Experiencing intense, record-breaking cold while hearing reports about accelerating global warming can be confusing. It seems counter-intuitive that the planet is warming when local weather feels colder than ever. This contradiction raises the question of whether winter seasons are becoming colder despite the long-term upward trend in global temperatures. Scientific analysis of atmospheric patterns and long-term data distinguishes between short-term weather events and sustained climate trends.
Differentiating Climate and Weather
The confusion between a cold winter and a warming world often stems from a misunderstanding of the difference between weather and climate. Weather describes atmospheric conditions that occur over a short period, such as a day or a week, in a localized area. Climate, by contrast, represents the long-term average of weather patterns in a region, typically calculated over periods of 30 years or more. A single cold snap, or even a severely cold winter, is an instance of weather. It does not negate a change in the climate, which is the baseline expectation.
Global Winter Temperature Trends
When examined through the lens of climate, data clearly shows that winters are not getting colder on a global scale. The scientific consensus is that the planet is warming, and this trend holds true for the winter season. Globally, the average surface temperature has been increasing at an accelerated rate, warming about 0.20 degrees Celsius (0.36 degrees Fahrenheit) per decade since 1975. Even with regional cold outbreaks, temperatures during the winter months are consistently warmer than historical averages, especially in the Northern Hemisphere. The long-term trend points toward shorter, milder winter periods overall, with the frequency of extreme cold days decreasing in many regions.
Atmospheric Changes Driving Cold Events
The paradox of a warming world causing intense, regional cold is explained by a change in atmospheric dynamics that begins in the far north. The Arctic region is warming at least twice as fast as the global average, a process known as Arctic Amplification. This accelerated warming is driven by a feedback loop: as rising temperatures melt reflective sea ice and snow, the darker ocean or land surface absorbs more solar energy, which further increases the regional temperature.
The temperature difference between the frigid Arctic and the warmer mid-latitudes is a key driver for the atmospheric circulation patterns that govern weather. A large temperature gradient creates a strong pressure contrast, which acts like a wall to contain the cold air. This contrast powers the Jet Stream, a fast-moving, high-altitude river of air that typically flows west to east, separating the cold Arctic air from the temperate air masses below.
As the Arctic warms faster, the temperature difference between the Arctic and the mid-latitudes decreases, which weakens the Jet Stream. A weaker Jet Stream tends to become more distorted and wavier, allowing it to meander significantly north and south. This wavier path can cause weather systems to slow down or stall, leading to more persistent weather events, including prolonged periods of cold air.
The weakening Jet Stream can also disrupt the Polar Vortex, a massive, swirling ring of cold, low-pressure air that typically remains locked over the poles during winter. When the Jet Stream’s meanders become large enough, they can push warm air into the Arctic, causing the Polar Vortex to stretch or destabilize. This disruption allows frigid air masses to break free and “spill” southward into regions like North America, Europe, and Asia, resulting in severe cold snaps.
These outbreaks of intense, unseasonable cold are not evidence that global warming is not occurring; rather, they are a predictable consequence of the destabilized climate system. The increasing frequency of these deep southward dips of Arctic air links the warming of the pole to extreme weather events in the lower latitudes. This mechanism explains the paradox: an overall warmer world is capable of producing more intense, localized cold events by shifting where the cold air is held.