Figure 2 : Climate drivers of the Cook Ice Cap mass loss.

From: Atmospheric drying as the main driver of dramatic glacier wastage in the southern Indian Ocean

Figure 2

(a,b) Time series of historical surface ocean temperature from ERSST.v2 dataset (black line, a), of air temperature at PAF (red line, a,b) and the logarithm of precipitation at PAF (blue line, b). The horizontal blue lines in a) are periods of glacier front stability14 for which our glacier model was used to retrieve past precipitation amounts (as a % compared to the 1950s), to allow Ampère Glacier extent as given in Fig. 1b. (c) Time series of the modeled specific mass balance of CIC assuming that elevation and extent are those observed in 2009 (orange) and 1963 (black). Red (blue) lines and numbers are the contribution of precipitation to the negative glacier-wide mass balance for each decade, assuming that the conditions observed in the 1950s (respectively in the early 1900s) represent reference climatology. In the 1960s, the contribution of dryness reaches 119% because cool conditions reduced ablation (see Methods). The vertical dashed line represents the year 1975. The thin solid and dashed lines are trends computed over the timespan corresponding to the length of each line. (d) Time series of the cumulative modeled specific mass balance of CIC assuming that elevation and extent are those observed in 1963. The thick black line represents observations, the thin black line is hypothetical climate without warming or drying compared to the 1950s, the red line is without drying but with warming, the blue line is without warming but with drying. The yellow and orange lines are ERA40 and NCEP1 mass balances. The green line is the CMIP5 multi-model mass balance mean. The shaded areas are the spreading of all CMIP5 model values (blue area) and of 90% of CMIP5 model values (pink area). For each CMIP5 model, the temperature and precipitation biases with respect to observed data were removed based on the 1950–2005 period.