70-year-old climber Bill Burke eyes second Everest ascent

Three years ago, at the age of 67, Bill Burke become the oldest American to ever climb Mount Everest.

Now 70, Burke is doing it again — twice.

The California native is planning to climb the world's tallest peak from both sides this time. He'll summit "Mt. Everest from the south (Nepal) side of the mountain and then turn right around and head for the north (Tibet) side of the mountain and summit once again."

"It is going to be very tight climbing both sides in the same season," Burke told Reuters.

The Eco Everest leader's major climbing obstacle? Time. The climbing season ends this month, before the monsoon rains arrive in June.

Burke holds the record for being the only person to climb the "Seven Summits", which are the highest peaks on all seven continents after the age of 60.