Newsletter Issue 54 (April 2025)

The weather of March 2025 – A relatively dry and mild March

The weather of March 2025 was drier and milder than usual in Hong Kong. The monthly mean relative humidity of 74% was 8% below the normal of 82% and one of the fourth lowest on record for March. The monthly total sunshine duration amounted to 143.8 hours, about 44 percent above the normal of 100.0 hours. With more sunshine, the monthly mean maximum temperature of 23.5 degrees was 1.6 degrees above the normal and one of the tenth highest on record for March.

March 2025 was Earth’s third warmest on record

Temperatures were above average over much of the globe, particularly in the Arctic, but much below average over central Canada and eastern Asia. The March global surface temperature was 1.31°C above the 20th-century average of 12.7°C, making it the third-warmest March on record. According to NCEI’s Global Annual Temperature Outlook, there is a 6% chance that 2025 will rank as the warmest year on record.

Europe’s warmest year on record – striking climate contrasts in 2024

The European State of the Climate 2024 report, jointly published by the Copernicus Climate Change Service and the World Meteorological Organization, reveals that 2024 was the warmest year, both for Europe and globally, since records began. Across the continent, people experienced dramatic and contrasting climate conditions. While the east faced dry, scorching heat, the west endured heavy rainfall and flooding, marking a year of profound and disruptive climate extremes.

It’s the world’s northernmost airport. And its runway is melting

The Arctic is one of the world’s most environmentally fragile regions and the team at Svalbard Airport has already had a first taste of the effects of climate change. When Longyearbyen’s 2,300-meter-long runway was built in the early 1970s, no one expected the permafrost layer it was constructed on to start melting. But that is exactly what’s happening now.

HK forests can store over 7 million tonnes of carbon, study finds

Hong Kong’s forests can store more than 7 million tonnes of carbon, equivalent to one-fifth of the city’s annual emissions, according to estimates in a first-of-its-kind local study. The research, which looked at more than 100 native tree species, also found those with the best potential to capture the greenhouse gas, providing data for authorities and private developers when assessing the carbon footprint of their projects.

Celebrating 50 Years of Geostationary Operational Environmental Satellite program (GOES)

For 50 years, GOES data has been the backbone of short-term forecasts and warnings of severe weather and environmental hazards in the Western Hemisphere and forecasts and warnings of space weather hazards. GOES are our sentinels in the sky: keeping constant watch for severe weather and environmental hazards on Earth and dangerous space weather.

Trends in greenhouse gases at Mauna Loa

The graphs show monthly mean carbon dioxide measured at Mauna Loa Observatory, Hawaii. The carbon dioxide data on Mauna Loa constitute the longest record of direct measurements of CO2 in the atmosphere. They were started by C. David Keeling of the Scripps Institution of Oceanography in March of 1958 at a facility of the National Oceanic and Atmospheric Administration. NOAA started its own CO2 measurements in May of 1974, and they have run in parallel with those made by Scripps since then.

End-to-end data-driven weather prediction

[Summary by Deepseek] Aardvark Weather, a machine learning model, replaces traditional numerical weather prediction (NWP) by ingesting observations to produce global and local forecasts. It outperforms operational NWP systems, achieving skillful forecasts up to ten days without NWP reliance. This end-to-end approach reduces computational costs, speeds predictions, and enables customisable models, marking a shift in weather forecasting.

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