Photosynthesis does not always result in wood growth, a key factor in carbon dioxide sequestration

Trees may not be able to store as much planet-heating carbon as hoped, a study suggests, with researchers finding photosynthesis does not always lead to wood growth.

Scientists studied 137 sites across the US and found trees stopped growing months before the point in the year at which photosynthesis stopped.

Hongkongers sweated through the hottest day of the year on Friday, with the Observatory (HKO) recording a maximum temperature of 34.6 degrees Celsius at its headquarters.

The mercury neared 37 degrees Celsius in the northern part of the territory.

Meanwhile, the Observatory noted 1,263 instances of cloud-to-ground lightning on Friday, and 4,859 cases of cloud-to-cloud lightning.

The city is now set to see nine days of rain, the weather service predicts.

See also: How Hong Kong’s elderly face deadly heat inside cramped cage homes

“A broad trough of low pressure will linger over the vicinity of the coast of southern China to the northern part of the South China Sea during the weekend to midweek next week,” the Observatory said.

The amber rainstorm warning was raised at 10am on Saturday as violent gusts swept into the territory, raising the risk of flooding.

See also: NGO warns hot weather can worsen air quality, urges gov’t action on pollutants and cooling measures in hot districts

Climate crisis

Friday marked the hottest “Grain in Ear” solar term ever documented. The ninth traditional solar term, known in Chinese as Mangzhong, signifies a period when awny crops like wheat are ready to harvest.

This week, environmental NGO Friends of the Earth urged the Hong Kong government to prioritise the climate crisis and strengthen its climate adaptation policies, with the city expected to endure an extremely hot summer.

The Intergovernmental Panel on Climate Change has warned that the intensity and frequency of heatwaves have continued to increase since the 1950s due to human-caused climate change. The prevalence of greenhouse gases like carbon dioxide – which trap heat in the atmosphere – raises the planet’s surface temperature, with hotter, longer heatwaves putting lives at risk.

See also: How extreme heat became the deadliest silent killer among world weather disasters

Hong Kong has already warmed by 1.7 degrees Celsius since the Industrial Revolution, research NGO Berkeley Earth says. Heat and humidity may reach lethal levels for protracted periods by the end of the century, according to a 2023 study, making it impossible to stay outdoors in some parts of the world.

Climate minister Chris Bowen says country must prepare for changing world and can play bigger role in reducing emissions

Australia will find exporting fossil fuels increasingly difficult but can switch to exporting clean energy products, the president of the next UN climate negotiations has declared.

Speaking at a climate conference in Bonn, Germany, Chris Bowen, Australia’s minister for climate change and energy, argued his country had led the global push to “transition away from fossil fuels” – based on the rapid growth of renewable energy and batteries in its domestic power grids – and that its economy could manage the switch.

Critically endangered Tapanuli orangutan population falls after heavy rain and landslides, fuelled by climate crisis, in North Sumatra

Extreme rainfall and landslides fuelled by the climate crisis killed 7% of the remaining population of the world’s rarest great ape, a study has found, prompting fears for the species’ survival.

The research suggests 58 out of the remaining 800 critically endangered Tapanuli orangutans (Pongo tapanuliensis) were killed after more than 1,000mm (39in) of rain fell over four days in Indonesia’s North Sumatra province in November 2025. This equates to 11% of the local population and 7% of the entire species.

NGO Green Power has urged the Hong Kong government to better regulate ozone precursors as hot weather exacerbates air pollution across the city.

Chemical compounds – such as nitrogen oxides, methane, Volatile Organic Compounds (VOC) and carbon monoxide – form ground-level ozone by reacting in the lower atmosphere in the presence of sunlight. Ground-level ozone attacks and inflames lung tissue, but reducing underlying pollutants prevents harmful smog.

According to a Sunday press release, Green Power’s director, Cheng Luk-ki, said VOCs – which are emitted through oil and gas operations, petrol evaporation and chemical solvents – should be better regulated.

See also: How extreme heat became the deadliest silent killer among world weather disasters

“In the future, the public’s health may be affected by both high temperatures and air quality at the same time,” the press release said.

Last week, Hong Kong sweltered amid a days-long heatwave. Whilst rain brought some respite over the weekend, the Observatory predicts highs of 35 degrees Celsius by the end of this week.

Cooling measures for hottest areas

Green Power’s review of Hong Kong’s air quality situation in 2025 found that 15 air quality monitoring stations recorded “a total of 2,080 hours at High, Very High and Serious levels – collectively referred to as ‘High Risk (HR) hours.'”

See also: How Hong Kong’s elderly face deadly heat inside cramped cage homes

Cheng said Hong Kong was affected by a northern Chinese dust storm last April, pushing up the statistics. However, the NGO also noted that overall air quality has been improving thanks to the city’s diversification away from coal towards natural gas, as well as efforts to tighten emission standards for fuel-powered vehicles.

