At present there is no internationally-adopted legal instrument recognising the interconnectedness of all life. The proposed Universal Declaration of the Rights of Mother Earth was the first major move in this direction (this is a citizens initiative started in Bolivia in 2010). To date, over 124,000 citizens have signed the petition in support of its adoption internationally. The petition is available for signature here.
The closest that the United Nations has come to adopting anything approaching Earth Law was in the World Charter for Nature, which was ratified by the member nations of the United Nations on October 28, 1982. More recently, since 2009, the UN General Assembly has adopted six resolutions on Harmony with Nature, which contain various perspectives on the construction of a new, non-anthropocentric paradigm, in which decisions concerning the environment take into account more than only human concerns. The text of these resolutions and other information relating to the UN’s deliberations on creating harmony with nature can be found at the UN’s own website, Harmony with Nature.