Don’t Choke on the Climate Turkey

The Thanksgiving table at my house growing up was a less polite version of the British House of Commons—all the arguing, but without parliamentary procedures or a person to periodically yell “order!” It was the 1980s, so my relatives debated welfare, affirmative action, drug laws, and whether movies were too violent. (It was a simpler time.)

If we reassembled the gladiators today, no doubt climate change would roil the gathering.

It doesn’t have to be this way. You can talk climate change with crazy Uncle Larry (who gets his news from Fox and James Inhofe) and still keep the mood festive. There are a few well-cooked climate turkeys that he’s sure to whip out. I’ll provide the facts you need to carve them up. (And if you want to pass your mobile device around the table along with the mashed potatoes, even better; people have trouble arguing against charts that serve up actual, you know, evidence.)

Happy Thanksgiving to you and yours—even if yours are climate change deniers.

Crazy Uncle Larry: Global warming ended 15 years ago.

Your Response: First, commend Uncle Larry on paying attention to the news (or a small part of it, at least). In its Fifth Assessment Report released last year, the United Nations’ Intergovernmental Panel on Climate Change noted that the surface-warming trend was slower than forecast over the previous decade and a half. Remind him, however, that global warming didn’t stop—it merely fell short of forecasts. (And for humanity’s sake, that’s a good thing.) Next, show him this chart of the global average temperature by decade, starting when official records began in the 1880s.

As the chart demonstrates, decade-to-decade temperature variation is to be expected. The overall trend, however, is undeniable. Now show him this.

Worldwide, each of the hottest months on record came in the last 16 years—the very period during which climate change supposedly “stopped”—and 8 of the 12 happened in the last five years. In contrast, there hasn’t been a coldest month on record in 98 years. (To get the rest of the family involved, ask Great-Grandpa Lou what that was like.)

Conclude by explaining that climatologists have already proven why surface warming has been slower than anticipated in recent years. It’s all about the oceans.

We talk about surface temperatures because that’s where humans live, but analyzing climate change exclusively through that is like measuring an iceberg by looking at the tip. The oceans, in fact, absorb most of our excess heat. In recent years, currents have enabled the seas to absorb even more energy than anticipated, which slowed surface warming. Now take the gravy bowl and stir it. Explain to Uncle Larry that currents in a liquid affect how much energy it absorbs or releases. That’s exactly what the ocean has been doing in recent years. None of this changes the fact that the world is retaining ever more heat.

Crazy Uncle Larry: The earth’s climate is always changing. This is nothing but natural variation.

Your Response: Start by wowing him with the resourcefulness of scientists. Climatologists have devised amazing ways to estimate prehistoric temperatures. Glacial ice samples contain a record of the atmosphere, which provides a sense of the ancient climate. Temperature affects the thickness of tree rings and the bands in ocean corals. The types of plant pollen in sedimentary rock indicate the climatic conditions when the rock layer formed. We know these techniques—along with many others—are accurate, because their temperature estimates are largely consistent with each other.

Isn’t science grand, Uncle Larry? Now show him this chart, which combines all our amazing tree, ice, coral, and rock data to build a climate profile for the last 800 millennia.

Maybe this chart won’t concern skeptical Uncle Larry. The earth has, after all, been at least this warm on a handful of occasions. Our big problem, however, is not the current temperature but the rate of change. Usually when the planet exits an ice age, the temperature rises between 4 and 7 degrees Celsius over a 5,000-year period. That’s a fast rate of change, by historical standards. Now show him this chart, which shows only the last 1,500 years.

In the last century alone, the average temperature has risen 0.7 degrees Celsius. That means we’ve already experienced at least 10 percent of the expected post–ice age warming in 2 percent of the ordinary time period. That is not normal variation, as we understand it.

Crazy Uncle Larry: Global warming is a conspiracy. Climategate proved it.

Your Response: For the benefit of the rest of the folks at the table, give a little primer of so-called Climategate. In November 2009, hackers stole more than 1,000 e-mails from the Climatic Research Unit at the U.K.’s University of East Anglia, a small but important center for documenting global temperatures. Climate change deniers believed they found a handful of quotes proving that climatologists were manipulating data and suppressing evidence that would have disproved global warming. Don’t bore your family going through the e-mails one at a time; instead, explain why each quote was taken badly out of context. (If your want an example, here’s one about the misconstruing of the word trick.)

Soothe crazy Uncle Larry by blaming the media. He’ll eat that up, since he probably hates the mainstream media. Several journalists jumped at the chance for a little bit of gotcha without thinking through what the e-mails actually meant. Point out that no fewer than seven—seven!—inquiries by governments and universities on either side of the Atlantic analyzed the purloined e-mails and found no wrongdoing by any of the scientists. If you want to be particularly dramatic, read out the conclusion from the Penn State investigation of renowned climatologist Michael Mann: “Dr. Michael E. Mann did not engage in, nor did he participate in, directly or indirectly, any actions that seriously deviated from accepted practices within the academic community for proposing, conducting, or reporting research, or other scholarly activities. The decision of the Investigatory Committee was unanimous.”

Even if there were a rogue scientist who manipulated data—and I’m not aware of one—it wouldn’t change the fact that our observations and what we know about chemistry both support the reality of anthropogenic global warming.

Want to show them something visual? Here is a bio page for James M. Taylor, the skeptic at the Heartland Institute who was one of the main Climategate accusers: nothing but screeds and a few non-peer-reviewed reports. And here is the CV for Michael Mann. He has more than 150 peer-reviewed scientific articles to his name. Who are you going to believe?

Crazy Uncle Larry: The sun is getting hotter. There’s nothing we can do about that.

Your Response: Uncle Larry is right on the theory: Changes in the amount of sunlight reaching us do impact the climate. The planet wobbles slightly as we circle the sun, causing us to receive more or less solar energy, which is partially responsible for our progression into and out of ice ages. However, as we’ve already discussed, the rate at which the climate is changing does not resemble those wobble-induced transformations. Here’s the key graph to pass around.

This is a depiction of the amount of solar energy reaching us over the past 35 years. It goes up and down quite a bit, but it looks nothing like the graph of global average temperature over the same period.

There is an unmistakable upward trend, no matter how much beer Uncle Larry has enjoyed. In fact, solar irradiation actually dropped between 2005 and 2010, and the global average temperature increased over the same period, so the excess heat is not coming from the sun. On the other hand, Uncle Larry sure is getting hot now that you’ve defused all his climate-denying arguments. Offer him the last spoonful of mashed potatoes and grab another beer for him. We're all family here, after all.