According to a new report from Forbes, Al Gore is now worth more than last year’s Republican presidential candidate, Mitt Romney.

Last Wednesday, Al Jazeera announced that it would be purchasing Gore’s cable TV network Current TV for a price of $500 million. Because Gore owns about 20 percent of the network, he will be receiving roughly $100 million in the deal, pushing the former vice president’s net worth up to $300 million.

In contrast, Romney, who was often criticized during the campaign as wealthy and out of touch with the average American, currently maintains a net worth of about $230 million, according to last May’s Forbes analysis.

But how exactly did Gore become so rich? And why isn’t he as widely criticized for his wealth as Mitt Romney?

Gore left office in 2001 with a net worth of somewhere between $780,000 and $1.9 million, according to reports from Bloomberg. And while that certainly represents a lot of money, it didn’t exactly make him a big hitter in the financial world.

However, after a series of excellent investments, Gore vastly increased his net worth. His first big move was joining the board of Apple in 2003. As a board member, Gore received numerous shares of the tech company that have exploded in value over the past 10 years.

Given the fact that Gore’s position at Apple earned him $50,000 each year and 100,000 shares in stock, equating to roughly $56 million at today’s share prices, the former vice president certainly increased his net worth by an order of magnitude.

Besides his position at Apple, Gore also serves as an adviser to Google for significant stock options. And since launching Current Media in 2002, Gore has earned as much as $1 million each year as  salary, as well as collecting profits from films such as “An Inconvenient Truth.” And after selling the company, Gore is due between $70 and $100 million.

Finally, Gore has been known to make as much as $175,000 per speech on the lecture circuit. Add that all up, and it amounts to quite a large net worth, certainly larger than Mitt Romney’s.

As for Gore’s lack of criticism from the left due to his wealth, it may come from two main reasons. For one, many liberals simply aren’t aware that Gore is so wealthy, even though his net worth is now higher than Romney’s.

Another reason may be Gore’s perceived attitude towards his relatively recent wealth. While many liberals see Romney as detached and entirely profit-driven, Gore has spoken at length about responsible capitalism.

“We and others have called for a more responsible form of capitalism, what we call sustainable capitalism: a framework that seeks to maximize long-term economic value by reforming markets to address real needs while integrating environmental, social and governance (ESG) metrics throughout the decision-making process,” Gore and ex-Goldman Sachs executive David Blood wrote in a Wall Street Journal op-ed in December 2011.