Environmental History Timeline May 9, 2013

First record of average daily CO2 concentration exceeding 400 PPM

May 9, 2013, NOAA's Mauna Loa Observatory recorded an average daily CO2 concentration in the atmosphere above 400 parts per million. This is not a surprise but nevertheless it's a milestone moment in atmospheric science. Charles Keeling first began measuring CO2 concentrations at Mauna Loa, Hawaii in 1958, measurement continues. Graphical representation of the data, known as the Keeling Curve, illustrates seasonal variation and the global trend. Many climate scientists suggest that we must find ways to reduce CO2 to 350 PPM, the 1990 level, to avoid catastrophic ecological, social and economic outcomes during the mid 21st Century.

Keeling Curve illustration from the keepers of the data, UC San Diego

Small amounts of CO2 in the atmosphere wield disproportionate impact on surface temperatures. This phenomenon is known as the greenhouse effect. Like window glass covering a greenhouse, CO2, methane, and other heat holding compounds known as greenhouse gases allow light to pass through to earth's surface, heating things up, but capture and hold the heat in; as CO2 and other greenhouse gases increase, more heat, long-wave energy emanated from the surface, is held in the lower atmosphere by the greenhouse gases.

Proxy data from ice core and ocean sediment core chemistry tells us surface temperature has changed in the past. Oxygen isotope ratios, CO2 and other measures indicate past temperatures. The last time CO2 PPM was this high was three to five million years ago during the Pliocene Epoch, before the advent of the current Ice House Climate and its big ice sheets that recently reshaped the earth's surface. The present global C02 increase is destabilizing global climate and ecosystems due to the unprecedented rate of increase. The rate at which temperature is changing is outpacing the capacity of human and ecological systems to adapt. The current trend suggests global CO2 concentration will reach 450 PPM in the not so distant future. Atmospheric warming is expected to continue to parallel this increase. Global warming occurs most rapidly at the poles where ice is melting at unprecedented rates. More than polar bears are at risk, many are concerned that melting of permafrost is releasing trapped methane, one of the most powerful greenhouse gases. Permafrost areas are methane generators on ice. As the ice melts, methane frozen in the permafrost, and generated by increased decay of long accumulated organic materials, is liberated. Possible serious consequences are rarely discussed openly outside of knowledgeable circles and professional journals.

Regrettably, scientists who are willing to share their results and predict outcomes based on climate modelling are attacked both personally and professionally for coming out with their data and concerns. A small number of well funded conservative political groups defending fossil fuel subsidies successfully sustain a political climate of doubt around the issue. Dedicated scientists are portrayed as fear mongers and nefarious actors in grand schemes to divert public resources to their laboratories, ridiculous notions. If only climate modellers were subsidized as generously as energy producers! The press and special interest groups too often shoot the messengers. The press gives "equal time" to both sides of an artificial controversy. A tiny number of climate change deniers' voices are aired whenever new research brings the problem into focus. Just a few spokespersons associated with a handful of organizations are able to sustain doubt and controversy, though consensus opinion among science groups contradicts both doubt and controversy. It's kind of like giving equal time to a witch doctor when a new medical paper is published by researchers.