Climate change and the impact on taro in Papua New Guinea

In this paper we present a brief summary of recent historical climate of Papua New Guinea (PNG), finding that rainfall has been increasing greatly compared to pre-1995 levels, but that temperature has only been rising at a moderate rate. We then examine the 5 climate models used in this study from the Inter-governmental Panel on Climate Change (IPCC) / ISIMIP / CMIP3b, discovering one – IPSL – which best reflects the climate trends noted in PNG since 1995. The climate model projections show that temperature changes in PNG are expected to be less than most other places in the world and precipitation changes in PNG are projected to be higher than most other places in the world. Despite noting that IPSL seems to best represent climate changes observed thus far, we use all 5 climate models in the DSSAT crop model for taro, investigating how each climate model will lead to changes in taro yields at each half-degree pixel. In the aggregate, we find that the IPSL model leads to the greatest projected reduction in taro yield at -6.4% for the nation, with Southern region projected to have greater than 10% yield reduction for taro. Across the 5 climate models, the median across model results suggest only a 1.6% yield reduction, while the most optimistic model projects a 4.4% gain. Because of uncertainty across climate models and different impacts across regions, as well as potentially increasing climate variability which would lead to more extreme events including droughts and floods, we recommend developing a suite of options to help farmers navigate future climate uncertainty. For example, developing and testing crop varieties that would offer better yields whether the future is wetter or drier, as well as varieties that are less sensitive to temperature extremes. These could include new varieties of taro but might also include alternative crops and farming techniques designed to protect the plants during ad-verse climate events.