Is Australia’s Heat Wave Linked to ENSO?

By February 13, 2013 Ocean News


Climate change is something we’ve all heard about, and have hopefully accepted as fact.  Major scientific agencies around the globe are in agreement the climate is changing and it has been greatly influenced by an increase in greenhouse gases (carbon dioxide, methane, nitrous oxide, fluorinated gases, etc.).  There have been record breaking temperatures found around the globe, changes in rainfall severe storms, heat waves, melting glaciers, not to mention ocean warming, acidification and sea level rise.

art-weather-620x349The most recent example of this has been seen in Australia, where their weather forecast chart had to add new colors! Pinks and purples now show up on Australian weather charts to show extreme heat (right).  How extreme?  Previously Australia’s top color (burnt orange to black) indicated 50℃ (for those in America, that’s a whopping 122℉). These new colors represent temperatures from 51-54℃ (≈124-130℉), which forecasters believe to be possible in certain parts of the country.

Beyond the areas predicted for extreme heat, the entire country has been going through the longest and hottest heat wave on record (which have been taken since 1910).  On December 7th the entire countries average temperature was Australia_wildfires_1-6-2013_NASA_Terra-e135790803297740.33℃ (105℉), and they have had 7 consecutive days where the average temperature was above 39℃ (102℉)— the previous record was only 4 days.  This heat wave has caused many wildfires throughout the country, with nearly 741,000 acres burned as of January 8th! The image is a NASA satellite picture taken on Jan 6th showcasing all the wildfires!

What is to blame??? Unusual climate, the ocean, or both?
Generally the northern Australian monsoon season arrives in December and lasts through March, these months may vary in different areas of Australia.  As the heatwave shows, the monsoon season has not arrived when it normally should. Could this be due to an El Niño Southern Oscillation (aka ENSO) event?

What is an ENSO Event?
An ENSO event is influenced by warming ocean waters in the Pacific. To put it simply, changes in the atmosphere and ocean circulation lead to warmer than normal Pacific Ocean temperatures, increased cloudiness, weaker trade winds, and low SOI (Southern Oscillation Index) values (focused in the central and eastern tropical Pacific).  The SOI is just a mathematical representation of pressure differences at sea level between Darwin Australia and Tahiti which indicate the development of ENSO events.  The picture below is a great explanation if you are a bit confused.  An El Niño event typically occurs every 3 to 7 years.


What does this have to do with climate?
These events effect not only Australia, but the entire world, influencing temperatures and precipitation worldwide.  How? Sea Surface temperatures actually have a great influence on rainfall, which in turn effects wind patterns. A warmer atmosphere is able to hold more moisture. When there is an extreme high or low sea surface temperature it can alter the normal rain and wind patterns, leading to unusually wet and cold or hot and dry conditions. These events are natural sources of climate variation and are monitored to ensure people are ready for the extreme temperatures, flooding and droughts they can bring to the world.

What do the Experts think?
The Climate Prediction Center/NCEP/NWS and the International Research Institute for Climate and Society currently say that we are El Niño Neutral for Spring 2013, but Summer is still up in the air.  These conditions were also not seen during December 2012, meaning the extreme weather in Australia is not due to an El Niño event and natural climate variation.  Instead this weather has been brought on by our own changes to the climate.

If extreme El Niño-esque weather conditions can now occur separately from El Niño events, then what will El Niño events look like in the future?  What does this mean for our climate worldwide?


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