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examBoard: Cambridge
examType: IGCSE
lessonTitle: Climate Change and Drought Patterns
Climate change is altering how droughts develop and impact different regions around the world. As our planet warms, the water cycle is changing in ways that make some areas more prone to severe dry spells, while others may experience more intense rainfall events.
Key Definitions:
Climate change influences drought in several important ways:
Higher temperatures increase evaporation from soil and water bodies, drying them out faster. Plants also lose more water through transpiration, increasing water demand. Even if rainfall remains the same, the increased evaporation can lead to drier conditions.
Climate change is altering when, where and how much rain falls. Some regions experience less frequent but more intense rainfall, which can lead to more runoff and less water absorption into soils. Other areas see overall decreases in precipitation.
Scientists have observed several worrying trends in drought patterns worldwide:
The world's dry regions are expanding poleward as climate patterns shift. This means areas that weren't historically prone to drought are now experiencing more frequent dry spells. The Mediterranean, parts of Africa, Australia and the southwestern United States are particularly affected.
Many regions are experiencing shifts in when dry and wet seasons occur. This disrupts traditional farming calendars and water management systems. Even if annual rainfall totals remain similar, changes in timing can severely impact agriculture and water supplies.
Understanding the connection between climate change and drought requires looking at several key processes:
For every 1°C rise in temperature, the atmosphere can hold about 7% more moisture. This changes how water moves through the water cycle and affects rainfall patterns globally.
The jet stream high-altitude winds that influence weather patterns is becoming more erratic due to Arctic warming. This can lead to weather systems getting "stuck," causing prolonged dry or wet periods.
Changing ocean temperatures affect weather patterns like El Niño and La Niña, which influence drought conditions in many parts of the world. Warmer oceans can intensify these patterns.
The effects of climate change on drought vary significantly by region:
The Mediterranean basin is considered a "hot spot" for climate change impacts. Models predict a 20% decrease in rainfall by 2100 in some areas, with more frequent and intense droughts. Countries like Spain, Italy and Greece are already experiencing more severe dry periods.
Many parts of Africa are experiencing more variable rainfall and higher temperatures. The Sahel region has seen significant shifts in rainfall patterns, affecting millions who depend on rain-fed agriculture. Droughts in East Africa have become more frequent and severe.
Australia has experienced increasingly severe droughts, including the "Millennium Drought" (1997-2009) and more recent droughts linked to climate change. The country is seeing higher temperatures, reduced cool-season rainfall and more frequent heatwaves.
The southwestern United States and parts of Mexico are experiencing more persistent drought conditions. California's 2012-2016 drought was intensified by climate change, with record-high temperatures increasing evaporation and water demand.
California experienced its worst drought in 1,200 years between 2012 and 2016. While low precipitation was a key factor, scientists determined that climate change made this drought 15-20% more severe through increased temperatures. The drought cost the state approximately $2.7 billion in agricultural losses in 2015 alone and led to the death of over 100 million trees. It prompted unprecedented water restrictions and highlighted the vulnerability of even wealthy regions to climate-change-enhanced drought.
As climate change alters drought patterns, prediction systems are becoming increasingly important:
Modern drought monitoring combines satellite data, ground measurements and computer models to track soil moisture, vegetation health and precipitation patterns. Systems like the European Drought Observatory and the U.S. Drought Monitor provide regular updates on drought conditions.
Scientists use complex climate models to project future drought risks. These models simulate how the atmosphere, oceans and land interact. While they can't predict exactly when a drought will occur, they help identify regions at increased risk due to climate change.
Communities and countries are developing various approaches to cope with changing drought patterns:
Implementing efficient irrigation systems, reducing water leakage and promoting water-saving practices in homes and industries can help communities become more resilient to drought.
Farmers are adapting by planting drought-resistant crop varieties, changing planting times and implementing soil conservation practices that retain moisture.
Building water storage facilities, improving groundwater management and developing water recycling systems can help buffer against drought impacts.
In 2018, Cape Town, South Africa, nearly became the first major city to run out of water. After three years of unprecedented drought, reservoir levels dropped to critical levels and the city prepared for "Day Zero" when taps would be turned off. Through extreme water conservation measures limiting residents to 50 litres per person per day and emergency water management, the city avoided disaster. Climate change had made this drought three times more likely to occur. The crisis highlighted how climate change can push even well-developed urban water systems to the brink.
Looking ahead, scientists project several key trends:
The Intergovernmental Panel on Climate Change (IPCC) warns that limiting global warming to 1.5°C rather than 2°C could significantly reduce the number of people exposed to water stress and drought. This highlights the importance of both adapting to drought risks and mitigating climate change through reduced greenhouse gas emissions.
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