Radiocarbon dating assumes that the abundance of \({ }^{14} \mathrm{C}\) in the environment has been constant. Suppose \({ }^{14} \mathrm{C}\) was less abundant 10,000 years ago than it is today. Would this cause a lab using radiocarbon dating to overestimate or underestimate the age of a 10,000-year-old artifact? (In fact, the abundance of \({ }^{14} \mathrm{C}\) in the environment does vary slightly with time. But the issue has been well studied, and the ages of artifacts are adjusted to compensate for this variation.)