More rain, more flood warnings, more perfect storms: Britain's weather declined to offer much peace on earth in the week before Christmas.

A year full of record-breaking months, driest or wettest, attempted a new title: nastiest. It also caused a fresh outbreak of people starting conversations with: "Is it just me, or is the weather a bit strange?"

Most of us have heard that the jet stream has gone wandering. Few of us understand why this should be so, or why it matters. We hear that the storms battering the east coast are "the worst in living memory" and forget that the statement is an instant reaction, not an explanation.

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We see summers disappear and a couple of winters become brutal. We believe we are detecting something new in the absence of familiar patterns. However, that doesn't amount to science. When it comes to the science, meteorologists are cautious.

Not about processes: those can be explained. The hammering handed out to the east coast happened because of a combination of high tides, strong winds, "sea state" and atmospheric pressure. The last of these describes the weight of air. It is related to temperature and movements in the upper atmosphere. But you won't catch a TV weather person speculating about what wrought the temperature changes that actually cause a sea to "bulge". That would count as politics.

It's no comfort, in any case, to North Berwick, Lossiemouth or Stonehaven. It does not console the bereaved. For the rest of us, any mention of climate change leads to arguments that veer, often enough, towards madness. Some well-organised and well-funded people are so determined to "prove" that man's industry has nothing to do with weather, they miss the point that matters: what's to be done?

Even if you accept – and I do not – that ancient cycles govern every present event, or that cosmic rays and raindrop formation mechanisms are just facts of natural life, it doesn't really help. Even if you notice that river management and coastal defences have been neglected for too long, or remember that it was never smart to build housing estates on flood plains, none of it counts as a plan.

Crops have been miserable this year. During the last heavy snows, Scotland was stunned almost into immobility. Severe weather has its effects on fisheries, oil production, and on the fragile, just-in-time delivery systems on which, daily, our society makes big bets. Whether planetary warming can yet be averted is a major question, but there are more than a few supplementaries to be going on with.

Paid optimists can always be found to remember the big freeze of 1963, the cataclysmic North Sea floods of 1953, or even – because history always has something up its sleeve – the last little ice age. The friends of effluence, as we might call them, are always around to fight the fight for unfettered development. They falter, however, if you accept their zany notions, and then ask how we should proceed.

Fifty-two-billion metric tonnes of humanity's rubbish has gone into the atmosphere this year. Among the thousands of scientists studying climate change who believe that this matters, influential voices say we are between five and 10 billion tonnes over our allowance if 2ºC of warming is to be averted by 2020. You can dismiss such people as agents of a conspiracy – sceptics say so – but seriously: 52bn tonnes and there's nothing to worry about?

Polar ice is melting fast. Those who run the computer models suspect this explains the wobbly jet stream, hence atmospheric pressure, hence our perfect storms. Logicians could meanwhile remind you that causality does not depend on the invocation of past events as an explanation for what comes next.

But let it go. There are plenty of elaborate and abstruse tales around to say that it doesn't matter how many coal-burning power plants the Chinese choose to build. The 52bn tonne figure, calculated by Switzerland's Institute for Atmospheric and Climate Science, is 13.8bn tonnes higher than the total excreted by humanity in 1990. But let's also say that's of no account.

If the species does not degrade its environment, can the animal at least protect its living space? If arguments over warming have become sterile, how does anyone justify the leap to saying that nothing could or should be done for my patch of the planet? If America's Christian conservatives refuse to exercise a duty of care towards God's creation, can we at least agree on a few practical measures?

After all, the smarter sceptics have given up on wholesale denial. They quibble still over "anthropogenic" – man-made – change, but the conservative heartland in the US has endured too many droughts, hurricanes and sundry upheavals lately to allow plausible deniability of the fact that something unpleasant is going on. Batten down the hatches: it's not much a rallying cry, but a start.

Britain's poor harvests can be borne. The country is rich and powerful. It imports its pleasures from every corner of the globe. But our weird weather is being mirrored in the southern hemisphere. Our difficulties with a changing climate are the merest taste of what happens when a monsoon fails, or harvests and herds die away on other, bigger continents.

Environmentalism, in the broadest sense, isn't about polar bears or trees needing a hug. It is a matter of planetary security, the security of food supply above all. As every newspaper has noticed, your Christmas lunch is a lot more expensive than it used to be. The price of sprouts is shocking, that of potatoes a disgrace. But extrapolate that to 7.059 billion people, as of this morning, and causes are the least of it.

Don't let me put you off your lunch. Don't imagine, meanwhile, that I even pretend to understand exactly what a "carbon dioxide equivalent" is, or how the sums are done. But anyone should be able to smell what's coming on the prevailing winds. Best get ready.