Every blog must have an origin story, so I think it’s best to start the recount of our adventures with the basics: who are we? What are we doing? Where are we doing it? And why?
In short, we are a group of Indonesian and American archaeologists and climatologists who are interested in how people adapted to the constraints of island ecosystems during periods of climatic instability. This is interesting because one of the arguments for changes in culture (like increased interisland voyaging, changes in pottery styles, and changes to agricultural systems) seem to be occurring alongside changes in rainfall, ocean temperatures, and other climate events such as El Nino. Some of our basic research questions involve understanding how closely culture change and climate change are related, a relationship that has implications for us today as global warming drastically alters our environment.
We are interested in getting more climate records for the past 1000-5000 years (if possible!) so that we have a better idea of how people in the past responded to environmental change. What can we use as climate data? Our main proxy for this field season was mangrove cores. Mangroves are hardy, coastal trees that grow throughout the Pacific in brackish swamps that fringe the shore. There are several species of mangrove, and they all respond differently to changes in rainfall. Dry seasons with less rainfall and wet seasons with more rainfall will cause mangrove leaves to produce different chemical signatures (in this case, changes in the proportion of different oxygen isotopes that mangrove trees take up from the rain). Mangrove leaves regularly fall to the ground/swamp surface and decay. Eventually, these leaves will accumulate into various layers (like a layer cake). We can use a special augering tool to pull out a sediment core composed of all these layers of mangrove leaves. These layers can be radiocarbon dated to determine how long ago they were deposited by the mangrove trees, and then the chemical signature can be measured. From these chemical signatures, we can figure out how much relative rainfall that mangrove swamp received during a certain time period.
Where are we doing this kind of research? Our climatologist colleagues have done similar research across the Pacific, but never in Indonesia. Indonesia is really interesting because it has diverse geology – large and small islands and atolls, some without freshwater resources and very little area for agriculture. Indonesia has also played a critical role in terms of its location, nearly all Pacific islands were settled by people who moved through this region, so understanding how long-distance voyagers adapted to different islands is very important to human history in this part of the world. Indonesia is also an area that will be strongly affected by climate change, and any insight that we can gain from the past about how people managed to survive, increase productivity, and create sustainable agricultural practices will be important to the long-term development of the region. Indonesia is also a fascinating area to do research, because so few international teams have done climatological or archaeological research – our team being one of the first to do so in Eastern Indonesia.
And I suppose that answers part of the why – learning about climate change in the past is as close as we can get to predicting and preparing for climate change in the future. The other reason for why we are doing this kind of research is that we find it interesting, and as scientists and humans we are curious. Sometimes curiosity leads to great adventures!