> **来源：[研报客](https://pc.yanbaoke.cn)** # Summary of the State of the Global Climate 2025 ## Core Content The **State of the Global Climate 2025** is an annual report by the World Meteorological Organization (WMO) that provides a consolidated assessment of global climate conditions, key indicators, and high-impact weather events. It serves as a complementary resource to the Intergovernmental Panel on Climate Change (IPCC) and is intended for a broad audience, including policymakers, scientists, educators, and the general public. The report highlights the continued warming of the Earth system, driven by increasing greenhouse gas concentrations, particularly carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O). These gases have reached record levels, with CO₂ concentrations in 2024 being the highest in the last 2 million years and CH₄ and N₂O reaching their highest levels in the last 800,000 years. The 2025 report confirms that these concentrations continued to rise, reinforcing the ongoing climate crisis. ## Key Climate Indicators ### 1. **Atmospheric Carbon Dioxide** - **Key Messages**: - CO₂ levels reached a new high in 2024, with the largest annual increase since 1957. - CO₂, CH₄, and N₂O all increased in 2025. - **State of the Indicator**: - Global average CO₂ concentration in 2024 was **423.9 ppm**, representing about **3306 Gt** of CO₂ in the atmosphere. - The airborne fraction of CO₂ emissions remained around **50%** in the 2015-2024 period, with the ocean absorbing **29%** and land **21%**. - **Indicator Background**: - CO₂ is the largest contributor to climate change, responsible for **66%** of radiative forcing from long-lived greenhouse gases since 1750. - The report notes that while CO₂ helps buffer climate change, it also leads to **ocean acidification**, which has significant ecological and economic impacts. ### 2. **Global Mean Near-Surface Temperature** - **Key Messages**: - 2025 was the **second or third warmest year** on record, slightly cooler than 2024. - The **past eleven years (2015–2025)** were the **eleven warmest** on record. - **State of the Indicator**: - The annual average global mean near-surface temperature in 2025 was **1.43°C ± 0.13°C** above the 1850–1900 baseline. - The warming trend is consistent with the **Paris Agreement's long-term temperature goal**, but single years do not indicate exceeding the **1.5°C warming level**. - **Indicator Background**: - The report uses **nine global temperature datasets** to assess temperature changes, with minor discrepancies due to differences in measurement methods and data coverage. ### 3. **Ocean Heat Content** - **Key Messages**: - Ocean heat content reached a **record high** in 2025, surpassing the previous record set in 2024. - The rate of ocean warming over the past **20 years (2005–2025)** was more than **twice** that of the previous **40 years (1960–2005)**. - **State of the Indicator**: - The global ocean heat content (to 2000 m depth) increased by **5.8 ± 0.5 ZJ per year** from 1971 to 2025. - The **deep ocean (2000–6000 m)** also warmed at a rate of **1 ± 0.2 ZJ per year**. - **Indicator Background**: - Ocean heat content is a key indicator of **climate change**, as the ocean absorbs **91%** of the excess energy trapped by greenhouse gases. - Ocean warming has **irreversible** effects on marine ecosystems, biodiversity, and contributes to **sea-level rise**. ### 4. **Global Mean Sea Level** - **Key Messages**: - Global mean sea level in 2025 was **comparable to 2024** levels, with a smaller year-to-year increase due to **La Niña conditions**. - The rate of sea-level rise since **2012** is higher than in the earlier satellite period (1993–2011). - **State of the Indicator**: - By the end of 2025, global mean sea level was **11 cm higher** than in January 1993. - The average rate of sea-level rise from 1993 to 2011 was **2.65 ± 0.3 mm/year**, and from 2012 to 2025, it increased to **4.75 ± 0.3 mm/year**. - **Indicator Background**: - Sea-level rise is driven by **ocean thermal expansion** and **melting of land ice**. - The report warns of **cascading impacts** on coastal communities, ecosystems, and infrastructure, including **flooding, salinization, and habitat loss**. ### 5. **Ocean pH** - **Key Messages**: - The global average ocean surface pH has **declined by 0.017 ± 0.001 units per decade** over the past 41 years. - Regional variations in pH decline are notable, with the **Indian Ocean, Southern Ocean, and Pacific regions** experiencing the most rapid acidification. - **State of the Indicator**: - The decline in ocean pH is **unprecedented** for at least **26,000 years**, according to the IPCC. - The ocean continues to absorb **29%** of anthropogenic CO₂ emissions, leading to **acidification** and affecting **marine life**. - **Indicator Background**: - Ocean acidification is linked to **increased CO₂ absorption**, which lowers pH and disrupts **carbonate chemistry**. - The report emphasizes the **impact on marine biodiversity**, **shellfish aquaculture**, and **fisheries**, as well as the **contribution to Sustainable Development Goals (SDGs)**. ### 6. **Glacier Mass Balance** - **Key Messages**: - The 2024/2025 hydrological year saw **exceptional glacier mass loss**, ranking among the **five most negative balances** on record. - **Eight of the ten most negative annual glacier mass balances** since 1950 have occurred since 2016. - **State of the Indicator**: - Observations from **155 glaciers** indicate **extremely negative mass balance** in 2024/2025. - **Iceland** and the **Pacific coast of North America** experienced the most severe mass loss. - **Indicator Background**: - Glacier mass balance is a critical indicator of **climate change**, reflecting the **net gain or loss** of ice mass. - The report highlights the **long-term trend of glacier retreat**, with **significant ice loss** from **Antarctica and Greenland** since satellite records began. ## High-Impact Weather and Climate Events - The report documents **extreme weather events** in 2025, including **heatwaves, cold extremes, floods, droughts, and tropical cyclones**. - These events are linked to **climate drivers** such as **El Niño-Southern Oscillation (ENSO)** and the **Indian Ocean Dipole (IOD)**. - **Case Study**: The report includes a detailed analysis of **climate and heat impacts on health**, highlighting the **increased risks** to vulnerable populations. ## Conclusion The **State of the Global Climate 2025** underscores the **accelerating pace** of climate change, with **record-breaking greenhouse gas levels**, **rising global temperatures**, **increased ocean heat content**, **accelerated sea-level rise**, and **ocean acidification**. These changes are having **cascading impacts** on both natural and human systems, emphasizing the need for **continued monitoring**, **adaptation**, and **mitigation efforts** to address the challenges posed by a warming planet.