Oppenheimer – False prophet or multi-layered alarmist?

Haunting the Library has a posting “Flashback 1988: Michael Oppenheimer Warn Seas to Surge 83 Feet Inland by 2020“.

Apart from being a false and alarmist forecast in retrospect, even if in 1988 the climate models on which it was based were correct and unbiased, there could still have been less than a 1 in 1000 chance of this scenario being forecast. Here is why.

The relevant quote from the “Hour” newspaper is

“Those actions could force the average temperature up by 2 degrees Fahrenheit in the next three decades….Such a temperature increase, for example, would cause the sea level to rise by 10 inches, bringing sea water an average of 83 feet inland”

There are at possibly three, or more, levels of alarmism upon which this conclusion depends:-

  1. The sea level rise was contingent on a 2oF (1.1oC) over 32 years would have been at the top end of forecasts. Although the centennial rate of increase is around 3.5oC, my understanding of the climate models it is not just the global temperatures that are projected to rise, but the decadal rate of increase in temperatures. This is consistent with the accelerating rate of CO2 increase. Normally the range of projections is over a 95% probability range, so the models would have projected a 2.5% chance of this temperature increase.
  2. The rise in sea levels would lag air temperature rises by a number of years. This is due to the twin primary causes of sea level rise – thermal expansion of the ocean and melting pack ice. Therefore, I would suggest a combination of three reasons for this projection. First, the models projection of 10 inch (25cm) rise was exaggerated, due to faulty modelling. (IPCC AR4 of 2007 estimates a centennial rise of 30cm to 60cm, with accelerating rates of sea-level rises correlating with, but lagging, temperature rises). Second it was at the top end of forecast probability ranges, so there was just a 2.5% change of the sea level rise reaching this level for a 2oF rise. Third, time lags were not fully taken into account.
  3. The mention of the impact on the horizontal average sea water movement of 83 feet (25m) is to simply spread alarmism. For low-lying populated coastal areas, such as Holland, it probably assumes the non-existence (or non-maintenance) of coastal defences. The calculation may also assume land levels do not naturally change. In the case of the heavily populated deltas and the coral islands, this ignores natural processes that have caused land levels to rise with sea levels.

So it could be that, based on the climate models in 1988, there as a 2.5% chance of a 2.5% chance of sea levels rising by 10 inches in 32 years, subject to the models being correct. There are a number reasons to suspect that the models of climate and sea level rise are extreme. For instance, the levels of temperature rise rely on extreme estimates of sensitivity of temperature to CO2 and/or the feedback effect of temperature increases on water vapour levels (See Roy Spencer here). Sea level rises were probably overstated, as it was assumed that Antarctic temperatures would rise in parallel with those of the rest of the world. As 70-80% of the global pack ice is located there, the absence of warming on the coldest continent, will have a huge impact on future sea level forecasts.

Although this forecast was made a climate scientist, it was not couched in nuanced terms that the empirical scientific modelling techniques require. But it is on such statements that policy is made.

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