Humans, Comfort-Loving Animals That They Are, Are Changing Their National Park Habits With Climate Change

Visitors to Mesa Verde National Park are coming earlier in the summer than in the past, a response to climate change, according to a University of North Carolina at Chapel Hill biology professor. Kurt Repanshek photo.

Humans are creatures of comfort, so perhaps it should not be a surprise that warming temperatures associated with climate change are altering the seasons slightly when it comes to visiting national parks, according to a study.

Lauren Buckley, a biology professor at the University of North Carolina at Chapel Hill, made that discovery when she and an undergraduate assistant analyzed visitation data from the National Park System.

“I usually work on other species’ responses to climate change, like grassphoopers and butterflies, and actually we do do some work in the national parks, in Rocky Mountian National Park, for that," Professor Buckley said the other day. "But we do spend a lot of time trying to find pretty sparse data, so it occurred to us there’s all this human data out there and we were wondering whether we could see similar responses in human data, and there hadn’t been much research on it.

“So we gave it a try, and I think we found some pretty interesting results.”

According to their calculations, "peak attendance in U.S. national parks experiencing climate change has shifted (on average) four days earlier since 1979. Of the nine parks experiencing significant increases in mean spring temperatures, seven also exhibit shifts in the timing of peak attendance. Of the 18 parks without significant temperature changes, only three exhibit attendance shifts."

Granted, a four-day shift over 32 years isn't earth-shattering, but it does reflect that human visitors to the parks have comfort zones and, like animals, birds, and plants, are changing their habits in response to climate change.

“At this point it’s probably not that big of a deal in terms of park planning and such, but it is a statistically fairly strong relationship and sort of proof of concept that human behavior does actually appear to be shifting in response to climate change," Professor Buckley says. "That rate of change is fairly similar to that that we see for other organisms, so that’s about what we would have expected if the human behavior is tracing the advancement of spring weather."

In compiling the research, the professor only considered parks that have had annual visitation of more than 100,000 during the entire three-decade period she analyzed, and excluded parks with user limits, such as Mammoth Cave National Park, where there are limits on the number of people who can join any one tour.

At some southwest parks, the peak attendance date shifted more than four days. For example, at Grand Canyon National Park it shifted from July 4 to in 1979 to June 24 in 2008, and at Mesa Verde National Park it has moved from July 10 to July 1.

In redrock parks such as Bryce Canyon, Zion, and Capitol Reef national parks in Utah, increasing attendance in the fall months -- which are seeing longer periods of nice weather -- initially moved the peak attendance date later into summer, the professor found, although it later reversed course towards earlier in the summer.

While one conclusion that can be reached is that humans are looking to avoid the hottest days of summer when visiting national parks, Professor Buckley added that, "I would also think more so what we see for a lot of organisms is just sort of the earlier arrival of spring. So we did see the shift in a lot of alpine parks and my sense would be that if the snow is melting earlier, the flowers start coming out earlier, there’s more pleasant weather to come to the parks earlier."

Interestingly, the human movements in response to the warmer temperatures mirror those of species.

"The consistency of our response across parks is similar to that observed across species," the two wrote. "Of the nine parks that have experienced significant temperature increases since 1979, 78% exhibit shifts in the timing of peak attendance; 71% of species exhibited a phenological shift."

The paper was published in the International Journal of Biometeorology.


I think this is a bit of a jump. Honestly here, what other factors were considered in this study? Could changing school schedules be causing this? Could it be that people are more used to air conditioned spaces and chose to travel earlier to avoid the heat of summer. Could it be that people are flying more, causing their arrival at their destination to be ealier than before.
From the research paper:

The correlative nature of our evidence prevents attributing causation.
The blog should also be careful not to make the same mistake.

Anoymous, also from the paper:

Our analysis suggests that humans are among the organisms shifting behavior in response to climate change.
And from Professor Buckley herself: "It is a statistically fairly strong relationship and sort of proof of concept that human behavior does actually appear to be shifting in response to climate change."

