Mark Hertsgaard

Outlines how the organization founded by US climate activist Bill McKibben in 2007 was still promoting climate activism: supporting the indigenous struggle against the Keystone XL oil pipeline, urging universities and other bodies to stop investing in fossil-fuel companies and playing a significant role in organizing hundreds of thousands at the September 2014 People's Climate March in New York city. Hertsgaard also notes 350.org's role in international lobbying and activism in the run up to the UN Paris Climate Conference in 2015. The article was written just as McKibben was standing down as chairman. 

See also: https://www.influencwewatch.org/non-profit/350-org/ for a brief history and assessment, including explanation of the organization's name, which sums up McKibben's belief that the concentration of carbon dioxide in the atmosphere needs to fall to 350 parts per million, or below.