A new report from WMO reveals how rising temperatures, record ocean heat and intensifying climate impacts are reshaping the case for urgent, systemic climate action.
The latest State of the Global Climate 2025 report from the World Meteorological Organization (WMO) delivers a message that is becoming increasingly difficult to separate from the realities facing businesses, communities, and ecosystems: the climate system is not simply getting warmer; it is becoming increasingly disrupted across multiple dimensions at once.
2025 was not the warmest year on record. At 1.43°C above the 1850–1900 average, it ranked as the second- or third-warmest year ever recorded, depending on the dataset. But that distinction should not obscure the larger trend. The 11 years from 2015 to 2025 were the 11 warmest years on record, with 2023–2025 comprising the three warmest years across all nine datasets assessed by the WMO. Emphasizing that temperature is only one part of the story.
The WMO’s 2025 report brings together a suite of indicators that show a climate system continuing to accumulate heat and undergo fundamental change. Greenhouse gas concentrations remain at record levels. Ocean heat content reached a new high. Sea levels remain near record levels. Glaciers continue to lose mass. Arctic and Antarctic sea ice remain exceptionally low. Ocean acidification is progressing. And extreme weather events are creating increasingly significant consequences for people, economies and ecosystems. Taken together, these indicators tell a much bigger story than any single annual temperature record.
One of the most important elements of the 2025 report is its focus on Earth’s energy imbalance: the difference between the energy entering the Earth system and the energy leaving it. That imbalance reached a record high in 2025, the highest level in the observational record dating back to 1960. And the vast majority of that excess energy – approximately 91% – is being absorbed by the ocean.
A year can be slightly cooler than the year before without the underlying climate problem improving. The planet is still accumulating energy. In fact, global ocean heat content reached a new record in 2025, marking the ninth consecutive year in which a new annual record was set. The rate of ocean warming between 2005 and 2025 was more than twice the rate observed between 1960 and 2005.
The implications extend well beyond the ocean itself. Warmer oceans contribute to sea-level rise, influence tropical cyclones, accelerate ice loss, and place increasing pressure on marine ecosystems. This is why the climate challenge cannot be reduced to a single number on a temperature chart. The climate system is an interconnected set of physical systems, and those systems are changing together.
The atmospheric data reinforces the same conclusion. Global average atmospheric CO₂ concentration reached 423.9 parts per million in 2024, an increase of 3.5 ppm from the previous year and approximately 152% of pre-industrial levels. Methane and nitrous oxide also reached record observed concentrations, while preliminary observations indicate that greenhouse gas concentrations continued to increase through 2025.
The planet’s natural carbon sinks are absorbing a significant share of our emissions. Between 2015 and 2024, approximately half of human-caused CO₂ emissions remained in the atmosphere, while the ocean absorbed roughly 29% and land ecosystems approximately 21%. But this natural buffering capacity comes with limits and consequences.
The ocean’s absorption of CO₂ is contributing to ongoing acidification, while changes in temperature and precipitation can affect the ability of terrestrial ecosystems to continue absorbing carbon. The systems that have historically helped regulate the climate are themselves being affected by climate change. That makes protecting and strengthening natural carbon sinks increasingly important, not as an alternative to emissions reductions, but as part of a broader climate strategy.
In 2025, significantly drier-than-average conditions affected parts of Asia, Africa, Europe, South America and Australia, while unusually wet conditions affected large parts of Asia, Africa, the Americas and the Arctic. Drought persisted in parts of the Amazon and subtropical South America, while other regions experienced exceptionally high precipitation. This matters because climate change does not manifest itself uniformly. The same warming climate can produce drought in one region and extreme precipitation in another, and these physical changes increasingly translate into economic and social disruption.
The WMO highlights wildfires, floods, droughts, extreme heat, and tropical cyclones that affected millions of people in 2025. California’s January 2025 wildfires, for example, resulted in more than 30 deaths, destroyed more than 16,000 structures, and displaced more than 260,000 people, with estimated economic losses exceeding US$60 billion. Pakistan’s monsoon flooding affected approximately 1.57 million people and resulted in more than 1,000 reported deaths.
These events also demonstrate why climate risk cannot be viewed as a standalone environmental issue. A climate hazard can become a supply-chain disruption, an insurance challenge, a food-security issue, a public-health crisis, or a loss of productive capacity. The WMO notes that climate-driven impacts on food systems can compound through agricultural losses, food-price volatility, livelihood disruption, migration and broader social instability.
Climate risk is increasingly interconnected and perhaps nowhere is that interconnectedness more evident than in human health. The WMO reports that changing temperatures and precipitation patterns are influencing the timing, location and severity of health risks. Extreme heat can increase mortality and illness while also affecting productivity and livelihoods. Changes in temperature and rainfall can influence the transmission of vector-borne diseases such as dengue, while extreme weather can place additional pressure on already vulnerable health systems.
The implications for workers are particularly significant. More than one-third of the global workforce – approximately 1.2 billion people – is exposed to workplace heat risk at some point each year, with agricultural and construction workers among those particularly exposed. Heat can affect worker health, safety, and productivity, creating consequences that extend well beyond individual workplaces.
But the report also offers an important reminder that climate impacts are not simply something societies must passively absorb. Early warning systems, climate-informed disease surveillance and predictive modelling can allow communities to act before hazards become disasters. The WMO points to anticipatory action ahead of extreme events as an increasingly important component of climate resilience. That same principle applies to climate action more broadly: better information should enable earlier, more targeted and more effective decisions.
The most important takeaway from the WMO report is not that 2025 was another exceptionally warm year. It is that multiple parts of the climate system are sending the same signal at the same time. Greenhouse gas concentrations are rising. The Earth is accumulating energy. Oceans are warming. Glaciers are retreating. Sea ice is declining. Sea levels are rising. Ocean chemistry is changing. Extreme weather is creating cascading impacts. And the communities most exposed to these impacts are often those with the fewest resources to adapt.
For businesses and climate professionals, this reinforces the need to move beyond thinking about climate as a single emissions metric. Decarbonization remains fundamental. But so does protecting and restoring natural systems that store carbon and support biodiversity and resilience. So does investing in adaptation. So does improving the quality of climate data and the ability to translate it into action.
The climate challenge is no longer simply about understanding whether change is happening. The evidence is increasingly clear. The challenge is determining how quickly and effectively we can respond.
💡Looking beyond the annual temperature record, the bigger signal is the continued accumulation of heat across the climate system, with ocean heat content and Earth’s energy imbalance reaching record levels in 2025. Climate strategies should be guided by long-term physical trends, not short-term fluctuations, which means organizations and governments should be accelerating action now rather than waiting for another record-breaking year.
💡We should be treating nature as critical climate infrastructure. Natural ecosystems are already absorbing a significant share of human-caused CO₂, while also supporting resilience against climate impacts, but their ability to do so is increasingly under pressure from a changing climate. Protecting and restoring high-integrity natural systems should therefore be an integral part of climate strategies, alongside direct emissions reductions.
💡The world needs to shift from reaction to action. The report shows how climate information, early warnings and predictive tools can help communities anticipate impacts and reduce avoidable harm. For businesses and investors, the same principle applies: use better climate data to identify risks earlier, prioritize where action can have the greatest impact, and direct capital toward mitigation, resilience and high-integrity climate solutions.
