Article Executive Director's Message Chris McKenzie

Climate Change at a Tipping Point

Every few hundred years an individual or idea comes along that focuses the lens through which we see our world and our role in it. For scientists this is known as a “scientific revolution.” 

The rest of us have by now become familiar with the term “paradigm shift” from Thomas Kuhn’s pioneering work in his 1962 book The Structure of Scientific Revolutions. He defined it as a change in basic assumptions within the ruling theory of science. Although Kuhn himself apparently did not do so, the term is now widely used to describe social or political revolutions as well, such as the signing of the Magna Carta in England in 1215 or the Declaration of Independence in 1776.

It is well understood that scientific paradigm shifts also have applications outside the context of science. Just as advances in medical science have extended human life in recent decades (and caused attendant challenges with our Social Security system and other programs), the convergence of scientific views around specific issues (evolution, for example) can have a profound effect on how nonscientists view their world. When scientific theories are the basis for advances in technology, however, more frightening social and political changes can occur. One need look no farther than the way in which advances in nuclear research in the 1940s made possible the development (and limited use) of nuclear weapons for war purposes and nuclear power production for peaceful uses.

A few years ago, the author Malcolm Gladwell introduced us to the concept of the “tipping point” — how ideas reach common acceptance in society, often as a result of complex social interactions in which critical information, scientific and otherwise, is exchanged until it becomes popular wisdom.

So what do paradigm shifts and tipping points have to do with cities? You could safely say: anything and everything.

Cities Lead the Way

As the most developed form of human settlement, cities embody reactions to the social trends and ideas that affect mankind. The “City Beautiful” movement of the late 19th and early 20th centuries can be seen as a direct result of public concern about the evils of industrial pollution in our urban areas and the importance of parks and open space in expanding human happiness and health.

Today, few city leaders would fail to see a connection between the expansion of the early streetcar system in California and the development of our first suburban cities, only to be followed by the demise of those same streetcar systems and the development of even more far-flung suburban communities when automobiles became popular and gasoline was cheap. These ideas and developments have significantly affected our view of the modern American city, and the next generation of ideas may be even more profound. The speed with which “climate change” has become the top issue on most public officials’ list of concerns indicates where the next challenge may be coming from.

In 1988, the Intergovernmental Panel on Climate Change was established by the United Nations Environmental Program and the World Meteorological Organization to assess the scientific, technical and socio-economic information relevant for the understanding of human-induced climate change, its potential impacts and options for mitigation and adaptation. After 24 years of research and analysis, the 2,000 scientists from around the world who have been engaged in this important undertaking issued a report recently. Called Climate Change 2007: The Physical Science Basis (Summary for Policy-Makers), the report revealed some shattering conclusions, including:

Most of the observed increase in globally averaged temperatures since the mid-20th century is very likely (i.e., greater than 90 percent) due to the observed increase in anthropogenic greenhouse gas concentrations….
… The observed widespread warming of the atmosphere and ocean, together with ice mass loss, supports the conclusion that it is extremely unlikely (i.e., less than 5 percent) that global climate change of the past 50 years can be explained without external forcing, and very likely that it is not due to known natural causes alone.

The fact that 2,000 scientists agreed about man’s impact on global warming is extraordinarily significant. This and related reports are being viewed, along with former Vice President Al Gore’s documentary An Inconvenient Truth, as a new framework for political and social action. Across this country and around the world, people are taking stock of their personal role in hastening global warming and what can be done to deal with its consequences.

U.S. Mayors Make a Commitment

Nationwide, city officials are leading the way in advancing new strategies to reduce climate change. In the past year, more than 300 mayors, representing over 50 million Americans, have signed the U.S. Mayors Climate Protection Agreement. Under the agreement, participating cities commit to take the following actions:

  • Strive to meet or beat the Kyoto Protocol targets in their own communities, through actions ranging from anti-sprawl land use policies to urban forest restoration projects to public information campaigns;
  • Urge their state governments and the federal government to enact policies and programs to meet or beat the greenhouse gas emission reduction target suggested for the United States 
  • in the Kyoto Protocol (7 percent reduction from 1990 levels by 2012); and
  • Urge the U.S. Congress to pass the bipartisan greenhouse gas reduction legislation, which would establish a national emission trading system.

For more information about the U.S. Mayors Climate Protection Agreement, including how to sign it and who is already on board, visit  

In the early 20th century, the harnessing of electricity and development of the internal combustion engine affected the form and function of cities. What effects can we expect from the examination we are undertaking at present about how we can limit greenhouse gas emissions? While it is impossible to tell with certainty, here are a few areas in which some change may occur.

Transportation and Land Use Planning

The transportation sector is responsible for the largest share of climate change emissions in California. State leaders have initially focused on lowering emissions from vehicles and expanding the production of alternative fuels. It is already widely known that reducing trips by single occupant vehicles saves energy; the same can be said for carbon emissions. While I am still waiting for clean personal aircraft like those we saw as children in the cartoon The Jetsons, increasing the number of clean-running high-speed buses seems much more cost effective and likely.

Moreover, many expect cities to factor in climate change control strategies into the land use and housing elements of future general plans. Reducing greenhouse gas emissions may become the overarching goal of the 21st century — one so significant that it trumps all others as cities contemplate development and redevelopment in the next few decades. What has been called “smart growth” in the past decade may become the equivalent of “green growth.”

Green Public Buildings

The interest among city officials in making existing public buildings more energy efficient and climate friendly has reached new levels. The U.S. Conference of Mayors and the American Institute of Architects recently formed a partnership to promote integrated, sustainable building design with a goal of reaching 50 percent fossil fuel reduction by 2010 and carbon-neutral buildings by 2030. Their green building toolkit can be accessed at

Rebuilding the Urban Forest

A number of cities, including some in California, are starting massive new tree planting programs to help rebuild the urban forest. Like green buildings, urban trees not only help reduce greenhouse gases, they also reduce temperatures on hot days and thus the energy demand to power air conditioning systems.

Concluding With Western Siberia

Everyone engaged in shaping public policy knows that anecdotes can influence policy-makers. I came across a particularly startling one during the course of doing research for this column. Western Siberia has been experiencing the fastest rate of warming on the planet in recent years. It contains an area the size of Germany and France combined that, after being frozen for the past 11,000 years, began thawing three to four years ago.

The area consists primarily of peat bogs containing large amounts of methane. As the bogs melt during the next decades, scientists estimate that the annual methane releases will be roughly equal to the methane released annually from the world’s wetlands and agriculture. It would effectively double atmospheric levels of the gas, leading to a 10 to 25 percent increase in global warming.

Concern about climate change has become widespread in our country and abroad because of this and similar stories. While mistakes will no doubt be made by federal, state and local policy-makers in addressing global warming in the years to come, there now seems near-universal acceptance of the fact that if we fail to act, it will be at our and other species’ peril. Never has the saying, “Think globally, act locally” had more meaning.

This article appears in the May 2007 issue of Western City
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