The ozone hole kills plants and raises global temperature

One of the most successful environmental treaties in history was finalized 34 years ago to phase out industrial chemicals that erode the earth’s fragile ozone layer.

The Montreal Protocol introduced an international agreement to phase out chlorofluorocarbons or CFCs, ozone-depleting chemicals that were once found in refrigerants and other industrial processes.

In the decades since, CFCs have fallen sharply, and the notorious “ozone hole” in the earth’s atmosphere is steadily recovering. The worries that humans will not be able to walk safely in the sun in the future have disappeared.

This is not all. Studies have shown that without the Montreal Protocol, global warming could be worse than it is today.

This is partly because CFC itself is a potent greenhouse gas. They have a shorter lifespan in the atmosphere than carbon dioxide, but they have a stronger warming effect when they last. If there is no Montreal Protocol, research shows By 2050, this greenhouse effect may increase global warming by at least 1.8 degrees Celsius or 1.8 degrees Fahrenheit.

Now, new research shows that the treaty may save the world from further warming in a completely different way.

According to a study, without the Montreal Protocol, plants all over the world would wither and wither. Learn Published in the journal this week nature. Many of them will die and disappear completely. They will be hit by harmful ultraviolet rays that penetrate the earth’s damaged ozone layer.

Plants provide important climate services and absorb carbon dioxide from the atmosphere. But damaged plants are less efficient, and over time, they store less and less carbon.

New research has found that the extra carbon in the atmosphere will further warm the earth.

If CFCs never decrease—if, in fact, they continue to increase indefinitely—additional plant-related CO₂ By the end of this century, it will cause additional warming anywhere from half a degree Celsius to a full degree Celsius. This is due to the additional warming caused by the greenhouse effect directly produced by CFCs in the atmosphere.

And, of course, all of this will happen on top of the climate change that has already taken place in other greenhouse gas emissions.

This new study, led by Paul Young of Lancaster University in the United Kingdom, uses models to simulate three scenarios.

The first one reproduced the real world, in which CFCs were eliminated under the Montreal Protocol. The second one introduces a hypothetical scenario in which CFC emissions remain at the level of 1960-no increase, but no decrease.

The last scenario is called the “Avoided World” and simulates a trajectory in which CFC emissions have been increasing from now to the future, increasing by about 3% each year.

With the horrible world averted, the ozone layer basically collapsed in the 2040s. By the end of this century, atmospheric ozone has fallen by about 72%. The amount of ultraviolet radiation reaching the surface of the earth has increased dramatically.

In response, plant growth began to decline. By the end of this century, the study estimated that in a world where the Montreal Protocol is in place, global vegetation has absorbed only about 15% of the carbon it absorbs.

Scientists estimate that by the end of this century, the extra carbon may warm the world by 0.5 to 1 degrees Celsius, most likely around 0.8 degrees Celsius. This is due to the additional warming of 1.7 degrees Celsius that may be caused by the greenhouse effect of CFCs in the atmosphere.

All in all, the Montreal Protocol avoided warming of approximately 2.5 degrees Celsius (4.5 degrees Fahrenheit) in a hundred years.

This means that “in addition to protecting the ozone layer, the Montreal Protocol itself is also a very successful climate treaty,” Yang wrote in a statement. Recent posts About publishing on dialogue.

So far, the climate impact of the Montreal Protocol has been a spin-off. But a recent amendment took the treaty one step further. The Kigali Amendment, which joined the Montreal Protocol in 2016, also aims to phase out the use of hydrofluorocarbons (HFCs) that warm the climate. Although it is not as harmful to the ozone layer as CFC, HFC is also a powerful greenhouse gas.

The United States has not yet approved the Kigali amendment, although the Biden administration has expressed interest.

Reducing lesser-known potent greenhouse gases, such as CFC and HFC, can have a significant impact on the global climate. The Montreal Protocol has proven this effect, even if it is unintentional.

Scientists said that despite this, eliminating global carbon dioxide emissions and other major greenhouse gases such as methane remains the biggest global challenge surrounding climate change.

Young admits that this is a more complex challenge than reducing CFC.

“[W]There are only a few companies that can provide CFC and alternative chemicals at any time, and the ozone problem is much simpler than reducing fossil fuel emissions,” he wrote.