Instrumental temperature record

**Temperature Measurement Methods:**
– Instrumental temperature records are based on direct measurements of air and ocean temperature.
– Data is collected from meteorological stations, buoys, and ships globally.
– Historical measurements used mercury or alcohol thermometers, while modern measurements use electronic sensors.
– Upper atmosphere temperatures are monitored using radiosondes, satellites, and aircraft.
– Recent datasets include extensive sampling of ocean temperatures at different depths.

**Global Temperature Trends:**
– Reliable instrumental records of near-surface temperature date back to around 1850.
– Global surface temperatures have warmed by about 1.09°C from 1850–1900 to 2011–2020.
– Most warming occurred around 1900-1940 and from 1970 onwards.
– The record shows a consistent rise in global average surface temperatures.
– Global warming projections range from 1.0°C to 5.7°C by the late 21st century.

**Warmest Periods and Records:**
– New high temperature records surpass low temperature records on Earth’s surface.
– Warmest years occurred in the last decade (2012-2021).
– Each year from 2015-2021 was warmer than any pre-2014 year.
– Year 2023 was 1.48°C hotter than the average in 1850-1900.
– Long-term warming trend with natural variability factors.

**Scientific Consensus and Data Sources:**
– Scientific consensus confirms climate change driven by human-emitted greenhouse gases.
– Global surface temperature trends from HadCRUT3, NOAA, and NASA/GISS are independent.
– NOAA, NASA, and other organizations maintain global temperature records and datasets.
– IPCC and U.S. Global Change Research Program support the evidence of climate change.
– Various scientific reports and studies contribute to advancing climate change science.

**Climate Variability and Predictions:**
– Global warming did not stop in 1998 due to internal climate variability.
– Climate changes will not be uniform across the Earth.
– Factors influencing global temperature include greenhouse gases, El Niño, La Niña, aerosols, and land use changes.
– Projections based on climate models and observations suggest varying future temperature increases.
– Regional temperature changes impact melting ice, hydrological cycles, and ocean currents differently.