What is the fine-grained topic of the following text: We suggest that 1880-1920 is a good choice for “preindustrial” base period; alternative choices would differ by only about ±0.1°C, and 1880-1920 has the advantage of being the earliest time with reasonably global coverage and reasonably well-documented measurement technology. Only return the topic.
Choosing 1880-1920 as the "preindustrial" base period for climate measurement technology.