A coalition of 11,000 scientists has published a stark warning urging people and policy-makers to act to stave off the impending climate crisis or it will cause 'untold suffering'.
According to the scientists, who come from more than 153 countries, they had a 'moral obligation' to warn people about the scale of the threat.
They used a 'suite of graphical vital signs of climate change over the last 40 years' to present their case.
The statement, published in the journal BioScience, says major changes are needed to ward off the crisis. These include reducing meat intake, stopping deforestation, slashing population growth, and using alternatives to fossil fuels.
It adds that there is good news, saying 'such transformative change, with social and economic justice for all, promises far greater human well-being than does business as usual'.
The statement adds: "We believe that the prospects will be greatest if decision-makers and all of humanity promptly respond to this warning and declaration of a climate emergency and act to sustain life on planet Earth, our only home."
"An emergency means that if we do not act or respond to the impacts of climate change by reducing our carbon emissions, reducing our livestock production, reducing our land clearing and fossil fuel consumption, the impacts will likely be more severe than we've experienced to date," said Dr. Thomas Newsome, from the University of Sydney, a lead author of the statement.
"That could mean there are areas on Earth that are not inhabitable by people."