International visits create climate conundrum

Greenhouse gas emissions generated by visitors' air travel to New Zealand are far greater than commonly quoted, according to new research by University of Otago scientists.

Physics researchers Dr Inga Smith and Dr Craig Rodger say their findings on the sheer size of the emissions and difficulties in offsetting them have far-reaching implications for both the tourism industry and efforts to achieve carbon neutrality.

"Awareness of the environmental impact of long-haul flights is increasingly influencing tourists' destination decisions. As tourism is New Zealand's number one export earner, these findings are cause for some concern," says Dr Rodger.

This trend, when combined with mounting pressure for the inclusion of international aviation emissions in post-Kyoto climate accords, mean the findings should sound a loud and clear wake-up call, he says.

The researchers set out to quantify the contribution of international visitors' air travel to New Zealand's greenhouse gas emissions profile from 1983-2005. Emissions from international aviation are not currently liable under the Kyoto Protocol, but may be in future international agreements.

"Our calculations show that in 2005, the CO2-equivalent emissions from the 2.4 million international visitors' return air flights was nearly 7.9 million tonnes - roughly the same as the emissions from all the country's coal, gas and oil-fired power generation.

"This equates to 10 per cent of the country's Kyoto-liable greenhouse gas emissions for that year. We were surprised by this percentage as it is much higher than the widely quoted world average, even considering New Zealand's geographical isolation" says Dr Rodger.

The researchers then went on to evaluate the feasibility of potential measures to offset the emissions to make the visitors travel carbon-neutral.

"We investigated several domestically-based offsetting scenarios involving either increased reliance on sustainable energy sources or reducing emissions. Unfortunately, none of the scenarios currently appear to be economically or technically feasible," says Dr Smith.

For example, the installation of 4,250 one megawatt wind turbines to replace existing fossil fuel-based power generation would offset the visitors' emissions, but only at a cost of at least $10 billion, or $4,150 per visitor, she says.

"Such a switch would be highly challenging both in cost and finding acceptable places to put them."

Replacing current fossil-fuel generation with more efficient technology would be similarly problematic. More than eight combined-cycle gas-turbine plants would need to be built, she says.

Installing 248 million energy-efficient light bulbs - working out at 105 per visitor - could also offset the emissions, but is obviously unrealistic within New Zealand households, she says.

Alternatively, regenerating 26,000km2 of bush offsets the emissions. However, this would require an area the size of 15 Stewart Islands, she says.

"This means increasing New Zealand's forested area by a third, a move which would probably require halving the amount of land used for pasture – again, an approach that would be severely disruptive economically."

Another offsetting measure they quantified was cutting back the use of land transport.

"Achieving the required emissions reduction would involve on average taking almost two-thirds of all New Zealand's vehicles off the road. Clearly, that is not an option."

Dr Rodger says that while the solutions may not be obvious, the message is clear.

"As a country we need to think seriously hard and come up with meaningful offsetting strategies if tourism is to remain a cornerstone of the New Zealand economy.

"The technology to do this does not exist today. Some combination of approaches in the future may well work, but this will require significant research efforts combined with societal changes."