ABSTRACT
The rise in the presence of the so-called greenhouse gases (GHG) in the Earth’s atmosphere experienced in the past decades has caused a rise in the amount of heat from the sun withheld in it. This greenhouse effect has resulted in climate change, which is expected to increase average global temperature (global warming) and produce effects such as changes in cloud cover and precipitation, a rise in sea levels, melting of ice caps and glaciers and more frequent and severe extreme weather events. Thus, the rate of warming averaged over the last 50 years (0.13 °C ± 0.03 °C per decade) is nearly twice that for the last 100 years (IPCC, 2007). According to recent studies, some extreme weather events have changed in frequency and/or intensity over the last 50 years (Durack et al., 2012). There are suggestions of increased intense tropical cyclone activity in some regions (Webster et al., 2005) and emerging evidence of increased variability of climate parameters such as temperature and precipitations (Seager et al., 2012). There is also high confidence that hydrological systems are being affected due to increased runoff and earlier spring peak discharge in many glacier- and snow-fed rivers (Diffenbaugh et al., 2012). Melting of ice sheets, glaciers and ice caps has accelerated (Joughin et al., 2012) and, globally, sea levels have raised an average of 18 cm since the late 19th century at an accelerating rate of rise (Cazenave and Llovel, 2010).
