Relevant

Notes on MIT Joint Program on the Science and Policy of Global Change Report 169 - “Probabilistic Forecast for 21st Century Climate Based on Uncertainties in Emissions (without Policy) and Climate Parameters"

By: Kesten C. Green, PhD & Professor J. Scott Armstrong, PhD 

See PublicPolicyForecasting.com

1 June 2009

MIT Joint Program objectives and forecasting implications:

(see front material from second page of MIT report)

“The MIT Joint Program on the Science and Policy of Global Change is an organization for research,independent policy analysis, and public education in global environmental change. It seeks to provide leadership in understanding scientific, economic, and ecological aspects of this difficult issue, and combining them into policy assessments that serve the needs of ongoing national and international discussions.”

“To inform processes of policy development and implementation, climate change research needs to focus on improving the prediction of those variables that are most relevant to economic, social, and environmental effects. In turn, the greenhouse gas and atmospheric aerosol assumptions underlying climate analysis need to be related to the economic, technological, and political forces that drive emissions, and to the results of international agreements and mitigation. Further, assessments of possible societal and ecosystem impacts, and analysis of mitigation strategies, need to be based on realistic evaluation of the uncertainties of climate science.”

These objectives are at odds with the evidence from Green, Armstrong, and Soon (2009) that the no-change benchmark forecasting method provides forecasts with errors one-tenth of the size of IPCC forecast errors. The MIT program has the objective of educating about “environmental change” and therefore implicitly rejects the possibility of no or unimportant change or, despite mention of uncertainties, the possibility of unpredictable change.

The second paragraph makes it clear that the MIT researchers are not really concerned with “global environmental change” as is stated in the first paragraph of the program's objectives, but with the implications of the suspect and very limited manmade global warming theory. In pursuing the objective of studying the implications of the AGW theory, they perforce ignore consideration of the evidence that climate continues to warm and cool naturally with little or no global impact from human activities. They also ignore variables that demonstrably affect or that may affect global climate.

Most importantly, the MIT modelers in seeking to improve prediction ignore the evidence from the temperature data described by Green et al. (2009) that any improvement in accuracy beyond what can be achieved by assuming no change in  global temperatures would be too small to be of any use to policy makers or the public. In making their forecasts of dramatic warming, the MIT modelers take the dangerous and unscientific assumption implicit in the AGW theory that the future will be different from the past and run with it.

Are policy makers being informed and the public being educated that these so-called forecasts of the MIT modelers are nothing more than the elaborately-dressed opinions? Certainly people should be free to express their opinions, but it is not proper to claim that these are based on scientific forecasts. To date, we have found no scientific forecasts to support global warming. Nor is it likely that any forecast will be more useful for policy makers and the public than forecasting that there will be no change.

Given that the MIT forecasts are for greater warming than the IPCC forecasts, the Green et al. (2009) analysis suggests that the MIT forecasts errors will be much larger than those of the IPCC. This is an irresponsible kind of “independent policy analysis” and “public education”.

A quick forecasting audit of the MIT procedures

The MIT approach to forecasting is in substance the same as the approach adopted by the IPCC. The forecasting audit conducted by Green and Armstrong (2007) and its conclusion therefore applies also to the MIT forecasting effort. Green and Armstrong concluded that the IPCC predictions were not scientific forecasts but were rather the opinions of scientist transformed by mathematics. They further concluded that claims that the Earth will get warmer over the 21st Century have no credence.

One of us (Green) conducted a quick audit of the MIT procedures (summarized in the table below) as described in their Report 169 and came to the same conclusion as Green and Armstrong had done about the IPCC predictions. No more than 30% of forecasting principles were properly applied by the MIT modelers and 49 principles were violated. For an important problem such as this, we do not think it is defensible to violate a single principle—the situation is analogous to flying a large passenger plane or designing a major bridge.

Among the principles that were not properly applied were that the forecaster should shrink forecasts of change if there is uncertainty about predictions of the explanatory variables (Principle 10.9) and should be conservative in situations of high uncertainty or instability (Principle 7.3). Given that there is a great deal of uncertainty about the situation and about predictions of explanatory variables in this case, a forecast of little or no change is appropriate.

Table 1: MIT Climate Model Forecasts Analyzed in Comparison with 139 Basic Forecasting Principles - see "Standards and Practices for Forecasting", Armstrong, 2001.

Another important principle is that the forecasting method should provide a realistic representation of the situation (Principle 7.2). An interesting statement in the MIT report that implies (as one would expect given the state of knowledge and omitted relationships) that the modelers have no idea to what extent their models provide a realistic representation of reality is as follows:

“Changes in global surface average temperature result from a combination of emissions and climate parameters, and therefore two runs that look similar in terms of temperature may be very different in detail.” (MIT Report p. 28)

While the modelers have sufficient latitude in their parameters to crudely reproduce a brief period of climate history, there is no reason to believe the models can provide useful forecasts.

We recognize that judgment is required in rating the forecasting procedures against the forecasting principles and we encourage others, including the MIT authors, to independently rate the procedures and we will post their audit reports on PublicPolicyForecasting.com.

References

Green, K. C., Armstrong, J. S., & Soon, W. (2009). Validity of climate change forecasting for public policy decision making. International Journal of Forecasting, forthcoming.

Green, K. C. & Armstrong, J. S. (2007). Global warming: Forecasts by scientists versus scientific forecasts. Energy and Environment, 18, 997-1021.

Also see Green, K. C., Armstrong, J. S., & Soon, W. (2008). Polar Bear Population Forecasts: A Public-Policy Forecasting Audit. Interfaces 38(5), pp. 382–405, ©2008 INFORMS