| µmol | micromole |
| 20C3M | 20th Century Climate in Coupled Models |
| AABW | Antarctic Bottom Water |
| AAIW | Antarctic Intermediate Water |
| AAO | Antarctic Oscillation |
| AATSR | Advanced Along Track Scanning Radiometer |
| ACC | Antarctic Circumpolar Current |
| ACCENT | Atmospheric Composition Change: a European Network |
| ACE | Accumulated Cyclone Energy or Aerosol Characterization Experiment |
| ACRIM | Active Cavity Radiometer Irradiance Monitor |
| ACRIMSAT | Active Cavity Radiometer Irradiance Monitor Satellite |
| ACW | Antarctic circumpolar wave |
| ADEC | Aeolian Dust Experiment on Climate |
| ADNET | Asian Dust Network |
| AeroCom | Aerosol Model Intercomparison |
| AERONET | Aerosol RObotic NETwork |
| AGAGE | Advanced Global Atmospheric Gases Experiment |
| AGCM | Atmospheric General Circulation Model |
| AGWP | Absolute Global Warming Potential |
| AIACC | Assessments of Impacts and Adaptations to Climate Change in Multiple Regions and Sectors |
| AIC | aviation-induced cloudiness |
| ALAS | Autonomous LAgrangian Current Explorer |
| ALE | Atmospheric Lifetime Experiment |
| AMIP | Atmospheric Model Intercomparison Project |
| AMO | Atlantic Multi-decadal Oscillation |
| AMSU | Advanced Microwave Sounding Unit |
| AO | Arctic Oscillation |
| AOGCM | Atmosphere-Ocean General Circulation Model |
| APEX | Atmospheric Particulate Environment Change Studies |
| AR4 | Fourth Assessment Report |
| ARM | Atmospheric Radiation Measurement |
| ASOS | Automated Surface Observation Systems |
| ASTEX | Atlantic Stratocumulus Transition Experiment |
| ATCM | Atmospheric Transport and Chemical Model |
| ATSR | Along Track Scanning Radiometer |
| AVHRR | Advanced Very High Resolution Radiometer |
| BATS | Bermuda Atlantic Time-series Study |
| BC | black carbon |
| BCC | Beijing Climate Center |
| BCCR | Bjerknes Centre for Climate Research |
| BIOME 6000 | Global Palaeovegetation Mapping project |
| BMRC | Bureau of Meteorology Research Centre |
| C4MIP | Coupled Carbon Cycle Climate Model Intercomparison Project |
| CaCO3 | calcium carbonate |
| CAMS | Climate Anomaly Monitoring System (NOAA) |
| CAPE | Convective Available Potential Energy |
| CCl4 | carbon tetrachloride |
| CCM | Chemistry-Climate Model |
| CCCma | Canadian Centre for Climate Modelling and Analysis |
| CCN | cloud condensation nuclei |
| CCSR | Centre for Climate System Research |
| CDIAC | Carbon Dioxide Information Analysis Center |
| CDW | Circumpolar Deep Water |
| CERES | Clouds and the Earth’s Radiant Energy System |
| CERFACS | Centre Europeen de Recherche et de Formation Avancee en Calcul Scientific |
| CF4 | perfluoromethane |
| CFC | chlorofluorocarbon |
| CFCl3 | CFC-11 |
| CH2I2 | di-iodomethane (methylene iodide) |
| CH2O | formaldehyde |
| CH3CCl3 | methyl chloroform |
| CH3COOH | acetic acid |
| CH4 | methane |
| CLAMS | Chesapeake Lighthouse and Aircraft Measurements for Satellites |
| CLARIS | Europe-South America Network for Climate Change Assessment and Impact Studies |
| CLIMAP | Climate: Long-range Investigation, Mapping, and Prediction |
| CLIVAR | Climate Variability and Predictability Programme |
| CMAP | CPC Merged Analysis of Precipitation |
| CMDL | Climate Monitoring and Diagnostics Laboratory (NOAA) |
| CMIP | Coupled Model Intercomparison Project |
| CNRM | Centre National de Recherches Météorologiques |
| CO | carbon monoxide |
| CO2 | carbon dioxide |
| CO32– | carbonate |
| COADS | Comprehensive Ocean-Atmosphere Data Set |
| COARE | Coupled Ocean-Atmosphere Response Experiment |
| COBE-SST | Centennial in-situ Observation-Based Estimates of SSTs |
| COWL | Cold Ocean-Warm Land |
| CPC | Climate Prediction Center (NOAA) |
| CREAS | Regional Climate Change Scenarios for South America |
| CRIEPI | Central Research Institute of Electric Power Industry |
| CRUTEM2v | CRU/Hadley Centre gridded land-surface air temperature version 2v |
