Climate Letter #1524

An interview with professor John Holdren at Harvard University (Phys.org).  He covers a lot of ground in this post, most of it treating the same subjects that I look for every day in seeking the latest news about the climate problem.  His comments about the IPCC need to be taken seriously because they reflect the same view expressed by any number of other older professionals in the field.  That means the solutions that are called for, when based on the certified conclusions of the IPCC, are almost sure to be inadequate.  The professor observes that this has been a year of great awakening that an urgent problem really exists.  The interviewer did not ask him to comment on the current degree of willingness of the awakened ones to make the deep lifestyle changes that would surely be needed in order to achieve a satisfactory outcome.  His assessment of the level of risks implied by recent research studies (like the one that follows) is generally consistent with what regularly appears in these letters.

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New research helps confirm previous theories of very high sea level rise during the Pliocene (The Conversation).  The two lead authors, both from the University of Wellington in New Zealand, wrote this review of a newly published study which is hidden behind the usual paywall.  The team used a new method to measure past changes in sea level and came up with a figure of up to 20 meters associated with a period of time from about three million years ago—“we constructed a record of global sea-level change with significantly more precision than previously possible.”  Based on other research that is now well-accepted they go on to say, “The Pliocene was the last time atmospheric carbon dioxide concentrations were above 400 parts per million and Earth’s temperature was 2°C warmer than pre-industrial times. We show that warming of more than 2°C could set off widespread melting in Antarctica once again and our planet could be hurtling back to the future, towards a climate that existed three million years ago.”  Most of the rise had to come from Antarctica’s ice sheet, and maximum melting of that sheet would have developed during those periods when solar insolation, which runs in cycles over many thousands of years, was making a maximum approach toward the South Pole.

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Extreme wildfires are transforming forestlands into shrublands (University of California – Davis).  New research found that low-to-moderate burning was advantageous for forest health.  “On the extreme ends of the spectrum, unburned areas and high-severity burn areas showed relatively low plant diversity. Five to 10 years or more after experiencing high-severity burns, many forest stands were replaced by shrub fields that supported few plant species.”  Fire suppression policies allowing too much density have often resulted in fires of the severe type.

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