Tuesday, February 7, 2017

Worst Great Barrier Reef bleaching event to ‘become commonplace’

Last year during the 2016 Federal election I felt great despair about the Great Barrier Reef. It was clear that Politicians were offering token funding to the Great Barrier Reef already facing extinction. It is already a climate emergency.

The Great Barrier Reef is not going to survive our experiment with global warming. Even if we could magically keep average global temperatures to below two degrees Celsius, it will be very much diminished, such is the great inertias involved in the climate system which we have irrevocably changed.

A study on climate departure, done in 2013, found that Oceans are already outside historical variability as cities and land ecosystems will inevitably follow this century. Mitigation of emissions will slow down the process, but we are already committed to a new climate, no matter where we live.

In December 2016 Hooidonk et al published a study in Nature: 'Local-scale projections of coral reef futures and implications of the Paris Agreement' revealed that there is high local-scale variation in model projected Annual Severe Bleaching (ASB), but that annual bleaching will be inevitable for most of the world's reefs by 2043. Portions of the Great Barrier Reef would likely avoid annual bleaching for a further 25 years if Paris Agreement commitments are kept and more, on the RCP4.5 decarbonisation pathway.

The report says explicitly about the Great Barrier Reef:
There is an inshore-offshore gradient in the northern Great Barrier Reef, Australia, with offshore locations projected to experience ASB 15–25 years earlier than inshore locations (Fig. 1). This increases the impetus to reduce anthropogenic stress at inshore locations where, for example, efforts to reduce land-based sources of pollution and improve water quality will have
greater impact anyway.

Good reason for Australia to actually lift it's Nationally Determined Contribution (NDC) climate plan (PDF) and targets. Australia's targets are rated as 'Inadequate' by the Climate Action Tracker.

There was a near real time attribution of the mass bleaching event on the Great Barrier Reef done in April 2016. It found that Great Barrier Reef bleaching would be almost impossible without climate change.

The lead researcher on the attribution of the Great Barrier Reef bleaching in 2016, Dr Andrew King, released a media release at the start of the Australian Meteorological and Oceanographic Society conference in Canberra. He was presenting his results today to his peers. Dr King is a Research Fellow at the University of Melbourne School of Earth Sciences and ARC Centre of Excellence for Climate System Science.

The press release in full:

Human-induced climate change increased ocean temperatures in the early months of 2016, making a significant contribution to the worst bleaching event on record for the Great Barrier Reef. The heat killed about a quarter of the coral, with 93% of the reef affected by bleaching – a situation that may become commonplace within a generation.

‘As the seas warm because of our effect on the climate, bleaching events in the Great Barrier Reef and other areas within the Coral Sea are likely to become more frequent and more devastating,’ said Dr Andrew King from the University of Melbourne.

Dr King and his colleagues analysed recent and historic ocean temperature measurements and completed a series of climate model simulations.

‘The year 2016 represented the worst Great Barrier Reef bleaching event on record. It would be virtually impossible for that level of bleaching and damage to occur without human-caused climate change,’ said Dr Andrew King.

‘Our results also suggest that this kind of event will become commonplace in the next few decades. Climate change damage to the reef has implications for the reef’s ecosystems as well as for industries like tourism.’

During March 2016, the Coral Sea was the warmest on record.

‘The 2016 warmth associated with the bleaching was unprecedented in at least 350 years,’ said Dr King.

‘As the effects of climate change worsen we expect this warming effect to increase.’

It's not only Australian reefs feeling the heat: it is a global phenomenon as sea surface temperatures rise.

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