2.1.5 Part 2: Amazon Rainforest Case Study

How much of its own rainfall does the Amazon Rainforest generate through evapotranspiration?

Approximately 40–50% of its regional rainfall.

What meteorological changes are causing dry season lengthening in the Amazon?

Mean temperatures have risen by ~1°C in 50 years, and warmer Atlantic sea surface temperatures shift the ITCZ, extending dry seasons by 3–4 weeks in southern/eastern zones.

Name three major extreme drought years in the Amazon over the last two decades.

2005, 2010, and 2015–16 (linked to strong El Niño conditions).

How did soil moisture drop during the 2010 Amazon drought?

Satellite and ground measurements recorded soil moisture levels falling 20–30% below average across vast areas.

Explain the positive feedback loop between drought and vegetation in the Amazon.

Moisture stress causes tree dieback → reduces canopy transpiration → lowers atmospheric humidity → suppresses rainfall → intensifies drought.

How many trees were damaged or killed during the 2010 Amazon drought?

An estimated 2.2 billion trees.

Define "savannisation" in the context of the Amazon.

The potential tipping point where combined climate change and deforestation permanently transform rainforest into seasonally dry tropical savannah.