The UN-backed study said the impacts of climate change, from droughts to rising seas, will be less extreme if temperature rises are curbed at 1.5C above pre-industrial levels than if they climb to 2C.
The Intergovernmental Panel on Climate Change (IPCC) report said limiting warming to 1.5C is possible but will require fast and far-reaching changes to power generation, industry, transport, buildings and potential shifts in lifestyle such as eating less meat.
Action will also be needed to cut carbon emissions to zero by 2050.
The report warns the world is set to breach the 1.5C threshold by around 2040 and is heading for 3C by 2100 and even warmer after that.
Scotland’s new Climate Change Bill, published earlier this year, proposes reducing harmful emissions by 90% by 2050 - up from the previous target of 80%.
The Scottish Government said it will look at targets again in the wake of the IPCC report.
A Scottish Government spokesman said: “We welcome the publication of the UN Intergovernmental Panel on Climate Change report on the scientific evidence around the Paris Agreement aim of limiting global warming to 1.5 degrees Celsius.
“In line with our evidence based approach to tackling climate change, we are committed to considering the report carefully, including seeking updated independent, expert advice from the UK Committee on Climate Change on its implications for our targets.”
The IPCC report says a 2C rise will lead to more heatwaves and extreme rainstorms, more people facing water shortages and drought, greater economic losses and lower yields for major crops than 1.5C.
While coral reefs could decline 70% to 90% with 1.5C of warming, virtually all the world’s reefs would be lost at 2C, while far more creatures and plants across the world face losing a large part of their range.
Stop Climate Chaos Scotland said the report is a “game changer” and urged the Scottish Government to set a net zero emissions target by 2050.
Campaigns Manager Gail Wilson said: “Climate change is the biggest threat to the planet and everyone that lives here.
“Unless governments urgently take much more concrete action to reduce emissions, we will soon be in a scenario where it is simply too late.”
Friends of the Earth Scotland called on the SNP to commit to cutting climate emissions “further and faster” in the next few years.
Director Dr Richard Dixon said: “Today’s IPCC report is an unprecedented warning on climate change. It makes clear that governments have a narrow and shrinking window for action in which to avert further catastrophic temperature rises.
“It shows that a 1.5C world will be a nightmare but a 2C world would be unthinkable.”
The Scottish Greens have called for a summit of political and civic leaders throughout Scotland to discuss the issues in the report.
Scottish Greens’ co-convener Patrick Harvie said: “We’ve always challenged the government to go further in its response to dangerous climate change.
“However this report from an internationally respected organisation makes clear the urgent need for all nations to transform their economies to achieve zero-carbon.”