by Judith Curry

Politicians, activists and journalists have stimulated an ‘availability cascade’ [link] to support alarm about human-caused climate change.

Climate change may exacerbate environmental problems that are caused by overpopulation, poorly planned land-use and over-exploitation of natural resources. However, for the most part it is very difficult to separate out the impacts of human caused climate change from natural climate change and from other societal impacts.

Nevertheless, climate change has become a grand narrative in which human-caused climate change has become a dominant cause of societal problems. Everything that goes wrong then reinforces the conviction that that there is only one thing we can do prevent societal problems – stop burning fossil fuels. This grand narrative misleads us to think that if we solve the problem of climate change, then these other problems would also be solved.

Politicians, activists and journalists have stimulated an ‘availability cascade’ [link] to support alarm about human-caused climate change. An availability cascade is a self-reinforcing process of collective belief formation that triggers a self-perpetuating chain reaction: the more attention a danger gets, the more worried people become, leading to more news coverage and greater alarm. Because slowly increasing temperatures don’t seem alarming, the ‘availability entrepreneurs’ push extreme weather events and public health impacts as being caused by human-caused climate change, more of which is in store if we don’t quickly act to cool the planet by reducing fossil fuel emissions.

A deconstruction of this availability cascade is needed to avoid bias in our thinking and to better understand the true risks of human caused climate change:

The basis for this cascade originates from the 1992 UNFCCC treaty, to avoid dangerous human caused climate change through stabilization of CO2 emissions. Note, it was not until 1995 that the IPCC 2 nd Assess Report identified a discernible human influence on global climate.

Assess Report identified a discernible human influence on global climate. Then, the UNFCCC changed the definition of climate change to refer to a change of climate that is attributed directly or indirectly to human activity. This leads to the perception that all climate change is caused by humans.

Sea level rise and extreme weather events such as hurricanes, drought and heat waves are attributed to climate change, which are de facto assumed to be caused by human-caused climate change.

Human health impacts, national security risks, etc. that are exacerbated by extreme weather events are then inferred to be caused by human-caused climate change.

A critical link in this cascade is the link between human-caused climate change and extreme weather. In 2012, the IPCC published a Special Report on Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation (SREX). The Report found low to medium confidence of a trend in droughts in some regions and the frequency of heavy rains in some regions, and high confidence of a trend in heat waves in Australia. There is no trend in hurricanes or wild fires. Attribution of any trend in extreme weather events to human caused climate change cannot be done with any confidence. With regards to the perception (and damage statistics) that severe weather events seem more frequent and more severe over the past decade, there are several factors in play. The first is the increasing vulnerability and exposure associated with increasing concentration of wealth in coastal and other disaster-prone regions. The second factor is natural climate variability. Many extreme weather events have documented relationships with natural climate variability; in the U.S., extreme weather events (e.g. droughts, heat waves and hurricanes) were significantly worse in the 1930’s and 1950’s.

As a specific example of this cascade, consider the recent announcement from the White House that it will start a new initiative to focus on the health effects of climate change, with a draft report from the USGCRP [link]. Several years ago, the Cato Institute addressed this issue in their impact assessment of climate change on the U.S.[link]. The Cato Report concluded that the health effects of climate change on the U.S. are negligible today, and are likely to remain so in the future. They found that 46 percent of all deaths from extreme weather events in the U.S. from 1993-2006 were from excessive cold and 28 percent were from excessive heat, and that overall deaths from extreme weather events have declined in the U.S. They also found that diseases transmitted by food, water and insects have been reduced by orders of magnitude in the U.S. over the past century, and show no sign of resurgence.

Specifically with regards to asthma, which is an issue that influenced President Obama: the argument is that increasing heat waves will exacerbate smog, which exacerbates asthma. However, according to the EPA, smog levels have dropped 33% since 1980 [link]. Further, heat waves in the U.S. have not been increasing; the EPA’s analysis of the heat wave index for the U.S. [link] shows that the index during the 1930’s reached levels almost an order of magnitude greater than the recent decade. While asthma rates have been climbing, the cause cannot be global warming. Nevertheless, a recent survey [link] of the American Thoracic Society members found that 77% of the respondents observed an impact from climate change on increases in chronic disease severity from air pollution.

The availability cascade that leads to belief that climate change is exacerbating chronic respiratory diseases such as asthma misleads us away from a deeper investigation of the true causes of public health problems and from addressing these problems in a more meaningful way. And then multiply this consequence across the whole range of issues that climate change is allegedly making worse. The availability cascade of climate change as apocalypse acts to narrow the viewpoints and policy options that we are willing to consider in dealing with complex issues such as public health, weather disasters and national security. Should we be surprised when reducing CO 2 emissions does not ameliorate any of these problems?

Is climate change making us stupid? I fear that the answer is ‘yes.’ This problem is exacerbated by politically correct climate change orthodoxy, enforced by politicians, advocates and the media in an availability cascade, which is destroying our ability to think rationally about how we should respond to climate change. As a result, we have created a political log-jam over this issue, with scientists caught in the cross-fire.

JC note: this is a draft of something I’m writing, I would appreciate any feedback.