The Fukushima Daiichi nuclear plants were sited and designed to have about a one in twenty lifetime chance of being hit by a disastrous tsunami because TEPCO and Japan's nuclear regulatory agency denied the possibility of a worst possible case tsunami.
The United Nations' Intergovernmental Panel on Climate Change is rejecting the worst case calculations of the effects of climate change such as sea level rise, while embracing the best case calculations of the amount of warming that will be caused by human emissions of greenhouse gases. This is the same rosy scenario approach that Japanese regulators took when they approved the siting and design of the Fukushima Daiichi nuclear power plants. A New York Times review of the final draft IPCC5 report reveals that the U.N. is planning to taking the reckless approach of lowballing both the risk and consequences of climate change.
In one case, we have a lot of mainstream science that says if human society keeps burning fossil fuels with abandon, considerable land ice could melt and the ocean could rise as much as three feet by the year 2100. We have some outlier science that says the problem could be quite a bit worse than that, with a maximum rise exceeding five feet.Note: the Science is not "outlier". In regulatory risk assessment, regulators use best case and worst case scenarios and consequences based on sound science and engineering. The IPCC is acting like an industry captured regulatory agency. It is rejecting the worst case consequences and embracing the best case scenarios.
The drafters of the report went with the lower numbers, choosing to treat the outlier science as not very credible.
In the second case, we have mainstream science that says if the amount of carbon dioxide in the atmosphere doubles, which is well on its way to happening, the long-term rise in the temperature of the earth will be at least 3.6 degrees Fahrenheit, but more likely above 5 degrees. We have outlier science that says the rise could come in well below 3 degrees.
In this case, the drafters of the report lowered the bottom end in a range of temperatures for how much the earth could warm, treating the outlier science as credible.
My old friend John Randall, an expert on risk assessment who is retired from the US Nuclear Regulatory Commission commented at Climate Progress:
The use of the word conservative in climate discussions is opposite to its use in risk analysis. In risk analysis, a conservative estimate of a negative consequence overestimates the consequence.From the perspective of a regulator, conservative means erring on the side of caution. That approach results in a conservative design and "overengineering". The Fukushima nuclear meltdowns happened because TEPCO and the regulatory agency rejected recent research results they considered "outliers". This is exactly the approach the U.N. is taking in IPCC5.