Today there is increasing concern that biodiversity is being lost through human activity with respect especially to pollution and habitat disturbance, and that future global warming may cause rapid species migration and invasions on the one hand and range reductions and extinctions on the other, the consequences of which, in terms of ecosystem function and human livelihoods, are unknown. The starting point for most biodiversity research is the examination of present-day patterns and distributions.
However, contemporary biodiversity patterns are only a snapshot in time, the outcome of many processes acting and interacting dynamically on different time-scales. Understanding the present therefore also needs insights into the past. Our ability to track changes through time is compromised for many ecosystems by the rarity and brevity of long-term ecological records. For some ecosystems, on the other hand, it is possible to embrace the potential of palaeoecological techniques especially where they can be complemented by long-term observational records.