Australia pumped out an extra six months’ worth of emissions than previously recorded | Australia news

The Australian government has acknowledged it previously underestimated the country’s greenhouse gas emissions and has increased the official estimate for every year on record.

Revised data in the latest quarterly emissions update shows Australia pumped out the equivalent of 272.5m more tonnes of heat-trapping gas between 2000 and 2020 than suggested in the last report three months ago.

It adds about six months’ worth of emissions to the national accounts, pushing up emissions by 2.3% a year, on average. The full increase is likely to be greater as the report does not include data for before 2000.

As reported by Guardian Australia last year, the change reflects agreement from scientists that methane – a highly potent but short-lived gas that leaks during gas extraction and processing – plays a greater role in warming the planet than previously understood.

The Greens leader, Adam Bandt, said it showed that the use of gas was “cooking the planet”.

“When the real pollution from methane is taken into account, it is clear that the Liberal and Labor-backed Narrabri and Beetaloo gas developments [in New South Wales and the Northern Territory] must be immediately stopped,” he said.

In annual terms, the report finds national emissions fell 4.4% in the year to September 2020, reflecting both the continuing rise of solar and wind energy and the impact of Covid-19 restrictions.

Emissions from electricity generation were down 4% over that period, continuing a trend that began before the pandemic struck.

Falls in other parts of the economy were more circumstantial, and are more likely to be wiped out by emissions increases in the year ahead.

Transport emissions dropped 10.2%, fugitive emissions released during fossil fuel extraction were down 7.3% and agriculture emissions fell 2.5%.

The first two were affected by the pandemic. Agriculture emissions continued to be hit by the long-term drought, which forced farmers to significantly cut livestock numbers and reduce the amount of fertiliser used on crops.

An independent analysis by energy expert Hugh Saddler suggested much of the recent fall in emissions was likely to be reversed as Covid restrictions eased and farming recovered. He said this was because there were no meaningful national policies to reduce pollution from transport or agriculture.

The emissions reduction minister, Angus Taylor, said emissions were at the lowest level since 1995, and acknowledged the data reflected both long-term structural change and temporary drops.

He said transport emissions had begun to increase again in the most recent quarter measured (to September last year).

The minister said Covid-affected national emissions were now 19% below 2005 levels, and the government was on track to “meet and beat” its commitment under the Paris agreement – a 26-28% cut by 2030.

This is at odds with official projections released in December, which suggested current measurable policies would lead to a 22% cut between 2005 and 2030.

Tim Baxter, a senior researcher with the Climate Council, said the government could take “zero credit” for the emissions reduction shown in the latest data as it was driven by the pandemic and state government-backed wind and solar projects.

“Every state and territory has a net zero emissions target and is embracing clean, affordable renewable energy,” he said. “The federal government should be supporting this change instead of planning to spend billions of public dollars on polluting, unnecessary gas projects.”

The Morrison government is facing international pressure to do more over that timeframe, in line with the latest climate science and the goals of the Paris climate agreement.

Britain and the European Union have set targets of a 68% and 55% cut by 2030 compared with 1990 levels. The new US president, Joe Biden, has promised he will announce a 2030 target before hosting a leaders’ summit on climate in late April and China is also expected to say more about its plans before then.

Scott Morrison has said he will not lift Australia’s 2030 target, which is well below what experts believe is necessary for the country to play its part in addressing the problem.

The overall increase in Australia’s official emissions data follows an acknowledgement that methane has a “warming potential” 28 times greater than CO2, up from a previous estimate of 25 times. The change matters because methane emissions are converted to their “CO2 equivalent” before being counted in national emissions.

Baxter said this still understates the problem. A 2014 report by the Intergovernmental Panel on Climate Change suggested the warming power of methane from fossil fuels was actually 30 times greater than CO₂. The warming power of “biogenic methane” – released from living organisms such as cows – was 28 times greater.

A later reassessment, published in the journal Geophysical Research Letters in 2016, found it was greater still: 34 times greater than CO₂ for “fossil methane” and 32 times greater for biogenic methane. Baxter said even these figures were still not truly representative as they did not factor in the feedback effects caused when greenhouse gases are released.

One of the ramifications of Australia acknowledging it has previously underestimated its emissions is that it increases how much the country can put into the atmosphere while still hitting its climate target.

Previously, the data said the country emitted 615.5m tonnes in 2005, the year against which cuts are measured. Under the revised data, that has now leapt to 630.1m tonnes.

Because the 2030 target is relative, the amount that can be emitted to meet the goal increases too.

For example, three months ago a 26% cut would have put Australia at 455.5m tonnes in 2030.

Now the country can release 466.3m tonnes in that year and still claim to be meeting its target despite contributing more to the problem.

The overarching goal under the Paris agreement is to reach net zero emissions.