Work needed on climate change targets

(AAP file)
(AAP file)

The emissions targets agreed to last year at COP21 in Paris may need to be tweaked, a team of scientists say.

Led by Andy Reisinger from the New Zealand Agricultural Greenhouse Gas Research Centre, the team of New Zealand and European scientists examined the commonly-used 100-year global warming potential model.

Long-term pollutants such as carbon dioxide, and short-term pollutants such as methane and soot, have differing effects on the climate. The current greenhouse gas targets measure the cumulative effect of the pollutants.

When examining the effect on the climate 20 to 40 years after the emission, the 100-year model works, Dr Reisinger says.

For the targets to be effective short- and long-term pollutants need to be measured separately.

To maintain temperature balance in the long term, the level of long-term pollutants need to be reduced to zero. But short-term pollutants don't need to be completely cut out -- only stabilised.

"The conventional use of [the 100-year model] to compare pulse emissions of all gases is an effective metric to limit peak warming if and only if emissions of all climate pollutants, most notably CO2, are being reduced such that temperatures are expected to stabilize within the next 20–40 years," Dr Reisinger says in the report.

"This expected time to peak warming will become clear only when CO2 emissions are falling fast enough to observe the response."

The study was published in the Springer Nature journal today.