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The word “unequivocal” was first used by the Intergovernmental Panel on Climate Change (IPCC) — a UN-sponsored body that periodically releases a synthesis of current climate science — in 2007.
The phrase appeared three times in that 112-page synthesis report.
In its next assessment, released in 2014, the body used the term twice in a 167-page synthesis report.
On Monday, the IPCC released its latest assessment, a whopping 3,949-page report that sequestered 234 scientists around the world to comb over 14,000 studies and analyze a massive array of climate model simulations over the last three years. Every word of the report’s accompanying summary for policymakers was then scrutinized and approved by 195 countries in an around-the-clock Zoom call with scientists over the last two weeks.
In this full report, the word “unequivocal” is used 32 times, starting with the conclusion on the very first page: “It is unequivocal that human influence has warmed the atmosphere, ocean and land. Widespread and rapid changes in the atmosphere, ocean, cryosphere and biosphere have occurred.”
This is the first time scientists and governments from around the world have agreed that there is no doubt who is responsible for the climate crisis.
“The language is not chosen without a lot of consideration,” said John Fyfe, a senior research scientist with the Canadian Centre for Climate Modelling and Analysis, an Environment Canada Laboratory in Victoria, B.C., and lead author on the chapter of the report about future climate scenarios.
Fyfe explained that “unequivocal” has a very precise definition in the IPCC world, which uses very calibrated language that has statistical meaning. Unequivocal means “there’s 100 per cent probability that humans have had an influence or are having an influence on climate.”
“There’s no room anymore to question it anymore,” Fyfe said. “That is a big deal.”
According to the sweeping and comprehensive report, the planet is hotter now than it has been at any moment in the last 125,000 years. Burning fossil fuels, deforestation, land-use changes and other factors have caused the Earth to warm by 1.1 C above pre-industrial levels.
The past 50 years saw the fastest temperature increases in at least 2,000 years. Atmospheric CO2 concentrations, the presence of which determines how hot the planet is, were higher in 2019 than at any time in at least 2 million years.
This unprecedented warming is affecting every area of the globe and making the world a more volatile place. Some of the changes are locked in: sea levels will “remain elevated for thousands of years.” The report predicts more frequent and intense “compound extreme events,” two major hazardous climate events happening at the same time or right after each other like a heat wave during a drought or a wildfire following a storm.
As dire as these findings and predictions are, the report is clear: only rapid, steep and sustained greenhouse gas emission cuts, down to net zero at least, can avoid warming the world to catastrophic temperatures that would render the plant unrecognizable.
That’s where Fyfe comes in. He helped collate the findings of the 40 to 50 international climate modeling groups who have done “major computational exercises” over the past five years. The chapter he authored shows that the world will likely warm by 1.5 C — the threshold the IPCC warned in 2018 would have devastating consequences — between 2030 and 2050, potentially a decade earlier than predicted.
What follows is a transcript, edited for style and brevity, of The Narwhal’s interview with Fyfe:
There are three aspects that go into making these [conclusions]: observations, climate modelling and statistical analysis. The reason that the language is getting stronger and stronger is that all three of these are getting improved. We have improved observations.
For example, in the last report there were parts of the planet where there were no observations [of global temperatures] that were readily available. In the high Arctic, we’ve been able to fill a lot of observational gaps and correct other errors in observations over the course of the last 10 years. Improved observations means we have improved models, and we have also improved our methodologies.
I do a lot of work on polar climate, in Antarctica and the Arctic. So the fact that Arctic sea ice cover in the summertime has gone down by 40 per cent since 1979. That’s when we began observing sea ice cover. So there’s almost half as much now as there used to be.
The expectation for the future is this is going to carry on. Somewhere around the middle of the century, there’ll be no ice left in the Arctic in the summertime, and that’s irrespective of what we do in the future.
Every increment of warming will have consequences, in climate extremes, the frequency and severity of heat waves to drought and heavy rainfall. Every little bit matters is one of the messages we’re trying to get across.
If we stay below or near below 1.5 C, we’re still going to encounter about a half a metre sea level rise relative to 1900. That’s the most optimistic scenario where we really do enjoy immediate, rapid and sustained emissions reductions. If we remain on a high-emission scenario, say 3 C, we could see up to a meter sea level rise.
You can imagine what a metre of sea level rise looks like around the coastlines of Canada.
Any warming beyond that would involve a complete collapse of the Antarctic ice sheet.
Canada isn’t called out specifically in the report, although, generally speaking, what we see in Canada is what we’ll see in most high northern hemisphere countries.
The main feature is that we will get much more warming than the average warming on the planet. So far, we’ve had a global average since 1850 of 1.1 degrees of warming. For Canada, it’s been above 2 degrees. That’s going to be a similar story going into the future.
Every increment of warming in the global average gets magnified in Canada.
We also expect to have more severe and frequent extremes: heat waves, drought, heavy rainfall, all of those things are expected to become more severe and frequent. We expect mountain glaciers to recede even more. We expect our sea ices to decline even more. This is all happening now but we expect to see much more of it in the future.
We’ve known for decades the earth is warming. We’ve known of these impacts. What we predicted 20 to 30 years ago with our climate models have now been realized. So we’re in a situation of no particular surprise to me personally.
My emotions are probably no different from anybody else’s: it’s concerning and distressing. I’m in Victoria where you can’t even see the sky with these wildfires and heat waves.
Scientifically, we’re just trying to keep the eye on the ball; assess all the available information; put it together into a report; summarize that report for policymakers and hope that we’re providing the best possible information to politicians in order to do the things they need to do.
But it’s once it’s out of our hands, it’s in theirs and there’s nothing more I can do about it and I don’t particularly fret over it.
What we’re looking at for the most part are slow, inexorable changes. We’re not going to fall off a cliff if we reach 1.5 C. But it’s just another step towards higher and higher temperature levels and greater and greater impacts.
It’s the gold-standard, there’s no question about it.
It’s a major, major piece of work that is very robust. It has gone through several review processes, three of them: a draft was written, then it went out to get reviewed by scientists and then it was reviewed by governments. At the end of each one of those reviews we received tens of thousands comments that we needed to respond to and adjust the work to develop it further. It’s very, very exhaustive, and exhausting individually for those who are involved.
There is a meeting coming up in a few months where it will be centre-placed and very, very influential.
I want people to understand just how widespread, rapid, intensifying and unprecedented the changes are that we’re seeing.
There’s no going back on some of the changes in the climate system. Even if we stopped emitting carbon dioxide or greenhouse gases, these changes will continue for hundreds to thousands of years.
We’re going to suffer a certain amount of sea level rise, regardless. That can either be a very significantly larger sea level rise or much smaller depending on the choice we make in the future. But we are going to get some sea level rise; there’s no going back. Not only in the average amount of sea level going up but then on top of that there’s increased severity and frequency of storm surges due to human activity. So you put on top of a one-metre sea level rise a powerful storm and a hurricane. You’ll have severe consequences.
What we can do is slow the rate of change.
Updated August 13, 2021 at 8:53 a.m. PST: Clarifying report’s assessment of when the planet will likely warm by 1.5C
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