Storm warning: a new long-range tropical cyclone outlook is set to reduce disaster risk for Pacific Island communities



Photobank.kiev.ua/Shutterstock

Andrew Magee, University of Newcastle; Andrew Lorrey, National Institute of Water and Atmospheric Research, and Anthony Kiem, University of Newcastle

Tropical cyclones are among the most destructive weather systems on Earth, and the Southwest Pacific region is very exposed and vulnerable to these extreme events.

Our latest research, published today in Scientific Reports, presents a new way of predicting the number of tropical cyclones up to four months ahead of the cyclone season, with outlooks tailored for individual island nations and territories.

A new model predicts tropical cyclone counts up to four months in advance.

Tropical cyclones produce extreme winds, large waves and storm surges, intense rainfall and flooding — and account for almost three in four natural disasters across the Southwest Pacific region.

Currently, Southwest Pacific forecasting agencies release a regional tropical cyclone outlook in October, one month ahead of the official start of the cyclone season in November. Our new model offers a long-range warning, issued monthly from July, to give local authorities more time to prepare.

Most importantly, this improvement on existing extreme weather warning systems may save more lives and mitigate damage by providing information up to four months ahead of the cyclone season.

This map shows the expected number of tropical cyclones for the 2020/21 Southwest Pacific cyclone season (November to April).
http://www.tcoutlook.com/latest-outlook, Author provided

Tropical cyclones and climate variability

An average of 11 tropical cyclones form in the Southwest Pacific region each season. Since 1950, tropical cyclones have claimed the lives of nearly 1500 and have affected more than 3 million people.

In 2016, Cyclone Winston, a record-breaking severe category 5 event, was the strongest cyclone to make landfall across Fiji. It killed 44 people, injured 130 and seriously damaged around 40,000 homes. Damages totalled US$1.4 billion — making it the costliest cyclone in Southwest Pacific history.




Read more:
Winston strikes Fiji: your guide to cyclone science


Tropical cyclones are erratic in their severity and the path they travel. Every cyclone season is different. Exactly where and when a tropical cyclone forms is driven by complex interactions between the ocean and the atmosphere, including the El Niño-Southern Oscillation, sea surface temperatures in the Indian Ocean, and many other climate influences.

Capturing changes in all of these climate influences simultaneously is key to producing more accurate tropical cyclone outlooks. Our new tool, the Long-Range Tropical Cyclone Outlook for the Southwest Pacific (TCO-SP), will assist forecasters and help local authorities to prepare for the coming season’s cyclone activity.

This map shows the probability of below or above-average tropical cyclones for the 2020/21 Southwest Pacific cyclone season.
http://www.tcoutlook.com/latest-outlook, Author provided

According to the latest long-range sea surface temperature outlook, there is a 79% chance that La Niña conditions could develop before the start of the 2020-21 Southwest Pacific cyclone season. La Niña conditions typically mean the risk of tropical cyclone activity is elevated for island nations in the western part of the region (New Caledonia, Solomon Islands and Vanuatu) and reduced for nations in the east (French Polynesia and the Cook Islands). But there are exceptions, particularly when certain climate influences like the Indian Ocean Dipole occur with La Niña events.




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Improving existing tropical cyclone guidance

Current guidance on tropical cyclones in the Southwest Pacific region is produced by the National Institute of Water and Atmospheric Research, the Australian Bureau of Meteorology and the Fiji Meteorological Service. Each of these organisations uses a different method and considers different indices to capture ocean-atmosphere variability associated with the El Niño-Southern Oscillation.

Our research adds to the existing methods used by those agencies, but also considers other climate drivers known to influence tropical cyclone activity. In total, 12 separate outlooks are produced for individual nations and territories including Fiji, Solomon Islands, New Caledonia, Vanuatu, Papua New Guinea and Tonga.

Other locations are grouped into sub-regional models, and we also provide outlooks for New Zealand because of the important impacts there from ex-tropical cyclones.

Our long-range outlook is a statistical model, trained on historical relationships between ocean-atmosphere processes and the number of tropical cyclones per season. For each target location, hundreds of unique model combinations are tested. The one that performs best in capturing historical tropical cyclone counts is selected to make the prediction for the coming season.

At the start of each monthly outlook, the model retrains itself, taking the most recent changes in ocean temperature and atmospheric variability and attributes of tropical cyclones from the previous season into account.

Both deterministic (tropical cyclone numbers) and probabilistic (the chance of below, normal or above average tropical cyclone activity) outlooks are updated every month between July and January and are freely available.The Conversation

Andrew Magee, Postdoctoral Researcher, University of Newcastle; Andrew Lorrey, Principal Scientist & Programme Leader of Climate Observations and Processes, National Institute of Water and Atmospheric Research, and Anthony Kiem, Associate Professor – Hydroclimatology, University of Newcastle

This article is republished from The Conversation under a Creative Commons license. Read the original article.

