It spoke volumes that the first thing President Barack Obama did as soon as he arrived in Paris late last night for the major UN climate change conference was to go to the scene of the Bataclan theatre attack where so many people were killed in the terrorist attacks earlier this month.
The mass murder by Islamist extremists in Paris and elsewhere - from Bamako to Beirut to the Sinai Peninsula - overhangs this conference, and some say, helps to give it a greater sense of urgency and focus on achieving results than the last significant global effort in Copenhagen in 2009.
Indeed, President Francois Hollande said as much in his opening remarks when he told the thousands of delegates and 147 heads of government and other world leaders that what was at stake at these talks was the future of peace itself.
His words were echoed by Prince Charles who said “never before has a responsibility so great been in the hands of so few. Your deliberations over the next two weeks will decide the fates of future generations”.
Much has been focused on the staggering security operation surrounding this conference, with 120,000 armed police and soldiers on duty across France. The venue site on the outskirts of Paris is in effective lock down with roads to and from the venue closed off and only accessible by official buses, with heavy security screening in and out of the conference and delegate halls.
Some campaigners such as Naomi Klein have criticised President Hollande for banning marches and demonstrations, saying even in the wake of 9/11 the government of President George W Bush didn’t take such draconian action.
Despite that, large protests focusing on the talks have taken place around the world, including in central Paris the day before the conference opened.
There are two other critical differences this time compared to Copenhagen in 2009.
Unlike George W Bush in the aftermath of the Iraq invasion, President Obama is not seen as such a polarising figure and is in search of a real global legacy to his presidency, which is in its last year.
Furthermore, unlike Copenhagen when world leaders didn’t arrive until the end, this time they have been present at the start of the talks, thus giving negotiators a much-needed focus to work towards, rather than a tight last-minute deadline to meet.