Choose the correct statement from A, B, C, D to complete the following sentence:
The permafrost-carbon feedback loop accelerates global temperature rise because...
thawing of frozen arctic soils allows microbial decomposition of ancient organic matter, releasing carbon dioxide and methane into the atmosphere.
the physical collapse of thawing ground increases geothermal heat flux from the Earth's interior directly into the lower atmosphere.
warmer soils accelerate the chemical weathering of silicate minerals, which rapidly converts carbonate rocks into atmospheric carbon dioxide.
melting permafrost increases the rate of transpiration in boreal vegetation, drastically reducing the concentration of atmospheric water vapour.
18 exam-style questions on OCR A GCSE Geography Causes of climate change. Each one has a worked solution and a mark scheme showing where the marks go.