Is Climate Change Making Heat Domes Worse?
A stationary ridge has confined 200 million Americans and a substantial portion of Europe beneath a heat dome this week
The term ‘heat dome’ accurately describes the current atmospheric emergency, though it may understate its severity. And the heat domes are global. Over 160 million Americans were under heat alerts as they anticipated the Fourth of July celebrations. Forecasts indicated that Philadelphia and Washington, D.C., could approach their all-time high temperatures of 106 degrees. New York’s Central Park recorded temperatures above 100 degrees for the first time in nearly 14 years. Europe is preparing for a second heat dome within two weeks, with inland Spain potentially reaching 46°C. These events are not random; they result from a jet stream that is no longer effectively dispersing heat.
The central issue is rooted in atmospheric physics rather than isolated weather events. A heat dome is not simply a single hot day; it is a persistent high-pressure ridge that remains stationary over a region. The underlying cause of this persistence is closely linked to changes occurring in the Arctic.
The Ridge That Won’t Move
A heat dome forms when a strong high-pressure ridge develops in the upper atmosphere and remains stationary. Air beneath this ridge descends, compresses, and warms, much like the heating effect in a pressurized bike pump. This descending air inhibits cloud formation, increasing direct solar radiation at the surface and further amplifying the trapped heat. The process functions analogously to a lid on a pot, but without any mechanism for heat to escape.
In 2026, a persistent heat dome over the Midwest, Ohio Valley, and Northeast raised heat indices to 105-115 degrees, with some cities experiencing overnight lows that did not drop below the mid-80s. Prolonged exposure to high nighttime temperatures increases the risk of heat-related illnesses. Concurrently, Europe, already affected by a late-June heat wave that desiccated soils, faces model projections indicating a second heat dome forming between July 7 and 10, threatening record temperatures in the Iberia-to-Benelux region.
The same underlying atmospheric mechanism drives heat domes on two continents. This repetition indicates a broader climatic pattern.
Why This Keeps Happening: The Jet Stream Stopped Doing Its Job
The polar jet stream exists because of a temperature difference: cold Arctic air to the north, warmer mid-latitude air to the south. That gradient is what powers the jet stream and keeps it moving in relatively tight, fast waves across the globe.
The Arctic is warming at approximately three times the global average, a process known as Arctic amplification. The reduction in sea ice exposes more dark ocean, which absorbs additional solar radiation and accelerates warming. As the temperature difference between the Arctic and mid-latitudes decreases, the jet stream loses the pressure gradient that previously maintained its speed and linearity. Consequently, the jet stream slows, becomes more sinuous, and forms larger waves. These larger waves create favourable conditions for heat domes to persist for extended periods.
Researchers, including climate scientist Michael Mann, have documented a phenomenon known as quasi-resonant amplification, which has led to a near-tripling of the frequency of persistent, wavy jet stream events since the 1950s. These events now occur approximately three times per year during Northern Hemisphere summers, compared to once annually in the past. This significant trend reflects a shift in atmospheric patterns, explaining why the term ‘heat dome’ has moved from specialized scientific jargon to one featured in National Weather Service alerts.
A notable feedback loop is present: a higher global temperature baseline means that each subsequent heat dome develops atop increasingly warmer conditions. A high-pressure ridge that might have caused a moderate heat event 30 years ago now results in record-breaking emergencies, as current global temperatures are approximately 1.4°C above pre-industrial levels. Projections indicate that 2026 is likely to rank among the four warmest years on record.
Could This Be a Side Effect of War?
Given the prevalence of this question, it is important to address it directly. The answer consists of two distinct components: one is a misconception, and the other is based on fact.
The misconception involves the notion of weather modification as a weapon, suggesting that militaries are manipulating heat domes, artificially increasing temperatures, or employing ionospheric programs such as HAARP to target specific countries.
This conspiracy theory has historical roots, including Cold War-era concerns about the Pentagon’s limited cloud-seeding operations over the Ho Chi Minh Trail in Vietnam, which led to the United Nations banning military weather modification in 1977.
However, technology capable of initiating, steering, or intensifying a continental-scale heat dome does not exist.
The National Oceanic and Atmospheric Administration (NOAA) has explicitly stated that no technology can create, strengthen, or direct weather systems of this magnitude, and NOAA does not fund or conduct weather modification.
These physical limitations are even more pronounced for heat domes, which are larger and slower-moving than hurricanes. While cloud seeding can marginally increase rainfall in existing clouds, it cannot generate a high-pressure ridge that covers two-thirds of a continent.
The fact about the heatwave?
The factual aspect is that military activity significantly contributes to greenhouse gas emissions, which drive the warming responsible for these extreme events. Estimates from the Conflict and Environment Observatory and Scientists for Global Responsibility place the global military carbon footprint between 3.3 and 7 percent of total emissions, with a central estimate of approximately 5.5 percent.
If considered as a single entity, global militaries would rank among the largest emitters worldwide. These emissions are not required to be reported under the Paris Agreement.
Additional factors such as fires at fuel depots, destruction of forests and cropland, reconstruction efforts, and the displacement of millions of refugees further complicate emissions accounting. Researchers have found that emissions from the first two years of the war in Ukraine exceeded those of the Netherlands in an entire year.
Therefore, military conflict is not responsible for the formation of the current heat dome. However, it remains a significant yet often overlooked contributor to the elevated baseline temperatures that facilitate the development of such events, and it is a source of emissions frequently omitted from climate accounting.
What Happens Next
Some relief may occur in the mid-Atlantic region by the middle of next week if the high-pressure ridge shifts westward. However, this would primarily result in the heat moving toward the Plains rather than a true cessation of extreme temperatures. In Europe, the outlook is less favourable. If the Omega Block pattern associated with the second heat dome persists, as current models predict, the event could last 6 to 9 days, with the highest risk anticipated between July 9 and 14.
The primary concern is not any individual heat dome, but rather the underlying pattern: a warming Arctic, a decelerating jet stream, increasingly pronounced atmospheric waves, and cities across two continents repeatedly setting new temperature records. This phenomenon does not require a geopolitical explanation; it is a manifestation of atmospheric physics behaving as predicted by decades of research, albeit at a faster pace than anticipated.
