Weekend’s high temperatures and humidity ‘virtually impossible’ without climate crisis, researchers say
The scorching heat blanketing much of the US this week would have been “virtually impossible” if not for the climate crisis, researchers have found, warning that the high temperatures could threaten Independence Day celebrations and World Cup matches this weekend.
“The climate the country has today is fundamentally different to the one it had when the founding fathers signed the Declaration of Independence,” said Theodore Keeping, extreme weather and wildfire researcher at Imperial College London, in a press release.
In one area 76% of fishing boats were followed, with baby dolphins learning the technique from their parents
Bottlenose dolphins in the Adriatic are increasingly following trawlers to scavenge for food, with baby dolphins learning the technique from their parents, a study has found.
“These days the easiest way to find [bottlenose dolphins] is to look for trawlers,” said Giovanni Bearzi, a co-author of the study and the president of Dolphin Biology and Conservation in Italy. “Many of them are followed by the dolphins that go to forage and scavenge in their wake.
Europe’s summer heatwave has exposed tens of millions of people to temperatures above 35°C, broken records and claimed hundreds of lives.
Early climate attribution studies suggest Europe’s event would have been “virtually impossible” just 50 years ago without human-caused climate change.
Meanwhile in South Asia, where temperatures have been edging past 45C, schools have been forced to close. As the planet continues to warm, severe heatwaves like this are expected to grow more frequent – and even more intense.
New Zealand, with its mild, maritime climate, might seem insulated from such extremes. But it, too, is expected to experience significantly warmer temperatures in future.
By the end of the century, in centres such as Auckland and Christchurch, peak summer temperatures in the hottest years could climb several degrees higher than they reach today.
Our new research explores what that could mean for human health – and how cooling in summer, rather than heating in winter, may place greater pressure on Aotearoa’s electricity system.
Modelling homes in a hotter future
New Zealand’s houses have traditionally been designed to keep people warm in winter. As temperatures rise, managing overheating will increasingly require either expensive retrofits or greater use of air conditioning, which has historically been uncommon.
That is already beginning to change. A recent survey found nearly three-quarters of households with heat pumps use them for cooling. But renters, families with children and M?ori are all less likely to have access to, or use, space cooling, largely because of cost.
To test how homes might respond to higher temperatures, we used a specific computer model that simulated how households use electricity under different conditions. It considered factors such as income, temperature and housing, and estimated when people would choose to use air conditioning.
We then modelled how rising temperatures over the rest of this century, under mid-range and high-end warming scenarios, could affect neighbourhoods across the socio-economic spectrum in Auckland and Christchurch. As well, we tested how greater access to heat pumps changed the results.
Our findings suggest climate change will have major consequences for both New Zealand’s health and electricity systems. In our highest warming scenario, summer electricity demand overtook winter demand and homes were more likely to overheat.
By 2100, this could mean thousands of additional heat-related deaths each year, with the greatest impacts falling on the most vulnerable communities. Under lower emissions scenarios and over shorter timeframes, the effects were much smaller.
We also found that coordinated policies could help reduce these impacts by improving access to cooling – but there was trade-off.
While greater use of heat pumps reduces overheating and saves lives, it further increases electricity demand.
In our highest-temperature scenario, annual cardiovascular deaths increased by between 1,264 and 2,390, depending on how many households had heat pumps.
Greater uptake of heat pumps also increased costs for electricity providers and consumers, with a combined average cost of around NZ$640,000 for each excess life saved.
Why adaptation should begin now
Without action, the burden of higher temperatures would not be shared equally. Lower-income households and older people would bear a disproportionate share of the health impacts.
Our modelling may also underestimate the scale of the risk. It does not account for the additional heat generated in urban areas, for instance, and may understate the intensity of future heatwaves.
In other words, these findings are unlikely to represent a worst-case scenario. Nonetheless, they clearly highlight a need for interventions spanning Aotearoa’s energy, health and infrastructure sectors.
So, what can be done? Our findings point to several priorities.
Space cooling should be recognised as a public health tool, with greater access to heat pumps helping save lives while also providing year-round heating and cooling benefits.
Support should be targeted towards lower-income and other at-risk communities, where access to cooling is often limited despite greater vulnerability to extreme heat. Building standards should also place greater emphasis on preventing overheating through passive cooling, reflecting a future where cooling becomes increasingly important.
At the same time, electricity generators, transmission companies and distributors will need to prepare for growing summer demand to ensure security of supply.
Most importantly, saving lives in the future means planning needs to begin now. While the effects of climate change are already being felt today, adapting homes, infrastructure and energy systems is likely to take decades.
Baxter Kamana-Williams receives funding from the Quadrature Climate Foundation.
Rebecca Peer receives funding from the Ministry of Business, Innovation and Employment and Royal Society Te Ap?rangi.
