Ms Sturgeon warned keeping global warming to less than 1.5C cannot simply be a “face-saving slogan” but must be met with real action.
The speech, delivered to young people and students in Glasgow, also called on international leaders to deliver a fair financial package for the global South.
The UK will host more than 120 world leaders at the COP26 summit in Glasgow on October 31 to November 12.
The First Minister also emphasized the unique position Scotland was in to make the UN climate change conference a success, and said the country will act as a “bridge” by creating dialogues and promoting understanding between countries.
“We can send a strong message of climate ambition for #COP26 in Glasgow.”
Devolved, state and regional governments play a crucial role in delivering net zero.
First Minister @NicolaSturgeon explains more ⬇️ #Under2Coalition pic.twitter.com/nFSk4pMx5Q
— Net Zero Scotland (@ScotGovNetZero) October 19, 2021
She said: “We will take seriously the responsibility of all governments, at all levels, to show ambition, and to galvanise action.
“If we do that, we can all contribute towards a successful summit.
“I have said that small countries can lead the way in this, and they can, but in the coming days, it is the countries which emit the most, who most need to step up.
“They need to make ambitious pledges to achieve net zero.
“And those pledges must be backed by credible actions.
“The idea of ‘keeping 1.5 alive’, cannot simply be a face-saving slogan. It must be real.
“And there must be progress in Glasgow which makes that outcome more likely.”
The talks in Glasgow have been billed as the last best chance to limit global warming to 1.5C in the long term.
Ms Sturgeon said that Scotland will do what it can to contribute to a successful outcome at the Glasgow summit.
She said: “Scotland is in a unique position to help make COP a success.
“And one of the ways in which we will do that, over the next three weeks, is by acting as a bridge.
“We will use our position, as the venue for COP, to create spaces and dialogues which encourage empathy, promote understanding and help people share perspectives.
“We will encourage national governments to match the ambition of cities, regions and state governments.
“We will help those around the negotiating table to hear from activists in the developed world and from the global South.”