Ian Hutton, The Lord Howe Island Signal

It depends on how you read the Bureau of Meteorology data – maximums, minimums, average daily etc. One way might be to add the minimum and maximum and divide by two to arrive at a daily average – then analyse these averages in past records.

However, if we take a simple measure of the number of days with maximums over 28 degrees C, then summer of 2023/2024, was Lord Howe’s hottest on record. There were 36 days when maximum temperatures exceeded 28C; the previous highest number of hot days was 2018/2019 summer with 33 days. The accompanying graph shows the number of days over 28 C each summer since 1988 (when the weather station was moved to the its current airport location).

Also, January/February/March 2024, was extremely dry – and if no more rain falls from the 25th to the end of March, this would be the driest 3-month January/ February/March on record; 2024 had just 66.6 mm rain falling up to March 25th. Some rain is forecast for the remainder of March, and the final three-month rainfall should be over 66.6mm, but it may not exceed the previous driest January/February/March of 2014, which had 96.4mm rain. The long term average rainfall for these three months is 337 mm.

These hot, dry conditions have impacted the forest with many of the larger-leafed plants wilting and even dying. This summer I have also heard many reports from residents about their favourite long-lived garden plants dying. The most concerning impact I have seen is the collapse of the heads of 15 mature Curly Palm trees in Steven’s Reserve in February, along with about 60 smaller ones not yet having a trunk. These palms may have been weakened by the water stress of the 2018/19 drought, with this second drought now killing them.

In the last big dry period, the summer 2018/2019, the forest on the summit of Mount Gower was severely impacted. This summer – 2023/2024 – we did have a lot of low cloud on the mountains which has protected the summit forest.

When I was there in early February, the cloud forest had not been greatly damaged by the hot, dry weather. However, I have noted since then that there has been less cloud around the summit so the unique plants there might still be adversely affected.

Our record hot summer air temperatures are, no doubt, linked to a hot pool of water that formed in the Tasman Sea and surrounded Lord Howe Island for many weeks, as the surrounding ocean temperature determines our air temperatures.

This hot pool of water has had a significant impact on our marine environment. Kingfish are hard to catch, as it is believed they have moved further away into cooler waters. The Marine Parks and Lagoon tour operators have reported significant bleaching of certain coral types across the lagoon this summer – perhaps worse than the March, 2019, bleaching event. As the water has cooled a bit now, it is hoped that the bleached corals will recover as we move into autumn. However, research has shown that with frequent severe bleaching events there can be permanent damage to coral reefs.

According to the World Meteorological Organisation State of the Global Climate 2023 report, 2023 was the warmest year on record, with the global average nearsurface temperature at 1.45 °Celsius (with a margin of uncertainty of ± 0.12 °C) above the pre-industrial baseline. It was the warmest ten-year period on record.

Global climate records were shattered in 2023, with air and sea temperatures increasing, sea-levels rising and sea-ice diminishing. Scores of countries recorded their hottest year and numerous weather disasters occurred as climate change reared its head.

Global average sea-surface temperatures (SSTs) were at a record high from April onwards, with the records in July, August and September broken by a particularly wide margin. Marine heatwaves are becoming more severe and frequent, with devastating consequences for iconic coral reefs, kelp forests and other marine ecosystems.

We should all be prepared for more variations in our climate, and more severe weather events affecting the Island. 

This article appeared in The Lord Howe Island Signal, 31 March 2024.