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Brian O'Neill has served as a lead author on several Intergovernmental Panel on Climate Change (IPCC) assessment reports. O’Neill has been prolific in crafting report chapters looking at future climatic conditions, looming vulnerabilities, and global climate risks.

O’Neill is an Earth systems scientist by training. But when it comes to IPCC reports, it helps that his first undergraduate degree was in journalism, and he nearly earned his first graduate degree in a science writing program.

The youthful devotee of Carl Sagan and Isaac Asimov knows he chose the right career path. “I love the science and clear, concise writing has always been important to me,” O’Neill said.

O’Neill is a chief scientist and lab fellow at the Joint Global Change Research Institute, a partnership between PNNL and the University of Maryland where researchers explore the interactions between human systems and the Earth system, focusing on the dynamics affecting our use of energy, water, land and the feedbacks of our choices about the environment.

At the Institute, O’Neill works closely with colleagues who are global leaders in developing integrated assessment models that look at a variety of projected impacts of climate change and society’s response to those changes.

The models have limits, said O’Neill, a former senior scientist at the National Center for Atmospheric Research, where he led the Integrated Assessment Modeling group, but they are improving all the time.

“We can't really predict many aspects of the future very well,” O’Neill said. “Future carbon emissions can’t be predicted with accuracy. Same with technological change. The impact of future legislation is yet to be known.

“What we try to do then, is use models to create alternative scenarios of what could happen. These models use enormous amounts of data and make conditional assumptions about the future. We have more and more experience with real world trends that we can base our models on, so there’s not as much guesswork as there was, say, 20 years ago. The models have been improving in other ways, too. So our projections are getting better as we continue to learn.”

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