Outside La Serena, Chile. May 2013. Francesco Fiondella

Climate Variability: What You Need To Know

By Elisabeth Gawthrop, International Research Institute for Climate and Society

Climate change is a fairly constant source of news, but this year’s El Niño is bringing more attention than usual to climate variability–changes in climate that unfold on shorter timescales. These are typically natural swings in our climate, be them year-to-year or decade-to-decade. They tend to be more dramatic than the projected average changes anticipated from climate change. Despite the fact that most areas of the world aren’t well-adapted to present-day climate fluctuations (e.g. the current California drought and Indonesian fires), the world puts many resources into understanding the changes expected in 50–100+ years.

Annual rainfall in the Sahel from 1900 to 2006, adapted from Mason et al, 2015. The red dots indicate the yearly observations, so the red line indicates variation in climate from year to year (also know as interannual variability). ENSO is a major influence of interannual variability for many places, especially in the tropics. The blue line represents decadal variability, or the trends in climate that occur over the span of 10–30 years. These clusters of relatively wet or dry years can result in prolonged drought or flooding. The Sahel droughts of the 1970s and 80s show up at this timescale, indicated by the dip of the blue line in this graph. Sometimes trends on the decadal timescale can be counter to long-term trends (those of >30 years). While a long-term trend is apparent in this dataset (black line), long-term trends caused primarily by climate change are generally more apparent for temperature than rainfall, which tends to be more variable.

This isn’t to say that climate change research is not important, of course, or that climate change and climate variability aren’t related. Madeleine Thomson, a scientist at IRI, has characterized the upcoming El Niño as an opportunity to test our public health systems on their ability to handle extreme climate events, which are expected to occur more frequently in the future. Moreover, studying climate variability now and understanding better how our climate system works on shorter-term scales will inform the study of how our climate might change on longer-term scales.

While El Niño is one of the most well-understood sources of climate variability, your weather at any given time is influenced by a multitude of naturally-occuring patterns of climate variability. As scientists study these patterns, the ability for new kinds of forecasts, and more accurate forecasts, is increasingly possible. Recent strides in the Madden-Julian Oscillation, for example, have opened up new possibilities of predicting climate events at the two-week to two-month timescale.

For more information, check out our new resource page that further explains climate variability and a handful of the many variability patterns scientists are currently exploring.

+ Just for fun! Find out which source of climate variability reflects your inner-self. No pressure, unless you’re an NAO.. Take the quiz here.