This week’s release of a massive report from the United Nations Intergovernmental Panel on Climate Change was the latest and most comprehensive look yet at a problem that, by all indications, will require an unprecedented and multigenerational response.
Exactly how the world handles the issue – and what is realistically achievable – remain wide-open questions. But if there is one key takeaway from the IPCC report, it’s that there is no longer a productive debate to be had around the question of whether climate change owing to fossil fuel emissions is actually occurring.
And yet, this message still has an uphill battle against online disinformation. With that in mind, here are five misconceptions that are often repeated by climate skeptics, along with a reminder of what nature has to say on the matter. While the IPCC report is intended to help policy makers chart a course for the future, it may also help steer the rest of us away from a summer of dead-end arguments.
Misconception 1: Earth isn’t warming
Climate scientists point out that the fundamental principles of their work are directly tied to the physics of everyday life. No one argues whether your car gets hot when the windows are rolled up and it’s sitting in the sun. Window glass lets sunlight get in, but keeps infrared radiation from getting out – an energy imbalance which heats up the car. Water vapour does the same thing, but rain limits the amount of water vapour the atmosphere can hold. There is no such safety valve for the carbon dioxide and other greenhouse gases we’ve been putting into the atmosphere in increasing quantities. They just keep piling up – and independent of anything else, this will drive warming.
The atmospheric concentration of carbon dioxide is measured in hundredths of a per cent. What matters more, however, is that the total amount of carbon dioxide in the air has gone up by over 40 per cent since the beginning of the 20th century. Meanwhile, the global average temperature has risen by approximately 1 C, according to all the evidence incorporated in the IPCC report.
A change in global average is not something that is readily apparent in local temperature records, where daily and seasonal swings can total many degrees. But observations and computer models show it’s enough to shift the frequency of severe weather events and create long-term changes in permafrost, glaciers and vegetation – which are already becoming obvious. The models also show there is a range in how much warming we can expect per ton of carbon emitted, but the direction of the trend is clear. For example, on Friday, the U.S. National Oceanic and Atmospheric Administration announced that this past July was Earth’s hottest month ever recorded.
Misconception 2: Climate change is nothing new
The climate is always changing. What’s different now is the rate of the change – and the reason behind it. Over the past few million years, periodic shifts in Earth’s tilt and the shape of its orbit around the sun have repeatedly taken our planet in and out of ice ages. That sort of climate change is like a pedestrian who takes a few steps one way, then a few steps another way, and over a long time wanders far from her starting point. What’s happening now is akin to the same pedestrian wandering around on a train that has suddenly started rolling in one direction and is picking up speed. The natural forces that gradually nudge the climate this way and that are getting swamped by something else.
Since the IPCC last weighed in on the state of climate science, researchers have significantly improved their understanding of what the atmosphere was doing in the remote past based on various lines of evidence. This has proved immensely useful for anticipating where we’re heading now.
“Previous reports relied heavily on information from tree rings, which are wonderful – but they don’t represent the oceans, and there’s only a few tree-ring records that go back beyond 2000 years,” said Darrell Kaufman, a professor at Northern Arizona University who specializes in paleoclimatology.
Dr. Kaufman said that organized campaigns to measure ocean and lake sediments around the globe have now allowed scientists to reconstruct the past climate record in richer detail, going back many tens of thousands of years. It shows that the warming that ended the last ice age peaked about 6500 years ago and that, on average, Earth was cooling down again until about a century ago, when the effect was abruptly reversed. Now it’s warming fast and shifting toward a range where it hasn’t been since Homo sapiens became the dominant species on the planet.
Misconception 3: People are not the cause
A variety of forces are at work on the climate, including the changing influence of the sun and volcanoes. Other factors, such as oceans and clouds, contribute to a random variability in the climate, and for years this has helped disguise the human impact. Now scientists say there is no room left to hide. One of the key findings from this week’s report is that the growing impact of greenhouse gas emissions on climate is now too big to mistake for something else. Variations in the sun, volcanic eruptions and ocean effects such as El Nino are in there, too, but only when greenhouse gases are thrown into the mix does the result match what we see.
“When we put it all together … we find that now it’s unequivocal: Human influence has warmed the climate,” said Nathan Gillett, a researcher at the Canadian Centre for Climate Modelling and Analysis in Victoria, who helped author the relevant chapter in the IPCC report.
The chapter includes a close look at methane and other gases that contribute to warming apart from CO2, as well as industrial pollutants – collectively known as aerosols – that have the opposite effect. It also puts into context temperature measurements during the first decade of the 21st century, when the rate of global warming was temporarily lower than expected.
Misconception 4: Cold weather proves the science is wrong
While human influence on the climate is getting easier to distinguish, the normal fluctuations that help hide that influence have not gone away.
“There is still a lot of variability happening in the climate naturally,” said Karen Smith, a climate scientist at the University of Toronto Scarborough whose research includes investigations of Arctic climate under warming.
That means freak cold snaps, such as the one that took down power systems in Texas last winter, are still going to happen. Efforts to investigate whether these may be an effect of climate change have so far proven inconclusive, and the IPCC report assigns low confidence to this idea. But while it can still get bitterly cold in the middle latitudes, including Canadian cities, the bigger picture suggests this is less likely to happen now.
Misconception 5: Don’t worry, we’ll adapt
We will surely have to adapt to a warmer climate later this century, including more protection from heat waves and severe floods. Some of this is happening already, but experts on the impact side of climate change say the best option is a multipronged approach that includes shifting to a low-emissions scenario while also adapting to the changes that are already baked in.
There will be a good deal more discussion about this early next year when the next two chunks of the IPPC report, looking at adaptation and mitigation, are released. In the meantime, the science suggests there are big risks associated with a high-emissions scenario. And as the COVID-19 pandemic has demonstrated, some of the ways that we use energy – such as by burning gasoline in cars that are going nowhere in rush-hour traffic – may not be as essential as once supposed. On that point, the laws of nature offer no argument.
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