Indian Ocean Dipole variability will continue to episodically bring extreme climate conditions to our region. But previous studies , as well as ours, have shown human-caused climate change has shortened the gaps between these episodes, and this trend will continue. This is because climate change is causing the western side of the Indian Ocean to warm faster than in the east, making it easier for positive Indian Ocean Dipole events to establish.
In other words, drought-causing positive Indian Ocean Dipole events will become more frequent as our climate continues to warm. In fact, climate model projections indicate extreme positive Indian Ocean Dipole events will occur three times more often this century than last, if high greenhouse gas emissions continue. Read more: The world may lose half its sandy beaches by Future extremes from the Indian Ocean will act on top of long-term warming, giving a double-whammy effect to their impacts in Australia, like the record-breaking heat and drought of But perhaps most importantly, rapidly cutting greenhouse gas emissions will limit how often positive Indian Ocean Dipole events occur in future.
Edition: Available editions United Kingdom. Become an author Sign up as a reader Sign in. The speed with which the impacts are felt is the flash drought's defining feature. It can be difficult to define exactly when a drought starts — rain could be just around the corner, after all.
It can also be difficult to define exactly when a drought breaks. A passing shower might make things look better temporarily, but it will not put a real dent in the damage done. For a drought to truly be over, a return to normal rainfall patterns and amounts is needed.
Australia is the second-driest continent in the world, with mean annual rainfall less than mm for more than 80 per cent of Australia.
Australia is so dry because we sit under the subtropical high-pressure belt, which encourages the air to push down, preventing the lift required for rain. Being under the high-pressure belt is enough to make it dry, but there are other systems called climate drivers that can make things worse from one year to the next. El Nino has become a bit of a household name after it got a lot of press during the millennium drought. It is commonly associated with drought in the east of Australia because it leads to more air being pushed down, which again prevents rain.
Its sister, La Nina, is generally the opposite, although it is all a bit messy when you get into the details, and every event is different. In this case a positive IOD is associated with drought in Australia. It works to the south and is involved with the extent to which rain-bearing cold fronts make it onto the continent. A positive SAM in winter is associated with winter drought in the south of Australia. Beyond the major climate drivers, there are also local conditions that affect the weather.
As the major climate drivers are currently neutral in the latest outlook, the bureau has attributed the current dry to cooler ocean temperatures to the north bringing less tropical moisture, and weak westerlies to the south. Try to replace some of the original verbs with your synonyms and discuss if any are better and why.
Describe what that is like. No one-word answers. Use full sentences to explain your thinking. No comments will be published until approved by editors. What is drought, how long does it last and what is a drought declaration? Picture: thepastyfarmer Source: Instagram.
Reading level: orange. Picture: Getty Images. This photo was taken in June last year, when there should be green grass rather than bare paddocks. Buying hay and grain to feed animals is expensive. Extra Reading in explainers.
Drought is a complex beast and can be measured in a variety of ways. Some aspects of drought are linked with climate change; others are not. In Australia, the Bureau of Meteorology uses rainfall deficiencies to identify regions that are under drought conditions.
Droughts are also exacerbated by low humidity, higher wind speeds, warmer temperatures, and greater amounts of sunshine. All of these factors increase water loss from soils and plants.
This means that other metrics are often used to describe drought which go beyond rainfall deficiencies alone. This means that there are hundreds of metrics which together can provide a more detailed representation of a drought.
But this also means that droughts are less well understood and described than simpler phenomena such as temperature and rainfall. Hydrological drought, often defined by a period of low streamflow, is a response to numerous upstream processes that are unique to each river system.
Hydrologists and water planners therefore often focus on directly observing and modelling runoff from water catchments. The point here is that droughts can be multidimensional, affecting agriculture and water supplies on a wide range of spatial and temporal scales. A seasonal-scale drought that reduces soil moisture on a farm, and a decade-long drought that depletes reservoirs and groundwater supplies, can both be devastating, but in very different ways.
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