Global Change

 Global Warming
    1. - Great Experiment on Planet Earth
    2. - Kyoto & Its Implications
    3. - The Rise of CO2 & Warming
    4. - The Scientific Assessment
    5. - Controversy & Debate
    6. - Scientific Background
    7. - Predicting the Future
    8. - Predictions for California
    9. - About this Site
    10. - Sources of Information

 The Greenhouse Effect
 The Keeling Curve

GLOBAL WARMING: The Great Experiment on Planet Earth

  • What is the most important event in the past millennium?
  • What is the most important event in the past century?
Answers to these questions will vary, of course, depending on who responds. A physicist might bring up the discoveries of Galileo or Newton for one, and those of Albert Einstein or Max Planck for the other. A historian might think of Columbus’s landfall in the Caribbean, and of the collapse of the British Empire or that of the Soviet Union. An engineer might suggest the invention of steamships and getting to the Moon. A sociologist might select the discovery of microbes and the military applications of nuclear energy.

Without doubt, all of these events qualify as enormously important in the history of humankind.

However, looking at the time scale of millions of years, a geologist would have to say that the most important event was the fact that human impact on the natural environment became the dominant geologic force in the last millennium, largely through the expansion of agriculture and fisheries. As to the last hundred years, the most important development is the alteration of the atmosphere. We are burning coal and oil at a rate roughly a hundred thousand times greater than it can re-form. In consequence, we have driven the trace gas composition of the atmosphere into a range not experienced in the last million years.

As expected, the result is global warming. The release of vast amounts of trace gases to the atmosphere is a great experiment on Earth’s climate. It is not a controlled experiment, as in the laboratory of a scientist. It is not known how long the experiment will run, nor how much the trace gases will build up. We do not have a good idea of what to expect in terms of overall warming, nor how different degrees of such warming would influence climatic conditions. Thus it is an experiment whose course and outcome are uncertain.

The rise of carbon dioxide as measured by Charles D. Keeling and collaborators on the top of Mauna Loa. The unit “ppm” stands for “parts per million by volume.” The rise results from burning of fossil fuels, with some contribution from deforestation and production of cement.
We are passengers on a voyage into fog-shrouded uncharted waters. Some say, there are reefs ahead. Others say, there are none. The truth is, no one knows.

Global warming has become, in the last 15 years or so, a major issue of international proportions. As documented in the reports of the Intergovernmental Panel on Climate Change (IPCC), this phenomenon is real, and it has potentially serious consequences. We should expect (and we apparently observe already) regional changes in availability of water for agriculture, large-scale stress in the coral reef ecosystems, melting of permafrost in high latitudes, destruction of mountain glaciers in low latitudes, and expansion of tropical insects (including carriers of disease).

The risks to society inherent in such expectations are substantial. Equally great are the uncertainties surrounding climate prediction. In consequence, the media have given much attention to fringe opinions on the subject, both on the alarmist side and on the side espousing denial. As a result, the intellectual level of discussion has suffered, and the search for solutions has been slowed.

In this site, we attempt to provide, to the general public, what we consider the minimum background for intelligent discussion of the topic. We are especially interested in providing this basic background to teachers in high- and middle-schools, mindful that they carry the responsibility of getting it straight when talking to their students.

It was at Scripps Institution of Oceanography (SIO/UCSD) that a central problem of CO2 emissions was first recognized, in the 1950s. As oceanographer Roger Revelle (director of SIO from 1950 to 1964) pointed out, the ocean cannot be relied on to absorb the excess CO2 immediately and on a short time scale, which means that a large portion of it will pile up in the atmosphere. Continuous measurements of atmospheric CO2 since 1957, at Mauna Loa, show that indeed about one half of the CO2 emitted has stayed in the air. These measurements, made under the direction of SIO scientist Charles D. Keeling, are the longest running data series on atmospheric chemistry in the world. They are the backbone of the scientific underpinnings for the global warming issue. The rise in the greenhouse gas CO2 (produced from burning fossil fuel) to levels well beyond the range ever experienced during the entire time since humans first appeared on Earth: this is arguably the most important event of the last century and indeed of the last millennium. (The natural background in the concentration of CO2 is near 275 ppm, as seen in ice core data.)

This event irreversibly changes the framework within which humans, animals, plants and all other living things on land and in the sea conduct their business of interaction and survival. The process continues. We are still at the beginning, since so much coal, oil and gas remain to be recovered and burned.

Picture of the Keeling building on Mauna Loa

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