Since humans don't go to the national parks naked, I really don't think that climate changes affect national park attendance. (A correlation with the advances in light weight jackets and Dri-weave type materials might be interesting).
The study really needed to take into account the biggest demographic factor in American history - the baby boom. 32 years ago, when the study data started, the baby boomers had kids in school. A typical boomer born in say, 1950, would be tied to school schedules for 18 years after his/her last child was born. If you have your last child at 35, the 1950 boomer would be free to travel in the 'off' season in 2003. A correlation with the biggest years of boomer births and the biggest years of boomers having babies would need to be done to adjust the data.
The study did say that 15 parks had no attendance date shifts. It would be interesting to know where those parks were. Were they close to cities for weekend visits, for instance.
As a mom the 'free from school schedules' explanation came to mind immediately. I can now go to the parks in October when a few years ago that was impossible.

Proof of causation as a result of weak correlation, I don't think so.

Of course, most of the above objections are more relevant to a sociology paper than to a biostatistical one.

What climate change was that? Where? Everybody get there quick before it all freezes over.

I don't find it hard to believe that people read weather forecasts, talk to friends, gain experience from multiple park visits, and otherwise make educated guesses about the weather in national parks when they plan a trip? I know I do.
I also know that my personal weather predictions for some parks in 2012 are different than they were in 2000, especially for spring break.
I haven't gone behind the publishing firewall yet, so I don't know if that article controlled for age of decision-makers and number of school-age kids. I'd be very surprised if they didn't, those are standard social science variables.
The school calendar issue is a good one and has some subtle effects depending on where you live, as Anonymous' comments suggest.
But even if you're limited to travel on school holidays, climate change affects you -- if the Smokies are getting warmer over spring break, if you live in the South you might go there instead of Everglades. It might affect your choice of California parks if you live in the Bay Area. And so on.

As a statistician, I found this paper painful to read. So much is left unaccounted for. Exactly how much is a "significant increase in temperature"? two, three or four degrees F? That may be significant when it comes to when the snow melts or flowers bloom but are we humans with our air conditioned cars and RV's, hotels and restaurants really going to drastically shift our vacation habits just because August is three degrees hotter? If the shift in visitation is at all due to climate change, it's most likely because we want to visit the parks as the snow melts to see the waterfalls at their best. Or when the flowers are brightest. That's an indirect response to climate change at best and, as someone has already suggested, is more of a sociological response than a biological one.
The most disturbing part of the paper for me was the this statement:
"Of the nine parks experiencing significant increases in mean spring temperatures, seven also exhibit shifts in he timing of peak attendance. Of the 18 parks without significant temperature changes, only 3 exhibit attendance shifts."

The fact that 3 parks without temperature changes still had similar attendance shifts indicates that there are other factors in play, at least at those three parks and maybe at the seven that had both temperature and attendance changes. Yet no attempt is made to determine what they are and factor them out. Until you do that, you can't draw any valid conclusions from your data.

In order for this study to have real meaning, it would have to look at the demographics of the visitors. Are the spring visitors empty nest baby boomers as several folks have suggested? I'm a boomer and I always hated vacationing around school schedules and putting up with the crowds and peak season pricing. Since achieving empty nester status, ALL of my vacations have been in the spring or fall. Are college students on spring break suddenly visiting our parks rather the Cancun (very unlikey in my mind but has anyone checked?) The paper stated that parks with restrictions such as Mamouth Cave tours were not included but did they consider full lodges and campgrounds. If they are fully booked in June, July and August people will be forced to go in the spring or fall or forgo the trip. The study did mention that overall attendance went up and I know, personally, that booking a room in many of the lodges must be done many months in advance for the summer months. I imagine the campgrounds are in a similar predicament. How about access improvements? Could that have an effect on visitation patterns? How about the current economic situation. Are more people vacationing in the off season to save a few bucks? The list goes on.....

Now, having done my best to shred the study, it does suggest to me that it may be worth doing additional study and try to account for the possible other factors. One really important statement made by th authors is this:
"The National Park Climate Friendly Parks Program—and the National and State Park agencies more roadly—
may need to plan for shifts in visitation in additional to wildlife responses."

Attendance patterns may not be changing strictly due to climate change, but they are changing.

