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The latest news about the protective effect of aspirin against a range of common cancers is cause for quiet celebration.

Anyone around 45 years of age now has another potential weapon to help minimise their risk of developing cancer. We already know it's important to avoid becoming overweight and drinking too much alcohol, now taking a daily dose of aspirin looks a sensible step to take for many.

If the are right, then taking just 75mg of aspirin for five years or more can have a dramatic effect.

In their paper, published in , a team from and other centres looked at data from some 25,000 patients, mostly from the UK.

The figures are impressive, with aspirin cutting overall cancer deaths by at least one fifth over 20 years.

Apparently, aspirin is best absorbed if taken at night and with calcium. So a 75mg dose along with a glass of milk (which might also dampen down stomach irritation) looks likely to become a common bedtime ritual. Though you have to stick at it for at least five years to see any benefit, the researchers say.

They stop short of urging healthy people to take aspirin because it is known to increase the risk of internal bleeding. But they say the new findings shift the risk-benefit balance in favour of taking it.

Of course there are some who should not just go ahead and self-medicate. In fact, everyone is being advised to talk to their GP first.

Aspirin can interact with other medicines, and anyone under 16; people prone to asthma, allergies, liver, kidney or digestive problems; pregnant or breast-feeding women and those with a stomach ulcer or bleeding disorders should certainly not start taking aspirin without professional advice.

Talking to the lead researcher, Professor Peter Rothwell of Oxford University, I wondered how he thinks aspirin performs its apparently remarkable feat.

He reminded me of our body's natural ability to stop the uncontrollable growth of cells, which is essentially what cancer is.

This cell death, or "apoptosis", is a normal, programmed process by which cells die to allow new, healthy tissue to grow.

"There's great interest in the effect of aspirin on the control of the development of cells that are beginning to be abnormal. Aspirin enhances this process... the ability of cells to self-regulate," he said.

He even hinted that aspirin might have an effect against cancers that have already started to develop, that is as a potential treatment as well as a preventative: "We should have more data on that in the next few months."

Prof Rothwell wants the (NICE), or perhaps the cancer charities, to come up with guidelines to help people decide if they should take aspirin everyday, or not.

He does not think advice should come from the scientists who did the work.

"I think some kind of national advice would be helpful. In general, there aren't situations where we insist... even on folic acid we only advise women to take it. On personal decisions about prevention, it's difficult to be dogmatic, but I'm 46 and I take aspirin myself", Prof Rothwell said.

So far, to the research.

Evidence to support the incredible value of aspirin has been increasing in recent years. We already knew it could be helpful for some people to protect against heart disease and stroke. Prof Rothwell says its protective signal for cancer is even stronger.

And encouragingly, it seems to work especially well against so-called adenocarcinomas. These are cancers linked to glandular tissue, and a type that is on the increase.

For anyone wondering about our early winter, and what it's got to do with El Nino/La Nina, Pacific and Atlantic Ocean temperatures and climate change I thought I'd jot down some notes from a chat I had with Dr Adam Scaife at the Met Office.

He is head of , which includes seasonal forecasting, decadal forecasting and modelling of climate variability.

After the barbecue summer fall out, the Met Office has of course stopped giving out seasonal forecasts - at least to the general public. But here's what he had to say about this week's record-breaking weather.

Why is it so cold in northern Europe so early?

"What's happened so far is consistent with El Nino/La Nina signals." Briefly put, in an El Nino year, like that of last winter, the Pacific is warm, and Europe's winters are cold and dry. In a La Nina year, which is where we are now, European winters are warmer and wetter.

But all of that is for LATE winter. In EARLY winter the situation is flipped, so cold and dry in a La Nina year - ie now. But later on this winter, possibly in January (though no one knows for sure), it should start to get warmer than it was last winter. Dr Scaife stressed that it's all very variable, so don't hold him (or me) to that.

The reason it is hard to be sure is that the El Nino/La Nina signal is strong enough only to be seen over a number of years, and not strong enough to use to determine an outcome. "In any individual year, there are lots of other fluctuations that can hide it," Dr Scaife said. Examples would be volcanic activity (strong enough for ash to reach the stratosphere), and what's going on over the Atlantic Ocean.

So what does this all mean for our understanding of climate change?

