In recent years, I have been to many of the yearly United Nations Conference of the Parties (COP) meetings. In this case, the document that nearly all countries are parties to is called the UN Framework Convention on Climate Change (UNFCCC). This document was signed at the Earth Summit, a famous international event held in Rio de Janeiro, Brazil, in 1992. At the time, the Earth Summit was the largest gathering of world leaders ever held. Representatives of 178 nations participated in the Earth Summit, and 117 heads of state attended. The objective of the UNFCCC is “stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic [i.e., human-caused] interference with the climate system.” COP meetings have been held in most years since the Earth Summit. The first COP meeting, known as COP 1, was held in Berlin in 1995. There have been almost 30 COP meetings since then. Each COP meeting attracts thousands of people and lasts about 12 days. These COP meetings have provided opportunities for countries to discuss topics such as the reduction of global emissions of carbon dioxide and other heat-trapping substances.

COP 13 was held in Bali, Indonesia, in December 2007. I was there. Two months earlier, the world had learned that the 2007 Nobel Peace Prize was to be awarded equally between Al Gore, the American politician, and the Intergovernmental Panel on Climate Change (IPCC). I think it is safe to say that in 2007, almost every American knew something about Al Gore, who had been the US Vice President from 1993 to 2001 and was the unsuccessful Democratic party candidate for President in the 2000 election. Gore had been a student at Harvard from 1965 to 1969. He had wide interests but was said not to do well in science classes, and he did not take mathematics courses. However, in his senior year at Harvard, Gore attended a course taught by Roger Revelle, an oceanographer who had been Director of Scripps Institution of Oceanography and who had been the leader in the founding of the University of California, San Diego. Al Gore later spoke often of his high regard for Roger Revelle and always credited Revelle as being the initial inspiration for Gore’s intense interest in climate change and other environmental issues. The 2007 Nobel Prize announcement said of Gore, “He is probably the single individual who has done most to create greater worldwide understanding of the measures that need to be adopted.”

Gore was indeed well known in 2007. However, I am confident that in 2007 relatively few Americans knew anything about the IPCC, the organization that shared the 2007 Nobel Peace Prize with Al Gore. As for me, in 2007 I had just finished three years of working almost full time for the IPCC, and I was thrilled by the Nobel Prize award. I had been Coordinating Lead Author for the 2007 IPCC Fourth Assessment Report. The chapter of this report that I had been a coleader of was called Historical Overview of Climate Change. I was also one of the signers of the 2007 Bali Climate Declaration by Scientists. In this chapter, I tell the story of the IPCC Fourth Assessment Report and the COP 13 meeting in Bali.

Reflections on the UN Climate Change Negotiations in Bali (2008)

The IPCC, long regarded as the single most trustworthy source of information on climate science, states unequivocally that the Earth’s climate is warming rapidly and that we are now more than 90% certain that human activities have caused most of the observed warming in recent decades. The research behind these findings, first published in the IPCC’s landmark 2007 Fourth Assessment Report (known as AR4), is rock-solid science. In recognition of the importance and excellence of its work in bringing climate science to the attention of policymakers and the public, the IPCC shared the 2007 Nobel Peace Prize. The prize was awarded jointly to the IPCC and to Al Gore, the US Vice President from 1993 to 2001, “for their efforts to build up and disseminate greater knowledge about man-made climate change, and to lay the foundations for the measures that are needed to counteract such change.”

Everybody at the UN Framework Convention on Climate Change (UNFCCC) negotiations, which took place in December 2007 in Bali, Indonesia, was aware of the IPCC’s latest conclusions. These negotiations are an annual event, and the Bali meeting attracted more than 10,000 people, including a large press corps and many stakeholders from the energy industry and environmental interest groups. I attended COP 13 in Bali representing a group of 200 climate science experts. We wanted to inject some quantitative scientific substance into the negotiations.

Climate science is now able to provide significant predictive power, meaning the science summarized in the 2007 IPCC AR4 report can link specific concentrations of greenhouse gases with the associated climatic consequences. How much sea level will rise or how much temperatures will change does depend on how much humanity allows greenhouse gas amounts to increase. Yet, what is said publicly by the negotiators almost never refers to the science in this way. Thus, in 2008 the term “dangerous” in the UNFCCC objective of preventing dangerous anthropogenic interference with the climate system remained quantitatively undefined.

