Overlapping environmental crises could tip the planet into a ‘global systemic collapse’, more than 200 global scientists have warned.

Climate change, biodiversity loss, dwindling sources of fresh water and food, and extreme weather events from hurricanes to heatwaves will provide a monumental challenge to humanity in the 21st century.

Out of 30 global-scale risks, these five topped the list both in terms of likelihood and impact, according to scientists surveyed by Future Earth, an international research organisation.

The report, published on Thursday, called on the world’s academics, business leaders and policymakers to ‘pay urgent attention’ to the five risks and consider them as interlinked.

In combination, they ‘have the potential to impact and amplify one another in ways that might cascade to create global systemic collapse,’ a team led by Maria Ivanova, a professor at the Center for Governance and Sustainability at the University of Massachusetts, said in a 50-page report.

‘Humanity is at a critical stage in the transition to a more sustainable planet and society,’ said Amy Luers, executive director of Future Earth.

‘Our actions in the next decade will determine our collective future on Earth.

‘2020 is a critical time to look at these issues.’

Of the five main issues, extreme heat waves are speeding global warming by releasing planet-warming gases from natural sources.

While Europe had its third-warmest and Asia its fourth warmest October on record, dry and warm conditions in Australia caused intense bushires this season that killed an estimated 1 billion animals in the country.

Australia’s bushfires and fires in the Amazon region in 2019 were partly caused by climate change, the report says, as warmer air pulls moisture out of vegetation, creating drier fuel and feeding wind to fan flames.

In the Arctic region, meanwhile, the last five years have been the warmest on record, melting sea ice and affecting wildlife, fisheries and local communities.

But the greater the warming, the greater the anticipated impacts of heatwaves in cities as well, mainly in places of high urbanisation rates, poverty and marginalisation in South East Asia and Latin America.

‘A warmer world has higher risks of flooding, landslides, fire and infectious and parasitic disease,’ the report says.

Biodiversity loss, meanwhile, weakens the capacity of natural and agricultural systems to cope with climate extremes, also putting food supplies at risk.

Elsewhere in the report, the authors highlight the undernourishment in impoverished parts of the world compared with the obesity crisis in developed countries.

‘The amount of food produced per person on the planet has gone up by more than 40 per cent since the 1960s,’ it says.

Yet the prevalence of undernourishment has started to go up again – the total number of people undernourished in 2018 stood at more than 820 million people, up from a record low of 785 million in 2015.

At the same time, some 1.9 billion people are overweight and 650 million are obese – highlighting a discrepancy in food security.

The world needs to feed an estimated 9 billion people on a planet with diminished natural resources.

But strains on food production are expected to increase caused by changing climate and environments, the report says – once again highlighting how the top five global-scale risks are closely related.

Scientists worry especially that rising temperatures could tip the planet’s climate system into a self-perpetuating spiral of global warming.

As it is, humanity is struggling – so far unsuccessfully – to cap carbon dioxide and methane emissions, mostly from burning fossil fuels.

If at the same time a warming Earth also begins to emit large amounts of these gases from, say, thawing permafrost, such efforts could be overwhelmed.

‘Many scientists and policymakers are embedded in institutions that are used to thinking and acting on isolated risks, one at a time,’ the report says.

‘We call on the world’s academics, business leaders and policy makers to pay attention to these five global risks and ensure they are treated as interacting systems.’

Nearly 1,000 decision makers and top CEOs highlighted the same threats in a similar survey last month ahead of the World Economic Forum meeting in Davos, Switzerland.

In October, the world’s nations are set to gather for a major United Nations meeting in Kunming, China to try to stanch the destruction of ecosystems and the decline of biodiversity.

Scientists agree that Earth is at the outset of a mass extinction event – only the sixth in half-a-billion years – which could drive a million species, or one-in-eight, into oblivion over the coming decades or centuries.

The following month, a critical UN climate summit in Glasgow will reveal whether the world’s major economies are willing to ramp up carbon cutting pledges that fall far short of what is needed to keep the planet hospitable for our species.

Some scientists have begun to look at the likelihood and impacts of cascading environmental crises in the last 12 months, including the Australian bushfires, floods in the Philippines and cyclones in Africa.

Research has shown that some parts of the world may soon be coping with up to six extreme weather events at once, ranging from heat waves and wildfires to biblical floods and deadly storm surges.

‘Human society will be faced with the devastating combined impacts of multiple interacting climate hazards,’ Erik Franklin, a researcher at the University of Hawaii’s Institute of Marine Biology and co-author of a key study in late 2018, told AFP.

‘They are happening now and will continue to get worse.’

Even if humanity caps global warming at two degrees Celsius (3.6 degrees Fahrenheit) above pre-industrial levels, as stipulated in the 2015 Paris Agreement, New York City will likely face one major climate hazard every year, on average, by 2100.

If, however, carbon pollution continues unabated, the Big Apple could be hit by up to four such calamities at once, including extreme rain, sea level rise and storm surges.