UK government's former chief scientific adviser says Iraq war was about oil, not weapons of mass destruction – and warns there will be more 'resource wars' to come

The Iraq war was just the first of this century's "resource wars", in which powerful countries use force to secure valuable commodities for themselves, according to the UK government's former chief scientific adviser.

Sir David King predicted that with human population growing, natural resources dwindling and seas rising because of climate change, the squeeze on the planet would lead to more conflict.

"I'm going to suggest that future historians might look back on our particular recent past and see the Iraq war as the first of the conflicts of this kind – the first of the resource wars," he told an audience of 400 in London as he delivered the British Humanist Association's Darwin Day lecture.

Implicitly rejecting the American and British governments' argument that they went to war to remove Saddam Hussein and search for weapons of mass destruction, he said that the US was very concerned about energy security and supply because of its reliance on foreign oil from unstable states. "Casting its eye around the world – there was Iraq," he said.

This strategy could also be used to maintain supplies of other essentials such as minerals, water and fertile land, he added. "Unless we get to grips with this problem globally, we potentially are going to lead ourselves into a situation where large, powerful nations will secure the resources for their own people at the expense of others."

King was the UK government's chief scientific adviser in the run-up to the Iraq war, which began in March 2003, but he said he did not express his views on the true motivation for the conflict to Tony Blair.

"It was certainly the view that I held at the time, and I think it is fair to say a view that quite a few people in government held at the time," he said, "but … the chief scientific adviser's view on that matter was not sought."

King, who is now director of the Smith School of Enterprise and the Environment at the University of Oxford, said he had previously tried to persuade the Bush administration to adopt more climate-friendly policies. "I went into the White House in 2001 to persuade them that decarbonising their economy was the way forward – I didn't get much shrift at that time," he said ruefully.

"What I can tell you is that if I had managed to persuade the government of America that investing – instead of going into Iraq – in decarbonising their economy with roughly a tenth of [the estimated $3 trillion the US spent on the war], they would have managed it."

King's lecture, entitled Can British science rise to the challenges of the 21st century? was part of the celebrations of Charles Darwin's 200th birthday and the 150th anniversary of the publication of On the Origin of Species.

He said that politicians should not allow the financial crisis to distract them from the imperative to tackle climate change. "I would like to see [in] every speech that Gordon Brown makes on the current fiscal crisis, that he also includes the current global warming crisis," he said.

"It's fine for the prime minister to make a very good speech on climate change, but then you need all members of the cabinet, because reducing carbon by 80% by 2050 will require every part of government to respond."

He added that in a world of growing population and dwindling resources, fundamental changes to the global economy and society were necessary. "Consumerism has been a wonderful model, I would suggest, for growing up economies in the 20th century. Is that model still fit for purpose in the 21st century when resource shortage is our biggest challenge?"