Assessment of the Impacts of Climate Change on Mountain Hydrology
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Figure 6.1. Changes in river flows: a) current annual flows (mm) and b) change between the present and the end of the century (%)
Source: Figure generated under the Memorandum of Understanding (MOU) between the MRI and the World Bank. Note: Picture a) presents the absolute annual flow, and therefore the scale is in mm. Picture b) presents the change, and the scale is in percentage.
possible, nor is one desirable. Each area of interest needs studies and analysis at resolutions adjusted to the size of the basin and the details of the information needed.
Visualization of Climate Change in the Santa Basin The two future climate conditions developed from the 16 GCM ensemble,2 along with results from the trend analysis, were used as the basis for the hydrological analysis of the Santa River Basin. The ensemble results were used to simulate the future glacier dynamics, while the trend analysis provided the climate data to estimate the hydrological response to future climate change. Simulation of Future Glacier Dynamics
According to the simulation, the glaciers of the Santa River Basin are likely to experience significant size reduction under warming climate scenarios. Using 2006 glacier coverage as a baseline, the simulated reduction in glaciated area in the Santa River Basin over the next 30 years would be 25 percent for the marginally warmer scenario and 47 percent for the much warmer scenario,3 as shown in Table 6.1. A comparison of these scenarios with data from the past 40 years shows that the decline of glacier coverage is expected to accelerate in a nonlinear fashion in the future with faster-increasing temperatures. During the 1970–early 2000 period, the glaciers in the Cordillera Blanca declined more than 25 percent with an average temperature increase of 0.35–0.39°C per decade (Bradley et al. 2009; Racoviteanu et al. 2008; Urrutia and Vuille 2009; Vuille et al. 2008). Naturally, it is not only warmer temperatures that cause glacier melting. Other variables, such as humidity and precipitation, also play critical roles in the process (Bury et al. 2010)