<html><head><meta http-equiv="Content-Type" content="text/html charset=windows-1252"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div><blockquote type="cite"><div><meta http-equiv="Content-Type" content="text/html charset=windows-1252"><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div><x-sigsep><p>To unsubscribe from this list go to:<a href="https://calmail.berkeley.edu/manage/list/reminder/climate@lists.berkeley.edu">https://calmail.berkeley.edu/manage/list/reminder/climate@lists.berkeley.edu</a></p></x-sigsep></div><div><a href="https://ir.citi.com/2kNY+EwkqKWZyfvy2LsQnHjRB5MYkqf8duslCBaL1XHgDsHFitjI4A==">https://ir.citi.com/2kNY%2bEwkqKWZyfvy2LsQnHjRB5MYkqf8duslCBaL1XHgDsHFitjI4A%3d%3d</a></div><br><div><div>On Aug 23, 2014, at 7:15 AM, Andrew Lockley <<a href="mailto:andrew.lockley@gmail.com">andrew.lockley@gmail.com</a>> wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><p dir="ltr">Forwarded at Mark's request. </p><p dir="ltr">The rebuttal is interesting, but doesn't directly consider the issue of cooking stoves, which are a big source of BC and won't be affected by a transition to solar. </p><p dir="ltr">A </p>
<div class="gmail_quote">---------- Forwarded message ----------<br>From: "Lawrence, Mark" <<a href="mailto:Mark.Lawrence@iass-potsdam.de">Mark.Lawrence@iass-potsdam.de</a>><br>Date: 23 Aug 2014 14:32<br>
Subject: Scary tipping points<br>To: "<a href="mailto:andrew.lockley@gmail.com">andrew.lockley@gmail.com</a>" <<a href="mailto:andrew.lockley@gmail.com">andrew.lockley@gmail.com</a>><br>Cc: <br><br type="attribution">
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<div><p class="MsoNormal"><span lang="EN-US"><u></u> <u></u></span></p><p class="MsoNormal"><span lang="EN-US">Hi Andrew,<u></u><u></u></span></p><p class="MsoNormal"><span lang="EN-US"><u></u> <u></u></span></p><p class="MsoNormal"><span lang="EN-US">I read your post “The scary tipping point nobody talks about here” on the Google Groups discussion.<u></u><u></u></span></p><p class="MsoNormal"><span lang="EN-US"><u></u> <u></u></span></p><p class="MsoNormal"><span lang="EN-US">Your concern is that once we switch from fossil fuels to solar, we will suddenly no longer have the emissions of SO2 which are contributing to the current “masking” cooling effect (which is of the same rough magnitude,
but in the opposite direction, as enhanced CO2 since pre-industrial times).<u></u><u></u></span></p><p class="MsoNormal"><span lang="EN-US"><u></u> <u></u></span></p><p class="MsoNormal"><span lang="EN-US">This is a valid concern.<u></u><u></u></span></p><p class="MsoNormal"><span lang="EN-US"><u></u> <u></u></span></p><p class="MsoNormal"><span lang="EN-US">However, at the same time, there are other short-lived climate-forcing pollutants besides SO2, which warm instead of cooling. In particular, black carbon (in soot), methane and ozone add up to a total warming which is
comparable to CO2 (and thus offsets the planetary mean of aerosol particle direct and indirect cooling). A lot of soot and other SLCPs comes from diesel buses and trucks, and from biofuel and biomass burning, and in some places still from power plants, and
of course major sources of methane are leakage and emissions during coal and oil mining. All of these should also get replaced by solar, so that we should simultaneously see a reduction in the warming by the other SLCPs, which on a planetary average will
roughly balance the “unmasked” warming due to reduced SO2 emissions. (Of course these are regionally differing, so it is only the planetary average that is balanced, but while the total global warming is still < 1C, that’s not going to be very noticeable
in weather patterns in most places.)<u></u><u></u></span></p><p class="MsoNormal"><span lang="EN-US"><u></u> <u></u></span></p><p class="MsoNormal"><span lang="EN-US">So we can confidently and comfortably head towards the “solar power revolution” that you envision without worrying about it causing a sudden call for SRM implementation.<u></u><u></u></span></p><p class="MsoNormal"><span lang="EN-US"><u></u> <u></u></span></p><p class="MsoNormal"><span lang="EN-US">I hope that helps clarify things. I would appreciate if you could post this on the google groups on my behalf (I have misplaced my password and am leaving for vacation tomorrow).<u></u><u></u></span></p><p class="MsoNormal"><span lang="EN-US"><u></u> <u></u></span></p><p class="MsoNormal"><span lang="EN-US">Thanks for your contributions at the CEC14,
<u></u><u></u></span></p><p class="MsoNormal"><span lang="EN-US"><u></u> <u></u></span></p><p class="MsoNormal"><span lang="EN-US">--mark <u></u><u></u></span></p><p class="MsoNormal"><span lang="EN-US"><u></u> <u></u></span></p>
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