## Thursday, April 19, 2007 ... //

### Probabilities of various theories: climate change

The following list is the global warming counterpart of a similar table for fundamental physics:

• 99.9% - The global temperature is cooling and in 100 million years, it will be measurably below the current 2.7 Kelvins ;-)
• 99% - Doubling of CO2 from 280 ppmv to 560 ppmv adds more than 0.2 Celsius degree to the expected average temperature
• 95% - Higher life can easily withstand three times higher fluctuations of the decadal average temperatures than those seen in the last 100 million years
• 90% - Scientists in 2100 will find contemporary climate models as naive as we view models from the early 20th century
• 85% - Temperatures that would instantly jump 2 Celsius degrees above the present ones (giving us no time for adaptation) would have a smaller negative economic impact on life and the civilization than a world war (such as WW2) under way (war-like death rate is not assumed to be a part of the impact here)
• 80% - A satisfactory theory of cloud formation and of the main drivers influencing it is necessary to get a good zeroth approximation for the climate at the millenial timescale or longer
• 75% - Annual average global temperatures have differed by more than 5 Celsius degrees from the present ones in both directions during the last 10 million years
• 70% - Cosmic rays have a detectable and statistically significant influence on temperatures at the multi-million-year timescale
• 65% - 2025 will be warmer than 2005
• 60% - Long-term solar variations have a detectable influence on the climate at the centennial scale
• 50% - A future warming by 1 Celsius degree - regardless of its origin - will be beneficial for the society, economies, and most animals, or a future cooling by 1 Celsius degree will not be beneficial
• 40% - Turbulence and largely unpredictable motion in the atmosphere and the ocean is responsible for more than 30% of the decadal variations of the climate at a fixed continent
• 30% - The climate sensitivity for CO2 doubling is a well-defined quantity, it is greater than 2 Celsius degrees, and it will be measured with a 20% error or more accurately by 2100
• 20% - The average decadal temperature in at least one of the decades in the last 20 million years differed from the most recent decade by more than 10 Celsius degrees in either direction
• 10% - Positive feedbacks amplifying the external perturbations influencing the temperature are stronger than the negative feedbacks
• 5% - Under business-as-usual scenario, newly emitted man-made CO2 will contribute more than 2 Celsius degrees to the temperatures in the next 50 years
• 5% - The temperature trend of the 20th century puts it among 3 most spectacularly changing centuries in the last 1 million years
• 3% - Under the business-as-usual scenario, the 21st century will be the warmest century in the last 1 million years
• 1% - Human production of CO2 is responsible for more than 80% of the decadal climate variations of the 20th century
• 1% - Benefits of CO2 reduction according to currently contemplated plans will exceed the costs
• 0.1% - Investments to influence the global climate using present technologies today are wiser and more economical than investments into similar plans in 2020 using future technologies
• 0.01% - The climate sensitivity for CO2 doubling is greater than 5 Celsius degrees
• 0.001% - The effects of climate change under the business-as-usual scenario will remove more than 50% of the integrated GDP by 2100 or its equivalent
• 0.0005% - The sea levels will rise by more than 5 meters in the next 50 years
• 0.000001% - Extinction of mammals because of any climate change by 2100 (includes solar dysfunction)
• 0.0000001% - Extinction of life because of any climate change by 2100
• 0.00000001% - Extinction of mammals because of CO2-driven climate change by 2100

Again, if you carefully negate the assertions and subtract the numbers from 100%, you get additional estimates. ;-)