“The SR1.5 report represents a very significant departure from previous IPCC reports in the direction of increased alarm regarding global warming, particularly as compared with the Fifth Assessment. No rigorous justification for this departure has been provided.
In reality, since the Fifth Assessment considerable evidence has accumulated suggesting that global warming is more of a long-term threat than a planetary emergency. This evidence consists mainly of observational results suggesting lower climate sensitivity (i.e. less warming in response to any given increase in greenhouse gas concentrations) and results indicating a greater contribution from natural variability to explaining observed global temperature trends. The IPCC has not passed on this evidence to policymakers in its SR1.5 report.
The report has also not passed on to policymakers some very important information published by climate modellers since the last IPCC assessment report regarding the empirical tuning of climate models to achieve desired results. The failure of previous IPCC reports to document the models’ tuning procedures has been described by these modellers as a ‘lack of transparency’. The projections of future warming published by the IPCC are completely dependent on the reliability of these models.
In view of these deficiencies, the SR1.5 report does not merit being regarded by policymakers as a scientifically rigorous document. There is much recent scientific evidence, not referred to in the report, to support a more considered mitigation strategy than the extreme measures proposed in the report.
Meanwhile, the worthy goals discussed in the report, such as sustainable development, poverty eradication and reducing inequalities, should be pursued on their own merits and not made dependent on unsettled climate science.”