| CRUTEM3 | CRU/Hadley Centre gridded land-surface air temperature version 3 |
| CSIRO | Commonwealth Scientific and Industrial Research Organization |
| CTM | Chemical Transport Model |
| DEMETER | Development of a European Multimodel Ensemble System for Seasonal to Interannual Prediction |
| DIC | dissolved inorganic carbon |
| DJF | December, January, February |
| DLR | Deutsches Zentrum für Luft- und Raumfahrt |
| DMS | dimethyl sulphide |
| D-O | Dansgaard-Oeschger |
| DOC | dissolved organic carbon |
| DORIS | Determination d’Orbite et Radiopositionnement Intégrés par Satellite |
| DSOW | Denmark Strait Overflow Water |
| DSP | Dynamical Seasonal Prediction |
| DTR | diurnal temperature range |
| DU | Dobson unit |
| EARLINET | European Aerosol Research Lidar Network |
| EBM | Energy Balance Model |
| ECMWF | European Centre for Medium Range Weather Forecasts |
| ECS | equilibrium climate sensitivity |
| EDGAR | Emission Database for Global Atmospheric Research |
| EMIC | Earth System Model of Intermediate Complexity |
| ENSO | El Niño-Southern Oscillation |
| EOF | Empirical Orthogonal Function |
| EOS | Earth Observing System |
| EPICA | European Programme for Ice Coring in Antarctica |
| ERA-15 | ECMWF 15-year reanalysis |
| ERA-40 | ECMWF 40-year reanalysis |
| ERBE | Earth Radiation Budget Experiment |
| ERBS | Earth Radiation Budget Satellite |
| ERS | European Remote Sensing satellite |
| ESRL | Earth System Research Library (NOAA) |
| ESTOC | European Station for Time-series in the Ocean |
| EUROCS | EUROpean Cloud Systems |
| FACE | Free Air CO2 Enrichment |
| FAO | Food and Agriculture Organization (UN) |
| FAR | First Assessment Report |
| FRCGC | Frontier Research Center for Global Change |
| FRSGC | Frontier Research System for Global Change |
| GAGE | Global Atmospheric Gases Experiment |
| GARP | Global Atmospheric Research Program |
| GATE | GARP Atlantic Tropical Experiment |
| GAW | Global Atmosphere Watch |
| GCM | General Circulation Model |
| GCOS | Global Climate Observing System |
| GCSS | GEWEX Cloud System Study |
| GEIA | Global Emissions Inventory Activity |
| GEOS | Goddard Earth Observing System |
| GEWEX | Global Energy and Water Cycle Experiment |
| GFDL | Geophysical Fluid Dynamics Laboratory |
| GHCN | Global Historical Climatology Network |
| GHG | greenhouse gas |
| GIA | glacial isostatic adjustment |
| GIN Sea | Greenland-Iceland-Norwegian Sea |
| GISP2 | Greenland Ice Sheet Project 2 |
| GISS | Goddard Institute for Space Studies |
| GLACE | Global Land Atmosphere Coupling Experiment |
| GLAMAP | Glacial Ocean Mapping |
| GLAS | Geoscience Laser Altimeter System |
| GLODAP | Global Ocean Data Analysis Project |
| GLOSS | Global Sea Level Observing System |
| GMD | Global Monitoring Division (NOAA) |
| GOME | Global Ozone Monitoring Experiment |
| GPCC | Global Precipitation Climatology Centre |
| GPCP | Global Precipitation Climatology Project |
| GPS | Global Positioning System |
| GRACE | Gravity Recovery and Climate Experiment |
| GRIP | Greenland Ice Core Project |
| GSA | Great Salinity Anomaly |
| Gt | gigatonne (109 tonnes) |
| GWE | Global Weather Experiment |
| GWP | Global Warming Potential |
| H2 | molecular hydrogen |
| HadAT | Hadley Centre Atmospheric Temperature data set |
| HadAT2 | Hadley Centre Atmospheric Temperature data set Version 2 |
| HadCRUT2v | Hadley Centre/CRU gridded surface temperature data set version 2v |
| HadCRUT3 | Hadley Centre/CRU gridded surface temperature data set version 3 |
| HadISST | Hadley Centre Sea Ice and Sea Surface Temperature data set |
| HadMAT | Hadley Centre Marine Air Temperature data set |
| HadRT | Hadley Centre Radiosonde Temperature data set |
| HadRT2 | Hadley Centre Radiosonde Temperature data set |
| HadSLP2 | Hadley Centre MSLP data set version 2 |
| HadSST2 | Hadley Centre SST data set version 2 |
| HALOE | Halogen Occultation Experiment |
| HCFC | hydrochlorofluorocarbon |
