Climate change will see temperatures rise 4C-5C higher than regular temperatures causing a “severe risks for health, economies, political stability, and ultimately, the habitability of the planet for humans”.
The doomsday warning comes from a team of international university researchers, who said global targets to keep temperatures from rising 2C are not tough enough to stop what is coming.
Writing in the journal Proceedings of the National Academy of Sciences, scientists said a Hothouse Earth would lead to rising sea levels, increased methane and carbon dioxide and melting permafrost.
Professor Johan Rockstrom, a leading member of the research team from the University of Stockholm, Sweden, said several “tipping points” will act as like a “row of dominoes”, occurring one after the other and posing catastrophic risk to climate change.
He said: “Once one is pushed over, it pushes Earth towards another. It may be very difficult or impossible to stop the whole row of dominoes from tumbling over.
“Places on Earth will become uninhabitable if Hothouse Earth becomes the reality.”
Catastrophic climate change will cause sea levels to rise by 60 metres, threatening residents inhabiting coastal towns.
Every year, the Earth’s forests and oceans absorb over 4.5 billion tonnes of carbon, which would otherwise end up in the air and increase global temperatures.
However, a Hothouse Earth could turn the world’s natural carbon storage systems or “sinks” into powerful greenhouse gas emitters, significantly rising temperatures.
The ‘tipping point’ dangers were identified as:
- Thawing permafrost,
- The release of methane trapped on the ocean floor, weakening land and ocean carbon sinks,
- Increased carbon dioxide production by ocean bacteria,
- Amazon rainforest die-back,
- Coniferous forest die-back,
- Reduced northern hemisphere snow cover,
- Loss of Arctic summer sea ice,
- Reduced Antarctic sea ice,
- Melting polar ice sheets.
The team of scientists wrote: “Our analysis suggests that the Earth system may be approaching a planetary threshold that could lock in a continuing rapid pathway toward much hotter conditions – Hothouse Earth.
“This pathway would be propelled by strong, intrinsic, biogeophysical feedbacks difficult to influence by human actions, a pathway that could not be reversed, steered or substantially slowed.
“Where such a threshold might be is uncertain, but it could be only decades ahead at a temperature rise of (around) 2C above pre-industrial.”
The only way to avoid a potential Hothouse Earth would be an active approach by scientists and environmentalists, to take “deep cuts” towards reducing greenhouse gas emissions as well as removing carbon dioxide from the atmosphere using technological advancements.
Climate researcher Dr Phil Williamson, from the University of East Anglia, said: “In the context of the summer of 2018, this is definitely not a case of crying wolf, raising a false alarm.
“The wolves are now in sight.”
Speaking about the impact of climate change, Chris Rapley, Professor of Climate Science at University College London said: “Previous research has shown that an increase in the mean global temperature of 11-12C would make more than half of the land area currently occupied by humans uninhabitable.
“So, a ‘runaway’ warming to a new and uncontrollable hot state would represent an existential threat to humanity and the majority of existing species.”