The Current Wisdom only comments on science appearing in the refereed, peer‐reviewed literature, or that has been peer‐screened prior to presentation at a scientific congress.
Three weeks ago, the National Academies of Sciences’ National Research Council (NRC) released a report Sea‐Level Rise for the Coasts of California, Oregon, and Washington: Past, Present, and Future. You can find it at: (http://www8.nationalacademies.org/onpinews/newsitem.aspx?RecordID=13389).
The apparent intent of the report was to raise global warming alarm by projecting rapidly rising seas (some two to three times higher than estimates from the United Nations’ Intergovernmental Panel on Climate Change (IPCC)) — along the California coast and elsewhere.
Unfortunately, to produce such a large and rapid sea level rise, the NRC had to throw overboard a lot of good science and do a lot of cherry‐picking of the rest.
Of course global sea level will continue to rise, with or without human‐induced climate change, as readers will see below. The NRC projects a wildly high upper bound of some 4–5 feet this century, while, in reality, the rate of future rise will likely be closer to the rise observed during the 20th century, about 8–12 inches. Coastal residents adapted to this with little or no overt effort.
How the NRC came up with a global sea level rise by the year 2100 of some 50 to 140 cm (20 to 55 inches) — is an example of using only a careful selection of available data and turning a deaf ear to warnings (made by the scientists themselves) of its unreliability for long‐term projections.
How did the NRC come up with such an enormous rise in sea level?
They independently projected the sea level rise from its two major components — ocean thermal expansion (from increasing ocean temperatures) and water input from the melting of ice — and then added them together.
But for each component, their high end projections are very likely much too high. And in combination, they represent something that is virtually impossible.
Consider thermal expansion. The NRC simply used the 21st century temperature change projections from the IPCC’s 2007 collection of climate models. Is there a problem here?
Since they started in 2001, the IPCC model projections have warmed at a rate over twice what is being observed in reality. So, if the current global temperature behavior under rapidly rising greenhouse gas concentrations is any indication of the future behavior under rapidly rising greenhouse gas concentrations, then the future projections of the sea level rise due to the thermal expansion of ocean water are grossly overestimated. The NRC did not even consider such a possibility, instead preferring to base their projections on the assumption that the future climate behavior will depart radically from the current climate behavior, i.e. throwing out observations in favor of what appear to be failing climate models. This model‐based method produces a lot more sea level rise than extrapolating observations would produce.
Which brings us to the NRC projections for the other element of sea level rise — melting of land‐based ice, primarily from Greenland and Antarctica. For this projection, the NRC turned their previous methodology on its head, and opted to extrapolate current trends (to the absurd) rather than rely on ice models. In this case, the models yield much less sea level rise than the NRC extrapolation of current trends.
This is how the NRC describes its method: