Yet another apocalyptic global warming report...

The TLDR: Let’s be honest. Isn’t that how we feel when scientists put out a climate change prediction—full of doom and gloom, leaving us feeling powerless and anxious? That said, the latest UN Assessment Report is important because it is based on the best available evidence. It gives us a clear picture of where we are, where we are headed—and how to change course. And we keep it focused so you don’t have to wade through monotonous prophecies of catastrophe.

Why this report matters

Every 6-7 years, hundreds of scientists from around the world put out an Assessment Report commissioned by the United Nations Intergovernmental Panel on Climate Change (IPCC). Authored by 234 experts from 66 countries, this one is the sixth since 1988—and has been eight years in the making. It is the most comprehensive and based on the best available data contained in 14,000 studies. So it is also the most precise: “It represents the world’s full knowledge to date of the physical basis of climate change.”

Also this: What is striking is the level of certainty—since scientists tend to hedge their bets in most such reports. As the BBC News notes:

“It is the confidence of the assertions that the scientists are now making that is the real strength of this new publication. The phrase ‘very likely’ appears 42 times in the 40-odd pages of the Summary for Policymakers. In scientific terms, that's 90-100% certain that something is real.”

Big point #1: Humans are guilty as charged

Previous such reports have posited a strong link between human activity and climate change. This IPCC report says the connection is “unequivocal and indisputable.” As one expert notes, it’s the “strongest statement the IPCC has ever made.” The Guardian’s graph below charting rising temperatures since 1850 lays this out fairly clearly. Note the steep upward spike since 2000.

Also important to note: Many changes triggered by warming temperatures are irreversible, and already here. And this is where we are:

• The average global temperature has risen by 1.09°C in the decade between 2011-2020—compared to pre-industrial levels (1850-1900). The target of the Paris Climate Accords is to limit that increase to 1.5°C—or at worst, to 2°C.
• The last decade has possibly been the hottest the planet has been in 125,000 years.
• Glaciers are melting at a rate “unprecedented in at least the last 2,000 years.”
• Levels of carbon dioxide in the atmosphere have not been this high in at least 2 million years.
• The recent rate of sea level rise has almost tripled compared to the period 1901-1971.
• Ocean levels have risen eight inches on average over the past century, and the rate of increase has doubled since 2006.

The big ‘but’: If we act now, we can avert the most harrowing future, and keep the temperature rise to just at 1.5°C.

Big point #2: It’s getting hotter, faster

Until now, experts projected that we will hit the 1.5°C threshold around 2050 or beyond. The report predicts we will hit it between 2030-2035—which is in our lifetime. Even with our best efforts, we will exceed the 1.5°C threshold for some period of time—before temperatures come down and stabilise at that threshold. 

The report lays out five different scenarios—based on how much we reduce greenhouse gas emissions. In the most optimistic scenario, we hit net zero around 2050. In the worst case, we double our emissions that same year. The world will look something like this based at what temperature threshold we hit:

Where we are: At current levels of emissions, we are headed toward a rise of 3°C.

Graphic to note: This is what the world would look like at various temperatures—with the darkest red indicating a rise of 7°C or more:

Big point #3: Rise in sea levels is irreversible

Irrespective of what we do, sea levels will rise 15-30 cm (6-12 inches) by the middle of this century: 

“Under the very low emissions scenario, the report estimates that global mean sea level rise could be between about one to two feet by the year 2100. But in a very high emissions scenario, that figure would be six and a half feet, and over 16 feet by 2150.”

One of the authors says: “That is just scary, because it's maybe not at the end of our lifetime, but it is around the corner and it will be committing this planet to a big legacy.” Here are the different levels of sea rise as per the five scenarios:

Big point #4: Extreme events will be routine

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