Betting on the End of the World: 2026 Edition

In this post, I gave Over/Under wagers for the global mean surface temperature anomaly, based on data availble through the end of 2024. I provided two methods to do this, one based on accelerating warming and the other based on temperature jerk. In the current post, I am going to update these forecasts using data through the end of 2025.

Accelerating Warming

The first method, valid through 2050, assumes we have (cough) ordinary accelerating warming that will continues to accelerate smoothly through 2050. I used historical decadal growth data to create future projections. This allowed me to come up with an Over/Under estimate for each year based on a 20-year window going 10 years into the past and 10 years into the future.

The estimates for 2026 and 2027 are not reliable, as we now have additional ENSO information about those years, with a likely El Nino before the end of 2026. It is likely these years will be hotter than the estimates I give. But for 2028 through 2050, these estimates can be used to make water-cooler fake-wagers.

Here are my Over/Under numbers for the global 2-meter surface temperature anomaly through 2050:

If you look closely, you will see that these numbers are slightly higher and faster than my previous Over/Under predictions, made in January, 2025. In particular,

• The Over/Under for 2026 is 1.52°C.
• The Over/Under for breaking 2.0°C is 2039.

In general the way to read this table is that it gives you guidance for setting lines for Over/Under wagers on the 2-meter global surface temperature anomaly for future years. For example, if you want to bet on the temperature in 2028 (which will come out in early 2029), you would take either the Over or the Under on 1.58°C, with a 50/50 chance that the final result will land on either side. If you want to wager on which year will be the first to break 2.0°C, you would take the Over or the Under on 2039, with a 50/50 chance the year will be before or after that date.

Temperature Jerk

If acceleration is constant, we physically experience that as gravity — a constant force holding us against a surface. When acceleration is increasing, the physical experience is that gravity is increasing, the force is becoming greater. Picture being on a jet when the engines throttle-up — you are pushed back into your seat with an increasing pressure over a short time. That’s temperature jerk!

Here is the Wikipedia page on jerk, in case you want to read more about it.

Based on an analysis of decadal data, the global surface temperatures appears to be experiencing a short-term jerk. There are many possible causes for this. The jerk may be due to changes in shipping fuel regulations, loss of cloud-cover, decreasing albedo, loss of polar ice, the short-term impacts of the ENSO cycle, a mis-calculation of the ECS (equilibrium climate sensitivity) or something else. The cause of this jerk is for someone else to determine.

What we cannot do is say this jerk is a feature rather than a bug. So, rather than extrapolate out to 2050, as I did with some confidence for the linear trendline, it is prudent to assume that this jerk will be short-lived. Even extrapolating out to 2040 may be dubious.

Nevertheless, for those who wonder what this jerk implies for Over/Under wagers, here are the Over/Under lines assuming that the ‘jerk’ continues through 2040:

In particular, assuming ‘jerk’ continues:

• The Over/Under for 2026 is 1.59°C. (Yikes!)
• The Over/Under for breaking 2.0°C is 2034.

Similar to the linear trendline model, you could use this table to make future wagers. For example, you could bet the Over/Under 1.68°C for 2028, or you could bet total global climate f&%kery and doom by 2040. You know, that kind of thing.

Anyway, jerk could end at any time, so be cautious in making wagers using this data. You wouldn’t want to lose, would you?