The Great Barrier Reef outlook is ‘very poor’. We have one last chance to save it



Tourists snorkelling on the Great Barrier Reef, the outlook for which has been officially rated “very poor”.
AAP

Terry Hughes, James Cook University

It’s official. The outlook for the Great Barrier Reef has been downgraded from “poor” to “very poor” by the Australian government’s own experts.

That’s the conclusion of the latest five-yearly report from the Great Barrier Reef Marine Park Authority, released on Friday. The report assessed literally hundreds of scientific studies published on the reef’s declining condition since the last report was published in 2014.

The past five years were a game-changer. Unprecedented back-to-back coral bleaching episodes in 2016 and 2017, triggered by record-breaking warm sea temperatures, severely damaged two-thirds of the reef. Recovery since then has been slow and patchy.

Fish swimming among coral on the Great Barrier Reef.
AAP

Looking to the future, the report said “the current rate of global warming will not allow the maintenance of a healthy reef for future generations […] the window of opportunity to improve the reef’s long-term future is now”.

But that window of opportunity is being squandered so long as Australia’s and the world’s greenhouse gas emissions continue to rise.

The evidence on the reef’s condition is unequivocal

A logical national response to the outlook report would be a pledge to curb activity that contributes to global warming and damages the reef. Such action would include a ban on the new extraction of fossil fuels, phasing out coal-fired electricity generation, transitioning to electrified transport, controlling land clearing and reducing local stressors on the reef such as land-based runoff from agriculture.




Read more:
Meet the super corals that can handle acid, heat and suffocation


But federal Environment Minister Sussan Ley’s response to the outlook report suggested she saw no need to take dramatic action on emissions, when she declared: “it’s the best managed reef in the world”.

Major coral bleaching events in 2016 and 2017 have devastated the reef.

The federal government’s lack of climate action was underscored by another dire report card on Friday. Official quarterly greenhouse gas figures showed Australia’s greenhouse gas emissions have risen to the highest annual levels since the 2012-13 financial year.

But rather than meaningfully tackle Australia’s contribution to climate change, the federal government has focused its efforts on fixing the damage wrought on the reef. For example as part of a A$444 million grant to the Great Barrier Reef Foundation, the government has allocated $100 million for reef restoration and adaptation projects over the next five years or so.

Solutions being supported by the foundation include a sunscreen-like film to float on the water to prevent light penetration, and gathering and reseeding coral spawn Separately, Commonwealth funds are also being spent on projects such as giant underwater fans to bring cooler water to the surface.

But the scale of the problem is much, much larger than these tiny interventions.




Read more:
Extreme weather caused by climate change has damaged 45% of Australia’s coastal habitat


Climate change is not the only threat to the reef

The second biggest impact on the Great Barrier Reef’s health is poor water quality, due to nutrient and sediment runoff into coastal habitats. Efforts to address that problem are also going badly.

This was confirmed in a confronting annual report card on the reef’s water quality, also released by the Commonwealth and Queensland governments on Friday.

The Great Barrier Reef attained world heritage status in the 1980s.
AAP

It showed authorities have failed to reach water quality targets set under the Reef 2050 Plan – Australia’s long-term plan for improving the condition of the reef.

For example the plan sets a target that by 2025, 90% of sugarcane land in reef catchments should have adopted improved farming practices. However the report showed the adoption had occurred on just 9.8% of land, earning the sugarcane sector a grade of “E”.

So yes, the reef is definitely in danger

The 2019 outlook report and other submissions from Australia will be assessed next year when the UNESCO World Heritage Committee meets to determine if the Great Barrier Reef should be listed as “in danger” – an outcome the federal government will fight hard to avoid.

An in-danger listing would signal to the world that the reef was in peril, and put the federal government under greater pressure to urgently prevent further damage. Such a listing would be embarrassing for Australia, which presents itself as a world’s-best manager of its natural assets.

Environment activists engaged in a protest action to bring attention to the dangers facing the Great Barrier Reef.
AAP

The outlook report maintains that the attributes of the Great Barrier Reef
that led to its inscription as a world heritage area in 1981 are still intact, despite the loss of close to half of the corals in 2016 and 2017.

But by any rational assessment, the Great Barrier Reef is in danger. Most of the pressures on the reef are ongoing, and some are escalating – notably anthropogenic heating, also known as human-induced climate change.




Read more:
Great Barrier Reef Foundation chief scientist: science will lie at the heart of our decisions


And current efforts to protect the reef are demonstrably failing. For example despite an ongoing “control” program, outbreaks of the damaging crown-of-thorns starfish – triggered by poor water quality – have spread throughout the reef.

The federal government has recently argued that climate change should not form the basis for an in-danger listing, because rising emissions are not the responsibility of individual countries. The argument comes despite Australia having one of the highest per capita emissions rates in the world.

But as Australia’s greenhouse gas emissions continue to rise – an outcome supported by government policy – the continued downward trajectory of the Great Barrier Reef is inevitable.The Conversation

Terry Hughes, Distinguished Professor, James Cook University

This article is republished from The Conversation under a Creative Commons license. Read the original article.