Global Climate Report: Record heat, rising seas and extreme Weather

Wednesday, 19 March 2025

Multiple records were smashed last year, according to the 2024 State of the Global Climate Report by the World Meteorological Organisation (WMO), released on Wednesday afternoon.

Global air temperatures last year were the highest on record for the tenth consecutive year - more than 1.5C above the pre-industrial era. Atmospheric carbon dioxide (CO₂) levels reached their highest in 800,000 years, while glaciers experienced record losses for the third straight year. Sea levels were rising at twice the rate observed when satellite measurements began in 1993, and for the eighth consecutive year, the world’s oceans were the warmest recorded.

“This latest report from the World Meteorological Organisation is more bad news about climate change,” climate expert Dr James Renwick said.

“All extremely worrying, yet apparently of little concern to the world’s policy-makers, since there is no sign the world is living up to the Paris Agreement to limit warming to 1.5-2C. Greenhouse gas emissions that drive climate change just keep increasing, regardless of the bad news.”

The report warned sea level rise was irreversible “on centennial to millennial time scales”. And even using low carbon emission scenarios, the ocean would continue to warm for the rest of the century.

“Scientists in the New Zealand Antarctic Science Platform, and their collaborators from around the world, are pushing hard to establish the trajectory from here, and the consequences for Antarctic ecosystems, for New Zealand weather and climate, and for the global climate system,” Renwick said.

Dr Melissa Bowen, Associate Professor of Oceanography at the University of Auckland, said 90% of surplus energy was absorbed by the ocean.

“Much of that heat is moving into deeper layers, keeping our climate stable. However, we are now seeing measurable temperature changes.”

Bowen said the uneven distribution of warming across the oceans leads to increased marine heatwaves and potential changes in storm patterns.

“This additional heat fuels the atmosphere, influencing weather events,” she said.

“For regions like New Zealand and its Pacific neighbours, stronger tropical cyclones could become more frequent.”

And last year those global events - Typhoon Yagi, Hurricane Helene, Tropical Cyclone Chido - were deadly, with more than a thousand lives lost, homes and livelihoods destroyed and the economic losses were huge.

“This new report emphasises the continued pressure we are placing on our climate - and the associated environmental, economic and sociocultural systems that make life on earth worth living,” Professor Craig Stevens, a physicist at the University of Auckland said.

He had seen the decline in Antarctic sea ice first hand during a research voyage to the Ross Sea.

“The reduction in sea ice throughout the region was obvious - we got to go places that had always been off limits.” he said.

“Reduced sea ice cover changes the reflectivity of the planet, changes thermal exchange between air and sea, changes the properties of the deep ocean, and reduces critical habitat for key parts of the Southern Ocean's ecosystem.”

Ice melt - particularly from the West Antarctic and Greenland ice sheets - was the main contributor to sea-level rise, Bowen said.

“We’ve got a warmer ocean, we also have it expanding. So we’ve got higher sea levels as well as that, we have ice melting on land and that’s flowing into the ocean.”

Beyond warming, excess CO₂ absorption was making the ocean more acidic, affecting marine biodiversity.

“When CO₂ dissolves in seawater, it forms carbonic acid, making the ocean slightly more acidic,” Bowen said.

“This has been happening for as long as we’ve had excess CO₂ in the atmosphere, leading to gradual changes in marine ecosystems.”

And although the report’s finding were not surprising to Bowen, she said it was important for people to know about it.

“People need to be aware that this is happening, that’s the main thing, and also to be prepared or preparing themselves for the impacts and consequences of it.”