Reviewing recent climate annals to establish a sense of perspective on present climatic events is valuable, but two haphazard efforts made it clear that such a year-to-year history means most if the accounts are consistent, with the same climate indicators. Before returning to them it's worth spending some time on the main lines of evidence and natural occurrences which scientists use to help explain climate change.
NOAA has a list of Essential Climate Variables (ECVs), measurable aspects of the climate which are monitored around the world. They have consistent enough spatial coverage and to provide an intelligible picture of the world, and have been collected for long enough to provide meaningful information on trends. A partial list of ECVs (presently there are 54, most of which can be tracked by satellite):
Atmospheric surface: Air temperature, precipitation, air pressure, water vapor, wind speed and direction, radiation budget;
Atmospheric upper air: earth radiation budget, temperature, water vapor, cloud properties, wind speed and direction, lightning;
Atmospheric composition: carbon dioxide, methane, ozone, nitrous oxide, various hydrocarbons, aerosols, aerosol precursors;
Ocean surface: temperature, salinity, sea level, sea ice, currents, sea state, wind stress, heat flux
Ocean subsurface: temperature (used to calculate heat content), salinity, currents;
Ocean chemistry: inorganic carbon (i.e. dissolved CO2), oxygen, nutrients, nitrous oxide, color (monitored but not widely enough to be an ECV: pH);
Ocean biology: marine habitats, plankton;
Cryosphere: ice sheets & ice shelves, snow cover, glaciers, permafrost;
Biosphere: land cover, above-ground biomass, albedo, fire, land surface temperature, soil carbon;
Hydrosphere: river discharge, lake level, groundwater, soil moisture, ground evaporation.
The list expands with time as improved methods, spatial coverage and dataset age increase. One of the basic tenets of environmental monitoring, for global warming or anything else, is to have self-consistent data streams, and as many as possible well-distributed spatially, to allow for meaningful comparison over time. The list of ECVs is absolutely central to that, and it includes what is called the “backbone of climate change science”, surface atmospheric CO2 concentration.
A small subset of these variables will be discussed in the State of the Climate summaries.
Tomorrow: ocean oscillations which affect climate 1: a quick review of El Niño (ENSO).
Be brave, and be well.
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