By Tess Riley for The Guardian - Just 100 companies have been the source of more than 70% of the world’s greenhouse gas emissions since 1988, according to a new report. The Carbon Majors Report (pdf) “pinpoints how a relatively small set of fossil fuel producers may hold the key to systemic change on carbon emissions,” says Pedro Faria, technical director at environmental non-profit CDP, which published the report in collaboration with the Climate Accountability Institute. Traditionally, large scale greenhouse gas emissions data is collected at a national level but this report focuses on fossil fuel producers. Compiled from a database of publicly available emissions figures, it is intended as the first in a series of publications to highlight the role companies and their investors could play in tackling climate change. The report found that more than half of global industrial emissions since 1988 – the year the Intergovernmental Panel on Climate Change was established – can be traced to just 25 corporate and state-owned entities. The scale of historical emissions associated with these fossil fuel producers is large enough to have contributed significantly to climate change, according to the report. ExxonMobil, Shell, BP and Chevron are identified as among the highest emitting investor-owned companies since 1988.