Looking back at each of the past four decades, there was one sector that would have been the “home run” sector to be invested in. Other areas provided good returns to be sure, but these were the most profitable:

1970s: Gold, up 1,250%. The price of gold was fixed until 1971. Once it was left to float, it proceeded to run from around $50 an ounce to $681 just after the start of 1980 as inflation reared its ugly head.

1980s: Nikkei Index, up 1,000%. The decade of the Japanese market turned out to be largely a bubble, but not before the smart money got very, very rich.

1990s: Nasdaq, up 1,000%. A proxy for technology stocks, the Nasdaq Composite started the decade just over 400 and finished the go-go ’90s just over 4,000.

2000s: Real Estate, up 200%. Even with real estate cratering the past few years, REITs have still doubled this decade, far outpacing every other asset class.

So that begs the question: What will be the home run in the coming decade?

This was one of the more interesting topics being knocked around by hedge fund managers and Wall Street executives at the Global Financial Leadership Conference, a Davos-like confab I attended at the start of the month in Naples, Florida.

I give credit to University of Notre Dame chief investment officer Scott Malpass for pointing out this run of big winning sectors listed above. As the investment strategist for the $8 billion Notre Dame endowment, Malpass has posted annualized 14% returns during the past 10 years. One of his priorities for the fund now, he told the GFLC conference, is making sure he gets Notre Dame good exposure to the home run sector of the 2010s. Malpass is focusing on three areas to find the next big winning sector: gold, real estate and Green.

Gold could be it if you believe inflation and a weak dollar are in the offing. Place your bets on real estate if you believe the fundamentals that sparked the original bull market are still basically in place and that the sell-off of the past few years is overdone. Go for Green if you recognize the dual need to respond to the global warming crisis along with the energy crunch. Both are converging to create a very firm fundamental push for alternative energy and energy efficiency stocks.

Now, as a student of the market, I know history shows bull moves rarely repeat themselves in specific stocks or sectors, so I’d say odds are against gold and real estate posting triple-digit gains again. Plus, with tighter individual and corporate credit, easy capital won’t be the norm for real estate like it was in the past. I also believe the Fed sees inflation as its worst enemy and will fight it tooth and nail for the long-term, damping widespread desire for gold. That leaves Green as the logical candidate to be the home run sector of 2010 and beyond.

But don’t just take my word for it. The International Energy Agency, the analysts paid by Western oil-consuming nations to provide accurate pictures of energy needs and outlook, believes that $2 trillion could be spent globally between 2010 and 2020 on end-use and power plant efficiency measures to help the world reach a stable carbon output level. Yes that’s trillion, with a T.

It’s worth noting, too, that President Barack Obama’s advisor Paul Volcker (the stagflation-slaying former Fed president) said at the GFLC that the president seems focused on energy efficiency and Green technology as the basis of U.S. economic growth, in contrast to the past 25 years of administrations that focused on boosting consumer spending for growth.

The world shift to Green is already starting, of course. China is mandating that 120 gigawatts of energy come from renewable resources like wind and solar by 2020, while here in the U.S. we are working toward our own carbon reduction program that will target reductions of between 17% and 25% by 2020, depending on how the Senate and House reconcile their bills on the matter.

Deutsche Banc Asset Management in October compiled a list of recent Green mandates implemented by major world governments since July and I thought it would be beneficial to reproduce them here:

Brazil: 54 GW new grid capacity including 1.1 GW wind, 3.3 GW biomass and 3.9 GW small

China: Reduce energy intensity by a notable margin by 2020

India: 20 GW solar by 2020

Indonesia: 26% reduction in emissions by 2020

Mexico: 8% emissions below 2009 levels by 2012; Increase renewable energy capacity from 3.3% in 2008 to 7.6% in 2012

New Zealand: 10% emissions below 1990 levels by 2020 and 50% below 1990 levels by 2050

Norway: 40% reduction in emissions from 1990 levels by 2020

Russia: 10% reduction in emissions below 1990 levels by 2020 and 50% by 2050

Scotland: 42% cut in emissions by 2020 from 1990 levels

South Korea: 4% reduction in emissions from 2005 levels by 2020

Switzerland: 20% reduction in emissions by 2020 from 1990 levels

Ukraine: 20% reduction in emissions by 2020 from 1990 levels

United States: 20% reduction in emissions by 2020 and 80% by 2050 from 2005 levels (Clean Energy Jobs and American Power Act, still pending final passage).