More methane cuts needed to avoid further warming - study/NZ Herald

The world's press is hotly reporting on our pressing need to cut emissions.  Methane levels are, many times, left out of the conversation or misunderstood.  Here we get a clear warning on their impact on the environment.



Methane accounts for nearly half of New Zealand's greenhouse gas inventory, and much of it is belched from sheep and cattle. Photo / File

Keeping New Zealand's methane emissions to today's levels won't be enough to prevent further global warming, new modelling has shown.

Research released today by Parliamentary Commissioner for the Environment Simon Upton comes amid debate around how - or whether - the greenhouse gas should be covered by the Government's proposed Zero Carbon Act.

The three options on the table are forcing carbon dioxide (CO2) and nitrous oxide (N2O) down to zero by 2050; doing this while also stabilising shorter-lived gases like methane; or requiring all gases to be reduced to net zero by the mid-century deadline.

But the new modelling, led by leading agricultural greenhouse gas expert Dr Andy Reisinger, suggested that simply holding the line on current livestock emissions wouldn't a"It shows that holding New Zealand's methane emissions steady at current levels would not be enough to avoid additional global warming," Upton said.

The work indicated that, to ensure methane from livestock contributed no additional warming beyond current levels, emissions would need to be cut by at least 10 to 22 per cent below 2016 levels by 2050, with further reductions of between 20 and 27 per cent by 2100.

It also found that "holding livestock methane steady at 2016 levels would cause additional warming of 10 to 20 per cent above current levels."

The research didn't show what would need to happen to methane flows if New Zealand wanted to hold global warming to 1.5C above pre-industrial levels, which was the aim of the Paris Agreement."

Methane - accounting for nearly half of New Zealand's greenhouse gas inventory - was a relatively short-lived gas and most of it broke down within a few decades.

Livestock methane - mostly belched from sheep and cattle - accounted for 85 per cent of New Zealand's methane emissions.

The remainder came from waste landfills and wastewater treatment (11 per cent), and extraction and use of fossil fuels for energy generation and industrial processes (3 per cent).

Most of the warming caused by methane emissions occurred during the first few decades, though some warming lingered for centuries after the emissions themselves had disappeared.vert more warming.