Blog Action Day is an annual event that unites the world's bloggers in posting about the same issue on the same day on their own blogs with the aim of sparking discussion around an issue of global importance. This year the issue is Climate change.

Blog Action Day 2009 will be the largest-ever social change event on the web. So far more than 4770 people from 122 countries have registered their blogd to participate by posting about climate change on October 15. More than 200 in Spain and a lot of them also in Catalonia. There are more than 10 million expected readers.

In addition to 11 of the top 100 blogs in the world, they have just formed partnerships with the blog platforms Blogger, blog.de, and BlogHer. The UK's government and the ruling party of Spain (PSOE) are both joining in and nonprofit organizations from around the world including Oxfam, 350.org, The Nature Conservancy, Greenpeace, The United Nations Foundation and more than 40 organizations affiliated with the TckTckTck campaign are participating.