” and instead use the term “climate change.” In the memo Luntz wrote, “while global warming has catastrophic communications attached to it, climate change suggests a more controllable and less emotional challenge.”

Luntz’s advice did appear to have an effect on which terms the Bush administration used. Back in 2003 both the New York Times and the Guardian reported that while “global warming” appeared regularly in President Bush’s speeches on the environment in 2001, the term nearly disappeared during 2002 to be replaced by “climate change.”

Overall, Cruz’s claim that “none of the alarmists say ‘global warming’ anymore — now it’s ‘climate change’ “ is inaccurate. Scientists still use both terms, but tend to use “climate change” more often because it refers to more phenomena. And it was Republican strategist Luntz who encouraged members of his party to use the term “climate change” over “global warming.”

Can Climate Science ‘Never, Ever’ Be Disproved?

As for Cruz’s claim that “climate change is the perfect pseudoscientific theory because it can never, ever, ever be disproven,” Mann told us that “absolutely” climate change could be disproved. “That’s true in any area of science,” he said. “It’s true in physics. It’s true in biology. It’s true in climate change.” As he explained above, the theory of climate change rests upon the accuracy of the theory of global warming, which, in turn, depends on the theory of the greenhouse effect.

One way to disprove climate change might be to disprove the greenhouse effect, Mann told us. This would entail finding strong evidence that suggests gases like carbon dioxide don’t trap the sun’s heat. But the likelihood of this occurring is slim to none, as the theory has been verified time and again since it was first proposed by the physicist Joseph Fourier in 1824.

In fact, Mann says, “things as basic as the design of heat-seeking missiles rely upon an understanding of the greenhouse effect.”

Another way to disprove climate change would be to challenge the theory of global warming, adds Mann. Since global warming can be thought of as an enhanced greenhouse effect (see NASA’s definition of the term here), this method of falsification would be related to — though different from — disproving the greenhouse effect.

In other words, instead of finding strong evidence that suggests carbon dioxide, for example, doesn’t trap the sun’s heat point blank, scientists would have to show that higher average global temperatures aren’t the result of increased levels of greenhouse gases. But scientists have found no evidence to support this claim.

Alternatively, if over the past few decades the planet hadn’t warmed on average as much as scientists thought it would, this would also have given them cause to reevaluate their current understanding of both global warming and climate change. For example, Mann says that if James Hansen’s predictions back in 1988 had been wrong, scientists would have reevaluated their theories.

But Hansen’s predictions, which concerned how much the planet would warm on average based on three scenarios for fossil fuel emissions (and about which he spoke to Congress in 1988), were “more or less spot on,” Mann told us.

As we have written before, the U.N.’s Intergovernmental Panel on Climate Change’s fifth assessment report that was released in 2013 concluded that it is “extremely likely” that more than half of the observed temperature increase since 1950 is due to human activities.

Cruz is off the mark when he says climate change “can never, ever, ever be disproven.” It could be, but it becomes less and less likely each time scientists verify the greenhouse effect, global warming and global warming’s effect on climatic patterns around the planet.

Is Climate Change Human-Caused? Is it a Fallacy?



Cruz’s claim that “if it gets hotter or colder, wetter or drier — the climate has always changed since the beginning of time” can be examined in two ways: Can natural phenomena alone explain changes to today’s climate, like an increase in extreme weather events? And does the theory of climate change entail a fallacy? A “fallacy” is a general term that refers to an error in reasoning. In this case, the fallacy is unfalsifiability.

Regardless, Cruz’s claim is misleading at best and inaccurate at worst.

Can natural phenomena explain all of today’s climatic changes? Scientists have found strong evidence that suggests anthropogenic causes, like the burning of fossil fuels, contribute to changes in our climate in addition to natural causes.

In 2014 the U.S. Global Change Research Program put out its third National Climate Assessment, which stated:

U.S. Global Change Research Program, May 2014: Long-term, independent records from weather stations, satellites, ocean buoys, tide gauges, and many other data sources all confirm that our nation [the United States], like the rest of the world, is warming. Precipitation patterns are changing, sea level is rising, the oceans are becoming more acidic, and the frequency and intensity of some extreme weather events are increasing. Many lines of independent evidence demonstrate that the rapid warming of the past half-century is due primarily to human activities.

