It may seem counterintuitive, but on the heels of the most recent IPCC report on our changing climate, Kyle Armour finds reasons for optimism.

“The degree of climate change we’ll experience this century depends on our future greenhouse gas emissions, which depend on the collective choices we make. Our future is up to us,” says Armour. He posted his thoughts on Twitter when many headlines about the report’s findings were overwhelmingly grave. Human beings have a lot of work to do, and the clock is ticking. But all is not lost.

6th IPCC Report Cover
The Sixth IPCC Assessment from Working Group 1 covers the physical understanding of the climate system and climate change.

The UW oceanographer and atmospheric scientist was a lead author of the report. It’s the sixth issued from Working Group 1 — the group of scientists charged with assessing the physical science of climate change — and it’s become even clearer that the Earth is warming because of human activity. The report is also clear that some further warming is inevitable because it will take time to substantially curb our greenhouse gas emissions. But a closer look tells us the choices we make today will have major impacts in the next few decades, and therein lies the key to staving off the worst warming and its impacts.

Established in 1988, the IPCC released their first assessment in 1990. Since then, five additional reports have been released, along with several special reports, each becoming increasingly confident in the role humans play in climate change. The first assessment was fairly cautious, stating that while humans are increasing greenhouse gas concentrations and that scientists expect global warming will occur, they had yet to assign unequivocal detection of a human influence. By the fifth assessment, scientists stated that global warming was certain and driven by humans. The latest report goes even further, saying with certainty that human influence has warmed the climate, quantifying the likely range of warming humans have contributed, and finding evidence that many aspects of recent climate change are unprecedented for thousands of years. This shift in language reflects significant scientific progress over the past few decades, and highlights that enough warming has occurred to unmask many climate change signals that were harder to see previously.

Over 230 scientists from 66 different countries wrote the current report. Working closely with a dozen of these scientists, Armour helped lead the writing of chapter seven focusing on the Earth’s energy budget, climate feedbacks and climate sensitivity. Their job was to assess the literature and “provide the physical science backbone” that then tees up subsequent reports on climate change impacts on human systems, ecosystems, economies, and importantly our options for limiting future climate change. Included in their assessment were responses to numerous comments that came from the peer-review process. Armour also contributed to additional chapters beyond his own, and helped write the report’s technical summary and high-profile summary for policy makers. The latter summarizes all the chapters and is written in collaboration with delegates from governments across the globe.

headshot of Kyle Armour
University of Washington
Kyle Armour

“The summary for policymakers is a totally unique document,” says Armour. “The scientists work closely with the delegates to write it as clearly as possible while making sure every statement is consistent with and supported by the underlying science in the full report. With each sentence receiving approval by all the governments, the document then serves as a starting point for international climate negotiations. Importantly, the IPCC does not advocate for any specific policies. Instead, it seeks to provide policymakers, and the public in general, with an up-to-date understanding of our climate and its changes.”

One of the biggest advances in the latest report is scientists’ ability to draw on additional sources of information that were previously unavailable. “In this report, we’re less reliant on numerical climate models to make projections of future warming,” says Armour. “While we relied partly on models for this report, we used many other lines of evidence too, like paleoclimate records, observations of recent global warming and new observations from satellites. We were better able to constrain the range of uncertainty in the climate’s sensitivity to greenhouse gases, which we narrowed for the first time in decades.”

Previously, the scientific observations were used to ground truth that models were in the right ballpark. This time, Armour and colleagues looked at the observations first, then compared that information against what the models predict. For the most part, the models remained robust, but “the observations allowed us to say with confidence that the most extreme warming scenarios predicted by the models are less likely to occur. Some good news for our climate.”

While the task at hand was daunting, Armour found bright spots in the process. “We were free as authors to provide our assessment of the literature without any influence from anyone else, except through several grueling rounds of peer review. It was a cool process because it was entirely written by scientists and the experts. The IPCC process is the gold standard for assessing climate change and its impacts.”

He also found enjoyment working with scientists around the world, people he would have otherwise never gotten to know. “On my chapter team alone, we had representation from nine different countries spanning six different time zones.” The team initially met in person at various locations around the globe, including China, Canada and France. But as the COVID-19 pandemic set in, they finished all their work virtually.

“IPCC authors volunteer their time and expertise, and the work is performed entirely on top of their day jobs,” says Armour. “The findings are based on an assessment of thousands of scientific papers, and the report has gone through multiple rounds of review by hundreds of scientists, experts and governments over a three year period. I’m proud of the way we responded to get this report done.”