The known, the unknown, and the possibly unknowable

An interesting paper addressing one of the foundational issues in the climate debate. My contention has long been that our claims and certainties far exceed our actual knowledge. We ought to consume less and we ought to inject fewer pollutants into the environment - those are fairly concrete and actionable policies based on sound knowledge.

But our knowledge of the actual record of facts (specific temperatures in particular places at particular times) is vestigial and hampered by incomplete and inconsistent records for the time spans with which we are concerned. Even today, temperatures in vast parts of the globe are still "imputed" rather than directly measured and virtually all direct measurements are subject to human "adjustments" introducing all the variabilities and uncertainties attendant to human processes.

From The importance of unresolved biases in 20th century sea-surface temperature observations by Luke L. B. Davis, David W. J. Thompson, John J. Kennedy, and Elizabeth C. Ken. From the Abstract:

Biases in sea-surface temperature observations lead to larger uncertainties in our understanding of mid-to-late 20th century climate variability than previously thought.

A new analysis of sea-surface temperature (SST) observations indicates notable uncertainty in observed decadal climate variability in the second half of the 20th century, particularly during the decades following World War II. The uncertainties are revealed by exploring SST data binned separately for the two predominant measurement types: “engine-room intake” (ERI) and “bucket” measurements. ERI measurements indicate large decreases in global-mean SSTs from 1950 to 1975, whereas “bucket” measurements indicate increases in SST over this period before bias adjustments are applied but decreases after they are applied. The trends in the bias adjustments applied to the “bucket” data are larger than the global-mean trends during the period 1950-1975, and thus the global-mean trends during this period derive largely from the adjustments themselves. This is critical, since the adjustments are based on incomplete information about the underlying measurement methods, and are thus subject to considerable uncertainty. The uncertainty in decadal-scale variability is particularly pronounced over the North Pacific, where the sign of low-frequency variability through the 1950s-1970s is different for each measurement type. The uncertainty highlighted here has important – but in our view widely overlooked – implications for the interpretation of observed decadal climate variability over both the Pacific and Atlantic basins during the mid-to-late 20th century.

Translating from crypto language - There are two forms of ocean surface direct temperature measurement, 1) dipping in a bucket and measuring, or 2) sucking water into the engine room and measuring. There are issues with both forms of measurement requiring manual adjustments to the measures.

The crticial sentence is

The trends in the bias adjustments applied to the “bucket” data are larger than the global-mean trends during the period 1950-1975, and thus the global-mean trends during this period derive largely from the adjustments themselves.

In other words, the accepted trends in oceanic temperatures do not reflect actual temperature changes but reflect the adjustments that are being made.

It doesn't mean that there is a conspiracy to deceive. It doesn't mean that the globe isn't warming. It means we don't know what is happening. The system is dynamic, chaotic, multi-system, non-linear, and multi-variable.

Much of the AGW initiative has been focused on transferring money from some countries, based on negative impacts arising from forecast models which have not yet been tested or proven, to others and therefore has been deemed a hoax or sham. Perhaps. Certainly there are bad actors in the drama who are simply after the money.

The fundamental issue is that we know enough to be concerned but we don't know enough to be confident. Until we have much more reliable data sets and models, and particularly data-sets and models which can be shown to be free from manipulation and design bias, then we are in a weak position to make hard forecasts.

The response from advocacy groups to these reasonable concerns is either ad hominem (science denier) or to invoke the precautionary principle. However, the precautionary principle is always invoked whenever there is uncertainty and when our cognitive reach exceeds our cognitive grasp. It is the failsafe position of the fallacy of the motte and bailey argument; the argument of every shady salesman in the world, especially insurance sales and financial dealers.

Limited time offer! You cannot afford not to have this! - AGW advocates and insurance salesmen make the same argument.

We know that there are risks which need to be insured (the motte). We know that there are risks which are real but unlikely. We know that there are risks which are real but can't be quantified (the bailey). It is the job of the insurance salesman to move us from insuring just the certain risks to spending scarce money on uncertain risks.

In parallel, climate change is real and always occurring. The uncertainty is two-fold. One is natural - how much is it occurring, in what direction and with what consequence? The second uncertainty is human - how much do we influence the naturally dynamic, chaotic, multi-system, non-linear, and multi-variable climate system, by what mechanisms and what can we realistically do to affect that which is already occurring naturally? Advocates want, for their own purposes, for us to insure against the possible but uncertain rather than simply address that which is smaller in scope but is known with greater confidence.

The paper above is a useful reminder of just how fundamentally nascent is our current state of knowledge.