CLIMATE · EXTREME HEAT
Climate change has already raised the temperature baseline. A rapidly developing El Niño may push more stored ocean heat into the atmosphere, making 2027 especially concerning.
Much of the Northern Hemisphere has endured an exceptional summer. Europe recorded its hottest combined June and July since measurements began, July became the warmest month ever measured across the contiguous United States, and South Korea registered a national temperature high.
The season is not finished, but attention is already turning to 2027. The developing El Niño is beginning to influence weather, and its strongest effect on average global temperature may arrive months after the ocean pattern itself takes shape.
Understanding what comes next requires separating two forces that work on different timelines. Human-caused climate change steadily raises the background temperature. El Niño rearranges heat already stored in the ocean and can temporarily amplify that warmer starting point.
Climate Change Raised the Baseline
Climate change is the foundation beneath today’s extremes. Burning coal, oil and gas adds greenhouse gases to the atmosphere, trapping more heat and increasing both the likelihood and severity of heat waves. The warming is global, but it is not distributed evenly.
Europe is warming faster than any other continent and, among major regions, trails only the Arctic. That makes its repeated heat waves less surprising, even though their human and economic consequences remain severe. Researchers studying Europe’s May heat estimated that current warming added roughly 3.5 °C, or 6.3 °F, compared with an equivalent event under the climate conditions that prevailed locally during 1976.
The United States has also crossed a symbolic threshold. July’s average temperature across the contiguous states surpassed a record held since July 1936. Breaking a mark set during the Dust Bowl—a period remembered for extreme heat, drought and ecological damage—shows how far the modern climate has shifted.
Records in different countries do not mean every place is hottest at the same time. Weather still moves heat, rain and storms unevenly. But the warmer baseline loads the odds toward more frequent extremes and gives short-term patterns more energy to work with.
How El Niño Moves Ocean Heat
El Niño adds a separate, natural rhythm. Scientists call the larger cycle ENSO, short for El Niño–Southern Oscillation: a recurring change in the relationship between tropical Pacific waters, winds and the atmosphere. The system moves between El Niño and La Niña over periods of several years.
Under more typical conditions, trade winds push sun-warmed surface water toward the western Pacific. Colder water then rises from depth in the east, while a broad circulation of rising and sinking air helps maintain the pattern. The ocean and atmosphere reinforce each other.
During El Niño, those trade winds weaken. Warm water builds farther east and in the central Pacific, heating the air above it. The resulting atmospheric disturbance changes circulation, rainfall and weather far beyond the tropical ocean.
The National Oceanic and Atmospheric Administration identifies an El Niño when a designated Pacific region stays at least 0.5 °C warmer than normal and related atmospheric changes are present. The threshold sounds small, but it describes a vast area of ocean capable of influencing conditions around the planet.
El Niño does not create extra energy or permanently warm the entire climate system. Instead, it transfers some heat held by the ocean into the atmosphere. That distinction matters because decades of greenhouse warming have increased the amount of heat stored in both places. A natural release is now occurring on top of an elevated background.
Why 2027 Could Be Worse
Forecasts suggest this event could become unusually strong. Some projections have put its possible peak at more than 3.5 °C above average, which could challenge the strongest El Niño measurements on record. Climate scientist Zeke Hausfather has also described its development as exceptionally rapid compared with the observational record.
The timing is as important as the strength. Global temperatures usually respond several months after the Pacific pattern develops, so the atmosphere may not register the full effect until the following calendar year. In earlier events, major temperature records arrived during year two.
That lag does not mean every region will experience the same conditions. El Niño can shift storm tracks and rainfall as well as temperature, producing drought in some places and floods in others. Its global signal is clear, but local consequences depend on geography, season and weather patterns.
The recent 2023–2024 El Niño offers a clear example: it formed in 2023, continued into 2024, and 2024 remains the hottest year measured globally. No two events unfold identically, and uncertainty remains around the current forecast. Still, the combination of a fast start, a potentially high peak and a warmer planet makes 2027 a serious concern.
Preparing for the Next Peak
Preparation cannot wait for another record. Households can improve cooling, insulation and backup power before extreme heat arrives. Air conditioning can be lifesaving, while rooftop solar paired with a battery may keep essential equipment operating during outages and reduce pressure on a strained grid.
Communities need broader measures: reliable early-warning systems, cooling centers, heat-safe work rules, resilient electricity networks and direct support for people who are older, ill, unhoused or unable to afford cooling. António Guterres, the United Nations secretary-general, has warned that El Niño intensifies the danger created by an already warming world.
Adaptation can reduce immediate harm, but it cannot stop the underlying trend. As long as fossil-fuel use keeps adding greenhouse gases, future El Niño events will arrive in a hotter climate. Moving faster toward renewable energy, protecting vulnerable populations and cutting emissions remain the only durable way to prevent each natural cycle from producing still more dangerous heat.
