Amazon founder Jeff Bezos said Monday that he plans to spend $10 billion of his own fortune to help fight climate change.Bezos, the world's richest man, said in an Instagram post that he will start giving grants this summer to scientists, activists and nonprofits working to protect the earth."I want to work alongside others both to amplify known ways and to explore new ways of fighting the devastating impact of climate change," he said in the post.Amazon, the company Bezos runs, has an