The recent floods have not only brought the effects of climate change to the fore – they have also ruined Christmas for many families. But the generosity of so many has shown that community spirit is alive and well throughout the north. I have seen at first hand people open their homes to strangers with nowhere else to go, and seen people who have lost much digging deep to help those who have lost everything.

The prime minister’s “big society” is a woolly concept – a halfhearted attempt by David Cameron to contradict his political hero’s assertion that “there is no such thing as society”. But the tangible sense of community in the north of England as the floods have hit has struck many observers. In Cumbria (where I have lived for many years and am an MP), Lancashire (where I was born) and Yorkshire, there is something almost overwhelming about the level of mutual reliance, the selfless support for others, the resilience and cooperation and the strong community spirit.

The danger is that Whitehall will just take all this for granted and continue to allow the public sector – including councils and the emergency services – to be eroded. Voluntarism needs to be backed up by effective and strategic government action.

That’s why I again call on the prime minister to rethink his swingeing cuts to the very departments that will help us deal with the long-term impacts of flooding and ensure that we both tackle climate change and work to make adaptations to mitigate its worst effects. The Departments of Energy and Climate Change, Environment and Local Government were all subject to drastic spending cuts at the comprehensive spending review last month. The government needs to think again about these if it is to tackle the long-term problems before us.

The Liberal Democrats believe in economic competence. I do not believe in spending for spending’s sake, but nor do I believe in the prime minister’s zealous drive to shrink the state. Small is not always better: we need a public sector and a capital spending plan that benefits Britain in the long term, rather than being blinded by dogma.

I recently gave a speech to the IPPR calling for more long-term thinking in policymaking. The tragedy of December’s floods brings this matter into sharp focus. Extreme weather conditions including flooding are likely to become much more frequent. Britain must be able to cope – even thrive – in these circumstances and not come to a standstill each time. That means proper planning and investment in durable infrastructure.

I have appreciated the ministerial visits to our part of the world over the last month – but I’d appreciate even more those ministers acknowledging that it is utterly shortsighted to slash nearly 30% from the departments that are there to help flood damaged communities get back on their feet.

Furthermore, the government’s approach to flood defences is shortsighted. In 2012, I raised the issue that more funding was needed to deal with the torrential rain and “freak” weather that was becoming more prevalent. In the years since I have repeated that call, and I do so again today. We need to urgently review every shelved flood defence scheme.

It breaks your heart when you meet people who have lost everything – like the lady, a week before Christmas, who came out of her home in tears to speak to me and said, “Where can I turn? I’ve lost everything and have no insurance”, or the homeowner whose home floods virtually every time we have heavy rain and now faces a premium of over £2,500. Of course, I do everything I can to help, but seeing their helplessness makes me angry and determined to do something to make it better.

But some MPs try to use a crisis like this to jump on their hobby horses. Conservative MPs are lining up to be quoted as saying “let’s slash foreign aid to pay for flood defence”. This is not only the wrong approach; it is stealing money from the world’s poorest and assuming the choice is either/or. It is cruel and heartless, and the aid budget is always used as a pot of cash that could be raided for any crisis. As a result, the right wing of the Tory party has already spent that cash many times over.

The government is also being shortsighted when it comes to Europe and not applying for a grant from the EU solidarity fund to help communities get back on their feet and fix vital infrastructure like the A591 in Cumbria, which is the main north-south route in the Lake District. We are often told after disasters like these that “money is no object”. It’s time to follow up these words with a cheque.

This period has been devastating for thousands of people across the north of England. The government has to see that standing in front of cameras and issuing press releases about Cobra conference calls means nothing to communities that have been calling for flood defences since the last time their homes were flooded. The action needed is simple; the Conservatives must now try to muster the political will to actually do something to help our northern communities.