Over 15,000 scientists have signed a warning letter about the Earth.

Twenty five years ago, a majority of the world’s living Nobel Laureates united to sign a warning letter about the Earth; today, scientists have taken grassroots action, with a scorecard - created in the United States and seeded in Australia - showing that of nine areas only one has improved: our ozone.

The scientists say urgent action must be taken to avoid substantial and irreversible harm to the Earth.

An article titled “World Scientists’ Warning to Humanity: A Second Notice”, has been co-signed by more than 15,000 scientists in 184 countries and is published today in the journal BioScience.

Co-author Dr Thomas Newsome, a research fellow at Deakin University and The University of Sydney, said he believed this was possibly the biggest number of signatories to any published scientific paper.

“It’s an overwhelming response we didn’t quite expect,” said Dr Newsome.

The initial warning 25 years ago identified trends that needed to be reversed to curtail environmental destruction, including ozone depletion, forest loss, climate change and human population growth.

“In this paper we look back on these trends and evaluate the subsequent human response by exploring the available data,” Dr Newsome said.

Among the negative 25-year global trends noted in the new article are:

· A 26 per cent reduction in the amount of fresh water available per capita

· A loss of nearly 300 million acres of forestland

· A collective 29 per cent reduction in the numbers of mammals, reptiles, amphibians, birds and fish

· A 75 per cent increase in the number of ocean dead zones.

Regarding Australia, Dr Newsome said habitat loss was the number one threat, and in 2017 Australia ranked number two in the world for global biodiversity loss, behind Indonesia.

“There’s been recent reports on an alarming rise in tree clearance in Queensland - about 400,000 hectares per year; the equivalent of 400,000 football fields - which puts us in line with Brazil,” Dr Newsome said.

“All the while we have very low public spending for example on threatened species - around $70 million each year, or less than one hundredth of a percent of the federal government’s annual revenue of $416.9 billion - we spend more rehabilitating mine sites each year,” he said.

The article states there is still time but notes the areas that need to be improved, including promoting dietary shifts away from meat, encouraging the adoption of renewable energy and limiting human population growth.