The privilege of governing Australia obliges a political party, whatever its ideological leanings, to offer voters two things – coherent policies to deal with the biggest issues confronting the nation and a competent and prepared team to implement them.

The climate emergency is the most pressing issue of our time. For decades, Australia has seen this existential crisis looming and has failed to act on it.

With just 12 years to limit the global climate catastrophe, citizens here and around the world are demanding governments stand up to vested interests and act. The UK parliament has declared a climate emergency, the idea of a Green New Deal is gaining traction in the US and beyond, and students around the world are engaging in spontaneous activism to force change.

But in Australia the Coalition appears deaf to the rising clamour from the electorate. After tearing itself apart and dumping a prime minister to avoid implementing a functional climate plan, it clings to an obviously deficient emissions reduction target and has been forced back to Tony Abbott’s discredited climate policy because the hard right will countenance nothing else. That’s a policy that has seen Australia’s greenhouse emissions continue to rise for the past five years and that would put no constraint on continuing increases in the future.

The idea that a major party should seriously propose we waste money for little result for another three years, when we have no more years to waste, is a shocking abrogation of responsibility. Scott Morrison’s dismissive response to a UN report finding that the world is sleepwalking towards an extinction crisis, and his parliamentary stunt of fondling a lump of coal, underline the contempt with which he seems to treat the electorate’s legitimate and rising concerns.

The prime minister’s positive election pitch has boiled down to personal tax cuts, targeted at low- and middle-income earners in the short term, but offering an additional $230bn of tax relief to higher income earners over the next decade.

The plan would improve the household budgets of many families but it would also make Australia’s tax system less progressive, reducing revenue so much that future governments’ capacity to offer services at their current standards would be constrained, and leeway to cope with global economic turbulence would be severely limited.

The Coalition’s plan also leaves no room for spending that Guardian Australia believes is urgently needed if Australia is to be a fair and decent society, in particular an increase to the pitiful level of unemployment benefit – the main reason about 10% of us live below the poverty line even though we have enjoyed 28 years of uninterrupted economic growth.

Mr Morrison has narrowed the contest with Labor in this campaign, but has carried the Coalition’s message almost as a one-man band, a solo act made necessary because the wounds of last year’s leadership coup are still open and the ideological divisions unresolved.

Ministers hastily elevated to plug gaps caused by the rush of resignations after Malcolm Turnbull’s demise have shown scant command of their brief, and little interest in talking about the important portfolios they manage. And yet, to shut down an uncomfortable line of questioning in a campaign debate, Mr Morrison has promised that one of those most conspicuously “missing in action” – the environment minister, Melissa Price – will stay in the role if the Coalition is re-elected. In some important portfolios he did not appoint new ministers before the election was called, meaning announcements continue to be made in the name of ministers who are not even contesting.

The task of government can never be a one-person undertaking, and voters have ample evidence to doubt the Coalition has a full team ready for the job.

Alarmingly, Mr Morrison is also boosting the incoherent populism of Clive Palmer, apparently in the hope that the vote for his United Australia party, inflated by an estimated $50m in advertising, will push some conservative lower house candidates over the line, with the help of a Liberal/UAP preference deal.

It may, and it may also put the Palmer party into the Senate. Mr Morrison implausibly insists Mr Palmer represents “no threat to the economy or national security”, despite UAP policies – where they can be deciphered – proposing hundreds of billions in extra spending and despite the erratic businessman’s rants about “communist China” planning a “clandestine takeover of Australia”. Given Mr Palmer’s chaotic behaviour when last in office, this short-term preference tactic could come at the cost of further voter disillusionment with the democratic system.

The Coalition has neither credible policies nor a competent team, and Guardian Australia believes it has failed the test for re-election.

Judged by the same standard, Labor presents voters with a convincing case.

It has set a higher target for emissions reductions, closer to Australia’s fair share of the global climate response, and has a credible policy to achieve it – much of it borrowed from what Mr Turnbull wanted to implement. It will boost renewables, encourage electric car uptake and strengthen national environment laws.

Its tax agenda is unashamedly progressive, with slightly more generous short-term tax cuts for low- and middle-income earners and a firm rejection of the Coalition’s bigger future cuts for workers higher up the income scales. Labor has had big-ticket tax policies on the table since the 2016 campaign, policy transparency that should be encouraged, despite the obvious political risks.

Labor will reduce tax concessions for negative gearing, capital gains tax, superannuation and family trusts and has more recently announced the abolition of cash payouts from shareholder franking credits and a further crackdown on multinational tax avoidance.

The revenue raised would be funnelled to social spending, on childcare, free dental care for pensioners, Medicare, schools and universities. Disappointingly, an increase in unemployment benefits is not on Labor’s list of concrete promises. Bill Shorten says he will review the payment in government, with a view to increasing it, but there is no provision for this expensive shift in the Labor leader’s costings.

There is also an obvious fiscal risk in Labor’s plan. The Senate seems certain to block at least some of the tax changes, while the spending is likely to sail through. Labor may well need the higher budget surpluses it is promising to cover the difference.

While Mr Shorten has failed to inspire voters, with net approval ratings still well in the negatives, he has approached the task of uniting and leading Labor with conscientious consideration, and the depth of experience and preparation on his front bench is clear.

We have always considered Guardian Australia readers capable of making their own voting decisions, but in 2019 we urge readers to heed the fact that Labor is the only party with a credible climate policy and a chance of forming government after Saturday.

For those with more a progressive leaning and a conviction Australia should work faster to reduce emissions, the Greens’ climate policy is more ambitious than Labor’s and its tax and spending policies more redistributive. Depending on the election outcome in the Senate, the Greens could work to toughen Labor’s stance.

But the pre-election positioning by Shorten and the Greens leader, Richard Di Natale, will require careful judgment from climate-minded voters about whether the two left-of-centre parties are preparing to rerun the climate negotiations of 2009 or of 2010.

Senator Di Natale has said he wants a “seat at the table”, as the Greens had with Julia Gillard to develop the carbon price in 2010. But he has also declared he is prepared to vote down a Labor climate plan that “locks in” insufficient ambition, as the Greens did to Kevin Rudd’s carbon pollution reduction scheme in 2009. Shorten insists he will have a mandate to implement the policy he is taking to the poll but his success will almost certainly depend on the Senate negotiation.

For more conservative voters who cannot stomach the Coalition’s wilful inaction on climate change, or who want to cast a vote against Liberal MPs who have worked hardest to prevent responsible policy, such as Mr Abbott, there are in many seats credible independent candidates who could make positive contributions in the parliament. Their success could also finally weaken the sway of climate sceptics within the Coalition.

We believe the Coalition’s indefensible attitude to climate change, its wafer-thin policy offering and the fact that it has not resolved the internal divisions that blighted its term in office mean it has forfeited the right to voters’ trust.

However you choose to exercise your democratic decision-making on Saturday, please consider your candidate’s position on climate and the rapidly shrinking timeframe for action. We have endured mindless scare campaigns and half-baked policy for too many decades. We don’t have three more years to waste.