| HCO3– | bicarbonate |
| HFC | hydrofluorocarbon |
| HIRS | High Resolution Infrared Radiation Sounder |
| HLM | High Latitude Mode |
| HNO3 | nitric acid |
| HO2 | hydroperoxyl radical |
| HONO | nitrous acid |
| HOT | Hawaii Ocean Time-Series |
| hPa | hectopascal |
| HYDE | HistorY Database of the Environment |
| IABP | International Arctic Buoy Programme |
| ICESat | Ice, Cloud and land Elevation Satellite |
| ICOADS | International Comprehensive Ocean-Atmosphere Data Set |
| ICSTM | Imperial College of Science, Technology and Medicine |
| IGBP | International Geosphere-Biosphere Programme |
| IGBP-DIS | IGBP Data and Information System |
| IGRA | Integrated Global Radiosonde Archive |
| IMO | International Meteorological Organization |
| INDOEX | Indian Ocean Experiment |
| InSAR | Interferometric Synthetic Aperture Radar |
| IO | iodine monoxide |
| IOCI | Indian Ocean Climate Initiative |
| IOD | Indian Ocean Dipole |
| IOZM | Indian Ocean Zonal Mode |
| IPAB | International Programme for Antarctic Buoys |
| IPO | Inter-decadal Pacific Oscillation |
| IPSL | Institut Pierre Simon Laplace |
| IS92 | IPCC Scenarios 1992 |
| ISCCP | International Satellite Cloud Climatology Project |
| ITCZ | Inter-Tropical Convergence Zone |
| JAMSTEC | Japan Marine Science and Technology Center |
| JJA | June, July, August |
| JMA | Japan Meteorological Agency |
| ka | thousand years ago |
| KMA | Korea Meteorological Administration |
| KNMI | Royal Netherlands Meteorological Institute |
| kyr | thousand years |
| LASG | National Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics |
| LBA | Large-Scale Biosphere-Atmosphere Experiment in Amazonia |
| LBC | lateral boundary condition |
| LBL | line-by-line |
| LGM | Last Glacial Maximum |
| LIG | Last Interglacial |
| LKS | Lanzante-Klein-Seidel |
| LLGHG | long-lived greenhouse gas |
| LLJ | Low-Level Jet |
| LLNL | Lawrence Livermore National Laboratory |
| LMD | Laboratoire de Météorologie Dynamique |
| LOA | Laboratoire d’Optique Atmospherique |
| LOSU | level of scientific understanding |
| LSCE | Laboratoire des Sciences du Climat et de l’Environnement |
| LSM | land surface model |
| LSW | Labrador Sea Water |
| LW | longwave |
| LWP | liquid water path |
| Ma | million years ago |
| MAM | March, April, May |
| MARGO | Multiproxy Approach for the Reconstruction of the Glacial Ocean surface |
| mb | millibar |
| MDI | Michelson Doppler Imager |
| Meteosat | European geostationary meteorological satellite |
| MFR | Maximum Feasible Reduction |
| MHT | meridional heat transport |
| MINOS | Mediterranean Intensive Oxidants Study |
| MIP | Model Intercomparison Project |
| MIRAGE | Megacity Impacts on Regional and Global Environments |
| MISO | Monsoon Intra-Seasonal Oscillation |
| MISR | Multi-angle Imaging Spectro-Radiometer |
| MJO | Madden-Julian Oscillation |
| MLS | Microwave Limb Sounder |
| MMD | Multi-Model Data set (at PCMDI) |
| MOC | Meridional Overturning Circulation |
| MODIS | Moderate Resolution Imaging Spectrometer |
| mol | mole |
| MONEX | Monsoon Experiment |
| MOPITT | Measurements of Pollution in the Troposphere |
| MOZAIC | Measurement of Ozone by Airbus In-service Aircraft |
| MPI | Max Planck Institute |
| MPIC | Max Planck Institute for Chemistry |
| MPLNET | Micro-Pulse Lidar Network |
| MRI | Meteorological Research Institute of JMA |
| MSLP | mean sea level pressure |
| MSU | Microwave Sounding Unit |
| Myr | million years |
| N2 | molecular nitrogen |
| N2O | nitrous oxide |
| N2O5 | dinitrogen pentoxide |
| NADW | North Atlantic Deep Water |
| NAH | North Atlantic subtropical high |
| NAM | Northern Annular Mode |
| NAMS | North American Monsoon System |
| NAO | North Atlantic Oscillation |
| NARCCAP | North American Regional Climate Change Assessment Program |
| NASA | National Aeronautics and Space Administration |
| NCAR | National Center for Atmospheric Research |
