Water, carbon, climate and life on Earth: Practice Questions

• a.

  It is a positive feedback loop where warming melts permafrost and hydrates, releasing methane that further enhances the greenhouse effect.

• b.

  It is a negative feedback loop where the release of methane triggers high-latitude precipitation that accelerates the carbon burial rate.

• c.

  It is a positive feedback loop where higher temperatures lead to increased cloud cover, reflecting solar radiation and cooling the Arctic.

• d.

  It is a negative feedback loop where increased methane release stimulates microbial growth that sequester more carbon.

• a.

  Increased precipitation enhances the rate of carbonation weathering, removing more \(CO_{2}\) from the atmosphere into river systems as bicarbonate ions.

• b.

  Increased precipitation always leads to higher rates of forest combustion, which releases more carbon into the atmosphere.

• c.

  Increased precipitation saturates soils, preventing the diffusion of \(CO_{2}\) and leading to a build-up in the atmosphere.

• d.

  Higher rainfall levels reduce the salinity of the ocean, which in turn decreases the solubility of carbon in surface waters.

• a.Higher atmospheric \(CO_{2}\) concentrations immediately increase the water-use efficiency of remaining trees, leading to a rapid rise in groundwater levels.
• b.Decreased albedo of the cleared land reflects more solar radiation, leading to a cooling effect that promotes cloud formation and restores rainfall.
• c.Reduced evapotranspiration leads to less regional rainfall, causing further forest dieback and increased carbon release through decomposition.
• d.Increased soil moisture from lack of tree uptake leads to higher rates of photosynthesis in remaining grasses, cooling the local climate.

Write your answer out first, then check it against the worked solution.

Write your answer out first, then check it against the worked solution.

Write your answer out first, then check it against the worked solution.