Question

Please note that I need answer in 10 minutes . Please post the answer as soon as possible.

Which of the following methods/“things” CANNOT be used to estimate past climate? (i.e are not considered climate proxies?)

Question 1 options:

	Unstable carbon isotopes
	Water fleas
	Diatoms
	Boreholes
	All of the above
	None of the above

2)

Which of the following statement in regards to pollen and diatoms as climate proxies is INCORRECT?

Question 2 options:

	Pollen records have a lower resolution than diatoms
	Pollen and diatoms both have the "no-analogue" present problem
	Diatoms can usually grow under a wider climate conditions than pollen and are therefore not giving a clear climate signal
	Pollen often react(ed) slower to climate changes than diatoms because plants often have a slower life cycle than diatoms.

Answer 1

1. Unstable carbon isotopes

most widely applied proxy in studying past climate change are the stable isotopes ( C₁₂ and C₁₃ / non radioactive isotopes )

radioactive isotopes ( C₁₄) are highly unstable cannot be used to estimate past climate because of their high decay rate

so they are widely applied in dating recently formed natural materials

2.Pollen and diatoms both have the "no-analogue" present problem

No‐analog communities occurred frequently in the past and will develop in the greenhouse world of the future.

the modern pollen and diatom fossil assemblages have no close analog in modern pollen assemblages .