Climate Letter #1572

The Arctic Report Card from NOAA, released yesterday, has an extremely troubling section about how permafrost is melting and releasing carbon to the atmosphere (Arctic Program).  This was written in the form of an essay by a scientist who is deeply involved with many others in permafrost studies.  It summarizes the present state of knowledge in a specialty that has extraordinary interest among climate forecasters.  Here is the key highlight:  “New regional and winter season measurements of ecosystem carbon dioxide flux independently indicate that permafrost region ecosystems are releasing net carbon (potentially 0.3 to 0.6 Pg C per year) to the atmosphere. These observations signify that the feedback to accelerating climate change may already be underway.”  For perspective, humans are currently releasing about 10 Pg (short for billions of metric tonnes) of carbon to the atmosphere each year by burning fossil fuels.  The permafrost release, if the calculations are correct, would be adding another 3-6% to that total, and growing, with no visible means of stoppage. Only a decade or two ago this type of release was just getting started.  There is plenty more carbon where that comes from in existing permafrost sites, readily available for future release if warming continues.  The essay in this post is clearly written and is followed by 17 references to past studies of a prominent sort.  (The IPCC, which to date has not accounted for any effects from permafrost carbon release in its carbon budgets, will surely be called upon to respond in one way or another.)

–Also from the main Report Card source, here is an outline of all the other highlights, with links to essays similar to the one above, plus a 3-minute video summary that pulls no punches:

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What is meant by the terrestrial carbon sink, how is it measured, and why is it important? (Chiba University – Japan).  A new study has been published showing how much progress has been made toward getting proper answers to these questions, including a description of the five primary processes that establish the sink.  Since this sink inhales about 30% of all human-based CO2 emissions the rationale behind the study is completely sound:  “The recent reports from the IPCC concluded that new land-use options to enhance this terrestrial carbon sink are needed to meet the goals of the Paris Agreement on Climate. Yet, it is important to understand the best science-based estimate of where atmospheric CO2 is fixed in terrestrial ecosystems today, and our study makes a significant step in that direction.”

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What should be done with abandoned agricultural land? (Yale e360).  “Abandonment of rural lands has become one of the most dramatic planet-wide changes of our time, affecting millions of square miles of land…..This change doesn’t appear to have affected global food supply, at least not yet, because the land lost was marginal to start with, and farming elsewhere has become more productive.”  Those are interesting facts.  Just as interesting is the observation that “grasslands and rangelands can prove more resilient than forests for carbon storage, according to a 2018 study from the University of California at Davis. That’s because they store carbon largely underground, where it is less vulnerable in drought- and wildfire-prone areas than the above-ground carbon stored in trees.”  These lands offer an attractive option, and not difficult to accomplish.

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