Earth Day and every day, we face significant environmental challenges tied to the way we live and use resources.  Effectively managing our scarce energy resources while addressing climate change – even as the world’s population steadily rises – will be one of the great challenges of the 21st century. Microsoft is working hard with our partners, customers and suppliers, as well as with governments and leading environmental organizations, to help address this critical environmental challenge.  This Earth Day, I want to share the latest information on our Environmental Sustainability Strategy, which focuses on three core areas:

Using information technology to dramatically improve energy efficiency. 

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Accelerating research breakthroughs.

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Demonstrating responsible environmental leadership at home.

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The full article is here : http://microsoftontheissues.com/cs/blogs/mscorp/archive/2009/04/21/why-earth-day-matters-to-microsoft.aspx