Wagers of Doom for 2025: Pay Up!

In this post, published on December 23, 2024, I gave twleve “Wagers of Doom” for 2025. I’ve listed them below, with the reconcilliation of each wager in red. Let’s see how they did, and if you made any wagers, it’s time to pay up (or fake-pay up)!

Here are the 2025 Wagers of Doom:

• The OVER/UNDER for the Arctic sea-ice minimum (usually in September) is set at 3,100,000 square kilometers. The previous record low was 3,177,000 square kilometers, set on September 16, 2012. The UNDER would represent a new low for the Arctic.

The minimum for Arctic sea-ice extent in 2025 was 4,550,822 square kilometers, set on September 8, 2025.  The OVER bet won.

• The OVER/UNDER for the Global sea-ice minimum (usually in February) is set at 15,400,000 square kilometers.  The previous record low was 15,503,000 square kilometers, set on February 11, 2023. The UNDER would represent a new low for Global sea ice extent.

The minimum for Global sea-ice extent was 15,225,380, set on February 9, 2025. This represents a new record low for Global sea-ice extent. The UNDER bet won.

• The OVER/UNDER for peak monthly CO₂, as measured at Mauna Loa, is 430.70 ppm. The peak usually occurs in April or May, and is available in the following month’s data release from NOAA. Who wants to purchase 430.org and start a non-profit?

The peak CO2 in 2025, as measured at Mauna Loa, was 430.51 ppm, set in May, 2025. The UNDER bet won.

• The OVER/UNDER for CO₂ emissions from fossil fuels is 37.5 billion tonnes. The OVER would be yet another new record high for anthropogenic CO₂ emissions, beating the previous record of 37.4 billion tonnes in 2024. In other words — we’re nearing peak emissions, but we aren’t quite ther eyet.

As of this writing, global fossil fuel CO2 emissions are projected to hit a record high in 2025, reaching approximately 38.1 billion tonnes, an increase of about 1.1% from 2024. The OVER bet won.

• The OVER/UNDER for the global mean surface temperature anomaly is 1.52°C. This is cooler than 2024, but much higher than my previous OVER/UNDER for 2025 of 1.44°C. The OVER would imply that the Paris Limit of 1.5°C is effectively history.

As of this writing, the global mean surface temperature anomaly for 2025 is 1.47°C and will certainly not break 1.50°C by year’s end. The UNDER bet won.

• The OVER/UNDER for the peak global mean surface temperature is 17.20°C. Note: the previous record is 17.15°C on July 23, 2024. I’d weight the UNDER heavily here, as ENSO conditions will probably keep extremes on the low end.

The peak global mean surface temperature in 2025 was 16.86°C, on July 15, 2025. The UNDER bet won.

• The OVER/UNDER for peak monthly methane is 1941.50 ppb. The last 2 years, the rate of methane growth has been slowing. I am expecting methane growth to pick up again. I’d say the OVER is the favorite here.

The peak for monthly methane was 1940.90 ppb for October, 2024 (reported in February, 2025).  The UNDER bet won.

• The OVER/UNDER for the highest North Atlantic sea surface temperatures is 25.40°C.  The previous record is 25.37°C on September 1, 2023. The North Atlantic isn’t impacted directly by El Niño, and the observed decline in cloud cover will continue to overheat the Atlantic. The OVER is a slight favorite here.

The peak North Atlantic sea surface temperature in 2025 was 24.66C, on August 16, 2025. The UNDER bet won.

• The OVER/UNDER on the highest temperature in the UK this coming Summer is 40°C (104°F). Yes. That again! This is brought to you by the overheated Atlantic.

The highest temperature recorded in the UK in 2025 was 35.8°C reached in Faversham, Kent, on July 1, 2025. The UNDER bet won.

• The OVER/UNDER for category 5 hurricanes is 4.5 hurricanes. (OVER = 5 or more, UNDER = 4 or less).  Without an El Niño creating shear, conditions should be very favorable for a record season. It will all come down to Saharan dust.

Three Category 5 hurricanes formed in 2025, all in the Atlantic basin: Erin (August), Humberto (September), and Melissa (October). This ties for the second-most Category 5 hurricanes in a single Atlantic season on record, behind only 2005 (which had four). The UNDER bet won.

• The OVER/UNDER for human deaths from bird flu (H5N1) in the US is 8. If the OVER happens, it will be VERY bad news. It’s very bad news anyway!

Reported human deaths in 2025 from H5N1 totaled approximately 12-13 globally, based on data from the World Health Organization, Centers for Disease Control and Prevention, and other public health sources.  The OVER bet won.

• The OVER/UNDER on the number of humans on this planet on December 31 2025 will be 8,265,000,000. That’s eight billion, two hundred and sixty-five million insects crawling on the planet’s face. Humans are not going extinct any time soon. You can bet on it!

As of December 19, 2025, the number of humans is 8,264,937,000 according to this source and rising by about 200,000 per day. With a few days to go in 2025, the OVER is declared the winner.

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Here’s a quick summary:

OVER BET WINNERS:

• Arctic sea-ice extent minimum.
• CO2 emissions from fossil fuels.
• Human deaths from h5n1 bird flu.
• Total human population.

 

UNDER BET WINNERS:

• Global sea-ice extent minimum.
• Peak monthly CO2 at Mauna Loa.
• Peak mointhly methane.
• Global surface temperature anomaly.
• Highest global mean surface temperature.
• Highest North Atlantic sea-surface temperature.
• Highest temperature recorded in the UK.
• Number of Category 5 hurricanes.