Complete Guide to Climate Science: What the Data Shows
Climate science is both well-established and routinely misrepresented — in both directions. This guide covers the actual data: what the measurements show, how confident scientists are in different projections, and where genuine uncertainty remains. Sources are primary datasets and peer-reviewed literature, not news reports.
The Baseline: What the Data Shows
Global average surface temperature has risen approximately 1.2°C above the pre-industrial baseline (1850–1900) as of 2023, according to the World Meteorological Organization’s State of the Global Climate report (2024). This figure comes from five independent global temperature datasets (NASA GISS, NOAA, HadCRUT, Berkeley Earth, JRA-55) that agree within 0.1°C of each other.
The rate of warming has accelerated. The decade 2014–2023 was the warmest on record. 2023 was the warmest single year in the observational record by a significant margin.
The Greenhouse Effect: Established Physics
The warming mechanism is not contested at the physics level. Carbon dioxide and other greenhouse gases absorb outgoing infrared radiation and re-emit it in all directions, including back toward Earth’s surface. This mechanism was established by Eunice Newton Foote in 1856 and confirmed by John Tyndall in 1859. It is the same physics used in thermal imaging and atmospheric modeling.
Atmospheric CO₂ has risen from approximately 280 ppm pre-industrial to 421 ppm in 2024 (Mauna Loa Observatory, NOAA). The isotopic signature of the added carbon matches fossil fuel combustion, not volcanic or oceanic sources. Multiple independent attribution studies confirm human activity as the dominant driver of warming since 1950 (IPCC AR6, 2021).
Sea Level Rise: Current Data
Global mean sea level has risen 21–24 cm since 1880, with the rate accelerating from 1.5 mm/year in the early 20th century to 3.7 mm/year in the 2006–2018 period (IPCC AR6). Satellite altimetry (since 1993) shows the rate is now approximately 4.6 mm/year. Contributors: thermal expansion of warming ocean water (~50%), melting glaciers (~25%), and ice sheet loss from Greenland and Antarctica (~25%).
Extreme Weather: What Attribution Science Says
Climate attribution science has advanced significantly since 2012. World Weather Attribution — a rapid-response research group — now publishes peer-reviewed attribution studies within days of major events. Their methodology: compare the probability of an event in the actual climate versus a counterfactual world without human warming.
Key findings: marine heatwaves are now 20x more likely. Many intense precipitation events are 40–90% more intense under current warming. Drought frequency and severity have increased in multiple regions. Attribution probabilities are event-specific — not all extreme events are attributable to climate change.
Where Genuine Uncertainty Remains
Climate sensitivity — how much warming results from a doubling of CO₂ — is estimated at 2.5–4.0°C (likely range, IPCC AR6). This range has narrowed significantly but still carries meaningful uncertainty for long-range projections. Ice sheet dynamics, particularly the West Antarctic and Greenland ice sheets, have higher uncertainty due to complex feedback mechanisms. Regional precipitation projections have wider confidence intervals than temperature projections.
Uncertainty in climate science, as in all science, is about quantified ranges — not about whether warming is occurring or human-caused. Those questions have converged toward high confidence across independent research groups.
Projections to 2100
Under high-emission scenarios (SSP5-8.5), models project 3.3–5.7°C warming by 2100. Under strong mitigation scenarios (SSP1-1.9), warming stays near 1.5°C. Current policies put the world on a path consistent with approximately 2.5–3.0°C (Climate Action Tracker, 2024). Projections are conditional on emission trajectories — they describe what happens under each scenario, not what will happen.
Reading the Data Yourself
Primary sources are publicly accessible. NASA GISS temperature data at data.giss.nasa.gov. NOAA Mauna Loa CO₂ record at gml.noaa.gov/ccgg/trends. Global sea level data from NASA Jet Propulsion Laboratory satellite altimetry. IPCC Assessment Reports at ipcc.ch. The underlying data is freely available and well-documented — you do not need to rely on any secondary interpretation.
Sources: WMO State of the Global Climate (2024). IPCC Sixth Assessment Report (2021). NOAA Mauna Loa CO₂ Observatory. NASA/NOAA global temperature datasets. World Weather Attribution (2023). Climate Action Tracker (2024).