In the prologue to the “The Family of Man,” the extraordinary 1955 photographic exhibition at the Museum of Modern Art in New York, Carl Sandburg wrote: “The first cry of a newborn baby in Chicago or Zamboango, in Amsterdam or Rangoon, has the same pitch and key, each saying, ‘I am! I have come through! I belong! I am a member of the Family.’ …

“Everywhere the sun, moon and stars, the climates and weathers, have meanings for people. Though meanings vary, we are alike in all countries and tribes in trying to read what the sky, land, and sea say to us. Alike and ever alike we are on all continents in need of love, food, clothing, work, speech, worship, sleep, games, dancing, fun. From the tropics to arctics humanity lives with these needs so alike, so inexorably alike.”

These remarkable words speak clearly to us across more than a half-century, and they now strike quietly deep but too often denied concerns: What are the sky, land and sea saying to us now?

Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global average sea level.

A United Nations Climate Change Conference of extraordinary importance is being held in Copenhagen Dec. 7 to 18. It is the 15th meeting of the Conference of Parties, and its goal is to craft a global climate-energy agreement to take effect after 2012, when the Kyoto Protocol expires.

The Kyoto Protocol was adopted at the third Conference of Parties in December 1997 in Kyoto, Japan. Most industrialized nations and some central European economies in transition agreed to legally binding reductions in greenhouse gas emissions. Between 2008 and 2012 — defined as the “first emissions budget period” — these reductions would amount to an average of 6 percent to 8 percent below 1990 levels. The United States would have been required to reduce its total emissions an average of 7 percent below 1990 levels. However, neither the Bill Clinton nor the George W. Bush administration sent the protocol to Congress for ratification, and in 2001, the Bush administration explicitly rejected the Kyoto Protocol.

Conferences of Parties and the protocols they produce are hostage to relatively short-term politics, but this needs to be juxtaposed against the dynamical nature of the climate system, whose warming is unequivocal: Anthropogenic warming and sea-level rise would continue for centuries due to the timescales associated with climate processes and feedbacks, even if greenhouse gas concentrations were to be stabilized.

What does it take to stabilize greenhouse gas concentrations in the atmosphere? If we focus on carbon dioxide alone, which is dominant and far from stabilized, the answer begins to clarify why we have been somewhat indifferent regarding what the sky, land and sea are saying to us.

To stabilize the concentration of carbon dioxide in the atmosphere, we must do far more than stabilize emissions at current levels — and we are far from even doing that much. We need to reduce globally carbon dioxide emissions by roughly 80 percent. This would require reductions not on the economic margins of today’s industrial societies, but rather at the very core of modern economies. This is why the “denial battle” is being waged with such vigor.

In addition, the challenging reality of the longer-term carbon-climate dynamic is why we must begin to address not just reductions but also adaptation strategies. This is not tossing in the towel on the goal of changing our emissions course; rather, it acknowledges that we already have committed to a future climate altered by human activity, no matter what reductions we might achieve in the future.

A scientific and societal question underlying any discussion on addressing the climate challenge is, “How will the future of the planet unfold?” This problem of seeing beyond the glass darkly is particularly acute when we try to make projections about a system, such as the climate system or more generally the Earth system, that has significant nonlinearities and chaotic aspects; that has widely varying time constants; that has not only physical dynamics but also chemical and biological interactions; and that directly involves humans and their institutions.

There do, however, appear to be predictable, coherent modes of climate variability, such as El Niño, that not only support a sense of optimism in attacking the prediction-projection problem but also offer measurable targets that can be used as benchmarks for evaluating our understanding of the climate system. In addition, predicting these modes of climate variability represent valuable contributions in themselves.

But progress in evaluating our abilities to project will be made only if we openly and aggressively test climate models. We must be able not only to predict patterns such as El Niño with accuracy but also to capture multiple aspects of the climate system today and yesterday and tomorrow. The litmus test of climate models comes when we compare their calculations against a broad suite of data from Earth-observing satellites. These global observations are providing an ever more challenging and necessary series of acid tests for our models. There is no other way.

Finally, as climate change assumes a more central place in human affairs, scientists are being thrust into the unfamiliar and uncomfortable arena of a heated and potentially divisive international debate about the very nature and severity of global environmental change and its implications for human ways of life. Nevertheless, and despite the risks, scientists must accept the responsibility of developing fully, and communicating openly and clearly, the essential knowledge that societies must have in order to decide how they will respond to climate change.

The linked challenges of confronting and coping with global environmental changes and addressing and securing a sustainable future are daunting for all cultures, but they are not insurmountable. These challenges can be met, but only with a new and even more vigorous approach to observing and understanding our changing planet and ourselves. There must also be a concomitant commitment by all to altering our actions. Those that consume the most must take the greatest of action. We simply must take some of the pressure off the Earth.

In 1968, on seeing the image taken on the Apollo 8 mission of the Earth rising above the moon’s horizon, the poet Archibald MacLeish, said, “To see the Earth as we now see it, small and blue and beautiful in that eternal silence where it floats, is to see ourselves as riders on the Earth together, brothers on that bright loveliness in the unending night — brothers who see now they are truly brothers.”

This image should be a guidepost for us. Humanity, for the sake of the Earth’s family, must now honestly confront the future as riders on the Earth together.


Berrien Moore
is executive director of  Climate Central and was co-chairman of the National Research Council’s first decadal survey on Earth science and applications.