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to 30 kilometres above the surface and protects the planet
from harmful ultraviolet rays from the sun. Ozone is a type of oxygen molecule with three atoms instead of the usual two that absorbs the sun's radiation.
The discovery of significant ozone holes above Earth's
polar regions was made in 1985. Researchers found that chlorofluorocarbons (CFCs), a common chemical used in aerosol cans, packaging materials and refrigerators at the time, were reacting with ozone in the atmosphere, leading to ozone
depletion. In response, the international community banned the use of CFCs in 1989, allowing ozone levels to gradually recover.
However, gaps in the ozone layer still appear above the polar regions during each hemisphere's winter months. This occurs when cold air creates polar stratospheric clouds (PSCs), which are exceptionally high clouds composed of tiny ice crystals. These clouds further deplete the already limited amount of ozone above the poles.
Earth’s energy imbalance –
world is starting to cook
Roberta Harrington in Los Angeles
The earth’s energy is out of balance and the world is starting to cook, says a new report. The authors include James Hansen, who testified to the US Congress on global heating as long ago as 1988.
More energy than ever before is coming into the planet (absorbed sunlight) than is going out (heat radiated to space), said the scientists.
The earth’s energy imbalance (EEI) has escalated in the past decade, they said. The imbalance so far in the 2020s is almost double the rate during the study’s calibration period, from mid-2005 to mid-2015.
In a study published in 2021, the EEI was found to have doubled in the 14 years from 2005 to 2019. The study was by scientists at NASA and the US National Oceanic and Atmospheric Administration.
Earth's climate is determined by a delicate balance between how much of the sun's radiation energy is absorbed in the atmosphere, and at the surface, and how much thermal infrared radiation the earth emits to space, says NASA.
A positive energy imbalance – which is what we have – means the earth system is gaining energy, causing the planet to heat up.
Earth’s energy imbalance (W/m2)
This is in addition to global climate change – also known as global warming – which is caused by emissions of CO2 and other greenhouse gases (GHGs).
EEI is the result of a decline in the cooling effect of human-made aerosols, according to indirect evidence, say Hansen et al. In fact, the present El Niño is expected to create such extreme high temperatures that it is now “almost certain” that the 12-month running mean temperature will exceed 1.5°C above pre-industrial levels by May 2024 or earlier, said the scientists.
El Niño is a cyclical warming of the surface of the ocean in the central and eastern tropical Pacific Ocean.
According to the Paris Agreement, the signatories must pursue efforts not to reach an average temperature rise of 1.5°C compared with pre-industrial levels.
Aerosol emissions can come from, for example, sulphate emissions from ship fuel. Aerosol emissions are not measured by today’s satellites.
“Without such data we will be flying blind into a future fraught with dangers,” said the scientists. “At the very least, we owe young people the knowledge of what we are getting them into.”
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