Bet 848

Duration 10 years (02020-02030)

“Between 2021 and the end of 2030, annual fossil fuel emissions (excluding carbonation) will not exceed annual fossil fuel emissions (excluding carbonation) from 2019.” Detailed Terms »

Ted Nordhaus


Ken Caldeira

STAKES $2,000

will go to Médecins Sans Frontières if Nordhaus wins,
or Médecins Sans Frontières (MSF)/Doctors Without Borders if Caldeira wins.

Nordhaus's Argument

Technological change and structural transformations of the global economy have been slowly decoupling carbon emissions from economic activity for many decades. Improving technical efficiency, the sectoral shift in advanced developed economies toward knowledge and service economies, the global glut of cheap natural gas, and falling costs of clean energy have accelerated those processes over the last decades, aided and abetted by two deep global economic shocks that have stranded older, inefficient, energy and carbon intensive capital stock. Prior to the Covid pandemic, global emissions appeared on track to likely peak by the middle of the 2020's. The deep recession and likely long and slow recovery has accelerated that date and it appears that global emissions are unlikely to exceed their 2019 peak over the next several years. As a result, given continuing technological change, it is extremely unlikely that carbon emissions associated with combustion of fossil fuels will ever again exceed their 2019 level globally.

Caldeira's Argument

There have been structural changes in the global economy and substantial technological improvement, but carbon emissions remain tightly coupled to overall economic activity. Emissions in the wealthiest countries may decline over the next decade, and it is possible that a sustained global economic downturn could impede economic development in the Global South, leading to lower future emissions.

However, I am somewhat optimistic about economic development in the Global South, and skeptical about the ability of near-term technologies to provide safe, reliable, power at least cost, and also skeptical about the Global North being willing to allocate sufficient resources to meaningfully address the climate change problem in both the North and the South, therefore I judge the probability of an increase in CO2 emissions to be high.

Therefore, annual CO2 emissions will likely exceed year 2019 emissions by year 2030, inclusive.

There are three ways I could be wrong:

1. Global economic growth will be tepid this decade
2. Energy innovation will provide us with least-cost low-emission power.
3. Energy policy will have substantive effects.

I hope I lose this bet because of items #2 or #3, and not item #1.

Detailed Terms

Results will be judged based on final (not preliminary) estimates from the Global Carbon Project. Global Carbon Project's final 2019 numbers is 36.46 GtCO2. If the Global Carbon Project is no longer calculating this number, The Long Now Foundation will find an alternate source, with the Department of Energy's Carbon Dioxide Information Analysis Center as the first alternative source.

The latest Global Carbon Project data is available on this page:
The data file is here:

From this file, the global fossil emissions excluding carbonation can be found in the "global carbon budget" tab; it is given as 9.95 GtC, which (using the conversion factor of 3.664 in the file) should amount to 36.46 GtCO2.