The effects of aggressive mitigation on steric sea level rise and sea ice changes

International audienceWith an increasing political focus on limiting global warming to less than 2 °C above pre-industrial levels it is vital to understand the consequences of these targets on key parts of the climate system. Here, we focus on changes in sea level and sea ice, comparing twenty-first century projections with increased greenhouse gas concentrations (using the mid-range IPCC A1B emissions scenario) with those under a mitigation scenario with large reductions in emissions (the E1 scenario). At the end of the twenty-first century, the global mean steric sea level rise is reduced by about a third in the mitigation scenario compared with the A1B scenario. Changes in surface air temperature are found to be poorly correlated with steric sea level changes. While the projected decreases in sea ice extent during the first half of the twenty-first century are independent of the season or scenario, especially in the Arctic, the seasonal cycle of sea ice extent is amplified. By the end of the century the Arctic becomes sea ice free in September in the A1B scenario in most models. In the mitigation scenario the ice does not disappear in the majority of models, but is reduced by 42 % of the present September extent. Results for Antarctic sea ice changes reveal large initial biases in the models and a significant correlation between projected changes and the initial extent. This latter result highlights the necessity for further refinements in Antarctic sea ice modelling for more reliable projections of future sea ice. © 2012 The Author(s)

Erratum to Regional hydrological cycle changes in response to an ambitious mitigation scenario

International audienceUnfortunately, in the aforementioned contribution, Fig. 5 (Monthly multi-model (mean and range) precipitation change (mm/day) for 2080–2099 minus 1980–1999 averaged over the 26 regions, E1 (black) and A1B (grey) scenarios) contains an error. For two of the contributing models (ECHAM5-C and INGVCE) the evapotranspiration data had the wrong sign, leading to an opposing annual cycle in these models compared to the other models. The corrected Fig. 5 is presented here. It can be seen that the annual cycles of the climate change signals in evapotranspiration in the two scenarios agree much better between the different models than previously estimated. The general picture clearly underscores the findings from the preceding Figs. 3 and 4 that the climate change signals are much reduced under the E1 scenario compared to the A1B scenario. This is true for the ensemble properties (means, percentiles, ..

Erratum to: Climate change under aggressive mitigation: The ENSEMBLES multi-model experiment (Clim Dyn, (2011), 10.1007/s00382-011-1005-5)

International audienceUnfortunately, in the aforementioned contribution, Table 2 of this paper erroneously reported two separate rows of data for the BCM-C model for both the A1B and E1 scenarios, only one of which was correct in each case. The lower of the two rows of data for each scenario (i.e. those corresponding to T changes of 2.44 K for A1B and 1.18 K for E1) contained correct data. The upper rows of data reported (i.e. those corresponding to T changes of 2.65 K for A1B and 1.38 for E1) contained some errors and should not have appeared. A corrected version of Table 2 appears below