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How will the interplay between climate change and El Niño modify climate impacts?

How the interplay between the El Niño Southern Oscillation (ENSO) and anthropogenic climate change will affect climate change impacts is a key question that scientists are trying to answer. The El Niño Southern Oscillation (ENSO) is a climate pattern with global effects that results from periodic variations in the sea surface temperature across the equatorial Pacific Ocean. Because ENSO affects seasonal climate around the world, the answer to this question has broad-ranging consequences. PCIC Director Dr. Francis Zwiers was recently interviewed for an article in the Globe and Mail that examines these questions with a focus on the impacts that Canada may see. The story provides a description of El Niño and some of its broader global impacts in terms of changes to temperature and moisture at different places in the world, along with a discussion of a paper that examines the economic impacts from two El Niño events in the past and estimates of the economic impacts from a potential future El Niño event, assuming an increase in El Niño magnitude and the strength of the teleconnections that transmit the influence of El Niño globally. There is as of yet no consensus on projected changes in ENSO amplitude (for more on this, see Chapter 4 of Working Group I's contribution to the Intergovernmental Panel on Climate Change's Sixth Assessment Report), but an increase is seen in some models from the sixth phase of the Coupled Model Intercomparison Project (CMIP6). The story also covers some important implications for Canada. These include the effects of El Niño on agriculture and aquaculture, the cost of freeze-thaw cycles on municipal budgets, and some of the concerns for hazard planning. This article follows on the heels of the return of El Niño conditions, which were discussed in an earlier news article written as the conditions were developing.

Dr. Zwiers's comment in the article relates to a paper in the Journal of Climate that examined how global warming could change how El Niño and La Niña events affect daily precipitation extremes in the boreal cold season. This PCIC-led research found that future warming is projected to intensify extreme precipitation in all of the regions they examined and across all three ENSO phases (El Niño, La Niña and neutral conditions). The projections also showed an increase in the differences in the intensity of extreme precipitation under El Niño and La Niña conditions. Commenting on this increase in the magnitude and variability of extremes, Dr. Zwiers said, "If you’re living in a place where this difference magnifies, it becomes that much harder to cope, in a sense, because of the bigger discrepancy between extremes."

Read the article in the Globe and Mail.

Read the related open-access paper in the Journal of Climate.