“We really can't forecast all that well, and yet we pretend that we can, but we really can't.” 
Alan Greenspan, former Chairman of the Federal Reserve Bank.

It wasn't meant to be like that. A new year and a fresh new start was supposed to be the narrative. The Fed starts its rate rising cycle into an unassuming, benign environment. Well, it seems stock markets around the world simply haven't been listening.

It was only months ago that we were celebrating multi-year highs across a number of global indices. Now all the talk is about guessing which stock market will next fall into bear-market territory. Whether it's China, the UK, Japan or Australia, all regions have markets at least flirting with the 20% decline from their peaks that would define such a slump. 

So what's driving this? In a nutshell, wherever you live in the world and whatever your geographic market bias, it's back to stressing how much we live in an interconnected world.

One of the biggest headline grabbers of late has been the collapse in the oil price. The West Texas Intermediate (WTI) grade has fallen more than 25% so far this year and now sits below $27 a barrel for the first time since 2003. 18 months ago we had $100 oil and all was right with the world.

The trouble with what's happened with oil of late is that it encapsulates a number of different concerns: economic growth, politics, geopolitics, and corporate debt.

On the global economic front we've got China's slower growth story continuing to unnerve investors. Whether the data coming out of the country can be trusted remains open to debate. Critics only see exaggeration. Nonetheless, the 6.9% growth figure China released for 2015 did fall short of 7% government estimates, was below the 7.3% for 2014, and marked the slowest rate in 25 years. Analysts forecast 6.5% for 2016, which wouldn't be much of a problem if the rest of the world hadn't become so reliant on this economy to take up the global growth slack. And a slower-growth China also means lower demand for oil.

Not only is the oil space being hit by a weaker demand environment, it's also facing a new wave of supply coming onto the market. In the US, Congress voted in December to lift a 40-year ban on crude oil exports as part of a broader spending bill that averted the possibility of a government shutdown. The legislation will finance the government through September 2016. The political compromise is proving to be unfortunate timing for the oil market. Who knows what the changing of the presidential guard in the US this year will do for future energy policy?

Events in the Middle East have also added to the oversupply dynamic. Diplomatic relations have become even more strained than normal between Iran and Saudi Arabia, the world's largest oil producer. Unfortunately, this is also playing out messily when it comes to oil. US and European Union sanctions have recently been lifted on Iran, restoring the country's access to world markets. With the country planning to immediately ramp up oil production by 500,000 barrels per day, it aims to boost output by as much as 1 million barrels within a year. Rather than trying to support oil prices by cutting output, Saudi Arabia seems set on maintaining levels and market share to nullify the Iran threat. So for expediency's sake, Saudi Arabia appears happy to keep oil prices low to hurt Iran. That's how it appears anyway.

And then there's the issue of debt. In the post-financial crisis world, banks had to rebuild their loan books with safer, more reliable borrowers. It was time to step away from the consumer and target corporates. What could be safer in a low interest rate environment than energy companies looking to expand production into new growth markets with the oil price at $100? Well, it's become a bit of a perfect storm – interest rates are rising, the strong dollar is impacting the value of overseas earnings, emerging markets aren't emerging so much and we all know what's happening with the oil price. So this is could become an earnings concern for coming quarters – will banks struggle with escalating defaulting loans from energy companies?

So investors have plenty to think about. With the beauty of hindsight a number of commentators have come out to say that the Fed shouldn't have raised rates at all in December. The counter to that view is that markets are telling a different story to the broader economics, which really aren't that bad. Yes, China's expansion has slowed but that's not new news, while the US has been showing steady if unspectacular growth.

But this is very much a sentiment-driven market. And sometimes sentiment can make certain scenarios self-fulfilling. Understandably money is flocking to gold and other safe havens. There's also plenty of cash sitting on the sidelines, waiting. Who knows whether in five years' time we'll even remember any of the current narratives. For now, though, it's not a time to panic. Keep calm, carry on and make the most of the cheap flights the oil price should give us.