{"id":166913,"date":"2020-08-17T12:00:32","date_gmt":"2020-08-17T11:00:32","guid":{"rendered":"https:\/\/www.transcend.org\/tms\/?p=166913"},"modified":"2020-08-16T15:04:03","modified_gmt":"2020-08-16T14:04:03","slug":"are-worst-case-climate-scenarios-less-likely-as-media-reports-of-a-new-scientific-paper-suggest","status":"publish","type":"post","link":"https:\/\/www.transcend.org\/tms\/2020\/08\/are-worst-case-climate-scenarios-less-likely-as-media-reports-of-a-new-scientific-paper-suggest\/","title":{"rendered":"Are Worst-Case Climate Scenarios Less Likely, as Media Reports of a New Scientific Paper Suggest?"},"content":{"rendered":"

28 Jul 2020 – <\/em>Reading the media reporting of a new scientific paper released on 22 July, it was easy to get the impression that some \u201cworse-case\u201d climate warming possibilities are now off the agenda. \u201cSo this is good news?\u201d a friend emailed. \u201cNo\u201d was my answer.<\/p>\n

It would be a grave mistake, and an illustration of how media reporting can get complex climate stories wrong, to find good news in this research.<\/p>\n

\"\"<\/a><\/em><\/p>\n

The research in question is \u201cAn assessment of Earth\u2019s climate sensitivity using multiple lines of evidence\u201d<\/a>. Climate sensitivity is the amount of warming to be expected from a doubling of the amount of carbon dioxide in the atmosphere. The most recent Intergovernmental Panel on Climate Change (IPCC) report found the range was 1.5 to 4.5 degrees Celsius (\u00b0C).<\/p>\n

The new paper uses multiple lines of evidence \u2014 observations over the last 150 years, climate models, and climate history reaching back almost four million years \u2014 to constrain the estimated range for climate sensitivity.<\/p>\n

One major finding was that very low estimates of climate sensitivity of less than 2\u00b0C \u2014 which climate sceptics like to emphasise \u2014 are inconsistent with the evidence. The Washington Post headlined<\/a> with \u201cMajor new climate study rules out less severe global warming scenarios\u201d, reporting that the research \u201cfound that Earth\u2019s global average temperature will most likely increase between 2.3 and 4.5\u00b0C\u201d compared to the IPCC range of 1.5-4.5\u00b0C. And it reported that there \u201cwould be a 6 to 18 percent chance of exceeding the upper bound defined by the study 4.5\u00b0C.\u201d Which was balanced reporting.<\/div>\n
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Other coverage gave emphasis to the claim that some high-end estimates might now be off the table. But if the IPCC range was up 4.5\u00b0C, and the new paper range is up 4.5\u00b0C, what has changed that is \u201cgood news\u201d?\u00a0 Some research papers over the last two years, reporting on preliminary results from updated climate models for the next IPCC report, had suggested that climate sensitivity could be much higher, due to unresolved issues with cloud feedbacks. But scientists such as NASA\u2019S Gavin Schmidt had warned<\/a> that this work-in-progess should be taken with a grain of salt: \u201cclaims that climate sensitivity is much higher, or that worst cases scenarios need to be revised upwards, are premature\u201d.\u00a0 His warning was prescient.<\/div>\n

And Science Daily reported<\/a> one of the paper’s authors, Gabi Hegerl, saying that \u201cthese estimates make it improbable that climate sensitivity is at the low end of the IPCC range and confirm the upper range<\/b>\u201d (emphasis added).<\/p>\n

Even though the new paper had found the upper bound of 4.5\u00b0C was the same as that of the IPCC report, media reporting included:
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