Why does CO2’s long atmospheric lifetime matter for climate policy?

• A. CO2 persists for centuries; past emissions continue to affect climate, creating inertia in the system.
• B. Past emissions vanish quickly and have no lasting impact.
• C. CO2 lifetime is irrelevant to policy decisions.
• D. CO2 does not contribute to radiative forcing.

Answer: (A)

The main idea is that CO2 stays in the atmosphere for a very long time, so the climate system has real inertia. When we emit CO2 today, a large portion remains for centuries, so the warming that results from those emissions persists far into the future. Past emissions continue to influence the climate long after they occur, which makes climate change a problem of cumulative emissions rather than just annual rates. This means policy must aim for rapid and sustained cuts now, because delaying reductions lets more CO2 accumulate and lock in more long-term warming. The other statements misstate CO2’s behavior or its role in forcing, so they don’t fit the way long-lived greenhouse gases shape policy decisions.