Countries are under pressure to make progress on a first-ever global plastics treaty this week, but they face tense negotiations in the Canadian capital with parties deeply divided over what the treaty should include as talks begin on Tuesday. If governments can agree on a legally binding treaty that addresses not just how plastics are discarded, but also how much plastic is produced and how it is used, the treaty could become the most significant pact to address global climate-warming emissions since the 2015 Paris Agreement. The production of plastics accounts for some 5% of climate emissions and could grow to 20% by 2050 unless limited, according to a report last week from the U.S. federal Lawrence Berkeley National Laboratory. When countries agreed in 2022 to negotiate a legally binding treaty by the end of this year, they called for addressing the full life cycle of plastics — from production and use to waste. But as negotiations kick off in Ottawa, there is staunch opposition from the petrochemical lobby and some governments dependent on fossil …