In a week of climate headlines, the European Union has unveiled its much-awaited "taxonomy” rulebook of investments that may be labelled green. However environmental experts advising the process say the result is at odds with science. The classification scheme, three years in the making, is intended to be a gold standard checklist to avoid “greenwashing” and help investors work out which investments are truly climate-friendly.Nuclear and gas activities were left off the list, published Wednesday by the European Commission, following uproar over a leaked document, seen by RFI, that suggested gas plants could be considered partially sustainable under certain conditions.A decision on the status of nuclear and gas activities was put off until the summer, when the EU is to table separate legislation.“This is groundbreaking and I think that’s something we should not lose sight of today as Europeans," said financial services commissioner Mairead McGuinness, adding the taxonomy's credibility was "based on science". 'Many shades of green'But environmental groups have accused the EU of having “many shades of green”, arguing the taxonomy rules –due to take effect early next year – risk becoming a greenwashing tool themselves.Several NGOs walked out of an advisory group that helped the EU draft the rules in protest at the inclusion of the forestry and bioenergy sectors. Alarm over leaked EU plans to label gas plants as 'green' EU rolls out trillion-euro plan for green economy“The commission’s final taxonomy on forestry and bioenergy ... has been strongly influenced by unbalanced lobbying by Finland and Sweden," said Sébastien Godinot, an economist at the WWF’s European office."It is at odds with environmental science, discredits the taxonomy and creates a disastrous precedent.”Work in progressThe commission said the taxonomy tool, which will be updated over time, covers the economic activities of about 40 percent of listed companies that are domiciled in the EU, in sectors that account for 80 percent of emissions.It is part of the EU’s wider efforts to become the world’s first carbon neutral continent by 2050. To achieve this, the bloc has pledged to cut carbon emissions by 55 percent this decade.