Every summer the sea ice in the Arctic shrinks, usually reaching a minimum around early September, and every winter at least some of the ice reforms as temperatures drop. But in the three decades since records began in 1979, the area covered by ice in early September - the 'sea ice minimum' - has been decreasing, shrinking by around 13% per decade. To date, the record sea ice minimum was in 2007.

That is, until last weekend. While some of us were enjoying the only really sunny day of the August bank holiday, the Arctic sea ice passed the 2007 record, and it's not yet reached its minimum. So 2012 is definitely a new low for the melting of the Arctic ice. We'll see over the next couple of weeks how deep the new low goes.

Clearly the impacts of changing sea ice patterns, and the possibility of ice-free summers in the foreseeable future, have major consequences for the Arctic wildlife and people whose lives and livelihoods have evolved around the ebb and flow of the sea ice. And it is lamentable that some people view the melting Arctic as an opportunity for oil and gas exploration - activities that have made such a great contribution to global warming in the first place - rather than as a portent and a glimpse of the future that awaits us in a climate changed world.

Because the Arctic is the 'canary in the coalmine' for our warming world; the poles warm more quickly for several reasons, with the result that the Arctic and the Antarctic Peninsula warm up most quickly, serving as an indicator of things to come and a warning to the rest of the world. Already we are seeing increasing 'global weirding' - changing weather patterns and more extreme weather events as climate change exerts its influence.

In addition, as this year's American drought begins to hit world food prices, climate change ceases to be an issue that can be batted around without consequence or responsibility in the British press, and becomes a very real part of people's lives - particularly the world's poorest and most vulnerable.

Over the past few years governments and policymakers have talked about a target of limiting climate change to 2oC [above pre-industrial levels]. But recent science has shown that two degrees of warming isn't nearly as 'safe' as people thought ten years ago, which is why WWF and many other countries and organisation are calling for a target of 1.5oC.

And last week Professor Sir Bob Watson - a highly respected UK scientist and currently Chief Scientific Advisor to Defra - warned that the chances of keeping the global temperature increase under 2oC (never mind 1.5oC) were 'largely out of the window'.

So we have a choice now, and much of that choice is linked to our awareness, and whether or not we choose to act now on that awareness. We can either work very hard to protect the Arctic, by reducing greenhouse gas emissions from our energy use and from deforestation (which is perfectly possible to do) and learn to adapt to a world of moderate climate change. Or we can follow the current example of our own UK Treasury, concentrating on the short-term and doing as little as possible.

But if we take the second path we can't pretend we didn't know, because the Arctic has just given us another clear warning of what is happening. We will have to acknowledge openly that young people today, and certainly their children, will not be able to aspire to the same safe and beautiful world to which we have aspired. We'll be seen as the generation that knew but didn't act - the ones who watched the devastation of our natural world, and did nothing to stop it.

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