The Coalition plans to spend its $2bn “climate solutions fund” over 15 years, not 10, as promised when it unveiled the rebadged emissions reduction policy in February.

The decision, revealed in Tuesday’s budget, effectively cuts the amount spent per year from $200m to $133m over the life of the fund, which pays polluters to implement greenhouse gas abatement projects.

Labor’s climate spokesman, Mark Butler, has accused Scott Morrison of already cutting the “main policy to deliver his weak 2030 pollution reduction targets”, while the Greens attacked the Coalition for spending just $189m over the first four years.

The $2bn relaunch of the Abbott-era emissions reduction fund was part of the Morrison government’s effort to bolster its environmental credentials in the face of rising community concern about the impact of climate change and challenges from independent candidates targeting the Liberal party on its climate record.

In February the prime minister’s office briefed journalists, including Guardian Australia, that $2bn would be invested over 10 years in the climate fund to build on the ERF’s record of reducing emissions by 193m tonnes.

On 25 February Scott Morrison told Sky News the Emissions Reduction Fund was a $2bn investment “over the next 10 years”, a comment he repeated in a speech the f0llowing day.

But in the budget papers released on Tuesday, the climate solutions fund is allocated $2bn over 15 years from 2019-20, including $189m over four years.

Butler said: “This was the policy that was meant to do the heavy lifting to deliver the government’s 2030 emission reduction targets, even though government data projects Australia will fail to meet even this government’s weak emission reduction targets.

“This is a budget from a government that has given up governing, and never tried to deliver real climate action.”

A spokesman for environment minister, Melissa Price, accounted for the discrepancy by explaining that auctions to deliver abatement will be conducted over a 10-year period but confirming the money will be spent over 15.

“The fund will deliver an additional 103m tonnes of abatement to 2030,” he said.

“There is scope to contract additional abatement between 2031 and 2035, or bring this funding forward to provide additional abatement in the period 2021 and 2030, depending on market conditions.”

The Greens climate spokesman, Adam Bandt, said the government planned to spend just $189m over four years on “its signature climate ‘policy’”, noting “there’s more new money for the Cairns ring road than for climate change” in the 2019 budget.

$189m.



That’s all the gov is spending on its signature climate ‘policy’ over the Budget period.



There’s more new money for the Cairns Ring Road than for climate change.



Turf this mob out.#Budget2019 #Greens — Adam Bandt (@AdamBandt) April 2, 2019

Labor’s climate policy is to reduce emissions in the electricity sector by 45% by 2030.

On Monday Labor added a target for the rollout of electric vehicles, the promise to introduce vehicle emissions standards and to beef up the safeguard mechanism to impose new pollution reduction requirements for the aviation sector, cement, steel and aluminium, mining and gas, direct combustion and the non-electricity energy sectors.

The budget showed that the balance of the Coalition’s $3.5bn climate solutions package includes:

Up to $1.38bn in equity over six years for the Snowy 2.0 pumped hydro project and $5.5m for oversight of that project

$61.2m for the energy efficient communities program

$56m for a feasibility study for the second inter-connector between Tasmania and the mainland

$18m on energy efficiency; and

$400,000 to develop a national electric vehicle strategy

An investigation by Guardian Australia last year found it was often difficult to determine if the emissions reduction fund was offering value for money.

Malcolm Turnbull, who once branded the approach “a recipe for fiscal recklessness on a grand scale”, let the ERF dwindle to almost nothing as he pursued policy alternatives, including the national energy guarantee resisted by conservatives and dumped by Morrison shortly after he took the Liberal leadership last year.