Stephen , Meteorolocally we are getting close to the point of no return. CO2 reduction is The only hope in town long term , but stopping before the point of no return is critical London will be in danger in 50 years time whatever. Best wishes Alan
T --- Alan Gadian, UK. Tel: +44 / 0 775 451 9009 T --- > On 6 Dec 2020, at 14:43, SALTER Stephen <[email protected]> wrote: > > > Hi All > > The highest estimate for Greenland ice sheet loss is 325 billion tonnes a > year. > > If I multiply this by the latent heat of fusion of ice and divide by the area > of Greenland 2.166 million square kilometres I get 1.59 watts per square > metre. I think that this could be done by marine cloud brightening in just a > month either side of midsummer provided that we can cool other places at the > same time to reduce problems of controlling direction. > > How do we square this with 40? > > Please do not use this to reduce the need for CO2 removal. > > Stephen > > From: [email protected] <[email protected]> On > Behalf Of Andrew Lockley > Sent: 06 December 2020 13:28 > To: geoengineering <[email protected]> > Subject: [geo] Reduction of the future Greenland ice sheet surface melt with > the help of solar geoengineering > > This email was sent to you by someone outside the University. > You should only click on links or attachments if you are certain that the > email is genuine and the content is safe. > > https://tc.copernicus.org/preprints/tc-2020-347/ > > Brief Communication: Reduction of the future Greenland ice sheet surface melt > with the help of solar geoengineering > Xavier Fettweis et al. > Received: 25 Nov 2020 – Accepted for review: 03 Dec 2020 – Discussion > started: 04 Dec 2020 > Abstract. The Greenland Ice Sheet (GrIS) will be losing mass at an > accelerating pace throughout the 21st century, with a direct link between > anthropogenic greenhouse gas emissions and the magnitude of Greenland mass > loss. Currently, approximately 60 % of the mass loss contribution comes from > surface melt and subsequent meltwater runoff, while 40 % are due to ice > calving. Where most of the surface melt occurs (in the ablation zone), most > of the energy for the surface melt is provided by absorbed shortwave fluxes, > which could be reduced by solar geoengineering measures. However, so far very > little is known about the potential impacts of an artificial reduction of the > incoming solar radiation on the GrIS surface energy budget and the subsequent > change in meltwater production. By forcing the regional climate model MAR > with the latest CMIP6 future scenarios ssp245, ssp585 and associated G6solar > experiment from the Earth System Model CNRM-ESM2-1, we evaluate the local > changes due to the reduction of the solar constant on the projected GrIS > surface mass balance (SMB) decrease. Overall, our results show that even in > case of low mitigation greenhouse gas emissions scenario (ssp585), the > Greenland surface mass loss can be brought in line with the medium mitigation > emissions scenario (ssp245) by reducing the solar downward flux at the top of > the atmosphere by ~40 W/m2 or ~1.5 % (using the G6solar experiment). In > addition to reduce Global Warming in line with ssp245, G6solar also decreases > the efficiency of surface meltwater production over the Greenland ice sheet > by damping the well-known positive melt-albedo feedback which mitigates the > projected Greenland ice sheet surface melt increase by 6 %. However, only > more constraining geoengineering experiments than G6solar allows to maintain > positive SMB till the end of this century without any reduction in our > greenhouse gas emissions. > > How to cite: Fettweis, X., Hofer, S., Séférian, R., Amory, C., Delhasse, A., > Doutreloup, S., Kittel, C., Lang, C., Van Bever, J., Veillon, F., and Irvine, > P.: Brief Communication: Reduction of the future Greenland ice sheet surface > melt with the help of solar geoengineering, The Cryosphere Discuss., > https://doi.org/10.5194/tc-2020-347, in review, 2020 > -- > 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 [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/geoengineering/CAJ3C-06ptbxFTh_qgzp85MJDHn237-c82SP0wCuEPFz2QHmZqQ%40mail.gmail.com. > The University of Edinburgh is a charitable body, registered in Scotland, > with registration number SC005336. > -- > 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 [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/geoengineering/PR3PR05MB73548657D79317F458253022A7CF0%40PR3PR05MB7354.eurprd05.prod.outlook.com. -- 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 [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/geoengineering/E4F5D454-4CD7-49AC-B8F7-9BF9837D6D0B%40gmail.com.
