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wayChanges in climate variability are as important for society as are changes in mean climate 1 .Contrasting last Glacial and Holocene temperature variability can provide new insights into the relationship between the mean state of climate and its variability 2, 3 . However, although glacial-interglacial changes in variability have been quantified in Greenland 2 , a global view remains elusive. Here, we present the first quantitative reconstruction of changes in temperature variability between the Last Glacial Maximum and the Holocene, based on a global network of marine and terrestrial temperature proxies. We show that temperature variability decreased globally by a factor of 4 for a warming of 3-8 • C. The decrease displayed a clear zonal pattern with little change in the tropics (1.6-2.8) and greater change in the midlatitudes of both hemispheres (3.3-14). In contrast, Greenland ice-core records show a reduction of a factor of 73, suggesting a proxy-specific overprint or a decoupling of Greenland atmospheric from global surface temperature variability. The overall pattern of variability reduction can be explained by changes in the meridional temperature gradient, a mechanism 1

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The early Eocene (49-55 million years ago) is a time interval characterized by elevated surface temperatures and atmospheric CO 2 (refs 1,2), and a flatter-than-present latitudinal surface temperature gradient 3,4 . The multi-proxy-derived flat temperature gradient has been a challenge to reproduce in model simulations [5][6][7] 10 , invalidating the apparent, extremely warm polar sea surface temperatures. We conclude that there is a need to reinterpret TEX H 86 -inferred marine temperature records in the literature, especially for reconstructions of past warm climates that rely heavily on this proxy as reflecting subsurface ocean.The combination of global warming and high atmospheric CO 2 during the early Eocene renders this time interval a potential analogue for anthropogenic climate change. A long-standing, unresolved issue in simulating warmer-than-present climates is the failure of models in reproducing the flat Equator-to-pole surface temperature gradient often observed in proxy data 5,6 . The model-proxy match is improved in the terrestrial realm in high-CO 2 scenarios 6 or via tuning model parameters 7 , but the extreme surface oceanic warmth in polar regions inferred from TEX H 86 has been irreconcilable. Although this discrepancy was attributed to missing processes in climate models 8 , inconsistencies in proxy data also suggest deficiencies in proxy understanding 11,12 To investigate this hypothesis, we examine 22 pairs of U K 37 -and TEX H 86 -inferred temperature records (in total 5,528 samples) measured in tandem on sediment cores from sites spanning diverse oceanographic settings and timescales from thousands to millions of years ( Supplementary Figs 1 and 2). Temporal leads and lags between proxy record pairs are possible, as these proxies might reflect different water depths, where the timing of temperature changes differ 20 , and proxy-specific sedimentary processes 21 can create temporal offsets. This inhibits a direct comparison of the time series, as timing differences generally destroy coherency.Instead, power spectra of each of the paired U K 37 and TEX H 86 records are estimated and the mean power spectral estimate (PSD) for each proxy type is compared. Spectra averaged over multiple regions attenuate local effects, thereby facilitating inter-comparison between proxy types. This technique is insensitive to temporal offsets between the records 22 and allows fingerprinting the reasons for discrepancies between the proxies 23 . The power spectra of U K 37 and TEX H 86 show a very similar shape, with increased energy towards lower frequencies (Fig.