The US faces freezing temperatures while La Nina typically moderates warming; yet, the planet has reached a new heat record.

In January 2025, the world experienced another record high in temperatures, as reported by the European climate service Copernicus. This record arose despite unusually cold conditions in the United States and the influence of a cooling La Nina, which had raised expectations for a less extreme global temperature rise in the coming years.


The January temperatures were notably 0.09 degrees Celsius (0.16 degrees Fahrenheit) above those recorded in January 2024, which had been designated as the hottest January previously. Furthermore, these temperatures were 1.75 C (3.15 F) higher than pre-industrial levels. Copernicus has noted that January 2025 marked the 18th month out of the last 19 to surpass the international warming threshold of 1.5 C (2.7 F) above pre-industrial means, although scientists indicate that this threshold must be sustained for a span of 20 years to be considered truly breached.


The Copernicus historical data goes back to 1940, while data from the U.S. and British meteorological records extend to 1850. Research utilizing proxy indicators like tree rings suggests that the current climatic conditions are the warmest experienced in approximately 120,000 years, coinciding with the early stages of human civilization.


Samantha Burgess, the strategic lead for climate at the European weather agency, emphasized that greenhouse gas emissions resulting from the combustion of coal, oil, and natural gas remain the primary catalysts for record-breaking heat. Yet, she noted that other natural influences on global temperatures have not been behaving as anticipated.


Typically, the natural cycles of temperature fluctuations in the equatorial Pacific play a significant role in global climate fluctuations. When waters in the central Pacific become warm, it leads to an El Nino, which often corresponds with increased global temperatures. Although a significant El Nino event occurred last year, it ended in June, and 2024, subsequently, was exceptionally warm, setting a record.


Conversely, La Nina conditions tend to mitigate the effects of global warming, making it less likely for record temperatures to emerge. A La Nina emerged in January after developing for several months. Just last month, scientists had initially predicted that 2025 would see cooler temperatures compared to the preceding years, with La Nina playing a significant role in this forecast.


Burgess remarked that even with the Pacific conditions that usually provide a cooling effect on global temperatures, record-high averages are still being reported. A significant contributing factor is the unprecedented warmth prevalent in other oceanic areas worldwide.


Typically, one would expect a rapid temperature drop following a significant El Nino like the one experienced last year; however, that hasn’t happened, according to Burgess.


For those in the U.S., the record warmth in January may come as a surprise due to the prevailing cold weather. However, it’s essential to acknowledge that the U.S. constitutes only a small portion of the Earth’s surface; thus, many other regions experienced significant warmth.


The Arctic, in particular, registered unusually mild conditions in January. Some areas in the Canadian Arctic saw temperature elevations reaching 30 C (54 F) above average, resulting in melting sea ice in several locations. As per Copernicus, January’s Arctic temperatures also matched the record for the lowest sea ice extent, with the National Snow and Ice Data Center in the U.S. ranking it as the second-lowest since measurements began, just behind 2018.


Despite starting February cooler than the previous year, expectations for 2025 still remain high in terms of potential heat records. James Hansen, the former NASA scientist acknowledged as a leading figure in climate science, pointed out that the last fifteen years have witnessed an acceleration in warming, occurring at roughly double the rate compared to the prior four decades.


Hansen conveyed confidence that this accelerated rate of warming will persist for several more years, stating that it would likely be close in temperature between 2024 and 2025 over the full year. He noted a consistent rise in temperatures even when accounting for natural fluctuations, such as El Nino variations that would otherwise influence climatic conditions.


While Hansen claims an acceleration in global warming, some scientists, including Gabe Vecchi from Princeton and Michael Mann from the University of Pennsylvania, express skepticism. Vecchi argues that available data lacks sufficient evidence to sufficiently attribute observed changes to non-random variability, while Mann asserts that the temperature increases remain consistent with climate model predictions.