Monday is the first day of the American Geophysical Union Fall Meeting in San Francisco, a huge scientific conference attended by climate scientists from all over the world. I am convening a technical session called “Betting on Climate Change” along with climate betting experts Stephen Lewandowsky (University of Western Australia) and James Risbey (CSIRO Marine and Atmospheric Research), as well as environmental scientist James Byrne (University of Lethbridge). We invited scientists as well as global warming deniers to submit abstracts and attend.

In preparation for our session, we compiled a list of notable climate bets and challenges that have been made over the last decade or so. Betting has a long history in all fields of science. It is usually a friendly, low-stakes competition among colleagues. In 1975, Stephen Hawking famously wagered Kip Thorne that black holes don’t exist, and ended up having to buy him a subscription to Penthouse when one was confirmed.

Active climate betting began about 10 years ago, when climate scientists started challenging deniers to wagers, and vice-versa.

In 2005, climate scientist James Annan arranged a $10,000 bet with two Russian solar physicists who claimed the Earth would cool. The bet had pre-defined and unambiguous terms, using global temperature records spanning two decades—a long enough period to be climatologically significant. It will settle just over a year from now, when data from 2017 are published. But global temperatures have risen so rapidly that Annan might as well start spending his money now. At this point, it is like having bet on an NFL team that is up by 49 points with three minutes to go in the final quarter.

Lewandowsky, Risbey, and Boslough, "Using bets to reveal people's opinions on climate change," American Geophysical Union Fall Meeting, 12-16 December, 2016 Global temperature time series that will be used to settle the Annan bet

In 2008, retired Exxon-Mobil executive Roger Cohen issued a $5000 challenge to any taker that the Earth would be cooler in 2017 than it was in 2007. With only 11 years of temperature history, this bet would be sensitive to interannual variability such as the El Niño Southern Oscillation or volcanic eruptions, but it is still long enough for climate change to dominate. The bet was accepted by Richard Grossman, a Colorado gynecologist. Last year, Cohen conceded, but Grossman didn’t gloat. “I don’t think I’ve won. I think I lost. I think we’ve all lost,” he told the Durango Herald.

In 2009, marketing professor Scott Armstrong created a “what if” imaginary bet. In 2007, he had challenged Al Gore to a wager on the ability of an unspecified climate model to make forecasts for ten unspecified weather stations over one-year periods spanning 10 years.

According to Armstrong’s 2007 challenge to Gore:

Starting at the beginning of 2008, one-year ahead forecasts then two-year ahead forecasts, and so on up to ten-year-ahead forecasts of annual “mean temperature” will be made annually for each weather station for each of the next ten years. Forecasts must be submitted by the end of the first working day in January. Each calendar year would end on December 31.

The criteria for accuracy would be the average absolute forecast error at each weather station. Averages across stations would be made for each forecast horizon (e.g., for a six-year ahead forecast). Finally, simple unweighted averages will be made of the forecast errors across all forecast horizons. For example, the average across the two-year ahead forecast errors would receive the same weight as that across the nine-year-ahead forecast errors. This unweighted average would be used as the criterion for determining the winner.

Does this make sense? Not to me. Apparently not to the former Vice President either. Gore politely declined. This challenge does not constitute a bet, because the settlement terms are not actually specified. As any sports betting enthusiast or futures market trader can tell you, terms must be well-defined, simply stated, and unambiguous. A bet is a contract, and must therefore clearly state a precise specification of the outcome that determines the payoff (as in “the Denver Broncos will beat the Oakland Raiders in their game on January 1, 2017”). Armstrong’s challenge breaks this Golden Rule of betting.

The Annan and Cohan bets were both about global temperature averages over long enough periods of time (decades) that they have climatological significance. By contrast, Armstrong’s challenge was designed to test the ability of global climate models to make local weather forecasts for discrete locations—something they were not intended to do, and something they are never used for. Weather is not climate, and local is not global.

So the Armstrong challenge is neither about climate nor is it a bet.

Armstrong is not a physicist or climate scientist. He is an expert on marketing and has literally written the book on persuasive advertising, which lists media-specific tactics and describes strategies such as how to exploit emotion. He has apparently used these principles to market his non-climate non-bet as “The Climate Bet” to a media that craves controversy even where there is none. His website by that name began reporting on the progress of the imaginary bet with Al Gore that wasn’t defined until two years after it supposedly started (another rule of betting is that one party, if they realize they are losing, cannot change the terms after the bet starts). When bloggers report on Armstrong’s pretend bet with Gore, it is just another form of fake news.

What does a real climate bet look like? Last year, I led a prominent group of scientific skeptics, the Committee for Skeptical Inquiry, to issue a $25,000 climate challenge for 2015 to the Heartland Institute (a fossil-fuel-funded political pressure group with which Armstrong is affiliated). I personally reissued the bet at the end of the year for 2016, to all takers. And now I issue it again for 2017. This time I give Scott Armstrong the first right of refusal. I hope he is willing to risk his money on an actual climate bet.

Mark Boslough (MB) hereby presents a challenge to Scott Armstrong (SA) as to whether the Earth’s climate will set a new record high temperature in 2017. The challenge will be settled using the NASA GISS mean global land surface temperatures for the conventional climate averaging period (defined by the World Meteorological Organization as 30 years) ending on December 31, 2017. If the global average temperature does not exceed the mean temperature for an equal period ending on the same date in any previous year for which complete data exist, MB will donate $25,000 to a nonprofit to be designated by SA. Otherwise, SA will donate $25,000 to a science education nonprofit designated by MB. This offer will be void if it is not accepted by SA by Dec. 31, 2016. After that date, the bet will be open to any taker.