While attributing individual weather disasters to climate change remains a complex task, scientists say droughts and floods are likely to happen more frequently and become more intense, while storms are fuelled by warmer seas. "How dare you?" she thundered, her voice at times breaking with emotion.
What did Greta Thunberg say?
Mohamed Adow, who leads climate change work at worldwide charity Christian Aid, believes Africa is already suffering the damaging effects of global warming.
To those wielding power, the activist said, "You are failing us, but young people are starting to understand your betrayal".
Trump was initially expected not to attend the summit and was meant to be at a session on religious persecution instead. Thunberg told member nations participating at the Summit that the young generation will "never forgive" them if they fail to act on climate change deftly.
The petition names five countries - Germany, France, Brazil, Argentina and Turkey - which they say have failed to uphold their obligations under the Convention on the Rights of the Child, a 30-year-old human rights treaty which is the most widely ratified in history.
"You have stolen my dreams and my childhood with your empty words", Thunberg said, adding that the plans that leaders will unveil will not be enough to respond to the rate of the planet's warming. The president in the past has questioned man-made climate change, at one point calling it a Chinese hoax.
US President Donald Trump dropped by, listened to German Chancellor Angela Merkel's detailed pledges, including going coal-free, and then left without saying anything.
Although almost every nation on the planet, including the United States, promised to reduce their net greenhouse gas emissions when they signed the Paris Agreement, climate scientists warn that the cumulative pledges are nowhere near sufficient.
Murombedzi said it was getting harder for most African countries to meet a set of global development goals, including ending hunger and poverty by 2030, as their economies and ecosystems are hurt by climate change.
He, therefore, stressed the need for Member States to step-up their collective climate actions in line with the request of the Secretary General. We will not let you get away with this.
But she said that she saw progress too.
While presidents and premiers talked about what they hoped to do inside their own borders, French President Emmanuel Macron reminded them they must include climate change in their trade and finance policies so they don't import goods that increase carbon pollution, or fund polluting plants in other countries.
Shortly after the speech, Thunberg and other young people filed a legal complaint against five countries, saying their role in climate change has violated a widely ratified United Nations pact on children's human rights.