by Linnea Lueken at wattsupwiththat.com
Reason magazine recently posted an article on its website titled “There Is No 1.5°C Climate Cliff,” arguing that the 1.5°C threshold touted by the United Nations Intergovernmental Panel on Climate Change, world governments, and activists, is not based on any scientific investigation, but is rather arbitrary. This is true. The threshold value was first developed by a panel of advisors who had no data to show that 1.5° warming would be catastrophic, and the language used by the media has only become more extreme since then.
In the post, writer Ronald Bailey explains that the 1.5°C threshold was developed in the 1990s by the German Advisory Council on Global Change.
The advisors adopted two principles to guide their work. The first was the “preservation of Creation in its present form” achieved chiefly by staying within their guess of what would be “a tolerable ‘temperature window.’’’ The second was the “prevention of excessive costs.” Their analysis of what would constitute a tolerable temperature window occupies a single paragraph. There they reckoned that the mean maximum temperature during the last interglacial period was 16.1 C to which they arbitrarily added a further 0.5 C to establish tolerable maximum temperature of 16.6 C. They then assumed that in 1995 the current global mean temperature was around 15.3 C which would be only 1.3 C below their tolerable maximum. Finally, they presupposed the 1995 average was 0.7 C above the preindustrial average which yields an overall 2.0 C threshold.
This was clearly not a rigorous scientific investigation. Climate Realism has explained this fact in past posts as well, such as, here, here, and here, where we point out that there is also no evidence to suggest passing that arbitrary warming threshold would cause “climate chaos” or positive-feedback type cascading events. Climate at a Glance: Tipping Points concurs, showing that there is no evidence that irreversible tipping points exist at all. Since the conception of the threshold, only computer models with faulty assumptions built in have driven the alarmist claims and associated headlines tied to the 1.5C figure.