There are "unequivocal" signs that rising temperatures around the globe are clearly being caused by human influence, according to a major new report by the Intergovernmental Panel on Climate Change (IPCC), whose scientists are 95% certain the majority of global warming since the 1950s is down to human activity.
The report draws on thousands of scientific papers to warn ice sheets are melting, glaciers are shrinking, sea ice-cover has reduced in the Arctic and the permafrost is thawing in the northern hemisphere.
The Scottish Government has set tough targets to reduce Scotland's emissions by 42% by 2020 and ministers have urged other nations to follow a similar path.
Environment and Climate Change Minister Paul Wheelhouse said: "The Scottish Government welcomes the publication of this report, which provides a stronger warning than ever that human activity is changing the global climate.
"Reducing global greenhouse gas emissions, through domestic action, is the only way to limit the extent of future climate change.
"However, Scotland's actions alone are not enough, given the IPCC's warning. We need the rest of the UK, our European neighbours and, indeed, all countries to share our ambition.
He added: "We want to see an ambitious global deal on climate change agreed in 2015 and have been calling for the EU to raise its pre-2020 emissions target."
Temperatures are predicted to rise by more than 1.5C above pre-industrial levels by the end of the century unless action is taken and could rise by over 4C if emissions continue to increase.
The report says storms will become more intense and frequent, sea levels will rise by between 10in and 32in by the end of the century and the oceans will become more acidic.
Global warming is also likely to have a severe impact on the world's population in coming decades as rising sea levels mean action will have to be taken to safeguard major coastal cities, such as New York and London.
A warmer earth will mean hotter areas will experience heatwaves that last longer while temperate climates, such as Scotland, will get wetter, raising the fear of an increased flood risk.
Findings also show major impacts on our oceans are a huge concern, as more than one billion people live and depend on the sea as their main source of food and livelihoods.
Thomas Stocker, one of the scientists leading the first section of the IPCC's assessment, said: "Continued emissions of greenhouse gases will cause further warming and changes in all components of the climate system.
"Limiting climate change will require substantial and sustained reductions of greenhouse gas emissions."
Campaigners have called for tougher action from governments, warning that rising temperatures will be a "catastrophe" for the developed world.
Dr Richard Dixon, director of Friends of the Earth Scotland, said: "Scientists are clear that climate change is real, is caused by humans, and is already having severe impacts on people and nature.
"Tough action is urgently needed to end the planet's dangerous fossil fuel fixation and to develop the huge job-creating potential of renewable power, with countries like Scotland taking the lead."
He added that measures such as insulating people's homes, a major shift in focus from cars to public transport, walking and cycling and a continuing transformation of the electricity sector are needed to reduce the amount of greenhouse gases entering the atmosphere.
Dr Sam Gardner, head of policy at WWF Scotland, said: "Four years ago the Scottish Parliament listened to the scientific evidence and, in passing the Climate Change Act, signalled its commitment to respond to the risks.
"Today, the IPCC has strengthened the scientific evidence further and underscored the urgency of action. This must trigger the translation of Scotland's ambition into action."
Foreign Secretary William Hague said the report confirms climate change is already happening.