LOS ANGELES (CNS) — Scientists from UCLA and elsewhere warn in a new paper of a "ghastly future" for humanity with declining health, climate devastation, tens of millions of environmental migrants and more pandemics in the coming years unless extraordinary action is taken soon.

"Without fully appreciating and broadcasting the scale of the problems and the enormity of the solutions required, society will fail to achieve even modest sustainability goals, and catastrophe will surely follow," said one of the paper's co-authors, Daniel Blumstein, a UCLA professor of ecology and evolutionary biology and member of the UCLA Institute of the Environment and Sustainability.

"What we are saying is frightening, but we must be both candid and vocal if humanity is to understand the enormity of the challenges we face in creating a sustainable future."

In the paper published Tuesday in the journal Frontiers in Conservation Science, the 17 prominent scientists cite more than 150 studies, concluding that it is now "scientifically undeniable" that humanity is "on the path of a sixth major extinction."

The Earth has experienced five mass extinctions, each accounting for a loss of more than 70% of all species on the planet. The most recent was 66 million years ago.

The paper reports projected temperature increases and other human assaults on the environment mean that about 1 million of the planet's 7 million to 10 million species are threatened with extinction in the coming decades.

Blumstein said that during the next several decades, an extinction affecting as many as 70% of all species -- like the earlier mass extinctions cited in the paper -- could potentially take place.

One of the major trends discussed in the paper is the explosive growth of the planet's human population. There are now 7.8 billion people, more than double the Earth's population just 50 years ago.

By 2050, the figure is likely to reach 10 billion, the scientists write, which would cause or exacerbate numerous serious problems.

For example, more than 700 million people are starving and more than 1 billion are malnourished already; both figures are likely to increase as the population grows.

Population growth also greatly increases the risk for pandemics, the authors write, because most new infectious diseases result from human-animal interactions, the fact that humans live closer to wild animals than ever before and that wildlife trade is continuing to increase significantly.

Population growth also contributes to rising unemployment and, when combined with a hotter Earth, leads to more frequent and intense flooding and fires, poorer water and air quality, and worsening human health.

The authors write that there is a "near certainty that these problems will worsen over the coming decades, with negative impacts for centuries to come" and that the adverse global trends are obvious.

"Humanity is running an ecological Ponzi scheme in which society robs nature and future generations to pay for short-term economic enhancement today," said Paul Ehrlich, a Stanford University professor emeritus of population studies and a co-author of the study.

The paper elucidates issues that have been publicized over the past few years by many activists, including the Swedish 18-year-old, Greta Thunberg, Time magazine's 2019 person of the year. Blumstein said Thunberg has been absolutely right about the urgency of the dangers we face.

The authors also write the severity of the threats should transcend political tribalism, but so far they haven't -- and they're skeptical about when or if change can occur.

"Most of the world's economies are predicated on the political idea that meaningful counteraction now is too costly to be politically palatable," according to the paper.

"Combined with financed disinformation campaigns in a bid to protect short-term profits, it is doubtful that any needed shift in economic investments of sufficient scale will be made in time," the paper contends.

"While it is positive news that President-elect Biden intends to re- engage the U.S. in the Paris Climate accord within his first 100 days of office, it is a minuscule gesture given the scale of the challenge," according to Ehrlich.

The paper suggests concrete changes that could help avert catastrophe. Among them: completely and rapidly ending the use of fossil fuels, strictly regulating markets and property acquisition, reining in corporate lobbying and empowering women.

But it also acknowledges that humans' innate "optimism bias" has led some to ignore the warnings about our planet's future.

"By the time we fully comprehend the impact of ecological deterioration, it will be too late," Blumstein said.