Climate insights from ‘most influential scientific mind’
Professor Brian Soden of the University of Miami’s Rosenstiel School of Marine and Atmospheric Sciences, named one of the world’s most influential scientific minds by Thomson Reuters, lends his expertise on the prediction of climate change in this interview with Ria Persad.
AS a lead author for the 2013 and 2007 Intergovernmental Panel on Climate Change (IPCC), for which he shared the 2007 Nobel Peace Prize with former US Vice President Al Gore, Dr. Brian Soden’s research and expertise focus on understanding how rainfall, droughts, and extreme weather events respond to a warming climate and determining how much the climate will warm for a given increase in carbon dioxide. Scientists use global satellite observations to measure these changes in climate and compare this to what climate models predict as a way to test and validate the models.
Climate models are large-scale computer programs used to solve equations that quantify our understanding of how the climate system works. They compute the flow of energy, the movement of the atmosphere and the ocean, and how that movement transports energy within the climate system. If we perturb the flow of energy, say, by changing the amount of energy from the sun or adding greenhouse gas, the model predicts how the climate responds to that change. Both internal variations, such as naturally occurring oscillations like El Niño and La Niña, and external forcings, such as changes in sunlight or a large volcanic eruption, affect the climate system. External forcings also include the burning of fossil fuels, which increases the concentration of greenhouse gases in the atmosphere.
Dr. Soden explains that, starting on the shortest time scale, we can predict the weather, such as temperature and rainfall, out to about seven days. Beyond that, the atmosphere becomes too noisy to accurately predict the weather for a particular day. However, we can predict changes in the probability of different weather types or climate conditions for decades into the future. For example, even though the temperature on a particular day cannot be predicted beyond about a week, we can say that (in temperature climates) summers will be warmer than winters due to the increase in the amount of energy from the sun. Similarly, increasing the amount of greenhouse gases also warms the earth by increasing the net amount of energy flowing into the climate. In this way, scientists can make predictions of how the climate will change for decades into the future.
The IPCC, as the leading international body on climate change, is composed of thousands of scientists who convene every 6 to 7 years to assess the scientific understanding of climate change. The first IPCC report was published in 1990, making projections that have continued through five reports over 27 years. Dr. Soden notes that when we go back and examine these projections they have proven to be consistent with the observed warming of the climate since 1990. Additionally, natural events such as the volcanic eruption of Mt. Pinatubo, which injected large amounts of gas and particulates into the atmosphere resulting in a temporary cooling of the planet, can also be used to test climate models.
Dr. Soden comments that the IPCC reports inform policymakers by being “policy-relevant, but not policy-prescriptive” with an emphasis on transparency. They go through a rigorous review process with tens of thousands of comments on each draft, each of which must be responded to by the authors, archived, and made available to the public. The IPCC has concluded that the earth is warming and that human activities such as the burning of fossil fuels are the primary cause of that warming over the last half century. Associated with that warming are increases in sea level, heavy rain events, droughts, fewer cold days, and more frequent and extreme heat waves. Dr. Soden cautions that the amount and extent of future warming depend strongly on future choices regarding sources of energy and greenhouse gas emissions, namely, whether we continue to burn fossil fuels or start to convert over to cleaner, renewable energy.
Brian J. Soden received his bachelor’s degree from the University of Miami and masters and doctorate from the University of Chicago. He was lead author for the IPCC, sharing the 2007 Nobel Peace Prize with Vice President Al Gore. His 2006 paper in the Journal of Climate was ranked “one of most influential climate change papers of all time.” He is VP of science and technology at Coastal Risk Consulting and Fellow of the American Meteorological Society.
Ria Persad is a mathematician from Harvard, Princeton and Cambridge universities. She performed climate modeling at Lawrence Livermore Lab and solar system modeling at NASA. She is the founding CEO of the Philippine-based StatWeather.