Climate Change and Variability Questions and Answers

Answer: A

The four are distinct and confusing them muddles the policy discussion badly. Committed change is the reason adaptation is necessary whatever is done about emissions. Each term has a precise meaning. Confusing them muddles the policy discussion.

Answer: B

The ocean has not yet come into equilibrium with the forcing already applied, so warming would continue for some decades. This is why adaptation cannot be avoided by mitigation alone. The ocean lags the forcing by decades.

Answer: C

Both are true and the reason gives the necessity, and the two responses address different parts of the problem rather than being alternatives. Commitment makes both necessary. Neither substitutes for the other in practice.

Answer: D

Correct answer: reduce sunlight without addressing the cause

Stratospheric aerosol injection would mimic a large volcanic eruption, scattering some sunlight back to space and cooling the surface. It leaves the carbon dioxide concentration exactly where it was, so it treats the symptom rather than the cause - with all the consequences the next item lists.

Answer: A

Correct answer: 1 and 2 only

Statements 1 and 2 are correct: it addresses the symptom, and because the carbon dioxide remains, the ocean continues to absorb it and acidify regardless. Statement 3 is the opposite of the truth - the aerosol falls out within a couple of years, so the cooling must be sustained indefinitely, and stopping it after decades would release the accumulated warming very rapidly. That termination shock is the strongest argument against relying on it.

Answer: B

Each step depends on the one before, and attribution cannot precede detection. Skipping the variability estimate is what makes a claimed trend unconvincing. Each step rests on the last. Reversing any pair makes the argument invalid.

Answer: C

Correct answer: True

Extreme event attribution compares the probability of the observed event in the world as it is with its probability in a counterfactual world without anthropogenic forcing, using large ensembles of model simulations. The result is a change in likelihood - a heatwave made a certain number of times more probable - rather than a yes or no verdict, and the confidence varies greatly by event type, being high for heat and much lower for events driven by small-scale convection.

Answer: D

The gas with the highest global warming potential is N₂O.

Global warming potential (GWP) compares the warming caused by a mass of gas over a time horizon, usually 100 years, with the same mass of CO₂, which is defined as 1. Over 100 years, nitrous oxide has a GWP of roughly 270 to 300 because it absorbs strongly and lasts more than a century in the atmosphere. Methane's GWP is about 28 to 30: it absorbs strongly but survives only around a decade.

CO₂ is the reference, GWP 1. Water vapour is not usually assigned a GWP, because its concentration is set by temperature and it stays in the air only days; it acts as a feedback rather than a forcing.