It's easy enough to argue cause, but effect is more difficult, especially when it can be measured and it's sitting there, well, right in front of your face.

Whether you accept that global warming is a man-made effect or not- heck, there are still those who claim it doesn't even exist, regardless of evidence to the contrary - it's harder to simply dismiss that there's change afoot, and that the change involved has the potential for drastic effects.

Right now, scientists are examining an interesting Arctic situation: colder Arctic water is rapidly absorbing CO2 from the atmosphere, and as it does so, it's becoming more acidic. That acidity is a basic material fact - one that's been measured by thousands of water samples taken over a span of 11 years by researchers sampling an area of Arctic ocean 1,000 kilometres across.

As part of that study, scientists in the Canadian Arctic have been tracking the level of a crucial basic material - carbonate - that helps build shells for shellfish and plankton in the top 50 metres of water in the Beaufort Sea.

They've found the water has grown so acidic - so corrosive - that it's difficult for sea creatures to build calcium-based shells. In fact, in some places the water is so acidic that it is actually breaking down shells.

So who cares?

We should, for a number of reasons.

First of all, the Arctic is seen as a bellwether for the direction other oceans will go if CO2 levels continue to increase. Think about the species that use carbonate to build their shells. Crab, mussels, shrimp, lobster, scallop - sensing a harvesting theme here? - come to mind immediately, followed by, to a less obvious extent, by the plankton in the food chain that many species, including fish, depend on. Researchers have found that one important foodweb species, the Arctic sea butterfly, is already being affected.

Now, certainly, you can argue that just because the Arctic Ocean is acidic, doesn't mean the rest of the world's oceans will necessarily follow the same route.

But then, it would be wise to stop and look at the physical oceanography and the currents that flow out of the Arctic Ocean.

See pack ice in the winter and icebergs in spring and summer? That, if nothing else, should convince you of the direction of the flow of water from the Eastern Arctic. The same scientists studying the huge pool of acidic Arctic seawater say one thing that's certain about the situation is that it will move - and that it will move in a certain direction.

It will drain, with the Labrador current, into our corner of the Northwest Atlantic.

As if we didn't have enough to deal with in the fishery.

You can, of course, point all manner of fingers to try and suggest that global warming isn't the problem or that it isn't man-made.

You can argue all you want about why a car leaves the road. It doesn't matter much to anyone who the car happens to hit.

In the end, though, it's not the cause that will create the impact.

It's the effect.