J. Geoffrey Chase does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
Every summer, communities across northern Australia brace for the tropical cyclone season. Tropical cyclones draw their power from the warm seas, extracting heat and moisture from ocean water.
To improve cyclone forecasting – and better protect lives and property – we enlisted an unlikely ally: deep-diving sea turtles equipped with oceanographic sensors on their shells.
At times these turtles have encountered powerful tropical cyclones, allowing their sensors to gather and can gather critical information on how the temperature in the water changes as the storm passes overhead.
How oceans affect cyclones
Tropical cyclones are fuelled by warm tropical seas. Higher sea surface temperatures usually generate more powerful storms.
As a cyclone passes over the ocean, its powerful winds and waves churn the water around like a blender. This action mixes warm surface water with cooler water from deeper down, leaving behind a “cool wake” – colder ocean water left behind on the sea surface. This cooling reduces the heat available to the storm, which can in turn can limit its strength.
Traditionally, cyclone forecasters have focused on sea surface temperatures, but the ocean depths also matter. If cooler water sits just below the surface, a storm can rapidly cool the sea surface by mixing it upwards. But if warm water extends deeper down, the mixing does not have the same cooling effect. This means forecast accuracy is highly dependent on the ocean temperatures below the waves.
Observing northern seas
Despite the key role northern Australian seas play in shaping tropical cyclones, we have surprisingly few observations below the surface. The region, which includes the Timor and Arafura seas between Australia and Indonesia, is vast, remote, and shallow.
This makes it difficult or expensive to use traditional ocean observation methods. Ships and underwater ocean gliders can only sample small areas, and nobody wants to collect measurements in the middle of a cyclone.
Australia needs an ocean observing system that can work in all weathers in this region. Following a collaboration between the Australian Institute of Marine Science, the Integrated Marine Observing System, CSIRO and Macquarie University, the University of Western Australia, UNSW and traditional owners, we think we’ve found one.
Turtle power: how it works
To address the data desert to Australia’s north, we have enlisted the help of deep-diving olive ridley and flatback sea turtles, which lay their eggs on beaches around tropical Australia.
Biologists have tracked sea turtles for decades using miniaturised GPS tags. Building on experience from overseas, we paired a GPS tracker with an oceanographic probe that measures temperature when the turtle dives, sometimes as deep as 80 metres.
The temperature data is transmitted almost immediately by satellite, making it available to forecasters in near real time. Over several deployments on 46 animals between 2014 to 2024, the turtles took more than 8,000 ocean temperature snapshots across northern Australia, from the Pilbara to the Gulf of Carpentaria.
Locations of sea-turtle temperature profiles from the first deployment on flatback turtles between 2010 and 2014. Points are colored by individual turtles.Christopher Chapman
Into the maelstrom
In April 2023, a tropical storm formed off the Kimberley coast. This storm, named Ilsa, would go on to become a Category 5 cyclone and register the Bureau of Meteorology’s fastest-ever recorded sustained winds: 219 kilometres an hour. Tragically, two fishing vessels were caught in the storm, and eight people died.
As Ilsa was drawing energy from the warm Timor Sea, it passed directly over one of our turtles carrying ocean instruments. This reptile, seemingly unbothered by the maelstrom above, collected sub-surface observations within the eye of the storm – before, during, after the storm’s passage.
From the turtle observations, we found Ilsa’s cold wake cooled the ocean surface by about 2°C. Had the storm stayed still, this cooling would have potentially reduced Ilsa’s strength from category five to category 4.
Excited by this result, we matched turtle observations with the Bureau of Meteorology’s historical storm database. Our turtles had taken real time observations within the core of five tropical cyclones, including the category four Cyclone Rusty. In all but one case, turtles observed strong cooling of the ocean as the storm passed overhead.
When we compared the turtle data with a state-of-the-art ocean model, we found a potential weakness in Australia’s weather forecasts. Our turtle observations indicated the ocean model did not capture the mixing of deeper, cool water with the warm surface, the very process that causes the cold wake. This can lead to overestimates of cyclone intensity.
Sentinel turtles
To improve tropical cyclone forecasts, we need reliable sub-surface ocean observations.
But ocean observation is expensive and developing an all-weather observing system is beyond the capabilities of many of the nations most vulnerable to tropical storms.
The instruments we used can be deployed on land with minimal equipment, and the Olive Ridley turtle lives in tropical seas. Sea turtles could become a key part of observing cyclone weather systems, protecting lives and livelihoods across the tropics.
Christopher Chapman receives funding from the Australian Climate Service.
Clive McMahon receives funding from the Integrated Marine Observing System and the National Geographic Society.
Rob Harcourt receives funding from the Integrated Marine Observing System
