The world's super rich just got richer with China's Jack Ma, co-founder of the e-commerce company Alibaba, earning the most in 2014, even as concerns grow about rising global social inequality.

According to the Bloomberg Billionaires Index, the wealth of the world's top 400 richest individuals increased by $92 billion, upping their combined net worth to $4.1 trillion. To put into perspective, their current total net worth is greater than the gross domestic product of Germany, the world's fourth largest economy.

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According to the index, Bill Gates of Microsoft is still the richest man in the world with $87.6 billion, after making $9 billion in 2014. But it was Alibaba's Ma who earned the most in the past year, increasing his value by $25.1 billion to $28.7 billion after the company's successful initial public offering (IPO) in September.

Another Chinese businessman Jiang Jianlin almost doubled his net worth after benefitting from an IPO for the commercial properties division of his conglomerate Dalian Wanda, now worth $25.3 billion. Five of the six billionaires whose net worth more than doubled in 2014 came from China.

Warren Buffet, the world's second richest man, is now worth $74.5 billion, thanks to his $13.7 billion earnings last year, while Oracle CEO Larry Ellison saw his net worth grow by $5.7 billion to $49.4 billion. Facebook's Mark Zuckerberg added $10.5 billion to his $35.3 billion net worth.

While this year's billionaires' tally might come as no surprise to most, the list has again drawn attention to the growing concern about global social inequality.

The ever-increasing gap between the rich and poor is the subject of the unlikely bestseller Capital in the Twenty-First Century by the French economist Thomas Picketty where he recommended that governments step in by adopting a global tax on wealth to prevent widening inequality that could lead to economic or political instability. 

"Today, the richest 10 percent of the population in the OECD area earn 9.5 times the income of the poorest 10 percent; in the 1980s this ratio stood at 7:1 and has been rising continuously ever since," said a report by the Organization for Economic Cooperation and Development (OECD).

In another OECD report, it states that 860 million people or more than a tenth of the world population lives in poverty, while the UN Food and Agriculture Organization counts some 805 million people as chronically undernourished in a 2012 to 2014 study. Last year, the International Labor Organization said worldwide unemployment stood at an all-time high of 200 million.

TagsBill Gates, Jack Ma, jiang jianlin, warren buffet, thomas picketty