Answer to Question 1
There is plenty of climate history that supports this idea. We know that large
changes in the ocean conveyor have occurred. GISP ice cores have revealed swings of 16 C
within a decade in Greenland. The idea of flickering climate is e testament to how
extensive the evidence is.
Answer to Question 2
In any reaction, bonds may be made or broken. What determines whether it is
exothermic or endothermic is whether more energy has gone into making or breaking
bonds. Therefore, the statement is correct.