As a veteran observer of these difficult negotiations, I was reminded of the dark days of an earlier environmental crisis, the human-caused depletion of the stratospheric ozone layer, dramatized by the creation of an ozone hole over Antarctica. In the mid-1980s, frustrated by the lack of progress in reaching an agreement to end the manufacture of the chemicals that caused the problem, a prominent US atmospheric scientist, F. Sherwood Rowland, who would later share the Nobel Prize in chemistry, told a journalist, “What’s the use of having developed a science well enough to make predictions, if in the end, all we’re willing to do is stand around and wait for them to come true!”

Today, I feel exactly the same way about the procrastination and posturing that too many governments have substituted for meaningful action to limit global warming. The statements attributed to the United States, especially by Paula Dobriansky, who headed the US delegation, and James Connaughton of the White House Council on Environmental Quality, have been widely reported, and have clearly caused offense to many countries. But I do not want to single out the United States. China was notably unwilling to accept any restrictions on its greenhouse gas emissions, and several other countries followed or welcomed the US lead. The struggle to have major countries agree to specific targets and timetables has been unsuccessful so far.

Meanwhile, the rate at which humankind is emitting greenhouse gases into the atmosphere continues to increase every year. Only a sharp reversal of this trend offers hope of stabilizing the amount of these gases in the atmosphere and limiting climate change.

The international group that I represented in Bali went to publicize “The 2007 Bali Climate Declaration by Scientists.” Signatories of this document include many leaders of the climate science research community whose excellence and expertise are beyond doubt. They include Nobel laureate Paul Crutzen; National Academy of Sciences members Robert Dickinson, Kerry Emanuel, Stephen Schneider, and Carl Wunsch; quite a few lead authors and coordinating lead authors of the IPCC Fourth Assessment Report; and several heads of major research institutions. But we each signed the declaration representing only ourselves, not the IPCC, our employers, or any other organization.

“The 2007 Bali Climate Declaration by Scientists” had the immediate goal of asking the negotiators to reach an agreement limiting global warming to 2 degrees Celsius (3.6 degrees Fahrenheit) above the preindustrial temperature. Global warming is simply a symptom or measure of the magnitude of climate change, and 2 degrees Celsius is widely thought to be a low enough reasonable consensus estimate to prevent dangerous climate change. In fact, the European Union and other countries have already formally adopted this limit.

What actions are needed to ensure that the 2-degree Celsius target is not exceeded? This is where climate science has a key role to play. While we cannot know safe greenhouse gas concentrations or emission limits exactly – just as medical science cannot specify a precise value as a safe limit on, say, cholesterol – the science summarized in the 2007 IPCC report does provide excellent quantitative guidance.

The IPCC, which is mandated to be policy-neutral, cannot make policy recommendations. However, once a policymaker accepts 2 degrees Celsius above preindustrial levels as a target upper bound on allowable warming, then the IPCC report describes approximately what the limit must be for greenhouse gas concentration, in what year carbon dioxide emissions must peak before declining, and what percentage reduction in emissions is needed. (The information is succinctly summarized in table SPM.5 in the Working Group III Summary for Policymakers and is repeated as table 5.1 in the Fourth Assessment Synthesis Report.)

Taking a 2-degree-Celsius limit on global warming as the goal, the Bali declaration states,

The outcome of the Bali meeting was deeply disappointing, but not surprising. The science cannot make a subjective judgment on how much warming is acceptable or say in what ways society should stabilize greenhouse gas concentrations. Those are political judgments. In the end, after much bitterness, the negotiators reached an agreement to continue negotiating over the next two years, but they did not come close to agreeing on the substance of such an agreement. It is true that many international agreements took quite a few years to materialize. What is clear scientifically, however, is that time is running out. If an agreement is not possible in the next two, three, or four years, it may be too late to prevent serious climatic consequences.

At subsequent climate negotiations, the important question will be whether governments are willing to implement and enforce an effective agreement to halt the rapid rise in atmospheric carbon dioxide and other pollutants that cause global warming. My personal view is that governments, especially democratically elected ones, will respond to the will of their people. And what will it take to make large numbers of people increase the priority that they now give to this issue? Perhaps it will take some sudden, shocking, and unambiguous climate event such as the destabilization of a large part of the Greenland ice sheet and a sharp increase in sea level. The ozone hole would be a parallel case historically. It would be a pity if we needed to wait for that, which is like waiting to have a heart attack rather than heeding a physician’s warnings about cholesterol and weight. In climate science as in medical science, prevention is better than a cure, but not everybody is wise enough to act early.

Governments and businesses worldwide, and ultimately, humankind as a whole, will determine what actions will be taken. Climate science, however, is able to provide highly useful input to this policymaking process. Making wise climate policy includes taking sound climate science into account. The future depends on it.