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(CNN) - The Earth is heading towards a “global turning point” if the climate crisis continues its current path, scientists warned and called for urgent measures to avoid “a threat to civilization”.
The group of researchers, who published a comment in the journal Nature , says that there is growing evidence to suggest that irreversible changes are already taking place on Earth's environmental systems, and that we are now in a "planetary state of emergency."
A global turning point is the threshold of when the planet's systems go beyond the point of no return, such as the loss of the Amazon rainforest, the accelerated melting of ice sheets and the melting of permafrost, say the authors of the text .
Such collapse could lead to "greenhouse" conditions that would make some areas of the Earth uninhabitable.
"We argue that the remaining intervention time to avoid the inflection point could have been reduced to zero, while the reaction time to achieve zero net emissions is 30 years at best," the authors added.
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Active problem areas
Directed by Timothy Lenton, professor of climate change and earth system sciences at the University of Exeter, in the south west of England, the team identified nine areas where they say the turning points are already underway.
These include the widespread destruction of the Amazon, the reduction of Arctic sea ice, the extinction of large-scale coral reefs, the melting of the Greenland and West Antarctic ice sheets, the permafrost melting, the destabilization of boreal forests - which contain a large number of trees that grow in icy northern climates - and a slowdown in ocean circulation.
The team states that these events are connected and that the change in one will affect the other, causing a "cascade" of crisis.
For example, the Arctic is warming at least twice as fast as the world average. The melting of Arctic sea ice is driving warming even more because the heat that is reflected off the planet is less.
Regional warming is leading to further defrosting of the Arctic permafrost, the soil that remains frozen throughout the year, which releases carbon dioxide and methane into the atmosphere. The warming has also caused large-scale insect disturbances and fires in the boreal forests of North America "that can potentially turn some regions of carbon sink into a carbon source," the team said.
The researchers noted that the first results of the preliminary models suggest that the weather is much more sensitive than previously thought and that a global turning point is possible.
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"Last year's research analyzed 30 types of regime changes that cover the physical climate and ecological systems, from the collapse of the West Antarctic ice sheet to the change from the rainforest to savanna," they added. "This indicated that exceeding the inflection points in one system may increase the risk of overcoming them in others."
Emissions and global warming
The idea of a point of climate inflection is not new. The UN Intergovernmental Panel on Climate Change (IPCC) introduced the concept 20 years ago.
At that time, the UN suggested that such "large-scale discontinuities" would only occur when global warming exceeded 5 degrees Celsius above pre-industrial levels.
But the authors say that data from the two most recent IPCC reports in 2018 and September 2019 suggest that inflection points can occur between one and two degrees Celsius warming.
The global average temperatures today are around a degree higher than in the pre-industrial era and continue to rise.
A 2018 report, of which Lenton took part, suggested that a domino effect will be applied if global temperatures rise more than 2 degrees Celsius above pre-industrial levels.
The model highlighted the consequences of how interactions between a variety of climate change factors, such as loss or weakening of carbon sinks, forest death, ice removal and increased bacterial respiration, could combine to form a feedback loop that accelerates climate change.
The authors recognize that there are limits to their understanding of climate change, and that more research is needed. But they say that the possible impact could be so great and "irreversible" that "to err on the side of danger is not a responsible option."
In other words, from your perspective, not acting is "too risky to bet against."
And time is essential.
While the 2015 Paris Agreement set the goal of limiting global warming to 1.5 degrees Celsius, a UN report this month said that the promises that countries made to limit the climate crisis are not enough close to being fulfilled to avoid record temperatures.
The 2019 United Nations Environment Program (UNEP) emissions gap report said that at the current rate, temperatures are expected to rise 3.2 degrees Celsius by 2100.
Greenhouse gases reached a record in 2018, according to a recent report by the World Meteorological Organization. Carbon dioxide levels reached 407.8 parts per million, a unit used to measure the level of a pollutant in the air.
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However, hope is not lost. The researchers say that mitigating greenhouse gas emissions could still delay the accumulation of these climate impacts.
What is needed, they say, is an urgent international action to reduce emissions, curb sea level rise and keep warming to 1.5 degrees Celsius.
"Something in favor is that the speed at which the damage accumulates towards the inflection point, and therefore the risk posed, could still be under our control of some measure," they said.
“The stability and resilience of our planet are in danger. International action, not just words, should reflect this. ”
Global warming