As the UK and Europe froze over, the World Meteorological Organisation (WMO) issued its - and showing 2010 as almost certain to rank in the top three warmest years since the beginning of instrumental climate records in 1850.

"The feature we're seeing now and last winter, where the UK and most of Northern Europe are cold, are a result of a re-arrangement of the air. So for as many places that are cold, there are places that are anomalously warm. It's like a jigsaw with the pieces in the wrong place. So we have local anomalies, but on average it works out to zero," Dr Scaife said.

"For example, at the moment we have cold over northern Europe and Eastern US, but in Canada and the Mediterranean it's mild, so the heat is sitting in a different place. That kind of shuffling can happen locally, but the global mean temperature doesn't care about that."

And possibly feeling a little bruised by questions about the skills of Met Office seasonal forecasting (after that barbecue summer) Dr Scaife directed me to a paper he published in 2005, looking at trends in winter temperatures from the 1960s to 1990s. This work is beginning to look prescient. It talked about possible changes afoot in European climate.

The winter of 1962/63 was famously bitterly cold, but by the 1990s we had got used to warmer, wetter winters in the UK and Northern Europe. Dr Scaife's paper said that although some of this winter warming was directly attributable to climate change, the majority of European winter warming between the 1960s and 1990s appeared to be due to changes in Atlantic winds (Scaife et al, Geophysical research Letters, 2005).

"We worked out that 70% of the warming in that period was due to the change in the Atlantic winds, rather than a direct radiative effect of greenhouse gases. And in 2008, before the last two cold winters, we wrote in a second paper on that topic that future decades could see a reversal, if those winds changed back - and that is exactly what has happened," Dr Scaife told me.

Here's what he said back then: "Future decades could easily see a reversal of regional trends in European winter climate because North Atlantic Oscillation (NAO) effects can dominate the effects of global warming on Europe in winter, even on multi-decadal time scales. Indeed, this may already be underway given the recent decrease of the winter NAO" (Scaife et al, Journal of Climate, 2008)

So a vindication perhaps? Dr Scaife said his team does not yet know what causes those decade to decade natural fluctuations in Atlantic winds. But this is just one example of how a global trend in which the planet is warming, can be masked by local, natural changes.

And finally, he said the key point about recent global temperature change is the rate at which it's happening: "Obviously there were bigger temperature variations in the past, but they took a long time to build up, over many thousands of years*. It's the rate of change in just 50 years (a degree or so of warming) that's different."

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* Update on 13/12/2010. Please note there was an error in the reporting of this quote. We initially quoted Dr Scaife as saying: "Obviously there were bigger temperature variations in the past, but they took a long time to build up, over thousands of millions of years." This has now been rectified. Please accept our apologies.

Never heard of "fracking"? If not, chances are you will soon. It is short for hydraulic fracturing, and is part of a process by which the United States is tapping into a vast new source of energy - natural gas trapped in shale rock, deep underground.

But this new source of energy is controversial. Video sharing website YouTube is buzzing with clips showing .

They claim this happened only after drilling released methane gas and contaminated their private water wells.

There is a lot at stake - not just money, but also the reputation of a whole new industry.

Potential rewards

Some estimates suggest there is enough shale gas under US soil that in energy terms it represents at least a couple of Saudi Arabias. What is more, this trillions-of-dollars-worth of energy is home-grown, and cleaner than other fossil fuels.

Until recently it was thought too difficult to tap economically. But a new engineering approach that combines "fracking" with horizontal drilling has challenged that (see how fracking works in the video below).

If all goes well in the US, Europe could be next. Just this September, weighed up the prospects of a shale gas revolution.

But is it safe to go ahead?

'Learning by doing'

In early October, I went to the town of Dimock in the US state of Pennsylvanian to find out more. Residents there have become well known for their experience with fracking, and with the gas companies at work in their backyards.

The message I took away from the trip was similar to that highlighted by Chatham House, which in its report spoke about the industry as one which is "learning by doing".

When I spoke to one of the gas companies operating in Pennsylvania, Chesapeake Energy, I found that such "learning by doing" had uncovered a problem.

The company, the second largest gas company in the US, conceded this straight away. Brian Grove, from Chesapeake, told us that problems the company had encountered with shallow pockets of gas could explain how methane might reach people's drinking water.

The threat of methane in people's drinking water is one of two chief safety concerns about the industry.

