This is eerie. Everything has suddenly gone upside down in the global economy. Europe is growing and China is slowing. Emergent markets are faltering and mature ones are suddenly looking perky. The United States is about to become the world's top oil and gas producer.

A year ago, even six months back, anyone who suggested such an extraordinary reversal of seemingly inevitable trends would have been mocked. Europe appeared set on irreversible decline. China was on course to become the world's top economy.

The smart money was piling into emergent markets because this was going to be the Asian century. We were supposedly witnessing the reversion to that traditional 17th century pecking order, before the industrial revolution, when India and China accounted for more than half of global wealth.

The decline of the West and the rise of the rest were supposed to be deep-rooted historic trends, shaping the global future for the coming century and more. Well, at least from this summer's perspective, it does not seem to be working out like that.

Europe is the real surprise. According to the latest figures from Eurostat, economic output rose by 0.3 percent across both the euro area and the EU28 during the second quarter of this year. Europe could even post an overall growth rate for this year as a whole.

Portugal did best, despite the strikes, demonstrations and political turmoil over its bailout program; its economy grew by 1.1 percent. Finland and Germany recorded growth of 0.7 percent, while France scored a 0.5 percent growth rate, a welcome boost from the embattled government of President Francois Hollande. Italy and the Netherlands are still faltering but Spain has bottomed out. Even in stricken Greece, unemployment is dropping.

Of course, this could all be temporary, but it is clear some profound structural issues are now starting to weigh on emergent markets. Much of their growth in the last decade has come from China's apparently insatiable demand for raw materials to feed its infrastructure boom. Iron ore and coal, cement and fertilizer, grain and soy beans -- China was in the market for all of these goods, and emergent markets from Indonesia to Brazil, and Russia to Angola, boomed on the strength of that Chinese demand.

But now China is slowing, and the Beijing government is trying to rein in the infrastructure boom, fearing that much of that investment was ill-spent. The new state policy is to shift the economy from being investment-led to consumption-led. This won't be easy, and could well lead to social and political difficulties if China's masses no longer feel that their economy -- and their environmental health -- is safe in the hands of the new party leadership.

At the same time, the great floods in investment that went into emergent markets (EMs, as they are known in financial circles) may be slowing. Since the start of the finial crisis in 2008, net capital inflows into EMs have totaled $4 trillion, about a third of it from China. It was not just the hope of good returns that attracted so much money into the EMs, but also the dismally low interest rates available in Europe and the United States as the central banks kept interest rates low in the hope of boosting growth.

Now it seems that that period of low interest rates is drawing to a close. The Fed, the U.S. central bank, is talking of "tapering" its bond purchases which means interest rates in general are likely to rise. Yields on the 10-year U.S. Treasury bond have doubled this year already.

So more money is likely to stay at home in the United States, which means less going to the EMs. And the latest grim images of violence and repression in Egypt will serve to remind investors of the perils of political risk.

Then consider the oil price. The United States has gone from being the world's leading energy importer six years ago to its new status, after the fracking revolution, as a likely energy exporter. That means countries such as Russia and Saudi Arabia, hopefuls such as Brazil and the new African oil exporters may not see their oil getting $100 a barrel in future years.

All this adds up to what economist Uwe Bolt has called the coming "economic ice age."

Of course, the signs of recovery in Europe could prove to be a false dawn. The U.S. Congress could go through another bout of intransigence and abort the country's economic revival with another blockade of the budget or a new refusal to lift the debt ceiling.

China could navigate its great transition and avoid that middle-income trap, which has stopped other emergent markets from maintaining high growth rates. India could bring in the economic and anti-corruption reforms it needs, and the appointment of Rahuram Rajan as central bank governor is a positive sign. Brazil could get out of its current slowdown and Egypt may find a peaceful way out of its current mess. But it is not often that everything simultaneously goes right.

The likelihood is that the world is in for a period of much slower growth, with the United States as its healthiest component, Europe in modest recovery and all that conventional wisdom about the rise of emergent markets put on hold.