Protestors hold banners during an Amnesty International protest in Parliament Square to urge the British government to do more to help Syrian refugees in London. (AP Photo/Frank Augstein)

Why did millions of British citizens vote to exit the European Union?

Were they sick and tired of being ruled by nameless, faceless, unelected, unaccountable bureaucrats in Brussels? Did they pine for the good old days of Magna Carta and the English Bill of Rights? Were they reasserting the centuries-long British tradition of government by consent of the governed?

Nope.

Global warming.

No, your eyes aren’t playing tricks on you. Global warming—manmade, dangerous global warming—drove all those Brits to the insanity of Brexit.

Says who?

Says Joe Romm, perennial climate alarmist.

In a column at ThinkProgress.org, Romm wrote:

“… a major 2015 study confirmed: ‘Human-caused climate change was a major trigger of Syria’s brutal civil war.’ This study found that global warming made Syria’s 2006 to 2010 drought two to three times more likely. ‘While we’re not saying the drought caused the war,’ the lead author explained. ‘We are saying that it certainly contributed to other factors—agricultural collapse and mass migration among them—that caused the uprising.’ “And that mass migration ultimately fueled the mass refugee crisis of the last two years, a crisis the world has utterly failed to figure out how to handle.”

And those migrants, Romm quotes NBC news political director Chuck Todd saying, “had an outsized impact on the Brexit.”

Okay, I suppose the rapid influx of Syrian migrants—many giving all the appearance of radical Islamic jihadists rather than suffering refugees—into member states of the European Union, giving them automatic access to all EU states, including the United Kingdom, making the title of British journalist Melanie Phillips’s Londonistan perfectly understandable, definitely played a role in the vote. Whether it was more important than resentment at the EU’s imposing thousands of rules on the minutest aspects of Britons’ lives without so much as a by your leave, I don’t know. I’ll not challenge that.

But I will challenge Romm’s claim—and that of the study he cites—that human-caused climate change was a major trigger of the civil war that led to the refugee crisis. The study said:

“Century-long observed trends in precipitation, temperature, and sea-level pressure, supported by climate model results [emphasis added], strongly suggest that anthropogenic forcing has increased the probability of severe and persistent droughts in this region, and made the occurrence of a 3-year drought as severe as that of 2007−2010 2 to 3 times more likely than by natural variability alone.”

It concluded its summary, “human influences on the climate system are implicated in the current Syrian conflict.” And the conflict, of course, caused the refugee crisis, which caused Brexit. QED.

Or maybe not.

A graph in the paper suggests that in the Fertile Crescent, which includes Syria, the Palmer Drought Severity Index (scaled from +3 to -3) worsened from about +0.2 to about -0.8 since 1930. That’s not enough to explain the severe 2007–2010 drought.

So what caused the drought?

Since 1930, the Fertile Crescent experienced about a 7% decline in winter rainfall and about 0.5 C rise in annual surface temperature, both mostly before 1980, leaving little during the period of allegedly manmade warming, post-1980—not enough to explain the drought.

Again, what caused the drought, and, more important, the conflict over water? It helps to understand that “drought” designates not necessarily a time of low precipitation but a time of water shortage—which can be caused by increased consumption or accelerated runoff.

Retired U.S. Navy Rear Admiral David Titley, meteorologist and professor at Pennsylvania State University, explained that after decades of poor water policy “there was no resilience left in the system” and “you just set everything up for something really bad to happen”—like ISIS.

So in addition to slight temperature rise and precipitation decline, another cause of drought was poor water policy.

But there’s another, more important cause. From 1930 to 2010, Syria’s population multiplied 11 times, and its industrial and agricultural water use multiplied even more, driving greatly increased water consumption—and hence shortages—even with no change in temperature or rainfall.

But even if higher temperature and lower rainfall drove the drought, what caused those? The Intergovernmental Panel on Climate Change concluded in its report on extreme weather that it was impossible to demonstrate a connection between global warming and frequency or severity of extreme weather events, including droughts.

Even if global warming contributed to rising temperature and declining rainfall, human activity needn’t have driven it. The computer models on which the IPCC depends simulate warming from rising atmospheric CO2 at two to three times the observed rate, and none simulated the absence of observed warming from early 1997 to late 2015. So they are tenuous reasons to believe human activity was the main driver.

At most, human activity contributed a fraction of observed warming, so only a fraction of the rise in temperature and decline in rainfall, and only a fraction of that to the drought, and a fraction of that to the conflict over water.

In short, rising population and expanding industry and agriculture were greater causes of Syrian conflict than climate change—not to mention centuries-old religio-political conflicts, which dwarf them as causes of Syria’s civil war, the rise of ISIS, and the refugee crisis. And that was but one among many reasons for Brexit.

Did a “climate refugee crisis” cause Brexit? You decide.

E. Calvin Beisner, Ph.D., is Founder and National Spokesman of The Cornwall Alliance for the Stewardship of Creation.