In only two years time, the United Kingdom may undergo two fundamental changes. The coalition government headed by Prime Minister David Cameron has promised to hold two major referendums. The first is definitely going ahead, and will be held in September this year. It will be to decide whether Scotland remains part of the Union or becomes independent. The second, a national plebiscite on whether the UK remains within the European Union (EU) will happen if Cameron is reelected in May next year when the next general election falls due. He has promised if he remains the nation's leader that the ballot will be held in 2017.

These are massive decisions, and they will have an impact not just on the UK, but also on Europe and as far as China. The referendum on Scotland is the more dramatic of the two, but it could be the choice to leave the EU that would be more far reaching.

A tough decision

Although Scotland has been part of the UK since the Act of Union in 1707, that could all change soon. A desire for increasing autonomy and a majority win by the Scottish Nationalist Party in Scotland's local elections in 2011 resulted in an agreement between the national parliament in London and Edinburgh that a referendum on whether Scotland should be independent or remain part of the Union would be put to everyone resident in Scotland.

With the September 18 referendum approaching rapidly, surveys have consistently shown those wanting to maintain the union as the majority, but that gap has been closing in recent months. While unlikely, a majority for independence in September is still within the realms of possiblity.

It is already clear that no one really knows what the full impact of Scotland becoming a separate country will mean. Tax, legal, fiscal and debt issues need to be agreed on; there is the question of whether Scotland continues will adopt the Euro or maintain a currency union with the UK; and also whether it will "inherit" EU membership as a former part of the UK, or if it will have to negotiate membership anew.

 Many reports over the last two years have shown that separation will make life economically tougher north of the border, but the issue is ultimately an emotional rather than purely rational one, making the final outcome hard to predict.

If Scotland does vote to leave the United Kingdom, then there is the immediate issue of how and when other countries confer diplomatic recognition on it. China already has good links with Scotland. It loaned two pandas to Edinburgh Zoo only a few years ago, and has been a destination for visits by Chinese leaders from the 1970s onwards. As a financial hub, the city of Edinburgh in particular has strong links with China, with companies like Standard Life having investments in a number of coastal provinces. There are also strong Chinese language and history departments in Scottish universities, and a good flow of tourists between each country. However, a wholly independent Scotland would mean that China would have to recalibrate its trade and investment strategy, rather than maintaining the current one where a similar tax and regulatory regime applies across the UK.

The new Scottish government might want to compete more keenly with the UK, and offer incentives to Chinese companies coming to invest. It might also want to establish representation in China, and look to help its companies become more active there. Where there was once unity, there would be potential competition and greater rivalry between the rest of the UK and Scotland. China would have to decide on a way to deal with this, without alienating either side.

Separate from the continent

Despite leading a coalition government which many regarded as likely to be weak and incapable of making real decisions when elected in May 2010, Cameron has managed to promise not just one major decision about the shape and nature of the UK during his time in office, but also a second. As if Scottish possible independence was not enough to deal with, Cameron has also promised to hold a similar referendum on membership of the EU if re-elected next year. For his Conservative Party, the EU remains one of the hardest issues. Many of his colleagues in parliament regard the EU as a bureaucracy which costs the UK too much to belong to only to compromises its legal and political sovereignty. Some of the party accept its role as a free market and a common trade zone, but feel that in the last few years it has begun to transform into a sovereign state in its own right, rather than a collection of small members. It is to appease these elements on the benches that Cameron has made his promise, despite himself saying his personal preference is to remain a member but see reform of the EU.

The appointment of former Luxembourg Prime Minister Jean-Claude Juncker as the new president of the Commission when current leader Barossa retires later this year has made the prospect of a UK exit even more probable. Juncker is seen as anti-reform and federalist. The UK and Hungary alone opposed his appointment, but the fractious process by which this happened revealed just how reluctant the UK sometimes feels as an EU member.

The UK has refused to adopt the Euro, and was among the most critical of EU initiatives on banking regulation two years ago, as well as the reform of the Eurozone. Departure from the EU would have little immediate effect. The UK would remain committed to following many European regulations – similar to Norway, another non-EU member – simply because Europe is its largest market and trading partner. In order to preserve this, it will need to observe EU rules. On the other hand, supporters of continued membership argue that the UK would lose whatever decision making influence it has in Europe and risk becoming increasingly marginalized in the long run.

What that means diplomatically is hard to say at the moment. The UK might feel it is freer to act, but in a world where it has lost much of its former influence and power with the exception of its alliances, it is hard to see how it could exert more influence on global affairs outside the EU rather than within it. Despite the frustrations of handling the complicated internal systems of the 28 strong membership of the EU during negotiations on climate change, trade and even security issues, the UK will effectively have next to no direct voice after leaving. It will be left to complain loudly, or try to exert bilateral pressure on its neighbours. Departure from the EU could have a profound impact on the UK's global role and on its image.

Altered role

A United Kingdom that both lost Scotland and left the EU would be a very different sort of partner for China than one that remained united and within the EU. One of the main issues for Chinese practically is that the UK lies outside the Shengen visa area, meaning tourists, business people and students have to sort out separate visas in order to visit it. It splitting up and leaving the EU would make it a much smaller market, and even more isolated from the rest of Europe than it already is. As a center for finance and potential investment destination as well as its education system, it will still be important, though would likely become much more marginal partner for China, and one that would have a far less diplomatic weight than it currently does.

September 18 might send a strong signal that Scottish residents wish to stay part of the Union, and a referendum two years later on the EU might return a similar positive result there. That means that for Cameron, by 2017 he will have effectively cleared away two huge questions for his generation.

If things do go wrong, then he will go down less as a national leader than as a massive gambler, who played two massive wagers when there were alternative routes he could have gone down. This would be a high price to pay, and one that would have him marked in history as the man who saw one of the most stable of European countries transform into something smaller and less significant. The world can only hope that his instincts are right, and that both times he can get results that maintain the UK as a unified country, and as part of the EU. That way at least it will have the voice to shape the future of the world around it, rather than standing on the sidelines as a complainer.

The author is an op-ed contributor to Beijing Review and executive director of the China Studies Center at the University of Sydney