The new climate discourse: Alarmist or alarming?

The discourse on climate change is in part divided between a sense of alarm and a sense of alarmism in assessments of the magnitude and urgency of the problem. The divide in the discourse among climatologists relates to tensions in the use of key phrases to describe climate change. This article reviews evidence to support claims that climate change can be viewed as ‘catastrophic’, ‘rapid’, ‘urgent’, ‘irreversible’, ‘chaotic’, and ‘worse than previously thought’. Each of these terms are imprecise and may convey a range of meaning. The method used here is to assess whether the conventional understandings of these terms are broadly consistent or inconsistent with the science, or else ambiguous. On balance, these terms are judged to be consistent with the science. Factors which divide climatologists on this discourse are also reviewed. The divide over a sense of urgency relates to disagreement on the manner and rate at which ice sheets breakdown in response to sustained warming. Whether this rate is fast or slow, the amount of time available to reduce emissions sufficient to prevent ice sheet breakdown is relatively short, given the moderate levels of warming required and the inertia of the climate and energy systems. A new discourse is emerging which underscores the scope of the problem and the scope and feasibility of solutions. This discourse differentiates itself from existing discourses which view the magnitudes of the problem or of solutions as prohibitive. r 2007 Elsevier Ltd. All rights reserved.