Fig. 22.1 shows the effects of climate change on different regions of the world. Tropical cyclones are powerful rotating storm systems that form over warm o...

(a) Two effects of climate change on polar regions [2]

1. Ice sheets and glaciers in the Arctic and Antarctic are melting, which contributes directly to rising global sea levels as meltwater flows into the oceans. [1]
2. Polar habitats are being lost as sea ice shrinks, threatening species such as polar bears and penguins that depend on ice platforms for hunting, breeding, and resting. [1]

(b) How sea level rise threatens small island nations [3]

1. Permanent flooding: Sea level rise threatens to permanently flood low-lying areas of small islands, reducing the total habitable land area available for homes, agriculture, and infrastructure. Many small island nations have maximum elevations of only a few metres above sea level. [1]
2. Freshwater contamination: Saltwater intrusion into freshwater aquifers contaminates drinking water supplies. As sea levels rise, saltwater pushes further into underground freshwater reserves, making them brackish and unsuitable for consumption or irrigation. [1]
3. Infrastructure damage: Coastal infrastructure, including homes, roads, airports, and harbours, is damaged by increasingly frequent flooding and accelerated erosion. For some island communities, relocation to higher ground or other countries may become the only option for long-term survival. [1]

(c) How climate change can lead to increased drought and famine in Sub-Saharan Africa [3]

1. Altered rainfall patterns: Changes in atmospheric circulation patterns mean that some regions receive less rainfall overall, or experience longer and more severe dry seasons, reducing water availability for both people and agriculture. [1]
2. Increased evaporation: Higher temperatures increase evaporation from soils, lakes, and rivers, reducing the amount of water available for crops and livestock even when some rainfall occurs. This intensifies water stress on agricultural land. [1]
3. Crop failure and famine: Crop failures due to prolonged drought lead to food shortages and famine, particularly in communities that depend heavily on rain-fed agriculture and lack irrigation infrastructure or food reserves to buffer against poor harvests. [1]

(d) How climate change is linked to more intense tropical cyclones [2]

1. Warmer sea surface temperatures provide more energy (both heat and moisture) to developing tropical cyclones, fuelling their growth and intensification. [1]
2. This extra energy allows cyclones to intensify more rapidly and reach higher sustained wind speeds, causing more destructive storm surges and heavier rainfall when they make landfall. [1]

(e) What coral bleaching is and how it is caused by warming sea temperatures [3]

1. What it is: Coral bleaching occurs when corals expel the symbiotic algae (zooxanthellae) that live within their tissues. These algae provide the coral with up to 90% of its energy through photosynthesis and give it its colour. Without them, the coral tissue becomes transparent, revealing the white calcium carbonate skeleton beneath. [1]
2. The trigger: This expulsion is triggered by the stress of abnormally warm water temperatures. Even a rise of 1-2 degrees C above the normal seasonal maximum, sustained for several weeks, can cause the coral-algae relationship to break down. [1]
3. The consequence: If elevated water temperatures persist for prolonged periods, the coral cannot reacquire its algae and eventually starves and dies. The death of coral destroys the reef habitat that supports thousands of marine species, collapsing entire ecosystems. [1]

(f) Why effects of climate change are often more severe in developing countries [2]

1. Developing countries often lack the financial resources and infrastructure needed to adapt to climate change impacts. Building sea defences, developing drought-resistant crop varieties, and improving healthcare systems all require substantial investment that poorer nations struggle to fund. [1]
2. A larger proportion of their population depends on climate-sensitive livelihoods such as subsistence farming and fishing, making them directly and immediately vulnerable to changing weather patterns, crop failures, and shifts in fish stocks. [1]