The director said he had analysed last summer’s Air Quality Health Index data, and found that the nine days ranked as “high risk” all saw temperatures exceeding 29 degrees Celsius, “demonstrating a strong connection between heat and air quality.”

He warned that hot weather will become more frequent, as he urged the authorities to take action in the territory’s hottest districts.

The NGO recommended cooling measures in Tuen Mun, Tai Po, North District, Yuen Long and Tung Chung, “such as increasing greenery coverage, revitalising local rivers, and incorporating more ventilation corridor designs.”

See also: How extreme heat became the deadliest silent killer among world weather disasters

Hong Kong has already warmed by 1.7 degrees Celsius since the Industrial Revolution, research NGO Berkeley Earth says. Heat and humidity may reach lethal levels for protracted periods by the end of the century, according to a 2023 study, making it impossible to stay outdoors in some parts of the world.

Experts say climate pattern could supercharge extreme weather events and push temperatures to record highs

EL Niño has officially arrived, US officials at the National Oceanic and Atmospheric Administration (Noaa) said on Thursday, and scientists predict it could be the strongest of the century.

Forecasters had previously anticipated that a phenomenon known as a super “El Niño” would emerge this summer – supercharging extreme weather events and pushing global temperatures to record heights.

Exclusive A vast area of the Bellingshausen Sea should be covered by sea ice by now, with one expert calling the loss of ice ‘depressing’

Antarctica’s west coast is missing an area of winter sea ice the size of France, sparking concerns for threatened penguins other marine life and global sea levels.

One expert said the loss of ice in the Bellingshausen Sea was “depressing” and the failure of ice to form could have intensified a heatwave over the continent’s peninsula last week that saw daytime temperatures peak at 15.4C which is more than 20C above average.

An environmental NGO has urged the Hong Kong government to prioritise the climate crisis and strengthen its climate adaptation policies, as the city is expected to endure an extremely hot summer this year.

Friends of the Earth said on Monday that as May drew to a close, Hong Kong and many parts of the world had already experienced mid-summer temperatures ahead of schedule.

“Early onset of extreme heat in many parts of the world is a clear warning of the intensifying climate crisis,” the NGO said in the Chinese-language statement.

“We urge the government to put the climate crisis at the top of its agenda, by placing carbon reduction at the core and setting more aggressive emission reduction targets.”

Authorities should make a thorough climate risk assessment, utilising big data, artificial intelligence, and Geographic Information Systems (GIS) to analyse the vulnerability of various districts to extreme heat, torrential rain, storm surges, and sea-level rise, the statement said.

The NGO also called on the government to enhance the city’s infrastructure to withstand the climate crisis, including improving coastal flood defence facilities and drainage systems in older districts.

According to the statement, “global warming is making extreme weather more frequent and severe, and the climate crisis already poses a significant threat to public health, economic security, urban resilience, and social justice.”

Friends of the Earth also called for the protection of vulnerable groups, including the elderly, children, people with chronic illnesses, low-income families, homeless people, and those who work outdoors.

El Niño

Hong Kong has endured particularly high temperatures since early last week.

The Hong Kong Observatory (HKO) issued the “very hot weather warning” three times within a week: last Tuesday, Saturday, and Tuesday.

Choy Chun-wing, the HKO’s acting assistant director, said at a press conference on Thursday that Hong Kong would see “hotter than normal” temperatures this year and next year under the influence of climate change and El Niño.

Sea surface temperatures in the central and eastern equatorial Pacific will continue to rise, developing into an El Niño event during the summer and autumn, which will persist at least until the end of this year or the beginning of next year, Choy said.

Scientists have warned that the El Niño weather phenomenon will bring hotter temperatures, stronger storms, drought, and flooding.

Planet warming

The Intergovernmental Panel on Climate Change has warned that the intensity and frequency of heatwaves have continued to increase since the 1950s due to human-caused climate change. The prevalence of greenhouse gases like carbon dioxide – which trap heat in the atmosphere – raises the planet’s surface temperature, with hotter, longer heatwaves putting lives at risk.

See also: How extreme heat became the deadliest silent killer among world weather disasters

Hong Kong has already warmed by 1.7 degrees Celsius since the Industrial Revolution, research NGO Berkeley Earth says. Heat and humidity may reach lethal levels for protracted periods by the end of the century, according to a 2023 study, making it impossible to stay outdoors in some parts of the world.

Hong Kong has issued its first “very hot weather” warning of the year, with the city expected to endure a heatwave through Friday.

The Hong Kong Observatory (HKO) issued the warning at 7.45am on Tuesday, with the mercury expected to reach 35 degrees Celsius.

