 |
| Titel |
The radiative forcing potential of different climate geoengineering options |
| VerfasserIn |
T. M. Lenton, N. E. Vaughan |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 9, no. 15 ; Nr. 9, no. 15 (2009-08-06), S.5539-5561 |
| Datensatznummer |
250007558
|
| Publikation (Nr.) |
 copernicus.org/acp-9-5539-2009.pdf |
|
|
|
|
|
| Zusammenfassung |
| Climate geoengineering proposals seek to rectify the Earth's current and
potential future radiative imbalance, either by reducing the absorption of
incoming solar (shortwave) radiation, or by removing CO2 from the
atmosphere and transferring it to long-lived reservoirs, thus increasing
outgoing longwave radiation. A fundamental criterion for evaluating
geoengineering options is their climate cooling effectiveness, which we
quantify here in terms of radiative forcing potential. We use a simple
analytical approach, based on energy balance considerations and pulse
response functions for the decay of CO2 perturbations. This aids
transparency compared to calculations with complex numerical models, but is
not intended to be definitive. It allows us to compare the relative
effectiveness of a range of proposals. We consider geoengineering options as
additional to large reductions in CO2 emissions. By 2050, some land
carbon cycle geoengineering options could be of comparable magnitude to
mitigation "wedges", but only stratospheric aerosol injections, albedo
enhancement of marine stratocumulus clouds, or sunshades in space have the
potential to cool the climate back toward its pre-industrial state. Strong
mitigation, combined with global-scale air capture and storage,
afforestation, and bio-char production, i.e. enhanced CO2 sinks, might
be able to bring CO2 back to its pre-industrial level by 2100, thus
removing the need for other geoengineering. Alternatively, strong mitigation
stabilising CO2 at 500 ppm, combined with geoengineered increases in
the albedo of marine stratiform clouds, grasslands, croplands and human
settlements might achieve a patchy cancellation of radiative forcing. Ocean
fertilisation options are only worthwhile if sustained on a millennial
timescale and phosphorus addition may have greater long-term potential than
iron or nitrogen fertilisation. Enhancing ocean upwelling or downwelling
have trivial effects on any meaningful timescale. Our approach provides a
common framework for the evaluation of climate geoengineering proposals, and
our results should help inform the prioritisation of further research into
them. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|