Question

Which are true about changes in carbon dioxide in the Earth's atmosphere since 1860? Select the two correct answers.(1 point)
Responses

The increases in carbon dioxide are caused by human activity.
The increases in carbon dioxide are caused by human activity.

The increases in carbon dioxide can be explained by the Milankovitch cycle.
The increases in carbon dioxide can be explained by the Milankovitch cycle.

The rate of change in carbon dioxide is exponential.
The rate of change in carbon dioxide is exponential.

The changes are triggered by a new interglacial period.

Answer 1

Correct choices:
- The increases in carbon dioxide are caused by human activity.
- The rate of change in carbon dioxide is exponential.

Brief justification:
- Since ~1860 atmospheric CO2 rose from ~285 ppm to >410 ppm, closely tracking fossil‑fuel emissions. Isotopic evidence (δ13C decline), mass‑balance accounting, and the timing all point to combustion of fossil carbon as the source.
- The Keeling curve shows an accelerating (roughly exponential) rise in CO2 concentration over the industrial era. Milankovitch cycles act on 10^4–10^5 year timescales and cannot explain the rapid post‑1860 increase, nor is the rise due to entering a new interglacial.