 |
| Titel |
The origin and limits of the near proportionality between transient climate warming and cumulative CO2 emissions |
| VerfasserIn |
Andrew H. MacDougall, Pierre Friedlingstein, Reto Knutti |
| Konferenz |
EGU General Assembly 2015
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250105830
|
| Publikation (Nr.) |
 EGU/EGU2015-5415.pdf |
|
|
|
|
|
| Zusammenfassung |
| The transient climate response to cumulative CO2 emissions (TCRE) is a useful metric of
climate warming that directly relates the cause of climate change (cumulative carbon
emissions) to the most used index of climate change (global mean near surface
temperature change). In this presentation analytical reasoning is used to investigate
why TCRE is near constant over a range of cumulative emissions up to 2000 Pg
of carbon. In addition, a climate model of intermediate complexity, forced with
linear emissions of CO2, is used to explore the effect of the terrestrial carbon cycle
feedback strength on TCRE. The analysis reveals that TCRE emerges from the
diminishing radiative forcing from CO2 per unit mass being compensated for by
the diminishing ability of the ocean to take up heat and carbon. The relationship
is maintained as long as the ocean uptake of carbon, which is simulated to be a
function of CO2 emissions rate, dominates changes in the airborne fraction of carbon.
Strong terrestrial carbon cycle feedbacks have a dependence on the rate of carbon
emission and when present lead to TRCE becoming rate dependent. Despite these
feedbacks TCRE remains roughly constant over the range of the Representative
Concentration Pathways and therefore maintains its primary utility as a metric of climate
change.
Additional climate model experiments and analytical analysis suggests that a TCRE like
metric also emerges in scenarios where CO2 is artificially removed from the atmosphere.
However, this reverse TCRE is smaller in magnitude than the TCRE when net CO2 emissions
are positive. |
|
|
|
|
|
|