If colourless, odourless methane gas migrates into people's private drinking water wells it is not a health risk in itself, though in high concentrations methane gas is an asphyxiate.

More worrying, the gas could explode if it collects in a confined space.

Contamination claim

The second anxiety is over what is in the so-called fracking fluids. These are mixed in with millions of gallons of water, and pumped underground at high pressure to help ease the gas out of the dense shale rock.

One of the Dimock residents we met, Bill Ely, like many landowners in the area, leased his land to a company called Cabot Oil and Gas, hoping to make money from royalties.

Now he is suing the firm for contaminating his water supply with methane gas and putting his home at risk of explosion.

After a neighbour's private water well apparently did explode, Cabot installed ventilation pipes on Mr Ely's water well, and agreed to divert his well water through a hose, rather than into his home. They truck in all his drinking water too.

(You can see Mr Ely setting light to gas coming off his water in the video below)

George Stark is the spokesman for Texas-based Cabot, which has already invested $900m in exploiting gas in just this one county in Pennsylvania.

He says people have long been able to light up their water round in the area because of naturally-occurring methane:

"Our experts have checked over our casing, cementing, the drilling practice itself, the tubular that we're using to go down and they have determined that at this point that there's no Cabot operations that's occurring allowing for the discharge of methane into the waters," he told me.

But the state's environmental regulator says he has the equivalent of fingerprints linking the methane in local wells and Cabot's operations.

So there's a standoff.

UK tests

Vast tracts of North America sit on top of the ancient shale rock that holds natural gas in tightly compressed layers. Extraction or exploration is now underway in 30 US states, with attention focussed on the so-called Marcellus shale under Pennsylvania and New York states.

And in New York, they are watching Pennsylvania with interest. The state has a moratorium in place while its regulators weigh up the pros and cons.

There is growing interest in shale gas in the UK too. This summer, Cuadrilla Resources, a UK company, began test drilling near Kirkham in Lancashire.

Geoff Maitland, professor of energy engineering at London's Imperial College, told me there is probably significant potential in the UK, as yet unexplored:

"There are good indications both in the Lancashire area, and in Dorset in the onshore Kimmeridge shales. Scotland also has good prospects," he said.

Tony Ingraffea, is a civil engineer from Cornell University in the US, with expertise in fracture mechanics. He has spoken out against the way shale gas drilling is being carried out:

"You have steel casing, surrounded by cement, surrounded by rock. If any of those protection barriers fails we have an open pathway. A faulty cement job can be a failure by which gas or other fluids can find their way to the surface."

And it seems Chesapeake Energy might have hit upon at least one explanation for people's flaming tap water. The company told us that it had been forced to change its drilling mixture earlier this year, adding more latex.

Why? Because, just as Mr Ingraffea feared, problems with cement had allowed gas to migrate outside the well casing.

Brian Grove, from Chesapeake, explained: "In some cases it looks like, as the cement was drying, high pressure shallow methane kept it from drying properly, and would allow channelling to develop on the outside of the casing, which then could allow methane to move upwards through the shallower zone and to get into fresh water."

Mr Ingraffea is not surprised, but does not think this is the right approach: "I don't accept the notion that that industry can come in and say 'we're safe - oops, wait a minute, we found another mistake, we found another situation we hadn't anticipated, we're learning while we're doing'."

Haliburton subpoena

Much of the suspicion about the natural gas industry dates back to 2005, when US President George W Bush signed an energy bill which granted it exemptions from federal regulations, including the Safe Drinking Water Act.

Then-US vice-president Dick Cheney, the former CEO of Halliburton, worked prominently on energy policy at the time.

Halliburton is one of the major makers of fracking fluids, but appears to be the most reluctant to disclose their chemical make-up.

Earlier this month, the company was issued with a subpoena by the US Environmental Protection Agency (EPA) to force it to disclose more. Halliburton said it has worked to supply the EPA with the information it wants.

And as the gas companies expand their work across the US, this is a debate that is going global. As we finished filming in October, China's state gas company announced plans to invest in Chesapeake Energy's oil and gas fields.

The growing interest in the industry is not all positive. has fired up the debate.

While New York State weighs up its position, many landowners welcome the industry, and the jobs and wealth it brings. Others say they are determined to secure the best deal for themselves, and for the environment, from this new gas Gold Rush.