5 takeaways from the UN report on limiting global warming


According to a new report from the Intergovernmental Panel on Climate Change, a group of researchers convened by the United Nations, nations are not doing enough to prevent global warming from reaching dangerous levels in the lifetime of most people on Earth today. Limiting the devastation won’t be easy, but it’s also not impossible if countries act now, the report says.

The committee produces a comprehensive overview of climate science once every six to eight years. It divides its findings into three reports. The first, on the causes of global warming, was released last August. The second, on the effects of climate change on our world and our ability to adapt to it, was published in February. This is #3, on how we can reduce emissions and limit further warming.

The report is clear: nations’ current pledges to reduce greenhouse gas emissions are unlikely to prevent global warming from exceeding 1.5 degrees Celsius, or 2.7 degrees Fahrenheit, in the coming decades. And that assumes that countries follow. If they don’t, even more warming is in store.

This goal – to prevent the average global temperature from rising by 1.5 degrees Celsius above pre-industrial levels – is one that many governments around the world have agreed to pursue. It seems modest. But that number represents a host of drastic changes taking place as greenhouse gases trap more heat on the planet’s surface, including deadlier storms, more intense heat waves, rising seas and additional pressure on crops. The Earth has already warmed by around 1.1 degrees Celsius on average since the 19th century.

So far, the world is not becoming more energy efficient fast enough to balance the continued growth in global economic activity, the report says.

Carbon dioxide emissions from factories, cities, buildings, farms and vehicles increased in the 2010s, outpacing the benefits of power plants switching to natural gas from coal and using more renewable sources such as wind and solar.

Overall, it is the wealthiest peoples and the wealthiest nations that are warming the planet. Worldwide, the richest 10% of households are responsible for between a third and almost half of all greenhouse gas emissions, according to the report. The poorest 50% of households contribute about 15% of emissions.

Prices for solar and wind power, and electric vehicle batteries, have fallen significantly since 2010, according to the report. The result is that it may now be “more expensive” in some cases to maintain highly polluting energy systems than to switch to clean sources, the report says.

In 2020, solar and wind provided almost 10% of the world’s electricity. Average global emissions grew much more slowly in the 2010s than in the 2000s, partly due to greater use of green energy.

It was not obvious to the scientists that this would happen so quickly. In a 2011 report on renewable energy, the same panel noted that technological advances would likely make green energy cheaper, although it is difficult to predict by how much.

The world must invest three to six times what it currently spends on climate change mitigation if it is to limit global warming to 1.5 or 2 degrees Celsius, the report says. Money is especially scarce in the poorest countries, which need trillions of dollars in investment each year this decade.

As nations move away from fossil fuels, some economic disruption is inevitable, the report notes. Resources will be left in the ground unburned; mines and power plants will become financially unviable. The economic impact could be in the trillions of dollars, according to the report.

Even then, simply keeping planned and existing fossil fuel infrastructure running will pump enough carbon dioxide into the atmosphere that it will be impossible to keep warming below 1.5 degrees. indicates the report.

The report examines a host of other changes in societies that could reduce emissions, including more energy-efficient buildings, more recycling and more remote and virtual office work.

These changes don’t have to be economy-draining chores, the report points out. Some, like better public transport and more walkable urban areas, have benefits for air pollution and general well-being, said Joyashree Roy, an economist at the Asian Institute of Technology in Bangkok who contributed reporting. “People are asking for healthier cities and greener cities,” she said.

In total, measures that would cost less than $100 per tonne of carbon dioxide saved could cut global emissions to about half of 2019 levels by 2030, the report says. Other steps remain more expensive, such as capturing more of the carbon dioxide from the gases escaping from power plant smokestacks, the report said.

The world must also eliminate the carbon dioxide that is already in the atmosphere. Planting more trees is about the only way to achieve this on a large scale right now, the report says. Other methods, like using chemicals to extract carbon from the atmosphere or adding nutrients to the oceans to boost photosynthesis in tiny sea plants, are still in their infancy.

“We can’t ignore how much technology can help,” said Joni Jupesta, author of the report from the Research Institute for Innovative Earth Technologies in Kyoto, Japan. “Not all countries have a lot of natural resources.”


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