Satellite Data Records as a Tool to Monitor Changes in Air Temperature

Abstract. We analyze satellite-derived lower-tropospheric temperature (TLT) data for the period 1981–2025 and examine their relationship to the pronounced warming observed in in situ measurements during 2023–2024. To reduce uncertainty and improve the robustness of detecting long-term changes in Earth's warming rate, we construct an adjusted TLT record by removing variability associated with the El Niño–Southern Oscillation (ENSO) and atmospheric aerosols. This adjustment reduces the magnitude of annual TLT variability by nearly 50 %, substantially enhancing the robustness and reliability of the observed satellite temperature trends. Using the adjusted TLT record, we identify statistically significant warming trends of up to 0.482 ± 0.113 °C decade⁻¹ after 2015 across all satellite and reanalysis datasets examined in this study. These trends are approximately four to five times larger than those during the pre-2015 period. However, these trend estimates are likely conservative. At the upper end, statistically significant increases in the warming rate of up to 0.48 ± 0.12 °C decade⁻² are inferred near 2024, indicating that the pronounced warming observed during 2023–2024 are part of an ongoing increase in the underlying warming rate that was further amplified by the El Niño event. Projections based on these increased warming rates suggest the potential for an additional 0.5–1.0 °C of lower-tropospheric warming over the next decade. The physical mechanisms responsible for this unusually rapid warming, however, remain unclear. Resolving these mechanisms is therefore essential for improving future climate projections and informing effective mitigation and adaptation strategies.