| 英文摘要: | To the Editor —
In a recent Letter1, Hollin and Pearce suggest that the panel at the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report Working Group 1 (ref. 2) press conference fell into a “certainty trap” by presenting an “incoherent” message. We argue that this conclusion is incorrect because the authors misunderstand key points of the panel's message and misrepresent some of the press conference statements.
Hollin and Pearce argue that in trying to meaningfully present the scientific certainty about anthropogenic global warming, IPCC speakers selected some temporally short events to stress certainty, while dismissing other temporally short events that brought such certainty into question. The Letter focuses on global surface temperature anomalies and the recent slowdown in surface warming (1998–2012), which the authors termed 'the pause'. This period overlapped with the hottest decade since records began (2001–2010).
The IPCC was not incoherent, and clearly distinguished between the high confidence that human activity has led to multi-decadal warming and lower confidence in the specific causes of recent short-term variability (that is, the warming slowdown, 'pause' or 'hiatus'). The Letter quotes outgoing IPCC chair Rajendra Pachauri (transcript lines 261–262 in the Supplementary Information of ref. 1) as evidence of focusing on “recent and short-term climate changes”1 to make it more meaningful to the public. However, they omitted his preceding words: “each of the last three decades has been successively warmer at the Earth's surface than any preceding decade since 1850” (lines 258–260). Thus, as illustrated in Fig. 1, which was shown at the press conference, the recent “hottest” decade was explicitly placed in the context of long-term, climatically relevant trends2. |