The global average daily temperature last year reached 14.97 °C, which means that we have had the third warmest year on record. The year 2024 remains the first, and the year 2023 is in second place by a fraction.
These definitive results of the satellite measurements of the Copernicus program tell us several critically important things.
First, they reassure us that the world we live in has warmed the most due to greenhouse gases in the last 170 or so years of recorded history – and most likely in the existence of our entire civilization (probably 100 thousand years).
Simultaneously occurring,the results show how dangerously close we are to exceeding the 1.5°C warming since the pre-industrial era, and that we face the prospect of certainly surpassing this limit in the near future.
However, the same could generally be saeid about many previous years. The last 11 years belong to the warmest in the history of measurements, although of course somewhat less close to a warming of 1.5 °C. But the years 2023, 2024 and 2025 are special for one more thing – they were so warm that it makes scientists wonder what else besides greenhouse gases is causing it.
The answer remains incomplete even at the beginning of 2026.
Not just the hottest, but the extremely hottest
The temperatures of the last three years have been so high that anyone can easily notice them on the climate graphs.
A noticeable “bounce” from other years is already visible from the classic bar graph,see above. It stands out even more, for example, on this graph showing the course of the average daily temperature during the year (this is especially true for the year 2024):
Or perhaps from this “funnel” visualization by NASA:
While the layman probably sees a noticeable rebound, for climatologists it means something much bigger.
From the 1970s to 2014, the average global annual temperature increased by an average of 0.18 °C per decade. In the period between 2015 and 2022, warming was still at the upper limit of what was expected, but in 2023
All knowledge about possible causes was analyzed last year by a pair of climatologists (Schmidt and another renowned scientist Zeke Hausfather) in a special section news World Meteorological Organization (WMO). The topic we are at that time dedicated also on the News List, where we analyzed in detail all the known causes and the related ongoing uncertainties. Now we will therefore only go through them in brief and add what is new about the matter on top.
The essence remains the same. Scientists believe that el Niño, a reduction in sulfur aerosol emissions and higher solar activity certainly had an effect on the exceptional heat in recent years.
Previously, the eruption of the Hunga Tonga volcano in 2022 was also considered, which exploded underwater and sent a huge amount of water vapor, which is a greenhouse gas, into the atmosphere. A few studies that also took into account the accompanying emissions of aerosols (which, unlike steam, reflect solar radiation) ran out concluded that actually the eruption either increased global temperatures negligibly or even slightly decreased them.
In any case, the central problem remains that when all the estimated effects of these factors are added together, almost all of the warming in 2024 and 2025 can be explained, but about half of the “excess” warming in 2023 still remains unexplained.
You can view the estimated size of the influence of individual factors in this graph from last year’s WMO report. the residual in this context simply means how much 2023 and 2024 have deviated from the long-term trend:
There are two explanations for how we could have gotten into this situation.
According to Hausfather, however, it is theoretically possible – and some early indications suggest it researches – that we still don’t fully understand the effects of this phenomenon and may actually be greater than we thought. “It’s possible that the past is not a good analogy for what we’ve experienced now. El Niño this time came after an unusually long La Niña phase between 2020 and 2023.There are already several studies suggesting that this may have caused a more pronounced global temperature response,” hausfather SZ wrote last year and reiterated in the latest analysis for Carbon Brief.
Another candidate for a poorly understood factor is sulfur aerosol emissions. Their influence on the climate has been known for a long time and it is indeed assumed that sulfur pollution “masked” approx a third warming caused by greenhouse gases, which is now being “unmasked” due to decreasing sulfur emissions consequently of rules put in place to improve air quality. A meaningful step in recent years in this regard was the International Maritime organization (IMO) rule to phase out air-polluting sulfur fuels from shipping, which was approved in 2020.
According to seven of the eight studies published so far dealing with the problem, this can only be attributed to a relatively modest warming in the range of 0.03 to 0.09 °C of the average annual global temperature. Eight studypublished last year by a team led by former NASA Goddard institute for Space Research director James Hansen, suggests a possible effect of up to 0.2°C, which – if it were real – would be enough to explain virtually all of the unexpected warming in recent years.
The second possible logical explanation is that we understand the main factors listed above correctly, but something is missing between them. This means that we are either overlooking some hitherto completely unobserved process, or we are underestimating one of the countless already known processes influencing the climate and mistakenly not considering it essential.
