During the multi-year Millennium Drought from 1997 to 2010, south east Australia experienced its lowest 13-year rainfall record since 1865 over the years 2006 to 2010.
Temperatures were also much hotter than in previous droughts and temperature extremes peaked during the heatwave and bushfires in early 2009. This culminated in the loss of 374 lives in Victoria and many more over the larger southeast in the heatwave leading up to Black Saturday. There were 173 lives lost in the fires.
The years 2015 to 2016 saw El Niño combined with a positive Indian Ocean Dipole in the second half of 2015 further suppressing rainfall, so that rainfall was the equal fourth-lowest on record for Australia during September, Tasmania had its driest Spring on record and mean temperatures were also highest on record for October to December 2015. This El Niño also contributed to an early start to the 2015-16 southern fire season.
By 2017 Australia was again in the grips of a multi-year drought. Very dry conditions in the cool season were followed by only a limited recovery in the October–December period in 2017 and 2018. This meant record-low rainfalls over various multi-year periods.
By June 2018 more than 99% of NSW was declared as affected by drought. The most extreme rainfall deficiencies over multi-year periods occurring in the northern half of New South Wales.
In June-July 2019 New South Wales began a trial by mega bushfires, as did other east coast states, that lasted through to January 2020.
Widespread drought was not an issue for the remainder of 2020 through to the present day, given La Niña visited three times in three years bringing high rainfall events and record floods in the eastern states.
However, the Australian Dept. of Agriculture, Forestry and Fisheries (ABARE) is now drawing attention to this:
All but one international climate model surveyed by the Australian Bureau of Meteorology suggest sea-surface temperatures in the tropical Pacific will exceed El Niño thresholds in June. [ABARES Weekly Australian Climate, Water and Agricultural Update, 25 May 2023]
[ABARES, 25 May 2023] Click on image to enlarge
Suggesting in its climate update that there is now twice the risk of an El Niño event this year, with a likelihood of it making itself felt sometime between August and October.
The overall outlook for this Australian Winter continues to be below median rainfall and warmer median temperatures.
The main urban centres in the Clarence Valley have a chance of unusually warm temperatures over the winter months of between est. 55-60% (Maclean-Yamba-Iluka) and 59-65% (Grafton). While elsewhere in the Northern Rivers region unusually warm temperatures are expected in Lismore with est. 58-59% chance, Tweed Heads est. 59-62% chance, with Byron Bay & Ballina at est. 60-61% chance. [BOM, Climate outlooks—weeks, months and seasons, June-September 2023]
How this developing scenario affects agricultural growing seasons over the next twelve months is anyone's guess.
In New South Wales only the parishes of Newbold and Braylesford in the Clarence Valley are showing Combined Drought Indicator (CDI) at “Drought Affected”.
Nevertheless, root-zone soil moisture has been falling across north-east NSW so that by end of April 2023 it was very much below average in from the coast.
Remembering that drought 'safety net' Shannon Creek Dam, which supplies urban town water to both Coffs Harbour City and Clarence Valley resident populations (total 134,538 persons, June 2022) is currently at 92.6% capacity or 27,677 megalitres, perhaps we may see increased water restrictions by the next Christmas-New Year period. Given the tourist-driven seasonal population rise increases water consumption and that 80% dam capacity is the increased restrictions trigger.
It doesn't take a genius to suspect that should a drought develop, the 2024 and 2025 bush fire seasons might also be highly problematic for rural and regional areas across Australia.
No comments:
Post a Comment