IPCC WGI: Methane Below IPCC Models
The June 7th draft of the WGI 5th Assessment Report (AR5) released by the IPCC Monday contains this plot of atmospheric methane (CH4) concentrations measured since 1950 and projected out to 2035. Methane is a 20 times more powerful greenhouse gas than CO2.
The IPCC presents the graph without comment on meaning. So, exactly what does it mean?
It means the IPCC just invalidated the theory of human-caused global warming for methane four times!!! And… it is to science’s 95% confidence level!
What you talkin’ about, Willis?
The above plot has one undeniable characteristic… measurements are below all IPCC forecasts!
They are not just below, but more that two standard deviations below all four previous IPCC assessment forecasts.
That makes all the difference in the world.
Methane and the Null Hypothesis
Begin with this assumption:
Atmospheric methane concentrations result from human-caused global warming
Then, as the IPCC has done four times, apply the theory of human-caused global warming to predict future methane concentrations.
It is a statistical game that defines a range of acceptable possibilities. Science’s accepted range is two standard deviations, or a 95% probability that an assumption is correct.
Then go out and make actual measurements. That has been done for 23 years.
The null hypothesis says that if predicted measurements of an assumption fall outside the 95% confidence range then the assumption must be rejected.
The above graph clearly shows that, since 1990, forecast methane levels have fallen outside the 95% confidence range accept by science in all four IPCC assessments.
Therefore, the null hypothesis says that the theory of human-caused global warming MUST be rejected (at least for methane).
Two standard deviations is science’s 95% confidence level!
Science isn’t a value judgement made by an IPCC panel vote!
In AR5 fig.1.7, the IPCC proves the theory of human-caused global warming must be causally rejected for atmospheric methane effects.
Yet, the IPCC presents the graph without a whisper about its meaning. The IPCC forecasts doom and gloom on far less compelling evidence in countless other places in AR5.
Predictions of extreme weather, melting of the ice caps, sea level rise and all the rest are based on the cumulative effects of greenhouse gas concentrations in Earth’s atmosphere brought on by human activity.
A relationship between CO2 concentrations in Earth’s air and human activity is indisputable. It’s proven within the constraints of the null hypothesis. But a relationship does not exist for methane.
Critically important is that AR5 data also show that the relationship between CO2 and temperature rise is weak at best. Temperature rise is the crux of IPCC theory, yet the weak connection to carbon dioxide is totally ignored in the text of the AR5 reports.
The intensity of future predicted extreme climate events are based entirely on the cumulative effects of all the model forecasts combined. When a forecast proves incorrect or less than predicted then forecasts must be lowered.
The models are seriously off for two fundamental measurements: temperature rise and methane concentrations.
If the IPCC ignores major defects between empirical measurements and their assessments then their assessments can no longer be trusted.