Old and New Forecasts for Shares of the Global Economy in 2050.

In our recent paper forecasting global economic outcomes in 2050, we compared our estimates to the five shared socioeconomic pathways developed in 2018–scenarios used as part of climate change forecasting exercises by the IPCC. But these were far from the first global economic forecasts to reach 2050: there were similar exercises by the Paris School of Economics-CEPII in 2012, one by PWC in 2011, and one by the OECD in 2010, for example. 

The table below compares shares of global GDP over time and across the forecasts–the 2019 share, the Gehan-Kenny (GK) central estimate for 2050, the average of the five SSP scenario estimates for 2050, and the forecasts by these three earlier exercises.  

Overall, it is interesting how little an extra decade or so of data and experience has changed the basic picture: the US and EU are still predicted to considerably shrink their share, and China and India to grow. That said, there seems to be greater consensus on the future performance of China: the range across all SSPs and the Gehan-Kenny exercise on China’s share in 2050 is 19 to 24 percent compared to a range of 16 to 28 percent in the three earlier exercises. And recent forecasts for India cluster at the lower end of earlier forecasts–the ‘consensus’ (such as it is) has moved away from India considerably overtaking the US in global economic share by 2050. All of this will reflect methodological choices as well as the impact of additional data, but there is a fair amount of methodological similarity between the exercises old and new.  

As a rule, you’d expect more data and a shorter forecast period to improve forecast accuracy. But that isn’t always the case. We note in the paper that the UN forecast made in 1966 for the size of the world population in 2000 was more accurate than any subsequent forecast until as late as 1997. And it is unarguable that there’s still considerable uncertainty about any of these numbers. But perhaps it is fair to say that earlier estimates that China could control as much as 28 percent of the global economy by 2050, or that its share would not increase at all from the share in 2019, both look more unlikely, while its status as the world’s largest economy by some margin at midcentury looks increasingly secure.   

Share of Global GDP, PPP: 2019 and 2050 Forecasts