Global Warming Acceleration: Key Facts & Reference

The Earth’s mean surface temperature increased at an average rate of about 0.2°C every ten years between 1970 and 2015. That rate was concerning enough to spark decades of international discussions, a number of historic accords, and a whole field of climate policy. Then, in 2015 or so, something changed. The rate of warming has increased to about 0.35°C per decade over the last ten years. After using rigorous statistical techniques to eliminate the “noise”—natural year-to-year variations brought on by El Niño cycles, volcanic eruptions, and variations in solar activity—the researchers discovered a distinct and statistically significant acceleration in warming caused by human activity. With more than 98% statistical certainty, it is clear. That is not an initial outcome. That concludes it.

Officially, since the beginning of instrumental temperature records in 1880, the 11 years between 2015 and 2025 have been the hottest. That window encompasses all ten of the hottest years ever recorded. The hottest year ever recorded was 2023. Then 2024 exceeded it. For the first time in a calendar year, the average global temperature in 2024 was more than 1.5°C higher than pre-industrial levels. Regarding the Paris Agreement, it’s important to clarify that the 1.5°C target refers to a 20-year average rather than a single year. Technically, crossing it once does not constitute a violation of the agreement. However, the UN has made it clear that exceeding it for a month or a year is a sign that the world is approaching the long-term limit. Additionally, according to Rahmstorf’s analysis, that 20-year average will surpass 1.5°C before 2030 if the current rate of warming continues.

The researchers took care to note that they did not look into any particular reasons for the acceleration. However, the scientific community has been investigating this question, and the decrease in sulfur aerosols from international shipping is one explanation that frequently comes up in related discussions. Heavy fuel oil was burned by the maritime sector for many years, releasing massive amounts of sulfate particles into the lower atmosphere. These particles have been unintentionally serving as a partial counterweight to greenhouse warming because they are reflective, bouncing sunlight back into space. The aerosol cooling effect decreased in 2020 when international shipping regulations tightened to reduce sulfur emissions for air quality reasons. Several researchers claim that the outcome was an inadvertent amplification of the underlying warming signal. The full heat that greenhouse gases were already producing may have been partially revealed by a rule intended to safeguard human health.

It’s difficult to ignore the fact that the oceans are also following this acceleration. Ocean heat content, or the amount of warmth absorbed by the seas, set a new record in 2025 and is currently the main indicator of where the Earth’s stored energy is going. Sea level rise is accelerated by warmer oceans that cause ice to melt more quickly. According to a different study that was published this week in Nature, hundreds of millions more people are at risk of flooding because coastal sea levels are already eight inches to a foot higher than many current maps and coastline models reflect. Faster surface warming, record ocean heat, higher sea levels than predicted, and ice sheets under stress—which previous models predicted would take much longer to reach this point—are all interconnected systems.

The main contribution of the paper is both methodological and concerning. Rahmstorf and Foster effectively addressed the question that skeptics have been posing for years: how much of the recent warming is just natural noise? by removing natural variability from the temperature record. With 98% confidence, the acceleration since 2015 is not noise. It’s a signal. The underlying warming trend caused by humans is accelerating. “We filter out known natural influences in the observational data, so that the ‘noise’ is reduced, making the underlying long-term warming signal more clearly visible,” Foster said. When they did, they discovered a warming rate greater than any other decade in the instrumental record dating back to 1880.

Reading this study and the data it uses gives me the impression that the climate debate has been misguided for far too long. The question of whether global warming is real has been resolved. With 98 percent statistical certainty, the question of whether it is accelerating has also been resolved. Rahmstorf himself posed the more difficult question, “How quickly the Earth continues to warm ultimately depends on how rapidly we reduce global CO₂ emissions from fossil fuels to zero.” That is not a result of science. Every day, a political and economic decision is made or not made.

In an otherwise challenging picture, the study points out something that is truly worth clinging to: even though warming cannot be stopped on human timescales, it can be stopped if humanity achieves zero carbon emissions. Most likely, warming cannot be stopped. However, it can be stopped. Its current speed, which has almost doubled since the Paris Agreement was signed, is not set in stone. Legislative sessions, corporate boardrooms, energy grids, and individual decisions made by eight billion people continue to influence it. The trajectory is worse than anticipated, according to the data. According to the same data, the result has not yet been written.

The post Scientists Just Confirmed Global Warming Has Nearly Doubled in Speed Since 2015 — and the Implications Are Terrifying appeared first on Creative Learning Guild.