Malcolm Turnbull raised a very good question about Tony Abbott’s climate change policy on the ABC’s Q&A on Monday night when he said the Direct Action policy wasn’t a long-term one. We’ve asked four more questions of our own.

1. Global warming is a long-term problem that requires long-term solutions. Does the Coalition think Direct Action could work for longer than a few years or for an emissions reduction target tougher than 5%? Does the Coalition even have a policy for the long term?

This is the question left hanging after Turnbull’s appearance on Q&A. The Coalition’s messages are mixed.

When the Direct Action policy – of buying emissions reduction through competitive government grants – was discussed in late 2009, climate spokesman Greg Hunt suggested an emissions trading scheme could follow it, especially if the United States implemented one. This would be decided after a review, promised for 2015. Frontier Economics managing director Danny Price, who had been modelling the Coalition’s alternatives, said Direct Action was a “short to medium term stopgap measure”.

Hunt himself said the Coalition would use Direct Action “in the first instance” but added, “we won't have any carbon price at this stage, but we will consider one when we know what the US is going to do''.

Most business groups briefed by the Coalition at the time believed Direct Action was an interim or transitional policy and the Coalition would consider some form of carbon price in the longer run – probably the baseline and credit scheme it proposed during the failed negotiations with the then Rudd government the previous year.

But by July, 2010, as his “great big tax” campaign gained traction, Abbott said, "There will be no carbon price on consumers under a Coalition government."

His policy hasn’t changed since 2010 – proposing to use government grants to meet a 5% emissions reduction target by 2020. It is silent about what happens after that.

But, as Turnbull explained in 2011, continuing to use a big government taxpayer funded scheme to reduce emissions in the long term would “become a very expensive charge on the budget in the years ahead”.

Turnbull seems to still believe Direct Action is a stopgap. As he said on Q&A, “It is not designed to go any further than 2020, so it is not a long-term policy … if you want to reduce your emissions over the very long term, by which I mean 50 years or so, then you are going to have to have a long market-based price on carbon.”

On Tuesday, Abbott said there was no need to consider a carbon market because the rest of the world was in fact moving towards direct action-style policies.

But international negotiations measure Australia’s emissions reduction effort – our target – against the effort – the targets – of other countries. How Australia meets the target is up to us and, as Turnbull says, market-based mechanisms are widely viewed as the most effective. Whether or not other countries or states implement emissions trading (and many now are, including the EU, Switzerland, New Zealand, South Korea, California, some provinces of China and some Canadian states), a market-based mechanism is still likely to be Australia’s cheapest option.

On the real comparator with the rest of the world – emission reduction targets – Labor and the Coalition say they remain committed to exactly the same targets under the same conditions – and 5% by 2020 is just the minimum.

Labor is using the independent Climate Change Authority to assess what the rest of the world is doing and whether Australia’s target needs to be tougher. If it does, the “cap” on emissions under the emissions trading scheme will be adjusted.

The Coalition will abolish the authority. It says its 2015 review will assess Australia’s targets.

But how the Coalition would meet a tougher target, how it would meet any long-term target, and how much this would cost, remains entirely unclear.

2. How much money is allocated to the Direct Action fund to meet the 2020 target?

The 2010 policy allocates $300m, $500m, $750m and then $1bn to the “emissions reduction fund” over its first four years, from which government grants will be made. The Coalition has said it will spend $1bn a year after that. But in several recent speeches and media interviews, Hunt has only referred to the first three years of spending. Frontbenchers also refer only to the funding over the first three or four years. Other MPs have suggested funding should not be “locked in” for the long term. When Guardian Australia asked whether there had been any change, Hunt replied only that “our policy, our funding and our commitments remain unchanged since the last election.”

3. Would Direct Action reduce or even contain emissions from electricity generation, which represented about 35% of Australia’s total emissions?

In 2010, Hunt said Direct Action could pay a higher price for big-emitting brown coal-fired power stations to tender to the emissions reduction fund for their gradual replacement with cleaner gas. He said the tender could also include a subsidy to make sure this move did not push up consumer power prices. But in answers to Guardian Australia, the Coalition now seems to be saying there will only be one “reverse auction” which will be determined solely on which emission reduction bids are cheapest, making the participation of electricity generators less likely.

“As consistently stated, the reverse auction will be source-blind and will be based solely on the lowest cost abatement, ensuring it is a pure market mechanism,” Hunt said in a written answer. “The emissions reduction fund provides the opportunity for coal-fired power stations to switch to gas if it is the lowest-cost form of abatement. That has always been the criteria.”

Polluters, including generators, are free to ignore the voluntary Direct Action emissions reduction fund. And they will not be penalised for increasing their emissions if they expand. There is an unspecified provision to deal with businesses that “go rogue” but the Coalition has not said what this means and doesn’t seem to be planning financial penalties.

“We are assuming no revenue from the Direct Action program. It is an incentives based scheme rather than a penalty based scheme, although there remains a provision to deal with any businesses which go rogue,” Hunt said.

All of which poses some questions – would there be any incentive to change how we generate power or any limit on emissions from electricity generation under Direct Action; and could they in fact increase?

4. Will 60% of emission reductions still come from soil?

A widely criticised part of the original scheme was the estimate that 60% of emission reductions would come from soil carbon. Soil carbon is seen as a big potential carbon sink, but it was unclear whether farmers would make the necessary permanent changes to farming practice for the price being offered and there are scientific questions about how to measure the abatement and whether it is available in the quantities the Coalition was banking on.

Hunt says 60% was only ever an estimate. “The policy never dictated how much abatement must come from each sector. The original figures were to provide a guide as to how much might be available. That was clearly stated in the document. We expect soil carbon will play a potentially significant role but it will be the market which will determine the make-up.”

5. How will the Coalition determine the starting point for the emission reductions it is rewarding?

Hunt says emission reductions will be measured against a baseline, calculated through the average of a company’s emissions in the previous five years. He says he will use data from the existing National Greenhouse and Energy Reporting scheme. But Direct Action will be open to many businesses and organisations that don’t report to NGER and have no recorded data. And even for those companies that do have a clear baseline, the Coalition will need to be sure it is paying for emission reduction that wouldn’t have happened even without the Direct Action grant.

As Malcolm Turnbull said in his famous speech when he crossed the floor to support Kevin Rudd’s emissions trading scheme after being defeated as Coalition leader, “If a scheme operates whereby the government pays the firm to reduce its emissions intensity … there is firstly going to be a substantial and contentious debate about what the correct baseline is, and then whether it will actually be reduced … Arguments of considerable ferocity will arise as to whether a new piece of equipment would have been bought anyway, with the risk that the government ends up funnelling billions of dollars to companies to subsidise their profit without achieving any real additional cuts in emissions.”

The Coalition isn’t intending to answer any of these questions until after the election. Then – after leaving the policy unchanged and unexplained for over three years – it intends to answer them in a rush, calling for submissions on a white paper within 30 days of election, for legislation to be released within 100 days and passed within 150.