| NCDC | National Climatic Data Center |
| NCEP | National Centers for Environmental Prediction |
| NEAQS | New England Air Quality Study |
| NEP | net ecosystem production |
| NESDIS | National Environmental Satellite, Data and Information Service |
| NGRIP | North Greenland Ice Core Project |
| NH | Northern Hemisphere |
| NH3 | ammonia |
| NH4+ | ammonium ion |
| NIES | National Institute for Environmental Studies |
| NIWA | National Institute of Water and Atmospheric Research |
| NMAT | Nighttime Marine Air Temperature |
| NMHC | non-methane hydrocarbon |
| NMVOC | non-methane volatile organic compound |
| NO | nitric oxide |
| NO2 | nitrogen dioxide |
| NO3 | nitrate radical |
| NOAA | National Oceanic and Atmospheric Administration |
| NOx | reactive nitrogen oxides (the sum of NO and NO2) |
| NPI | North Pacific Index |
| NPIW | North Pacific Intermediate Water |
| NPP | net primary productivity |
| NRA | NCEP/NCAR reanalysis |
| NVAP | NASA Water Vapor Project |
| O(1D) | oxygen radical in the 1D excited state |
| O2 | molecular oxygen |
| O3 | ozone |
| OASIS | Ocean Atmosphere Sea Ice Soil |
| OCTS | Ocean Colour and Temperature Scanner |
| ODS | ozone-depleting substances |
| OECD | Organisation for Economic Co-operation and Development |
| OGCM | Ocean General Circulation Model |
| OH | hydroxyl radical |
| OIO | iodine dioxide |
| OLR | outgoing longwave radiation |
| OMI | Ozone Monitoring Instrument |
| OPAC | Optical Parameters of Aerosols and Clouds |
| PCMDI | Program for Climate Model Diagnosis and Intercomparison |
| pCO2 | partial pressure of CO2 |
| PDF | probability density function |
| PDI | Power Dissipation Index |
| PDO | Pacific Decadal Oscillation |
| PDSI | Palmer Drought Severity Index |
| PET | potential evapotranspiration |
| PETM | Palaeocene-Eocene Thermal Maximum |
| PFC | perfluorocarbon |
| Pg | petagram (1015 grams) |
| PMIP | Paleoclimate Modelling Intercomparison Project |
| PMOD | Physikalisch-Meteorologisches Observatorium Davos |
| PNA | Pacific-North American pattern |
| PNNL | Pacific Northwest National Laboratory |
| PNV | potential natural vegetation |
| POA | primary organic aerosol |
| POC | particulate organic carbon |
| POLDER | Polarization and Directionality of the Earth’s Reflectance |
| POM | particulate organic matter |
| ppb | parts per billion |
| ppm | parts per million |
| PR | Precipitation Radar |
| PREC/L | Precipitation Reconstruction over Land (PREC/L) |
| PROVOST | Prediction of Climate Variations on Seasonal to Interannual Time Scales |
| PRP | Partial Radiative Perturbation |
| PSA | Pacific-South American pattern |
| PSC | polar stratospheric cloud |
| PSMSL | Permanent Service for Mean Sea Level |
| PSU | Pennsylvania State University |
| psu | Practical Salinity Unit |
| QBO | Quasi-Biennial Oscillation |
| RATPAC | Radiosonde Atmospheric Temperature Products for Assessing Climate |
| RCM | Regional Climate Model |
| REA | Reliability Ensemble Average |
| REML | restricted maximum likelihood |
| RF | radiative forcing |
| RFI | Radiative Forcing Index |
| RH | relative humidity |
| RMS | root-mean square |
| RSL | relative sea level |
| RSS | Remote Sensing Systems |
| RTMIP | Radiative-Transfer Model Intercomparison Project |
| SACZ | South Atlantic Convergence Zone |
| SAFARI | Southern African Regional Science Initiative |
| SAGE | Stratospheric Aerosol and Gas Experiment or Centre for Sustainability and the Global Environment |
| SAM | Southern Annular Mode or Stratospheric Aerosol Measurement |
| SAMS | South American Monsoon System |
| SAMW | Subantarctic Mode Water |
| SAR | Second Assessment Report or Synthetic Aperture Radar |
| SARB | Surface and Atmosphere Radiation Budget |
| SARR | Space Absolute Radiometric Reference |
| SAT | surface air temperature |
| SCA | snow-covered area |
| SCIAMACHY | SCanning Imaging Absorption SpectroMeter for Atmospheric CHartographY |
| SCM | Simple Climate Model |
