1.7

• How is climate change likely to affect global water availability?

  Climate change will increase rainfall in some areas, reducing water scarcity, while causing deficits and drought in others. Drought impacts include reduced precipitation, lower water storage in soils, rivers, and lakes, higher reliance on groundwater, and increased evaporation rates.
• Why is the Sahel region an example of a potentially positive impact of climate change?

  The Sahel, located on the southern edge of the Sahara, receives 100–600 mm of annual rainfall, mostly during the July–September monsoon. After severe droughts in the 1970s and 1980s, rainfall has increased since 1996, raising hopes for "re-greening" and turning degraded land back into farmland.
• What drives global climate patterns and how do oceans play a role?

  Global climate is mainly driven by atmospheric circulation, especially large cells like the Walker Cell over the Pacific. Surface winds move ocean currents, which in turn influence climate. These interactions help regulate weather and precipitation patterns globally.
• What is the El Niño-Southern Oscillation (ENSO) and how does it affect climate?

  ENSO describes pressure changes between Darwin (Australia) and Easter Island. A sharp drop in pressure difference signals the start of El Niño, which disrupts wind patterns and ocean currents. It weakens or reverses the normal east-to-west Walker Cell circulation, causing floods in normally dry areas and droughts in wet ones.
• How are La Niña and El Niño different in terms of global effects?

  In a normal year, trade winds blow warm water westward across the Pacific. During La Niña, these winds strengthen, increasing rainfall in the western Pacific and cooling the east. El Niño weakens these winds, warming the eastern Pacific and shifting rainfall eastward, causing floods and droughts globally
• How might climate change affect the frequency and intensity of ENSO events?

  Climate change may make both El Niño and La Niña more frequent and intense. The warming planet increases ocean temperatures and disrupts air pressure systems, leading to greater unpredictability. This may result in more extreme weather swings—floods following droughts and vice versa—especially in Pacific regions.