by It’s official: 2023 was the hottest year ever recorded on Earth, beating the previous record set in 2016. Last year was also the first time the world came close to 1.5°C (1.48°C) warmer than the pre-industrial average (1850-1900). We are pushing against the threshold that scientists have urged us to limit long-term warming.
Some scientists, including former NASA cryologist James Hansen, are predicting that 2024 will be humanity’s first year above 1.5 °C. As dire warnings from climate experts become our shared reality, what can you expect?
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The 1.5°C temperature target, enshrined in the 2015 Paris agreement, has not been breached on the first touch. Most of the climate tipping points It is not expected that scientists will fear that warming will spiral out of control until the Earth is always warmer than 1.5°C. Average global temperatures are likely to drop again when the current El Niño (a warm phase in a natural cycle centered on the equatorial Pacific) dissipates.
Instead, 2024 could be our first look at Earth at 1.5°C. This is what research suggests it will be like for people and nature.
Ecosystems at hand
Tropical coral reefs are in warm water. These habitats include a network of polyp-like animals (related to jellyfish) and colorful algae covered in calcium carbonate. The complex forms they build in shallow water around the Earth’s equator are thought to support more species than any other ecosystem.
“Corals have adapted to live in a specific temperature range, so when the ocean temperature is too warm for a long period of time, corals can bleach – losing the colorful algae that live within their tissues and feed them through photosynthesis – and they can eventually die,” he says. coral biologists Adele Dixon and Maria Beger (University of Leeds) and physicists Peter Kalmus (Nasa) and Scott F. Heron (James Cook University).
Climate change has already increased the frequency of these marine heat waves. In a 1.5°C warmer world, 99% of reefs will be exposed to unacceptable heat too often to recover according to Dixon’s research, threatening food and income for an estimated billion people – not to mention biodiversity .
Coral reefs will earn their reputation as “canaries in the coal mine” for the impact of climate change on the natural world. As global warming approaches 2°C, the devastation already seen on reefs will be seen elsewhere according to analysis by biodiversity scientist Alex Pigot at UCL:
“We found that limiting global warming to 1.5°C 15% of the endangered species suddenly losing at least a third of its current geographic range. However, this increases to 30% of species on our current path of 2.5°C warming.”
Heat beyond human tolerance
Above 1.5°C, humanity risks triggering heat waves so intense that they demand the ability of the human body to cool itself.
Heat and humidity rarely produced “wet bulb” temperatures of 35°C. This is the point at which the air is too hot and humid for sweating to cool you down – different from the “dry bulb” temperature reported by a thermometer.
Rising Earth temperatures may soon change that according to climate scientists Tom Matthews (Loughborough University) and Colin Raymond (California Institute of Technology).
“Modelling studies have already shown that wet bulb temperatures could regularly cross 35°C if the world sails past the 2°C warming limit … with the Persian Gulf, South Asia and North China on the frontline of deadly humid heat,” a they say.
But different areas of the world are warming at different rates. In a world that is 1.5°C warmer on average, the temperature in your local area could rise by more than that.
To account for this, Matthews and Raymond studied records from individual weather stations around the world and found that many locations were closing in much faster on the lethal threshold of heat and humidity.
“The incidence of punishing wet-bulb temperatures (above 31°C, for example) has doubled worldwide since 1979, and in some of the hottest and most humid places in the world, such as the United Arab Emirates on coast, wet bulb temperatures have already disappeared. 35°C,” they say.
“The climate cover is pushing into territory that our physiology cannot follow.”
How long are we?
After 1.5°C species extinction and lethal heat are more likely. Do so catastrophic storms and falling ice sheets.
To have any chance of avoiding these horrors, we must eliminate the greenhouse gas emissions that warm the Earth and that means phasing out coal, oil and gas, which are 80% of energy use worldwide.
How fast? According to the latest estimate, published in October, very fast indeed.
“If humanity wants to have a 50-50 chance of limiting global warming to 1.5°C, we can only emit another 250 gigatonnes (billion metric tonnes) of CO₂,” says climate and atmospheric scientist Chris Smith at the University of Leeds and Robin. Lamboll at Imperial College London.
“This effectively gives the world just six years to go.”
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