2.8

• What caused rapid deforestation in Madagascar, and how much forest was lost by 1985?

  Driven by demand for tropical hardwood, population growth, and the need to repay debt, farmers cleared land for cash crops. By 1985, two-thirds of Madagascar’s forest was gone.
• How does deforestation in Madagascar affect the water cycle?

  It reduces infiltration and rainfall, increases runoff, erosion, sediment in rivers, flood peaks, and shortens lag times.
• How does deforestation impact soil health in Madagascar?

  It leads to nutrient loss from leaching and erosion, loss of biomass, and releases CO₂ from decaying wood.
• What are the impacts of deforestation on the biosphere and atmosphere?

  It reduces biodiversity, evapotranspiration, and carbon storage, while increasing sunlight on the forest floor and decreasing humidity and oxygen.
• What land use changes occurred in the American Midwest between 2007–2015?

  Over 5.5 million hectares of grasslands were converted to biofuel crops, equal to deforestation rates in Brazil, Malaysia, and Indonesia.
• What are the benefits of natural grasslands for carbon and water cycles?

  They store carbon, trap moisture, reduce flooding, maintain soil health, filter toxins, and support biodiversity.
• What are the negative effects of converting grasslands to biofuel farming?

  It releases CO₂, increases erosion, reduces soil carbon, and requires fertilisers, pesticides, and irrigation, reducing natural habitats and the “lung effect”.
• What is afforestation and how does it help counter climate impacts?

  Afforestation is planting trees on previously non-forested land, helping restore carbon storage and reduce atmospheric CO₂
• How has the ocean absorbed CO₂ since the 1800s, and what has been the effect?

  Oceans absorbed 30% of human CO₂ and 50% from fossil fuels. This lowers ocean pH, leading to acidification.
• Why is ocean acidification a threat to coral reefs?

  Acidification lowers pH, which can dissolve coral skeletons. Combined with warming seas, it causes coral bleaching and reef collapse.
• What are the wider consequences of coral reef degradation?

  It threatens biodiversity and removes vital ecosystem services like food supply, tourism, and coastal protection.
• How has drought affected the Amazon, and what risks does it pose?

  Droughts in 2005, 2010, and 2014/15 killed trees and reduced growth, halting its role as a carbon sink. Fires released CO₂, threatening a shift to a carbon source.