For many years, Nicholas Stern was one of the biggest pessimists when it came to countering climate change through international talks. All this changed though in December during the 2015 UN climate change summit in Paris.

The British lord, professor of economics at London School of Economics and author of the seminal 2006 "Stern Review on the Economics of Climate Change" recently told a forum held at Fudan University that "each time I go to international conferences I'm pessimistic, and each time I come back, it is even worse than I thought it would be."

The summit in Paris was, in his words, a "turning point" showing that countries are finally coming together in a "remarkable way" to tackle climate change.

Speaking at a regular forum at Fudan's School of Management, Stern claimed that agreements reached in Paris illustrate that countries are finally realizing the risks of sitting on their hands and doing nothing about global warming. Specifically, the summit was significant in that delegates pledged to pursue a goal of keeping global warming to two-degrees Celsius above pre-industrial levels — while also pursuing efforts to limit average temperature increases to 1.5 degrees if possible.

Citing past scientific studies, the former chief economist of the World Bank warned that a two degree hike in global temperatures could be catastrophic.

For example, in a two-degree warmer scenario, the permafrost would start to thaw, resulting in a massive release in methane that would accelerate the process of global warming. Once ice sheets in the Arctic and Antarctic melt, the damage would be irreversible, warned Stern.

In his opinion, the Paris agreement is also important in that leaders now seem to understand that the alternative to high-carbon growth is attractive precisely because it doesn't necessary mean sacrificing development, said Stern.

In fact, the Paris talks came after the UN reaffirmed its commitment to millennium development goals on sustainable growth. Having made it his mission to address the two defining challenges of our time — managing climate change and overcoming poverty — Stern suggested that these two goals are mutually reinforcing.