2025 among hottest years on record, says WMO

• The World Meteorological Organisation (WMO) has confirmed that 2025 was one of the three warmest years on record, continuing the streak of extraordinary global temperatures. 

• The past 11 years have been the 11 warmest on record, and ocean heating continues unabated.

• The global average surface temperature was 1.44°C (with a margin of uncertainty of ± 0.13°C) above the 1850-1900 average, according to WMO’s consolidated analysis of eight datasets. 

• Two of these datasets ranked 2025 as the second warmest year in the 176-year record, and the other six ranked it as the third warmest year.

• The past three years, 2023-2025, are the three warmest years in all eight datasets. 

• The consolidated three-year average 2023-2025 temperature is 1.48°C (with a margin of uncertainty of ± 0.13°C) above the pre-industrial era.

• The year 2025 started and ended with a cooling La Nina and yet it was still one of the warmest years on record globally because of the accumulation of heat-trapping greenhouse gases in our atmosphere. 

• High land and ocean temperatures helped fuel extreme weather — heatwaves, heavy rainfall and intense tropical cyclones, underlining the vital need for early warning systems.

• The WMO is a specialised agency of the United Nations responsible for promoting international cooperation in atmospheric science and meteorology.

• WMO monitors weather, climate, and water resources and provides support to its Members in forecasting and disaster mitigation.

Ocean Heat

• A separate study said that ocean temperatures were also among the highest on record in 2025, reflecting the long-term accumulation of heat within the climate system.

• About 90 per cent of excess heat from global warming is stored in the ocean, making ocean heat a critical indicator of climate change. 

• From 2024-2025, the global upper 2000 m ocean heat content (OHC) increased by ∼23 ± 8 Zettajoules relative to 2024, according to a study. 

• That is around 200 times the world’s total electricity generation in 2024.

• Regionally, about 33 per cent of the global ocean area ranked among its historical (1958–2025) top three warmest conditions, while about 57 per cent fell within the top five, including the tropical and South Atlantic Ocean, Mediterranean Sea, North Indian Ocean, and Southern Oceans, underscoring the broad ocean warming across basins.

What is climate change?

• Climate change is a long-term shift in weather conditions identified by changes in temperature, precipitation, winds, and other indicators. Climate change can involve both changes in average conditions and changes in variability, including, for example, extreme events.

• The Earth’s climate is naturally variable on all time scales. However, its long-term state and average temperature are regulated by the balance between incoming and outgoing energy, which determines the Earth’s energy balance. 

• Any factor that causes a sustained change to the amount of incoming energy or the amount of outgoing energy can lead to climate change. 

• Different factors operate on different time scales, and not all of those factors that have been responsible for changes in Earth’s climate in the distant past are relevant to contemporary climate change.

• Factors that cause climate change can be divided into two categories — those related to natural processes and those related to human activity. 

• Around the world, storms, floods and wildfires are intensifying. Air pollution sadly affects the health of tens of millions of people and unpredictable weather causes untold damage to homes and livelihoods too.

• Human-caused climate change is already affecting many weather and climate extremes in every region across the globe. For example, the changing state of our glaciers has caused significant sea level rise.  

• Risks and projected adverse impacts and related losses and damages from climate change escalate with every increment of global warming. 

• Climatic and non-climatic risks will increasingly interact, creating compound and cascading risks that are more complex and difficult to manage. For example, increased air pollution from burning fossil fuels can worsen the impact of natural disasters like heat waves and droughts on human health.

• Constraining global warming to 1.5°C, rather than to 2°C and higher, is projected to have many benefits for terrestrial and wetland ecosystems and for the preservation of their services to humans.

What is the Paris Agreement?

• The Paris Agreement is a legally binding international treaty on climate change. It was adopted by 196 Parties at the UN Climate Change Conference (COP21) in Paris on December 12, 2015. It entered into force on November 4, 2016.

• It mobilised global collective action to pursue efforts to limit the global temperature increase to 1.5°C above pre-industrial levels by 2100, and to act to adapt to the already existing effects of climate change.

• The agreement asks countries to review commitments every five years, provide financing to developing countries to mitigate climate change, strengthen resilience and enhance abilities to adapt to climate impacts.