Feedbacks on Earth There are 4 main forcing agents for climate on Earth. Perhaps

Question

Feedbacks on Earth

There are 4 main forcing agents for climate on Earth. Perhaps 5 if you include large impacts which are rare now, but were more common early in Earth's history. There are many feedbacks that control the actual response of Earth's climate to changes in forcings. Many of the responses are nonlinear, which is what makes modelling climate so challenging. The feedbacks pdf goes through a few very simplified responses to change (see course readings 'The Earth System and Climate Forcings and Feedbacks'). I'd like you to work through one of those examples here. A 'thought experiment'. Mantle convection and the resulting plate tectonics is relatively constant, but there are variations and there are changes in the convection patterns that develop and evolve over time.

Scenario (completely fictional, but quite reasonable):

Imagine a plate that includes both oceanic and continental lithosphere is moving along, being dragged by the leading portion of oceanic lithosphere which is being subducted beneath some other continental lithosphere. Finally, all of the oceanic lithosphere is subducted so that a continent-continent collision begins! (Very similar to what would have happened leading up to the India-Eurasian continent-continent collision.)

Before the collision, there would have been a long-lived continental volcanic arc. Once subduction stopped and the collision began, that volcanic arc would terminate once subduction and water release from the subducting plate stopped. On the other side of the incoming continental lithosphere there is still spreading at the ridgecrest, but that spreading has slowed down. The plate is still moving, crumpling up a big mountain belt - but moving slower and slower... So, in that region of the world, there is now no more subduction volcanism, less volcanism/upwelling of magma at the ridgecrest, and a big collision zone has begun to form high mountains.

There are all kinds of different effects this can have on global climate. This is only one region - and for simplicity we will assume that all other processes in all other regions remain constant (probably not true in reality!), but the goal is to think through what effects will be generated by the changes in this region.

Goal

Your goal with this problem is to figure out how climate would respond overall (cooling, warming or no change) to these tectonic/magmatic changes. To do this, consider the various feedbacks discussed here and how they would be influenced by these tectonic/magmatic changes when you work through the following questions. Why or how would a specific feedback respond? What would it affect and how would that affect climate? Over what sort of time interval would each specific feedback occur? (Please note that only a few feedbacks are included here. In reality there would be many more...)

QUESTION 10

Do you think the final result of a continent-continent tectonic collision like the one described in this scenario would lead to a warmer Earth or a cooler Earth? Can you say? (Hint: For part of your answer, think about one of the big assumptions we had to make in order to be able to examine the effects of the individual feedbacks to the area)

Explanation / Answer

due to decrease in volcanic activity, the global climate would cool down over the course of years.

Related Questions

Navigate

• Browse (All)
• Browse F
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.