According to the global greenhouse gas emission pathways shown, what is the expected temperature increase by 2100 if current policies are followed without additional action?

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BlackTom AI · Accepted Answer

The question asks about the projected global temperature increase by 2100 if current policies are kept, without additional action. We will evaluate each answer choice before identifying the correct one.
Option a: About 3.5°C. This is higher than many mainstream projections under current policies, which typically estimate around 2–3°C. The 3.5°C figure would imply more stringent policy action or more aggressive warming, so this answer overestimates the outcome given “current policies” as stated.
Option b: About 2.1°C. This falls within a plausible mid-range for some scenarios, but it is slightly lower than the commonly cited central estimate for business-as-usual trajectories, which tends to hover around 2.5–3°C depending on the model ensemble and assumptions. It does not match the most widely reported value for current policies.
Option c: About 1.5°C. This would correspond to a much more ambitious policy path, closer to the targets of limiting warming to 1.5°C or a scenario with substantial near-term action. Under “current policies” alone, this level of warming is not supported.
Option d: About 4.1–4.8°C. This represents a high-end warming range, typically associated with significant policy gaps or extreme assumptions, not the baseline for current policies. It is substantially higher than standard projections for current actions.
Option e: About 2.5–2.9°C. This range aligns with widely cited estimates of warming by 2100 under current policies (often around 2.5–3°C depending on emissions curves and climate sensitivity). It matches the commonly reported central tendency for a business-as-usual trajectory without new measures.
In sum, each incorrect option either underestimates or overestimates the expected warming relative to the established projection for current policies, while option e accurately reflects the standard estimate endorsed by many climate assessments. The reasoning shows why the other choices do not correspond to the current-policy scenario and why the 2.5–2.9°C range is the appropriate fit.

CCST9086_1A_2025 Quiz6

According to the global greenhouse gas emission pathways shown, what is the expected temperature increase by 2100 if current policies are followed without additional action?

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