Crossing the line: Global climate change enters the red zone

The World Meteorological Organisation has released its latest State of the Global Climate report, depicting an alarming picture of the global climate situation with the planet Earth entering the red zone with several climate parameters at historical highs. 

The report notes that the atmospheric concentrations of greenhouse gases (GHGs) such as carbon dioxide, methane and nitrous oxide reached their highest level in 800,000 years in 2024. The past three years have been the warmest in the 176-year combined land and ocean observational record. These annual increases in GHGs have continued unabated into 2025. The Paris Climate Agreement envisaged limiting temperature rise to 1.5 degrees Celsius above pre-industrial levels by 2100. Disturbingly, this threshold has already been breached in 2024, with temperatures rising to around 1.55 degrees Celsius above pre-industrial levels. The period from 2011 to 2025 now ranks as the warmest years on record.

Oceans, which generate about half the oxygen we breathe, absorb nearly 30% of carbon emissions and capture 90% of the excess heat generated by these emissions, are under severe stress. Global warming and pollution are disrupting these vital services provided by oceans, affecting marine biodiversity and leading to sea level rise. The report shows that in 2025, ocean heat content reached the highest level in the 66-year observational record, exceeding the previous high record in 2024. The rate of ocean warming over the past two decades, 2005–2025, is more than twice that observed over the period 1960–2005. The global mean sea levels peaked to record levels in 2025. The rate of global mean sea-level rise since 2012 is higher than the rate of global mean sea-level rise recorded during 1993–2011. Ocean pH (an indicator of ocean acidification) is critical for human beings because it maintains marine biodiversity, which provides food, livelihood, and oxygen for billions of people. The report shows that global average ocean surface pH has declined over the past four decades, which threatens marine food webs and fisheries and diminishes the ocean’s carbon sink services.

Glaciers are critical for regulating global climate, providing freshwater, protecting habitats and biodiversity, influencing ocean and river flows and nutrient cycling. They hold about 70% of the global freshwater resources. The melting of glaciers due to global warming affects their global climate regulation functions and other services, leading to extreme weather patterns, water shortages and sea level rise. The report notes that glacier mass loss was the highest in recent years. The ice sheets on Antarctica and Greenland have both lost significant mass since satellite records began. The extent of sea ice in the Arctic has decreased in all seasons since satellite measurements began in 1979, and the annual maximum extent in 2025 was the lowest or second lowest in the observed records. The sea-ice extent around Antarctica has dropped considerably since 2015, with the past four years recording the four lowest Antarctic sea-ice minima. 

The rise in global mean sea levels driven by ocean warming and the melting of glaciers and ice sheets threaten coastal cities and communities. As per the report, the rate of global sea level rise has increased since satellite measurements began in 1993. According to the National Oceanic and Atmospheric Administration, these levels have risen by approximately 11 cm between 1993 and 2025, based on satellite altimetry data. The rate of rise in these levels has accelerated from 2.1 mm/year in 1993 to over 4.5 mm/year by 2023. 

The report added a new indicator, i.e., Earth’s energy balance, to assess the status of global climate change. It measures how fast the heat trapped by anthropogenic-induced GHG emissions is accumulating in the climate system. This indicator shows that the Earth’s energy imbalance has increased rapidly since 1960, and the increase has been especially sharp during the past two decades. About 91% of the excess energy retained by Earth was absorbed by the oceans, leading to record-breaking ocean heat levels in 2025.

The frequency and intensity of extreme weather events have aggravated with adverse impacts on people and nature in all regions of the world. Governments and households are forced to allocate higher budgets to cope with and recover from these weather-related disaster events. Climate-sensitive health risks are rising–dengue and heat stress being of particular concern.

The prospects for a turnaround in the global climate situation are bleak, with the United States, which is the second largest emitter of GHGs, accounting for 11-15% of annual global GHG emissions after China, withdrawing from the Paris Climate Agreement in January 2026.

The ongoing war between Russia and Ukraine and between the US-Israel and Iran is a serious setback for achieving the Paris Climate goals of restricting global temperature rise to 1.5 degrees Celsius or 2 degrees Celsius above pre-industrial limits. The Initiative on GHG Accounting of War estimates that due to the military operations, landscape fires, fuel consumption and destruction of energy and other infrastructure, the first four years of the Russia-Ukraine war have emitted about 311 million tonnes of carbon dioxide equivalent (CO2e) with damages estimated at over $57 billion calculated at $185 per tonne of CO2e. The attacks and counterattacks in the ongoing war in the Gulf region involving damage to energy infrastructure, including nuclear assets and oil refineries, and damage to the built and natural environment will further aggravate the global climate situation.

The writer is lead author, GEO-7, UNEP, Nairobi, and chairperson, Centre for Economics, Environment and Society, Bengaluru

(Disclaimer: The views expressed above are the author's own. They do not necessarily reflect the views of DH.)