Exxon Mobile was ordered to turn over 40 years of documents on Wednesday showing the company's views on and knowledge of climate change. The ruling was made by a Massachusetts judge in an investigation led by the state's attorney general Maura Healy, who is working to determine how much the company knew about the link between fossil fuels and climate change, and also to determine whether Exxon intentionally hid or suppressed information from the public and investors.