The warning is triggered when the mercury is set to reach, or exceed, 33 degrees Celsius. As of around 1:30pm on Tuesday, Cheung Chau was seeing temperatures of 32.1 degrees Celsius.

The city recorded its hottest day of the year on Monday, as temperatures hit 32 degrees Celsius.

The HKO has alerted the public of the risks of heat stroke and sunburn.

The heatwave is expected to continue through to Friday, as an anticyclone aloft brings very hot weather and low pressure to the coast of Guangdong, according to the HKO.

Highs of 33 degrees Celsius are predicted between Tuesday and Friday, while the lows will range between 27 and 29 degrees.

Hong Kong may see showers during this weekend, as temperatures dip slightly to 26-30 degrees Celsius.

The Intergovernmental Panel on Climate Change has warned that the intensity and frequency of heatwaves have continued to increase since the 1950s due to human-caused climate change. The prevalence of greenhouse gases like carbon dioxide – which trap heat in the atmosphere – raises the planet’s surface temperature, with hotter, longer heatwaves putting lives at risk.

See also: How extreme heat became the deadliest silent killer among world weather disasters

Hong Kong has already warmed by 1.7 degrees Celsius since the Industrial Revolution, research NGO Berkeley Earth says. Heat and humidity may reach lethal levels for protracted periods by the end of the century, according to a 2023 study, making it impossible to stay outdoors in some parts of the world.

In a Tuesday statement, the Centre for Health Protection of the Department of Health reminded members of the public to hydrate regularly, and to avoid strenuous exercise and prolonged activities such as hiking.

It also suggested that outdoor or manual workers should reschedule work to cooler hours as far as possible.

Nevertheless, as of Tuesday lunchtime, the Labour Department had not yet issued a heat stress warning – a three-tier warning system introduced in 2023 to help protect Hong Kong workers from heatstroke. 

Outbound travel during long weekend

Hongkongers enjoyed a three-day weekend, with Monday marking Buddha’s Birthday.

According to the Immigration Department, Hong Kong residents made over 615,000 outbound journeys on Saturday, with over 557,000 travellers heading northbound to Shenzhen and other destinations in mainland China.

The figure marks a week-on-week increase of 36.7 per cent.

From Friday to Monday, Hong Kong residents made nearly 1.87 million outbound trips – a rise of 30.8 per cent compared to the same period last week.

Hong Kong sweltered on Friday, with temperatures exceeding 36 degrees Celsius in the northern New Territories by mid-afternoon.

Acting Assistant Director of the Hong Kong Observatory (HKO) Choy Chun-wing told RTHK on Friday that minimum temperatures remained at, or above, 28 degrees Celsius over the past six days – matching a record seen in mid-May 2021. The longest continuous record could be broken by the weekend.

The HKO has suggested some relief from the weeklong heatwave is in store, with rain predicted for the weekend.

“The anticyclone aloft will weaken tomorrow, while upper-air disturbances will bring showers and thunderstorms to Guangdong. An easterly airstream will affect the coast of Guangdong in the next couple of days. High temperature weather will be alleviated,” the weather service said on Friday.

But it added that high temperatures may soon return. “With the easterly airstream being replaced by a southerly airstream early next week, the weather over the coastal areas will be very hot again midweek next week.”

See also: How extreme heat became the deadliest silent killer among world weather disasters

At a Thursday press briefing, the Senior Citizen Home Safety Association’s CEO Maura Wong said that it had handled over 7,700 heat-related emergency assistance cases requiring hospitalisation last summer.

“The Association urges the elderly to take precautions against the heat during the height of summer, and carers should also take a more proactive role in looking after the elderly by providing timely care and support,” she said.

At the same event, the HKO’s Choy warned that sea surface temperatures in the central and eastern equatorial Pacific are predicted to continue rising, with an El Niño event set to develop in the summer and autumn.

See also: How Hong Kong’s elderly face deadly heat inside cramped cage homes

Stronger El Niño events often increase the likelihood of abnormally high temperatures across different regions. Choy warned of a high chance that this summer would be among Hong Kong’s 10 hottest on record.

The Labour Department hoisted the amber Heat Stress at Work Warning on Friday, urging employers to conduct risk assessments for staff who work outdoors or in non-air-conditioned environments.

A Guardian analysis reveals how most of 39 countries facing US entry restrictions are most vulnerable environmentally

• ‘Every day it’s more barriers’: how the US is shutting out climate refugees

Donald Trump’s immigration crackdown is largely targeting people from the countries most vulnerable to displacement from climate-driven disasters, a Guardian analysis shows.

As the Trump administration pushes policies to boost planet-heating fossil fuels, millions of people are being forced to flee their homelands due to storms, floods and droughts worsened by the climate crisis.