| SeaWiFs | Sea-Viewing Wide Field-of-View Sensor |
| SF6 | sulphur hexafluoride |
| SH | Southern Hemisphere |
| SIO | Scripps Institution of Oceanography |
| SIS | Small Island States |
| SLE | sea level equivalent |
| SLP | sea level pressure |
| SMB | surface mass balance |
| SMM | Solar Maximum Mission |
| SMMR | Scanning Multichannel Microwave Radiometer |
| SO | Southern Oscillation |
| SO2 | sulphur dioxide |
| SO4 | sulphate |
| SOA | secondary organic aerosol |
| SOHO | Solar Heliospheric Observatory |
| SOI | Southern Oscillation Index |
| SOM | soil organic matter |
| SON | September, October, November |
| SORCE | Solar Radiation and Climate Experiment |
| SPARC | Stratospheric Processes and their Role in Climate |
| SPCZ | South Pacific Convergence Zone |
| SPM | Summary for Policymakers |
| SRALT | Satellite radar altimetry |
| SRES | Special Report on Emission Scenarios |
| SSM/I | Special Sensor Microwave/Imager |
| SST | sea surface temperature |
| STARDEX | STAtistical and Regional dynamical Downscaling of EXtremes for European regions |
| STE | stratosphere-troposphere exchange |
| STMW | Subtropical Mode Water |
| SUNY | State University of New York |
| Sv | Sverdrup (106 m3 s–1) |
| SW | shortwave |
| SWE | snow water equivalent |
| SWH | significant wave height |
| T/P | TOPEX/Poseidon |
| T12 | HIRS channel 12 |
| T2 | MSU channel 2 |
| T2LT | MSU lower-troposphere channel |
| T3 | MSU channel 3 |
| T4 | MSU channel 4 |
| TAR | Third Assessment Report |
| TARFOX | Tropospheric Aerosol Radiative Forcing Experiment |
| TBO | Tropospheric Biennial Oscillation |
| TCR | transient climate response |
| TEAP | Technology and Economic Assessment Panel |
| TGBM | Tide Gauge Bench Mark |
| TGICA | Task Group on Data and Scenario Support for Impact and Climate Analysis (IPCC) |
| THC | Thermohaline Circulation |
| THIR | Temperature Humidity Infrared Radiometer |
| TIM | Total Solar Irradiance Monitor |
| TIROS | Television InfraRed Observation Satellite |
| TMI | TRMM microwave imager |
| TOA | top of the atmosphere |
| TOGA | Tropical Ocean Global Atmosphere |
| TOM | top of the model |
| TOMS | Total Ozone Mapping Spectrometer |
| TOPEX | TOPography EXperiment |
| TOVS | TIROS Operational Vertical Sounder |
| TransCom 3 | Atmospheric Tracer Transport Model Intercomparison Project |
| TRMM | Tropical Rainfall Measuring Mission |
| TSI | total solar irradiance |
| UAH | University of Alabama in Huntsville |
| UARS | Upper Atmosphere Research Satellite |
| UCDW | Upper Circumpolar Deep Water |
| UCI | University of California at Irvine |
| UEA | University of East Anglia |
| UHI | Urban Heat Island |
| UIO | University of Oslo |
| UKMO | United Kingdom Meteorological Office |
| ULAQ | University of L’Aquila |
| UMD | University of Maryland |
| UMI | University of Michigan |
| UNEP | United Nations Environment Programme |
| UNFCCC | United Nations Framework Convention on Climate Change |
| USHCN | US Historical Climatology Network |
| UTC | Coordinated Universal Time |
| UTRH | upper-tropospheric relative humidity |
| UV | ultraviolet |
| UVic | University of Victoria |
| VIRGO | Variability of Irradiance and Gravity Oscillations |
| VIRS | Visible Infrared Scanner |
| VOC | volatile organic compound |
| VOS | Voluntary Observing Ships |
| VRGCM | Variable-Resolution General Circulation Model |
| W | watt |
| WAIS | West Antarctic Ice Sheet |
| WCRP | World Climate Research Programme |
| WDCGG | World Data Centre for Greenhouse Gases |
| WGI | IPCC Working Group I |
| WGII | IPCC Working Group II |
| WGIII | IPCC Working Group III |
| WGMS | World Glacier Monitoring Service |
| WMDW | Western Mediterranean Deep Water |
| WMO | World Meteorological Organization |
| WOCE | World Ocean Circulation Experiment |
| WRE | Wigley, Richels and Edmonds (1996) |
| WWR | World Weather Records |
| ZIA | 0°C isotherm altitude |
| τaer | aerosol optical depth |