The 2015-2025 period, the hottest since records were recorded, according to the latest report of the World Meteorological Organization (WTO)

The last 11 years, the period from 2015 to 2025 , have been the hottest since records existed, as reflected in the report released today by the World Meteorological Organization (WTO). 

The La Niña phenomenon has produced a cooling effect in 2025, which has allowed the past few years not to break records, making it the second hottest year in terms of records collected for 176 years. The average annual temperature has been between one and a half degrees (1.43 ° C) higher than the pre-industrial average (between 1850 and 1900). 

So 2024 is the hottest yearof the last little more than a century, when 1.55 degrees above the pre-industrial average were measured. 

"When history repeats itself 11 times, it's no longer a coincidence, it's a direct call to action," UN Secretary-General Antonio Guterres stressed. 

Energy imbalance

the WTO has explained that warming is due to the energy imbalance due to the absorption of more energy from the Sun than it releases . a value that began to be measured in 1960 and since then the imbalance has only grown, especially in the last 20 years. The concentration of greenhouse gases (carbon dioxide, methane and nitrous oxide) has increased, capturing the highest value of the last 800,000 years, the organization has warned.

Indeed, in 2024, there wasthe largest increase in carbon dioxide  (CO2) in the atmosphere, which began to be measured in 1957, due to fossil fuel emissions, but also to a decrease in the energy absorption capacity of the Earth and the oceans.

Influence on the oceans

This excess energy accumulated is barely noticeable (1%) in the rise in temperature, and most (91%) is absorbed by the oceans and the rest (5% and 3% respectively) by the continental crust and ice masses. The heat accumulated in the oceans in 2025 has broken records, and in the last 20 years is twice as high as in 1960-2005. 

Among its conclusions, the report mentions the further degradation of marine ecosystems, the regression of biodiversity, the reduction of ocean absorption capacity to CO2, the increase in tropical storms and the aggravation of ice melting in polar regions. 

In connection with this, in Antarctica and Greenland  have suffered "significant losses" in their ice masses, and the loss of glaciers in Iceland and the North American Pacific coast has been "extraordinary", the WTO regrets. In addition, the average annual ice range of the Arctic Oceano has been the lowest and lowest recorded by satellites in 2025.

All these effects will, in the long term, lead to ocean warming and sea level rise. Since the first satellite measurements in 1993, the sea has increased by 11 centimetres. "Changes in ocean warming and the PH of ocean depths are irreversible on a hundreds and millennia scale," the report stresses.