The 2014 National Climate Assessment was produced by “a team of more than 300 experts guided by a 60-member Federal Advisory Committee” and reviewed by “the public and experts, including federal agencies and a panel of the National Academy of Sciences.”

The IPCC’s fifth assessment report also found evidence to support the existence of human-induced climate change. For example, the U.N. panel writes (see page 2): “Human influence on the climate system is clear, and recent anthropogenic emissions of greenhouse gases are the highest in history. Recent climate changes have had widespread impacts on human and natural systems.”

NASA’s website also cites collective and individual statements from a number of American and international scientific societies, academies and government agencies that all agree global warming and climate change are due, in part, to human actions. For example, in 2006 the Board of the American Association for the Advancement of Science, publisher of the journal Science, said: “The scientific evidence is clear: global climate change caused by human activities is occurring now, and it is a growing threat to society.”

In short, when Cruz said “if it gets hotter or colder, wetter or drier — the climate has always changed since the beginning of time,” he implied climate change is only due to natural causes. This is inaccurate. Scientists have found plenty of evidence to suggest that humans have been contributing to climate change since the Industrial Revolution.

Lastly, Cruz implies that the theory of climate change entails a fallacy when he juxtaposes the line “if it gets hotter or colder, wetter or drier” with his claim that the theory can never be proved wrong. This is misleading. Scientists have found evidence that suggests climate change includes an increase in both wetter and drier, hotter and colder conditions — including more extreme weather events — and this evidence doesn’t entail a fallacy.

Along with large-scale reports like those of the IPCC, independent studies have also found that human-induced global warming is the likely cause of changes to the global climate, such as an increase in extreme weather events. In April 2015, for example, Nature Climate Change published a paper that found that extreme heat waves and heavy rainfall may already be occurring with increasing frequency due to anthropogenic causes.

Back in April 2015 we also wrote about the relationship between global warming and extreme weather when we fact-checked claims made by Lamar Smith, a Republican from Texas and chairman of the House Committee on Science, Space, and Technology.

To be clear, scientists do not claim that climate change is at the root of every recent drought, flood, heatwave and snowstorm. In December of last year, the American Meteorological Society published a collection of 32 studies that examined 28 extreme weather events in 2014. Collectively, the researchers found that whether climate change plays a role in extreme weather depends on the region and meteorological phenomenon of interest.

“When you start talking about individual regions, forecasts become much more uncertain,” Mann told us. But “when you talk about some of these more general principles, those are pretty rock solid.”

By “general principles” Mann is referring to the many different mechanisms underlying fluctuations in the planet’s climate. To explain why climate change doesn’t entail a fallacy, we will outline how one of those mechanisms relates to extreme weather, namely floods and droughts.

One way to understand the relationship between global warming and climate change, relies on how H 2 O reacts to heat. When H 2 O in the form of water is heated it evaporates and turns into water vapor. When H 2 O in the form of ice is heated, it melts and turns into water. So in areas where there are mountains with snow pack, global warming may lead to increased flooding, Mann told us. Whereas in areas where there are lakes or moisture in the soil, global warming may lead to more droughts. Again, this explanation is simplified, and many more mechanisms contribute to increased flooding and prolonged droughts, among other extreme weather events.

There are mechanisms to explain how on a global level climate change can entail both droughts and floods simultaneously. As a result, Cruz was misleading when he juxtaposed the line “if it gets hotter or colder, wetter or drier” next to his claim that the theory can never be proved wrong.

To sum up, Cruz’s speech in Conway on Jan. 19 included both inaccurate and misleading claims.

First, he said “none of the alarmists say ‘global warming’ anymore — now it’s ‘climate change.’ ” Scientists still use both terms. Next, he claimed climate change “can never, ever, ever be disproven.” This is false. It could be, but the chances are slim. Third, he misled when he said “if it gets hotter or colder, wetter or drier — the climate has always changed since the beginning of time.” Natural causes influence the climate, but it’s unlikely these phenomena alone account for some more recent changes. And given the global climate’s spatial and temporal complexity, scientists expect that some areas of the planet will change differently from others. So there’s nothing fallacious about the theory of climate change entailing more weather extremes, for example.

Editor’s Note: SciCheck is made possible by a grant from the Stanton Foundation.