Dear Professor Mann, Most of us would like to keep global warming below 1.5C this century. But we are way off course.
Nobody likes to admit in public that we are already in dangerous territory. But we are! The rate of global warming (near-surface temperature rise) could now exceed 0.2 C per decade; CO2 is above 400 ppm (an excess of 120 ppm above pre-industrial 280 ppm) of which most will remain this century due to CO2's long lifetime in the atmosphere; and we have already had over 1 C anthropogenic global warming (AGW). This means that, even with the most drastic cut in CO2 emissions, we cannot avoid an extremely dangerous 3C this century without aggressive CO2 removal (CDR). Indeed, if we want to keep AGW below 1.5 C this century and halt ocean acidification, then we need to get global warming rate down below 0.05 C per decade, i.e. less than a quarter the current rate. Thus climate forcing has to be reduced by 75% within a decade or two, to have a chance to keep below 1.5 C this century. Thus we have to reduce the CO2 level to around 210 ppm (30 ppm above pre-industrial 280 ppm), and reduce methane from 1.8 ppm to around 1.0 ppm in order to reduce their combined forcing by 75%. This assumes we maintain aerosol cooling, especially the SO2 cooling from coal-fired power stations. This is exacerbated by climate forcing from the Arctic, at around 0.5 W/m2 and rising exponentially as albedo loss accelerates. Therefore, in addition to urgent CO2 emissions reduction, we need (i) aggressive CDR so that CO2 is soon being removed from the atmosphere faster than than it is being emitted, (ii) suppression of methane emissions, especially fugitive methane (iii) rapid cooling of the Arctic to restore albedo, and (iv) maintenance of SO2 aerosol cooling, if global warming is to be kept below 1.5 C this century. Do you agree or can you suggest an alternative course of action to avert extreme danger? Kind regards, John Nissen Chair, Arctic Methane Emergency Group (AMEG) On Sun, Apr 17, 2016 at 3:22 AM, Greg Rau <gh...@sbcglobal.net> wrote: > > > http://www.theguardian.com/environment/2016/apr/15/march-temperature-smashes-100-year-global-record > > "The UK Met Office expects 2016 to set a new record > <http://www.theguardian.com/environment/2015/dec/17/2016-set-to-be-hottest-year-on-record-globally>, > meaning the global temperature record is set to have been broken for three > years in a row. > > Prof Michael Mann, a climate scientist at Penn State University in the US, > responded to the March data by saying: “Wow. I continue to be shocked by > what we are seeing.” He said the world had now been hovering close to the > threshold of “dangerous” warming for two months, something not seen before. > > “The [new data] is a reminder of how perilously close we now are to > permanently crossing into dangerous territory,” Mann said. “It underscores > the urgency of reducing global carbon emissions.” > > GR - and the need to seriously consider additional ways of managing CO2 > and climate. > > -- > You received this message because you are subscribed to the Google Groups > "geoengineering" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to geoengineering+unsubscr...@googlegroups.com. > To post to this group, send email to geoengineering@googlegroups.com. > Visit this group at https://groups.google.com/group/geoengineering. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To unsubscribe from this group and stop receiving emails from it, send an email to geoengineering+unsubscr...@googlegroups.com. To post to this group, send email to geoengineering@googlegroups.com. Visit this group at https://groups.google.com/group/geoengineering. For more options, visit https://groups.google.com/d/optout.
