Yesterday saw the publication of the agenda for Liberal Democrat conference – including a particularly welcome motion on protecting the UK from the impacts of climate change.

‘Adapting to climate change’ (Policy Motion F19, debated at 9am on Monday 6th October) calls on the government to “Ensure flood defence spending is kept in line with that needed to protect against climate change impacts”. This is a vital commitment that we sincerely hope Lib Dem conference will support. It will directly help protect hundreds of thousands of households around Britain from worsening flooding.

After the wettest winter ever recorded, and devastating floods that inundated 7800 homes and left Somerset stricken, it’s clear that we need to ramp up our resilience to our changing climate. The past winter was no freak occurrence: 4 out of the 5 wettest years on record in Britain have taken place since the year 2000, and climate scientists have shown clearly how global warming is loading the dice in favour of torrentially wet British winters.

And yet we’re not investing nearly enough in protecting ourselves from this increasing threat. Friends of the Earth has been pointing this out over the past year – but we’re certainly not the first to do so. The Foresight Review of flooding concluded as long ago as 2004 that we needed to be spending £10m-£30m extra each year, plus inflation, on flood defences in order to keep pace with climate change. The Pitt Review in 2008 agreed. The Environment Agency in 2009recommended investing an extra £20m per year, plus inflation, on flood defences out to 2035 – or risk putting increasing numbers of homes at risk of flooding.

Unfortunately these warnings have not been heeded, and in the Coalition’s first spending review, George Osborne cut the flood defence budget by £100m. This year, the Committee on Climate Change ran the numbers, and say there’s a half-billion-pound shortfall between what’s been invested in flood defences, and what’s actually needed. The cut in investment is a colossal false economy: it is directly putting an extra 250,000 homes at significant risk of flooding.

Policy Motion F19 would help rectify this huge mistake. In doing so, it would help thousands of households living in the frontline of climate change in the UK: from farmers in Somerset, to families living in flood-prone coastal towns like Eastbourne, to vulnerable households on the North Norfolk coast facing sea-level rise. Environment Agency data shows there are 177,000 households living at risk of flooding in Liberal Democrat constituencies in England and Wales alone.

The motion also suggests a raft of other sensible and helpful policies to make Britain more resilient – such as planting trees in uplands to reduce flooding, and obliging councils to report on how they’re adapting to climate change (something Eric Pickles scrapped in 2010). Crucially, it asks the Government to “Prepare a national resilience plan to help the UK economy… adapt to the likely impacts of a 3-4 degree global average temperature rise.” This is eminently sensible – as the climate scientist Kevin Anderson says, “Policymakers must aim to avoid a 2°C temperature rise, but plan to adapt to 4°C”. Such preparations could also inform Britain’s negotiating position before next December’s UN climate talks – so that we know the costs of failing to get a new global climate deal, and put renewed impetus behind mitigation efforts to bring down our carbon emissions.

Also scheduled for debate later the same day is a second motion relating to flooding – F22. This motion contains many positive proposals – for example noting that “an extra £20 million per year above existing levels needs to be invested in flood defences between 2010 and 2035 to sustain current levels of protection” and calling for “real terms investment in flood defences to increase in accordance with Environment Agency recommendations”.

However, crucially, it does not propose that flood defence spending keeps pace with climate change. With an additional one million homes in Britain predicted to be at risk of flooding by the 2020s because of the increasing impact of global warming, it is essential that flood defence investment keeps step with climate change. We otherwise risk leaving  hundreds of thousands of households facing the same devastation felt by so many in last winter’s floods.

We urge all Liberal Democrats to vote for Policy Motion F19 (Adapting to climate change) on 6th October, and show they stand resolute in defending Britain from the impacts of global warming.

* Guy Shrubsole works for Friends of the Earth on climate change and flooding.