Global warming paused / stopped
The so-called global warming hiatus of the early 2000s to mid-2010s reflected a temporary slowdown in the rate of surface air temperature increase, driven largely by heat uptake in the deep ocean and natural variability, not a stop in warming, and updated temperature records show the slowdown was smaller than initially estimated.
What we know
The claim that global warming paused or stopped for a period, often cited to argue that climate projections are unreliable, refers to a real but narrower phenomenon that climate scientists themselves identified, studied, and explained: a slower than expected rate of increase in global average surface air temperature roughly between 1998 and the mid-2010s, sometimes called the global warming hiatus in scientific literature of that period.
The starting point of 1998 was itself an unusually warm year due to a very strong El Nino event, which temporarily elevates global surface temperatures by shifting ocean heat toward the surface. Measuring a warming trend starting from an anomalously warm year makes the subsequent years appear to show less warming than a trend calculated from a more typical starting point, a statistical framing effect that contributed to the appearance of a pause. When the full temperature record is examined using standard statistical trend analysis rather than cherry-picked start and end points, the underlying warming trend continued throughout this period.
Several peer-reviewed studies identified where the "missing" heat was going during this slower-surface-warming period. A influential 2013 study published in Nature Climate Change by Kevin Trenberth and John Fasullo, along with related work by other oceanographers, found that a larger than usual share of global heat uptake during this period was being absorbed by the deep ocean, below 700 meters, rather than remaining near the surface where it would show up more directly in surface air temperature measurements. Since oceans absorb roughly 90 percent of the excess heat trapped by greenhouse gases, shifts in ocean heat distribution between surface and deep layers can meaningfully affect surface temperature trends over periods of a decade or more without indicating any change in the underlying greenhouse effect or overall planetary energy imbalance.
A separate and influential 2015 study published in Science by Thomas Karl and colleagues at NOAA found that the apparent slowdown was partly an artifact of measurement bias: historical sea surface temperature records had a known cool bias in certain ship-based measurements relative to newer buoy-based measurements, and correcting for this bias reduced the apparent size of the slowdown considerably. Combined with the deep ocean heat uptake finding, later analyses concluded the hiatus was smaller in magnitude than initially estimated and fell within the range of natural decadal variability superimposed on a continuing warming trend.
Global average surface temperatures resumed rising sharply after roughly 2014, with the years 2015 through 2024 ranking among the warmest in the instrumental temperature record maintained by NASA's Goddard Institute for Space Studies, NOAA, and the UK Met Office's Hadley Centre, each using independently compiled data that agree closely. This resumption is consistent with the scientific explanation that the hiatus reflected natural variability in ocean heat distribution rather than any weakening of the greenhouse warming mechanism, and it directly contradicts the idea that the earlier slowdown indicated warming had permanently stopped. Climate scientists frequently point to this episode as an illustration of the difference between short-term natural variability superimposed on top of a longer-term trend, and any genuine reversal of that underlying trend itself, a distinction that matters for correctly interpreting any single decade of temperature data in isolation.
Common claims
- Global warming stopped after 1998False - caused by cherry-picking 1998 El Nino; subsequent years broke records
- The rate of surface warming slowed from 1998 to 2012Partially true but misleading - ocean warming, sea level, and ice loss continued unabated
- Scientists now admit there was a warming pauseFalse - updated analysis found no statistically significant pause
Evidence hierarchy
All sources
- Global warming 'hiatus' never happened, Stanford scientists sayStanford University · 2015
- Did global warming stop in 1998?NOAA Climate.gov · 2018
- IPCC AR6 WGI: Climate change widespread, rapid, and intensifyingIPCC · 2021
- Possible artifacts of data biases in the recent global surface warming hiatusScience · 2015