Climate change and PNG Agriculture Presentation: PNG Update 14 June 2018

1. Climate change and PNG AgriculturePresentation: 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

2. 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

4. 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

6. 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

8. 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)

9. 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 (egMortlock Islands, AR Bougainville) • damage to swamp taro (Cyrtosperma)

10. 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

11. 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?

12. 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)

13. 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

14. Population by altitude

15. 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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