Chicago has just made history!

Chicago has just made history! One of the world's most iconic skylines was plunged into darkness as Chicagoans sent a strong message to the world that they are committed to addressing climate change -- the greatest environmental threat the world has ever seen.

One by one the lights flicked off and the third largest city in America faded into the night sky. The Sears Tower, the largest bulding in the US, was barely visible. The John Hancock Center went out. As did the Tribune Tower, Wrigley Building and nearly every other office bilding in the city. Soldier Field, home of the Chicago Bears, went dark, along with the famous marquee at Wrigley Field.

Speaking of marquees, they were shut off throughout Chicaogo's theater district. Elphaba, the witch from the production "Wicked" shut off the lights with a dramatic "spell".

At Chicago's famous Navy Pier, thousands of lights were turned off, including those on the iconic ferris wheel. Michigan Avenue was completely dark as virtually every store along the "Magnificent Mile" joined the movement and switched off.

Nearly 500 golden arches were turned off at McDonald's restaurants throughout the Chicago region. Hotels went dark as well. The Swissotel hosted a candle-lit Earth Hour-themed wedding. The well-known Weathermark Tavern offered a special Earth Hour dinner, complete with a champagne toast at 8 pm.

Chicago was truly transformed in a dramatic yet humbling display of its "will do" spirit. Chicagoans showed that individual acts, taken collectively, can make a tremendous impact. It is in that spirit, that the city is leading the way to a greener, cleaner, more sustainable future.