How climate change will affect Papua New Guinea


Bob Hansen, MD of major agribusiness Mainland Holdings, considers the threats and opportunities to Papua New Guinea from climate change.

Cattle stranded due to flooding. Credit: Bob Hansen

Cattle stranded due to flooding. Credit: Bob Hansen

The climate is changing and most of us are aware of this fact. The earth has gone through very warm periods (22°C some 50 to 70 million years ago) and very cold periods (6°C some 600,000 years ago). The average global temperature is currently 14°C.

Historically, most of this variation was caused by the elliptical orbit the earth takes around the Sun or by the release of carbon by extreme volcanic periods such as the uplift of the Himalayas 60 million years ago. By studying the effects of these historical events, we have a good understanding of what the impacts of rising global temperatures caused by the release of carbon may have for the future of the Earth, and thus the impacts on industry.

Climate projections

Mainland's Bob Hansen

Mainland Holding’s Bob Hansen

The history of Climate Science is relatively recent. The first scientist to publish on the subject was probably Svante Arrhenius who, in 1896, postulated that ‘the human emission of carbon dioxide would be strong enough to prevent the world entering a new Ice Age’. Arrhenius’ greenhouse law is still used today.

More recently, the 1979 report by the United States National Academy of Science predicted that carbon dioxide in the atmosphere would double from its pre-industrial levels by about 2035. (Today, it’s expected this will happen by about 2050, depending on the scenario or model.)

A doubling of carbon dioxide would lead to an average warming of the planet of 2°C to 3°C. The polar regions would warm by approximately 12°C and the tropics by less than 1°C. These predictions are already coming true, with record meltings of the Arctic Sea ice during summer.

More recently again, the Intergovernmental Panel on Climate Change models predict a global average warming of 1°C to 4°C by 2100.

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The impact on PNG’s climate

The 2011 Pacific Climate Change Science Program report found that, for Papua New Guinea,

  • Temperatures would rise by between 0.4°C and 1.0°C by 2030
  • Annual rainfall would increase, with more extreme rainfall events
  • Sea levels are rising at 7.0 mm a year in the vicinity of PNG, double the global average of 2.8mm to 3.5mm a year.
  • The sea level is affected by the phenomena El Nino-Southern Oscillation. This is a rise of 140mm in the last 20 years.

Implications for PNG’s economy

Flooding along the Erap River in Morobe Province. Credit: Bob Elvin

Flooding along the Erap River in Morobe Province. Credit: Bob Elvin

The impacts of these forecasted changes are many and significant. Some of those changes are:

  • Increasing incidence of malaria in the Highlands (Mueller, 2007), now an annual event.
  • Regions like Lae will be wetter and therefore the Lae roads, Highlands Highway and Wau/Bulolo road will require increased maintenance due to wash outs. The rainfall in Lae PNG (see chart below) has increased by approximately 500mm per annum or nearly 11%. This is consistent with projected rainfall for the tropics (Seager 2007 and IPCC 2007) and rainfall trends in Northern Australia.
  • The production region for coffee and cocoa may expand with increased rainfall but there will also be increased disease challenges with the higher humidity in current production regions.

Civil engineers will need to take into account the increased river flows in road and bridge designs, as wash-outs will increase.

  • Rubber farming may become unviable as the latex is washed out of the cups on the trees.
  • Palm oil production (Duncan 2007) will benefit from the increased precipitation and the viable production areas will possibly expand. Palm oil production will be a potential winner from Climate Change.
  • The price of agricultural commodities will rise and be more volatile, as there will be increased demand and more weather events (too dry or too wet) impacting on the supply chain dynamics.
  • Increased rainfall will raise river levels in the Sepik River, which could affect the supply of crocodile eggs and hatchlings.
  • Civil engineers will need to take into account the increased river flows in road and bridge designs, as wash-outs will increase.
  • The increased atmospheric carbon will benefit those crops that are C4 convertors such as maize, sorghum and sugarcane will be favoured and C3 convertors such as wheat and rice will be subject to yield declines.
  • Sea level rise will impact coastal communities. Houses and gardens will have to be moved to higher ground if possible and island communities relocated to the PNG mainland. These will create social problems for many of these communities. A good example is the Salamaua Isthmus in Morobe Province, which has been substantially eroded in the last 20 years.
Lae's rising rainfall from 1950–2011. Credit: R Dawson

Lae’s rising rainfall in millimetres, from 1950–2011. Credit: R Dawson

In summary, the impact of climate change will have significant financial implications for PNG. There will be winners and losers and they are not all apparent presently. Additional budgetary funds will be required for infrastructure upkeep and relocation of infrastructure.

In addition to his role as Managing Director of Mainland Holdings, Bob Hansen is an Adjunct Associate Professor at the University of Southern Queensland’s Australian Centre for Sustainable Business Development.


  1. How is this going now? What’s changed? Anything improved? Anything got worse? What are the economic, social and ecological impacts ?

  2. Kennedy Sanis says

    In response to bulletpoint #3, oil palm companies may take advantage of wetter climate conditions however on the other hand the chances of disease affection occurrence maybe possible

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