STRASBOURG, France — Europe’s highest human rights court ruled Tuesday that its member nations have an obligation to protect their citizens from the ill effects of climate change, but still threw out a high-profile case brought by six Portuguese youngsters aimed at forcing countries to reduce greenhouse gas emissions. The European Court sided with the Swiss members of Senior Women for Climate Protection, who also sought such measures in a mixed session of judgements in which a French mayor… was also defeated. Lawyers for all three had hoped the Strasbourg court would find that national governments have a legal duty to make sure global warming is held to 1.5 degrees Celsius, in line with the Paris climate agreement. …Although activists have had successes with lawsuits in domestic proceedings, this was the first time an international court ruled on climate change. …Tuesday’s decision will open the door to more legal challenges.