In June, more than 60 climate scientists warned that the remaining “carbon budget” was exhausted after just three years at the current rate of emissions.
But passing that critical 1.5 degrees Celsius (2.7 degrees Fahrenheit) warming threshold makes a climate catastrophe unavoidable? And can we do something to reverse that temperature rise?
Crossing the 1.5c threshold creates problems, especially for island nations, increasing the risk of permanent transformation of ecosystems, but the planet does not dive into the Apocalypse. And if you keep emissions down, there’s a way to slowly lower the temperature by crossing that 1.5c threshold, experts told Live Science.
You might like it
Still, it should not stop trying to curb emissions now, which is cheaper, easier and more effective than reversing the temperature rise that has just occurred.
“A small portion of the warming we prevent will make us better,” Mann said.
The response was delayed
A report released on June 19 found that the world had only 143 billion tons (130 billion tons of carbon dioxide (CO2) remaining to release before it surpassed the 1.5C target set in the Paris Agreement signed by 195 countries to tackle climate change. According to the World Meteorological Organization, it currently emits approximately 46 billion tons of CO2 (42 billion tons) per year.
Reports show that the world is currently 1.2 c (2.2 f) warmer than the pre-industrial average, with almost all of this rise in temperature due to human activity. However, our emissions may have had an even greater impact on global warming so far, as the oceans absorb a lot of excess heat.
According to the National Oceanic and Atmospheric Administration (NOAA), the ocean will release this extra heat over the next decades, through evaporation and direct heat transfer, whether it suppresses emissions or not.
This means that even if carbon emissions drop to zero today, global temperatures will continue to rise for decades, with experts predicting an additional 0.5 C (0.9 F) of warming from the ocean alone.
However, when heat is radiated into space, the temperature eventually stabilizes. And for more than thousands of years, the Earth dials temperatures back to industrial levels through natural carbon sinks such as trees and soil that absorb CO2, according to NOAA.
Why 1.5 C?
Climate scientists consider 1.5 C to be an important threshold. Beyond this limit, Kirsten Zickfeld, a professor of climate science at Simon Fraser University in Canada, said that it is beyond safe for people living in economically developing countries.
The 1.5 C limit is “an indicator of the climate system’s condition that we feel can manage outcomes,” Zickfeld told Live Science.
A large amount of additional heat can be burned into the ocean and released later at over 1.5 C. This is another reason why scientists are worried about crossing this threshold.
Speeding above 1.5 C also increases the risk of passing through the climate change point. This is an element of the Earth System that allows you to quickly switch to dramatically different states. For example, Greenland’s ice sheets could suddenly fall into the ocean, and Amazon’s rainforest could transform into a dry savanna.
Reverse temperature rise
It is best to reduce emissions as quickly as possible, but passing that important threshold may allow for a temperature rise of 1.5°C or higher. The technology needed has not yet been fully developed, so there is a lot of uncertainty about what is feasible.
Once the temperature starts to drop again, the effects of passing through the climate turning point will not be reversed. For example, you won’t refreeze the ice sheet or the sea level will fall after it has already risen. However, it will significantly reduce the risk of ecosystems that respond rapidly to temperature changes, such as permafrost-covered tundras.
Zickfeld said that reversing temperature rise requires not only net zero emissions, but net negative emissions. Net Zero means sequestering as much CO2 as we emit through natural carbon sinks and negative emissions technology. Negative emissions require a system that sucks out carbon from the atmosphere, which can be buried underground.
Net Zero could stop warming. But if you want to reverse warming, you have to remove more carbon from the atmosphere than you emit, Zickfield said.
Scientists estimate that 0.1 c (0.2 f) of global warming equals 243 billion tonnes (220 billion tonnes) of CO2. This is “a huge amount,” Zickfeld said. “Let’s go to 1.6 c [2.9 F] You also want to drop down to 1.5C – about 220 billion tons of carbon dioxide need to be removed. ”
Currently, natural-based carbon removal technologies such as planting trees sequester approximately 2.2 billion tonnes (200 million tonnes) of CO2 each year. “So we need to scale that 100 times and shrink it at 0.1°C,” Zickfeld said.
Due to the competing demand for the land, it is unlikely that we could restore enough peatlands to plant enough forests or reverse temperature changes in meaning, Zickfeld said.
This means we definitely need negative emissions technology, she said. However, most negative emissions technologies are still being tested, so it’s hard to say how effective they are, Zickfeld said.
These technologies are also very expensive and likely to have been so long, Robin Lambor, a climate researcher at Imperial College in London and co-author of a recent report, told Live Science in an email.
“In reality, we’ll do very well if we find out that the deployment of these technologies is doing more than bringing us to net zero,” Rambol said. There is some uncertainty about how Earth responds to Net Zero, and at that point the planet could cool down. “If we’re completely cooled, we do so very slowly. In a very optimistic case, it could be 0.3 c. [0.5 F] Fifty years later, Rambol said.
Under the Paris Agreement, there is no requirement for the country to deploy negative emissions technologies. However, the agreement’s target of below 2C (3.6F) means that if it passes 1.5C, the government could decide to increase these technologies, Lamboll said.
Figures in the recent report show that the remaining carbon balance can fall below 1.6 C, 1.7 C (3.1 F), and 2 C at current emission rates.
“When you pass 1.5°C, 1.6C is much better than 1.7C. 1.7C is much better than 1.8C. [3.2 F]”The challenge at this point is to reduce carbon emissions as quickly as possible and avoid any worsening impacts,” Mann said in an interview with BBC World News America in June.
Mann added in an interview that it is worth noting that the world is making progress in reducing emissions. “Let’s realize we’re round the corner,” he said.
Source link