I agree with the comments above. Every article of advice on visiting the Grand Canyon and many other popular parks begins with the suggestion: "Summers are impossibly busy...consider going in a shoulder season."
I hope the author of this study is being critically reviewed by peers.

When I went to Canyonlands, Arches and Gettysburg in September and October, almost all the visitors were baby boomers. It's the increasing numbers of this demographic that in my opinion accounts for the increase in off season attendance.
The study apparently took none of the changing demographics of the country or the park's visitors into account, including the increasing numbers of Europeans visiting the parks and their patterns of vacation travel.

Actually, the study seems to have taken into account many of the aspects that are being called out:

Most potential coveriates of national park visitation (e.g., population, economic trends, travel costs, and preferences) are expected to act at interannual rather than monthly timescales and thus to influence the magnitude rather than seaonality of park attendance. Our analysis focuses on assessing the timing and amplitude of the annual seasonal trend and should therefore be robust to covariates. Shifts in park visitation may be constrained by fixed holidays such as school vacations, but these constraints should not bias temporal trends. These constraints are likely particularly acute for long-distance visitors. This focus on seasonality differs from most assessments of the relationship between recreation or tourism and climate, which use regressions to predict recreation or tourism magnitude as a function of climate and other covariates. ... We link recent temperature increases to shifts in human behavior via establishing a relationship between the monthly park attendance and air temperature and documenting corresponding shifts in temperature and peak park visitation over time.

The first sentence of the quote is an assumption and the study does not seem to account for the baby boomers becoming empty nesters.
Bottom line: Does anyone plan a national park vacation because the temperature in the shoulder season is now say, 70 instead of 67?

I'm sorry Kurt but I have to disagree. The paragraph you cite is statistics-speak for "There are probably other factors involved but we're going to assume they have no affect on what we're trying to prove. " When I see phrases like "are expected to act" and "should therefore be" or "should not be" I realize the authors are making assumptions. There's nothing wrong with making an assumption or two. But I'd also like to see an authority cited that lends weight to the assumption.

I doubt it very much. All chicken littles tend to think in the same way.

rich39, I've read a lot of research over the years, and can't recall when an author made a definitive statement without some qualifier involved...

I know Kurt. I'm guilty of it myself. But if the assumptions are based on other research then go ahead and say so. Otherwise you lose credibility.

Stating that you are making an assumption doesn't make the assumption correct. Does the author cite support for the assumptions?

Talk about beating a dead horse!!LOL

This is ridiculous nonsense from a tenured academic scientist (i.e. wizard of postmodern meaninglesness). I'm glad that even the most ardent national park Kool-Aid drinkers are finding the logic in these assertions not only flawed but brazenly stupid. The most recent government report from the National Climate Data Center shows that on the last ten years North America has been getting cooler, not hotter ( but don't expect Kurt to publicize that.

Beamis, welcome back!

You neglected, perhaps, to add this tidbit from the National Climatic Data Center:

3. Is the climate warming?

Global surface temperatures have increased about 0.74°C (plus or minus 0.18°C) since the late-19th century, and the linear trend for the past 50 years of 0.13°C (plus or minus 0.03°C) per decade is nearly twice that for the past 100 years. The warming has not been globally uniform. Some areas (including parts of the southeastern U.S. and parts of the North Atlantic) have, in fact, cooled slightly over the last century. The recent warmth has been greatest over North America and Eurasia between 40 and 70°N. Lastly, seven of the eight warmest years on record have occurred since 2001 and the 10 warmest years have all occurred since 1995.

You can read the rest at this NCDC site.

Kurt - did you notice that the chart ends in the year 2000 - which totally ignores Beamis's comment about the last ten years. Also can you explain why 1961-1990 is the "base" to which the comparisons are made?

ec, I don't try to explain why the NCDC does what it does, and I'm guessing they wouldn't try to explain why the Traveler does what it does. However, I will point out that last sentence in the narrative of theirs, which seems to cover Beamis's comment.

Lastly, seven of the eight warmest years on record have occurred since
2001 and the 10 warmest years have all occurred since 1995.