Thought Questions

Question 15.8

Give an example not discussed in this chapter of a positive feedback and a negative feedback in the climate system.

Question 15.9

Do Milankovitch cycles fully explain the warming and cooling of the global climate during the Pleistocene glacial cycles?

Question 15.10

How would the calcium cycle be affected by a global increase in chemical weathering?

Question 15.11

Draw a simple diagram of the geochemical cycle for the element sodium, which is found in marine evaporites (halite) and clay minerals as well as dissolved in seawater.

Question 15.12

What would the carbon cycle have looked like after life had originated, but before photosynthesis had evolved?

Question 15.13

If human activities keep pumping CO2 into the atmosphere at a steadily increasing rate and Earth’s climate warms significantly in the next 100 years, how might the global carbon cycle be affected?

Question 15.14

Why are scientists reasonably sure that most of the twentieth-century warming was due to changes in the climate system caused by human activities?