A senior climate risk expert has warned of increasingly frequent and irreversible catastrophic changes on Earth as global temperatures continue to approach dangerous highs.

Chao Qingchen, director of China's National Climate Center, called for stronger global cooperation to accelerate energy transition as an urgent means to mitigate the looming crisis.

Data from the World Meteorological Organization showed a global average temperature increase of 1.55 C last year, while China's National Climate Center recorded a rise of 1.49 C, she said.

Despite variations from different data sources and processing methods, Chao said the monitoring results — both comparable and verifiable — "consistently indicate that the global warming trend has continued, making 2024 the warmest year on record for the Earth".

However, she said it cannot yet be concluded that the average global temperature increase will exceed the Paris Agreement's target of limiting warming to within 1.5 C.

The agreement, adopted in 2015, aims to keep the global temperature rise this century below 2 C from preindustrial levels, while pursuing efforts to limit the increase even further to 1.5 C.

Chao noted that the agreement's 1.5-C target represents an average temperature increase over 20 to 30 years, rather than a temporary spike in any single year. This is meant to eliminate the impact of short-term natural variations, such as El Nino — a periodic warming of Pacific Ocean currents — on the climate system.

While global temperatures hit record highs for two consecutive years in 2023 and 2024, Chao said the spikes were due to the combined effects of long-term warming and El Nino, which lasted from May 2023 to May 2024 and amplified global warming to some extent.

Now, however, the planet is under the influence of La Nina, which began in December. Unlike El Nino, La Nina tends to mitigate global warming.

"From this perspective, it is unlikely that global temperatures in 2025 will surpass those of 2024," she said.

But Chao noted that the current La Nina is weak and expected to be short-lived, meaning its cooling effect may be weaker than in previous events. Even with La Nina, some countries and regions could still experience significantly higher temperatures and severe heat waves, she warned.

Chao expressed cautious optimism that the temperature increase may not exceed the 1.5-C threshold, citing a study published in the journal Nature Climate Change.

The study suggested that while the planet may have entered a 20-year warming period after surpassing 1.5 C last year, there remains a certain probability that this threshold will not be exceeded in the long run. Strong and rapid mitigation efforts could further reduce that likelihood in the coming years and decades, she said.

Still, Chao warned that global warming is intensifying. The planet's average surface temperature from 2015 to 2024 was about 1.2 C higher than preindustrial levels, making it the warmest decade on record.

Although the 1.5-degree threshold has not yet been officially exceeded, the frequent spikes nearing that level "have undoubtedly sounded the alarm, warning that the Earth will face increasingly frequent, systemic and irreversible catastrophic changes".

"In this pressing situation, the world urgently needs to join hands to accelerate the energy transition and strive for net zero emissions through technological innovation and international cooperation," she said. "At the same time, we must strengthen climate adaptation measures to urgently address the adverse impacts of the current climate change."