1 / 17

Can Cirrus Cloud Thinning Cool Climate Without Severe Climate Side Effects? CEC14 Berlin

Can Cirrus Cloud Thinning Cool Climate Without Severe Climate Side Effects? CEC14 Berlin. Lawrence J ackson, Julia Crook & Piers Forster. Geoengineering challenges. Stratospheric SO 2. Marine cloud brightening. Jones et al. (2011).

avalon
Download Presentation

Can Cirrus Cloud Thinning Cool Climate Without Severe Climate Side Effects? CEC14 Berlin

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Can Cirrus Cloud Thinning Cool Climate Without Severe Climate Side Effects? CEC14 Berlin Lawrence Jackson, Julia Crook & Piers Forster

  2. Geoengineering challenges Stratospheric SO2 Marine cloud brightening Jones et al. (2011) • To return global mean temperature to some earlier state, precipitation is reduced by too much • Regional variations • Side effects e.g. Stratospheric O3 depletion, whiter skies • Partial solution e.g. ocean acidification • Only temporary

  3. Cirrus clouds http://www.metoffice.gov.uk/learning/clouds/high-clouds Mean high cloud cover from CloudSat/CALIPSO 2B-GEOPROF R04 & 2B-GEOPROF-LIDAR P1.R04 data sets for 2006–2011 (Mace et al., 2009) http://www.climate4you.com/

  4. What do we know about cirrus cloud thinning? Microphysics • Homogeneous nucleation • Requires high super-saturation levels • Dominates ice crystal production T < -40oC • Heterogeneous nucleation • Out competes homogeneous nucleation for water vapour • Introduce efficient heterogeneous ice nuclei • Temperatures < T -40oC • Larger ice crystals with greater fall speed • “Negative Twomey effect” (Kӓrchar & Lohmann, 2003) Geoengineering (Mitchell & Finnegan, 2009) Bismuth(III) Iodide (BiI3) • Has potential to offset anthropogenic warming • Requires optimum particle concentrations Climate model simulations (Storelvmo et al., 2013)

  5. This study focuses on climate impacts • We adopt a simplified implementation in a GCM by modifying ice fall speed • Does cirrus cloud thinning: • Cool climate? • Change precipitation over land? • Cause regional variations in precipitation? • Could it complement stratospheric SO2 and MCB?

  6. HadGEM2 CC run on HECToR & ARCHER Martin et al. (2011) The HadGEM2 family of Met Office Unified Model climate Configurations, Geosci. Model Dev, 4, 723-757

  7. Simulation design • HadGEM2 forced with: • Historical data 1860-2005 • RCP4.5 2006-2099 • Geoengineering 2020-2069 • Control simulation is RCP4.5 • Climate baseline is 1986-2005 • Assess impacts of geoengineering on 2040-2059 climate means

  8. Climate engineering by cirrus cloud seeding Some results …

  9. Results – Changes in TOA radiation fluxes & cloud cover (2x fall speed) Outgoing shortwave radiation (Wm-2) Outgoing longwave radiation (Wm-2) Vertical profile of cloud cover (%) Cloud cover (%)

  10. Results - Cirrus cloud thinning TOA radiative forcing

  11. Results – temperature & precipitation

  12. Results – change in temperature (1.5 K) MCB (-1 K) CIRRUS x4 (-1 K) CIRRUS x2 (-0.6 K)

  13. Results – change in precipitation rate (kg m-2 day-1) MCB (land -0.2%) (land 3.2%) CIRRUS x2 (land 1.8%) CIRRUS x4 (land 1.4%)

  14. Results – effects of climate geoengineering Temperature Precipitation CIRRUS x4 MCB

  15. Conclusions A cooler climate without side effects? • But … • Regional variations in impact – especially precipitation • Is it scalable? • In practice how would we know if it works?

  16. Thank you

More Related