The science community is getting increasingly apprehensive about the prospect of significant cuts in funding when the public spending review takes place in October. Don't the prime minister and his chancellor recognise that investment in science (both pure and applied) has a vital role in creating the economic growth we need to solve our problems? Scientific investment creates and exploits new knowledge, as well as attracting inward investment. It also generates both new businesses and a highly-skilled workforce.

Cutting such investment will damage the prospects for economic growth and rebalancing the economy towards high-tech and manufacturing and away from our current over-reliance on financial services.

Cuts to science do not just mean a hiatus in some experiments: they force highly qualified individuals to go abroad or leave research. If they are forced to quit, the nature and speed of global research is such that these people will not be able to resume their careers a few years later when investment picks up again. The research and development labour supply is not a tap that can be turned on and off in line with short-term political decisions.

Our competitors, for example the US, France and Germany, are increasing, not cutting, their investment in science and technology as a key part of the return to growth and are doing so over both the short and medium term.

The government might claim it is maintaining science funding – which includes university research funding and departmental R&D budgets that don't originate in the Department for Business Innovation and Skills – when in fact it is only protecting the research council "science budget". This trick was used by the previous government in its claim that it had doubled "science spending" when in fact it rose only in line with economic growth and still leaves us lagging in sixth place in the old G7 group of industrialised nations for our R&D spending.

Some parts of the research council budget, like particle physics and astronomy, are very sensitive to cuts since a large proportion of current expenditure is committed to subscription to major international collaborations, such as the Large Hadron Collider at Cern or major space projects. These commitments are difficult to break without damaging the UK's reputation as a reliable partner in major international projects. Some of our domestic facilities, such as the Isis and Diamond synchrotrons, have cost a fortune to build and it is totally irrational not to provide the smaller-scale recurrent funding needed to exploit that existing infrastructure.

David Willets and Vince Cable are surely smart enough to recognise this, but the Treasury – the only government department without a chief science adviser – has a long history of failing to see the bigger picture unless protesters are at the gates of Downing Street.

Perhaps that's where scientists and investors now need to head.

Evan Harris was the Liberal Democrat science spokesman from 2003 to 2010