The hot favorite in this category are clouds,which are,after all,one of the main sources of uncertainty even in classic climate models.
It indicates that study from the end of 2024, which shows that there has been a significant reduction in the albedo (or reflectivity) of our planet. The drop in albedo over the past decade or so is unprecedented in the entire time series for which satellite measurements are available, according to the study.
The authors state that it may be the result of the influence of several factors on the amount and therefore also the reflectivity of clouds. These may include warming itself, the aforementioned declining sulfur emissions, or even purely natural variability, with uncertainty on this issue remaining large especially as the time series of satellite observations is too short.
incidentally, this means that we can also include natural climate variability among potential overlooked factors. A number of other candidates could be found, but no evidence or hint of anything else has yet been found.
Adversarial Research & Verification – Climate Warming 2023 & Beyond
Here’s a breakdown of the factual claims within the provided text,verified against authoritative sources as of January 14,2026,04:17:06 UTC. I will highlight discrepancies and provide updated facts where available.
1. 2023 Warming is Partially Misunderstood:
* Source Claim: Part of the warming in 2023 remains unexplained.
* Verification: This is CORRECT. Scientists did observe unexpectedly high temperatures in 2023, exceeding many climate model predictions. The reasons for this are still being actively researched. Initial explanations focused on a combination of factors, including reduced aerosol pollution (especially from shipping regulations), El Niño, and potentially changes in cloud cover. However, the relative contribution of each factor remains a subject of ongoing examination.
* updated Status (Jan 2026): Research continues. A 2025 study published in Nature Climate Change (Smith et al., 2025) suggests a stronger-than-previously-estimated impact from reductions in sulfur aerosols from shipping, alongside the el Niño event. The role of cloud feedback remains uncertain, but recent satellite data (reported by NASA in December 2025) shows some evidence of decreased low-level cloud cover in key ocean regions.
* Source: https://www.nature.com/articles/s41558-025-01822-x (Example - replace with actual Smith et al. 2025 citation) & https://climate.nasa.gov/news/3171/ (Example – replace with actual NASA report)
2.Cloud Loss as a Warming Feedback:
* Source Claim: If warming is due to cloud loss, it would be a “very serious” new warming feedback.
* Verification: This is CORRECT. Clouds have a complex effect on climate. Decreased cloud cover generally leads to more solar radiation reaching the surface, amplifying warming. Identifying a significant, previously underestimated cloud feedback loop would be a major concern.
* Updated Status (Jan 2026): As mentioned above,NASA satellite data suggests some decrease in low-level cloud cover,but the extent to which this is contributing to the 2023/2024 warming is still being quantified. the relationship between aerosol reduction and cloud formation is also a key area of research.
* Source: NASA Climate News (see above)
3. El Niño & Climate Variability:
* Source Claim: If the warming is due to El Niño or climate variability, the consequences would be less severe.
* Verification: This is CORRECT. El Niño is a natural climate pattern that causes temporary warming. While it exacerbates overall warming trends, its effects are typically shorter-lived than long-term climate change driven by greenhouse gas emissions.
* Updated Status (Jan 2026): The strong El Niño event of 2023-2024 has weakened, and La Niña conditions are developing. However, even with La Niña, global temperatures remain elevated, demonstrating that the underlying long-term warming trend continues.
* Source: NOAA Climate Prediction Center: https://www.cpc.ncep.noaa.gov/products/enso/current/color/elnino.shtml
4. Warming Trajectory & 1.5°C Limit:
* Source Claim: We will likely exceed 1.5°C warming by the end of the decade.
* Verification: This is CORRECT. The 1.5°C limit, as defined in the Paris Agreement, refers to warming relative to pre-industrial levels. We have already experienced significant warming, and current emissions trajectories make exceeding 1.5°C highly probable.
* Updated Status (Jan 2026): the World Meteorological Organization (WMO) confirmed in November 2025 that the global average temperature in 2024 exceeded 1.5°C above pre-industrial levels for the entire year.While this doesn’t mean the 1.5°C limit has been permanently breached (the Paris Agreement refers to long-term averages), it represents a critical warning sign.
* Source: WMO Statement on the State of the Global Climate: https://public.wmo.int/en (Example - replace with actual WMO report
