Yikes! Underestimation of risk can be dangerous eh.
One study the Copenhagen Diagnosis sited was by Rahmstorf et al. which found that the IPCC's projections of sea level rise were underestimated concluding, "It's well-known that the IPCC almost certainly underestimates future sea level rise, because their models do not include the effects of dynamic ice processes. Most sea level rise from ice melt comes from chunks of ice breaking off into the ocean, then melting. This calving process is accelerated by warming, but the dynamic processes are not well understood, and are thus not represented in climate models...the IPCC's central sea level rise predictions were too low by about 60%."
In addition to confirming the Rahmstorf finding that the IPCC has underestimated sea level rise, the Copenhagen Diagnosis also found that the IPCC has dramatically underestimated the decline in Arctic sea ice extent and that the northern hemisphere's snow cover may also be declining at a faster-than-expected rate also saying that "rainfall has become more intense in already rainy areas, and recent changes have occurred faster than predicted".
The Copenhagen Diagnosis similarly found that the IPCC had also underestimated recent CO2 emissions from developing countries and added, "The global warming amplification (feedback) from carbon released as a result of permafrost melting has not been accounted for in any of the IPCC projections. A recent UN Environment Programme report warned that failing to account for this feedback will result in an underestimate of future warming."
Another broadly cited study titled 'The Asymmetry of Scientific Challenge' concluded, "If the consensus estimates such as those from the IPCC are wrong, it is because the physical reality is significantly more ominous than has been widely recognized to date". In agreement is environmentalist Dr. William Rees, Professor emeritus UBC School of Community and Regional Planning who says "Climate change is occurring much more rapidly than the best climate change models suggest".
Then there's the comments made by Dr. James Hansen who concluded from his comprehensive study of past climate change (paleoclimate), that, in the long term, climate is twice as sensitive in the real world as it is in the models used by the IPCC. Hansen says, "The models include 'fast feedbacks' like water vapor, clouds, and sea ice, but exclude longer-term 'slow feedbacks' like ice sheets (ice is a feedback because an icy surface reflects more heat than a dark surface). There is a broad consensus that the fast-feedback climate sensitivity is 3°C." But, Hansen goes on to say, "Slow-feedback sensitivity has received far less attention. To cut a long paleoclimate story short, it turns out the total climate sensitivity is as high as 6°C when there are ice sheets on the planet, as there are today. That is, the slow ice sheet feedback doubles the warming predicted by climate models."
These underestimated projections are very important especially when considering the fact that none of the consensus' projections dares to take into consideration nature's dramatic phenomena sometimes referred to as Black Swan Events. It's crucial that all the risks be understood fully thereby alllowing precaution to prevail.
