Andrew Lockley emailed me these questions: 1. Please can you clarify if your envisaged geoengineering would be enough to keep the permafrost frozen?
2. Further, can you clarify whether or not you've taken into account ice dynamics in the altitude reduction leading up to your geoengineering date? We ran equilibrium runs for our climate and ice sheet modelling so the simulations aren't realistic 'scenarios' they explore the long term viability of the ice sheet in a geoengineered climate. In answer to the first question the simple answer is I don't know, the data are still around so I could find out but HadCM3 does have a fairly large cold bias at the poles and so i don't know whether it would be appropriate for this kind of analysis. This cold bias is not an issue for the ice sheet modelling as we used an anomaly method for the driving climatology. Saying that, we observed that even if the global average temperature is returned to the pre-industrial value with 1120ppmv of CO2 in the atmosphere there is still a warming of the poles so permafrost could still be in danger. For the second question, we used equilibrium runs so it is not a 'scenario' and so would not cover modern melting to then determine future melting. The current generation of ice sheet models (including ours) does not include a realistic representation of ice sheet fast- flow dynamics. approximately 50% of the current melting of the greenland ice sheet is due to these fast flow losses. Our study gives an estimate of the long-term viability of the greenland ice sheet, to investigate the effect of geoengineering on the fast-flow dynamics will require a next generation ice sheet model. -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en.
