The size of the event generated enormous media attention but also led some climate activists and observers to question whether the process is worth the time, effort, and expense. Based on more than 20 years attending such meetings, my view is that the growth in attendance is understandable, a reflection of the increasing recognition global climate change is an existential and urgent matter. While it may appear to be a large trade show or festival (even for many of those attending), the numbers only indirectly influence the outcomes — if at all.
The initial governmental climate meetings were modest affairs. Along with a few hundred others, I attended some of the negotiations leading to the 1992 Convention. The attendance grew over time to average about 25,000 and varied with the agenda (some meetings had little of significance to negotiate) and the ease and cost of participation (e.g., travel to Bali versus Warsaw). A major meeting such as that in Paris in 2015 attracted 40,000. Meanwhile other forums negotiating climate change related issues (e.g., a 2016 Kigali Amendment to the Montreal Protocol phasing down use of a powerful greenhouse gas) had far fewer participants.