Among his first acts as prime minister, Tony Abbott abolished the position of science minister. Defending this decision to an audience of scientists, Abbott said “please, judge us by our performance, not by our titles.”

With the canonical 100 days behind them, the government is now ready to be judged on performance. Is the "grown-up government" planning to rely on scientific evidence and analysis in formulating policy, or to be driven by interest groups and the politics of the culture war?

On one issue, that of climate change, the answer was obvious even before the election. For reasons that remain obscure the rejection of climate science has become a shibboleth for rightwing culture warriors, whose views drive not only Abbott himself, but the majority of his backbench.

More recently, it has become clear that the triumph of politics over science under the Abbott government will be total and unqualified. We have seen a string of recent announcements, including:

• The approval of dredging for an expanded coal port at Abbott Point

• Scrapping of previously approved management plans for marine reserves

• The handover to the states of Commonwealth environmental assessment powers

• The government disallowing the Labor government's declaration of threatened ecological communities in the Murray Darling basin as endangered under the Environment Protection and Biodiversity Conservation Act

The first of these decisions was at least part of the standard process under which projects are assessed. The others, however, represent the government’s determination to remove any scientific input from policy, allowing free rein to interest groups and industry lobbies. Even more they are typical of the Abbott government’s policy agenda, which consists almost entirely of reversing as many as possible of the achievements of the previous government.

The case of the Murray Darling basin is particularly striking. The problems of the basin have dogged state and federal governments since the early 1990s when the over-exploitation of water resources forced the imposition of a cap on extractions. Intended as a temporary measure, the cap is still in place and is not due to be removed until 2019.

After years of policy failure, the Howard government asserted control over thebasin in 2007, establishing the Murray Darling basin Authority to replace previous intergovernmental arrangements with the states. But Howard and his water minister Malcolm Turnbull made little progress, and it was left to the Rudd and Gillard governments to fix the problem against the background of the Millennium drought.

Hopes for a purely science-based policy were initially high, but soon ran into the ugly realities of politics. The process wasn’t helped by the Murray-Darling basin Authority (MDBA), which unnecessarily alienated irrigators by refusing to rule out compulsory cuts to water entitlements, even though the Labor government had clearly committed itself to voluntary buybacks. The MDBA’s draft plan for the management of the basin was publicly burned in a number of towns dependent on irrigation.

Despite this unpromising start, water minister Tony Burke managed to put together a management plan which secured the agreement of all the relevant state governments, and the grudging acquiescence of all the key stakeholders. The plan cost more than it should have, with a lot of money wasted on dubious water saving projects like Victoria’s Food Bowl Modernisation project, and returned less water to the environment than the scientific evidence suggested it should have.

Despite its limitations, though, it seemed that the passage of the plan in 2012 represented that rarest of political achievements in Australia, the permanent solution of a longstanding policy problem. After a political process which mostly involved concessions to irrigators, the (scientifically justified) declaration of the most sensitive parts of the Murray as endangered provided environmentalists with the security they needed that the plan would be implemented in a way that was consistent with sustainable management of the basin.

With the change of government, this prospect has disappeared. As in so many other areas, the Abbott government may not know what it wants, but it knows it wants to tear down anything done by Labor. And as will be true in many other cases, the gratuitous decision to reject science has set the government on path that will ultimately lead it to political, as well as environmental disaster.