Climate change and PNG Agriculture Presentation: PNG Update 14 June 2018 Dr Mike Bourke OL (PNG) College of Asia and the Pacific The Australian National University, Canberra Email: mike.bourke@anu.edu.au
Greenhouse effect Our planet is a natural greenhouse Keeps temperatures relatively stable Now more CO2, methane and N20 Extra atmospheric gas from human activity CO2 from fossil fuel, loss of forests Methane from rice cult., sheep, cattle Extra gases result in heating, sea level rise and changes in climate
Evidence for climate change in PNG Temperature increase in highlands greater than global mean (1.0 oC/30 years) Sea level rise (coastal; islands) Changes in rainfall, especially seasonal Some locations wetter; others dryer Possible increase in cloud cover
Crop altitude data Comprehensive dataset on the altitudinal range of 230 crop species available Data mostly recorded in 1979 to 1984 Changes in altitudinal limits is a surrogate for temperature change Bourke, R.M. (2010). Altitudinal limits of 230 economic crop species in Papua New Guinea. In S.G. Haberle, J. Stevenson and M. Prebble (eds). Altered Ecologies: Fire, Climate and Human Influence on Terrestrial Landscapes. Terra Australia 32. ANU E-Press, The Australian National University, Canberra. pp473-512. http://epress.anu.edu.au/wp-content/uploads/2011/02/ch271.pdf
Evidence for temperature increase in PNG highlands 1. Increase in recorded temperature, Aiyura 2. Coconuts in highlands bear nuts up to: 1310 m (1979) 1450 m (1999) 1560 m (2009) 1620 m (2015)
Impact of sea level rise in coastal areas of PNG Widespread anecdotal evidence, including: coastal erosion on most islands loss of coastal land relocation of villages sea level intrusion to fresh water lens on atolls (eg Mortlock Islands, AR Bougainville) damage to swamp taro (Cyrtosperma)
Impacts of CC on rainfall and cloud cover in PNG over past 30 years Changes in rainfall patterns Complex pattern Seasonal changes (since late 1980s) Some locations wetter; others dryer Longer data runs needed Possible increase in cloud cover
Likely impacts of climate change in coming decades Impact from: Sea level rise Temperature increase Rainfall (total and seasonal) Cloud cover Changes to El Nino/La Nina frequency?
Most vulnerable environments to impact of climate change Analysis of most vulnerable environments: Atolls (sea level incursion/coastal erosion) Other small islands (>100,000 people) Central highlands (1600-2200 m asl) V. high altitude highlands (2200-2800 m)
Vulnerability of highlands Highlands (1600-2200 m) excellent environment for agriculture Temperatures optimal for soil organic matter breakdown and nutrient release Temperatures at 1600-1800 m changing to those at 1200-1400 m Changing to much poorer environment Consequences for agricultural production
Population by altitude
How to reduce impact of CC Limited migration to other locations Increase cash income for villagers New food crops (very few available) Greater availability of relatively fast maturing crops (corn, sweet pot., potato) Cultivars more tolerant of rainfall extremes Especially sweet potato, banana, taro, yam, corn, cassava, potato
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