As the world’s financial leaders gather in Washington, D.C., for the annual spring meeting of the International Monetary Fund (IMF), their hopes - and fears - centre on China. After all, China is the one country that might be able to jump-start the sputtering global economy's recovery; and yet its own economic growth is based on a foundation that is increasingly showing signs of strain. The dilemma is that both Chinese failure and success carry risks for the world economy.
A failure scenario would be unique in post-World War 11 history. Because China's economy is so large, the consequences would reverberate worldwide. But, unlike in 2008, when the US dollar appreciated, allowing emerging markets to revive quickly, the renminbi would likely depreciate should China's economy experience a serious downturn, spreading deflation far and wide.
Other currencies might depreciate as well, some as a result of deliberate policy. Consequently, a China failure scenario could resemble the events of the 1930s, characterised by competitive devaluation and plummeting real economic activity.
But what if China succeeds in its current transition to a consumption-based economic model? When the Chinese current-account surplus reached 10 per cent of gross domestic product (GDP) in 2007, saving exceeded 50 per cent of GDP and investment surpassed 40 per cent of GDP.
These numbers seemed far too high to be dynamically efficient or welfare enhancing. As a result, a consensus rapidly emerged: Saving and investment should be reduced and brought into better balance. Investment should be reined in by imposing greater financial discipline on wayward public enterprises, while the social safety net should be strengthened, so that households would not have to save so much to meet the costs of having children and growing old.
Fast forward a decade, and what do we see? The government has built safety nets, and the current-account surplus has receded, exactly as hoped. Last year, the surplus amounted to less than 3.0 per cent of GDP, a fraction of its 2007 level.
But this hardly validates the theory. About half of the reduction in the current-account surplus has occurred because investment has actually increased as a share of GDP.
Meanwhile, there has been some decline in national saving, by perhaps 3.5 percentage points of GDP compared to 2007 (according to IMF estimates, as official data end in 2013). But this reduction is quite modest compared to the 15-percentage-point increase that occurred during 2000-2007.
Even more striking, all of this modest reduction in saving seems to have come from the corporate sector; household saving is roughly the same, relative to GDP, as it was in 2007. In other words, what went up during the boom has failed to come down. This is a real puzzle, and resolving it is important not only for China's future, but for that of the world.
There are two broad possibilities. It could be that the theory is basically correct, but needs more time to show results. In that case, as long as China's rulers continue to strengthen social safety nets, the decline in saving could match the envisaged decline in investment, keeping the current-account surplus low. But what happens if the theory is wrong, or incomplete?
For example, the beneficial effects of safety nets on saving may have been overestimated. Or those effects may be offset by the negative effects of population aging.
Over the next 15 years, the Chinese population aged 60 and above will increase by two-thirds. These aging workers might now be saving as much as they possibly can, to build up a financial cushion for impending retirement.
If some version of this scenario is realised, the household saving rate may continue to decline only gradually. In the meantime, the government would be closing unprofitable plants, which might boost corporate saving.
As a result, overall saving could remain high, even as investment falls sharply, causing the current-account surplus to surge again.
This would not be a pleasant prospect for the world economy.
As China slowed, so would global growth, and the remaining demand would be redistributed toward China, aggravating other countries' already-severe shortfalls.
This would be very different from the previous episode of global imbalances when large Chinese current-account surpluses were at least offset to some extent by rapid Chinese growth.
In short, whereas a hard economic landing for China could spur global deflation, avoiding that outcome could mean the return of global imbalances. These are the stark possibilities that leaders need to ponder as they gather gloomily at the IMF in Washington on April 15-17, 2016.
Arvind Subramanian is Chief Economic Adviser at India's finance ministry.
Project Syndicate, 2016 www.project-syndicate.org