Hurricane Isabel: Questions and Answers about Global Warming and Climate Change


Weather-related disasters are occurring with ever-greater intensity and frequency around the world. At the same time, Arctic ice and glaciers are melting, and diseases like West Nile virus and malaria are spreading. Are these events caused by climate change? Are they simply a reflection of the climate's natural variability or do they signal the revolt of Mother Nature? Do we humans contribute to extreme weather patterns and climate change? If so, what can we do to prevent future disasters? Answers to these and other questions follow.

Q. What does Hurricane Isabel have to do with global warming?

A. Although it is impossible to say that any individual storm is caused by global warming, there are clear connections. Heat in the atmosphere is the fuel that leads to stormy weather, and meteorological studies indicate that rising temperatures will tend to increase the frequency and intensity of extreme storms—particularly the violent thunderstorms that occur in some parts of the world. Hurricanes and cyclones are fueled by the warm tropical oceans, and as ocean temperatures increase, their intensity may increase as well. In addition, there are many other factors that contribute to hurricanes, and it is uncertain whether their number will rise due to global warming. However, rising sea levels, a certain result of global warming, will exacerbate the coastal flooding that is one of the most damaging impacts of hurricanes.

Q. What is global warming?

A. Global warming refers to an increase in average global temperatures, which in turn cause climate change. This increase in average global temperatures has accelerated since the industrial revolution began, as seen by temperature readings around the world in recent decades, and the scientific study of tree rings, corals and ice cores that record the average temperatures of Earth at different times in history.

To completely understand why global warming happens, it is important to know that our atmosphere, which is made up of gases such as nitrogen, oxygen, and carbon dioxide (Co2) as well as water vapor, has a profound influence on Earth's surface temperature. Some of these gases such as carbon dioxide and methane absorb heat, reducing the amount that escapes back to space.

As the atmosphere absorbs heat energy, it warms the oceans and the surface of the Earth. This

process is called the greenhouse effect. Without this effect, the Earth's atmosphere would average about 30 degrees Celsius (50 degrees Fahrenheit) colder, making it impossible to sustain life on Earth. Rising levels of heat absorbing greenhouse gases such as carbon dioxide in the atmosphere will increase global temperatures, which is called global warming. In the atmosphere of Venus, for example, a buildup of carbon dioxide has led to temperatures that are far too hot to support most forms of life.

Q. Where do greenhouse gases come from?

A. A variety of greenhouse gases occur in nature as a result of natural processes. Plants, for example, turn carbon dioxide into oxygen, reversing the process of respiration that allows humans and animals to inhale oxygen and exhale carbon dioxide. Similarly, the decomposition of cattle manure and peat releases methane, an even stronger, but shorter lived global warming gas.

Human activities also produce greenhouse gases. For example, carbon dioxide is released when we burn fossil fuels to produce electricity, use gasoline in our cars, or switch on our natural gas stoves for cooking. And methane is released from landfills. Such activities have increased the quantity of several greenhouse gases in the atmosphere. For example, carbon dioxide concentrations in the Earth's atmosphere are 31 percent higher today than they were at the onset of the industrial revolution in 1750—more than at any time in the last 400,000 years.

Scientists have documented that as atmospheric levels of carbon dioxide have increased, largely due to human activities, the average global temperature has risen substantially. In 2002, the average global temperature was the second highest ever recorded at 14.52 degrees Celsius, just slightly below the 1998 average. This reflects an increase of 0.5 degrees over the last three decades. Scientific analysis of natural climate change in the past shows that such rapid warming is highly unusual. And scientists predict that average surface temperatures will increase during this century at rates unprecedented in the past 10,000 years.

Q. Should I be worried about global warming? Will it affect me personally?

A. Rising global temperature means more than just extra time to wear shorts and sandals. An increase of just a few degrees in average temperatures can cause dramatic changes in conditions that are important to the quality of life—and even the Earth's ability to support life. We may not always see or feel it directly, but climate change affects us all. For one person it might mean paying more for food because flooding or drought has damaged crops. For another it might mean a higher risk of contracting a disease like malaria, which spreads more easily in warm, wet climates. Someone else might face losing her home or even life in a catastrophic weather disaster made worse by global warming.

Almost everyone is vulnerable to the effects of weather-related disasters, but people in poor countries face a far greater threat due to risk factors that include inadequate housing located on flood plains and steep hillsides, weak healthcare systems, and heavy economic dependence on agriculture. It is not uncommon for single weather events, such as tropical cyclones and floods, to kill thousands of people in regions such as South Asia, southern China, and Central America.

Q. Do "global warming" and "climate change" mean the same thing?

A. These are not the same terms, although they are often used interchangeably. "Climate change" describes changes in seasonal temperature, precipitation, wind, and humidity for a given area. Climate change can involve cooling or warming. "Global warming" refers to increases in the average global temperature such as those that have been scientifically confirmed over the past 100 years. Although the Earth has experienced climate change throughout its history, the current rate of warming is highly unusual and correlates closely with the rise in human-produced greenhouse gases in recent decades.

Q. Is it true that some scientists disagree with the scientific consensus that the world is warming?

A. The global average temperature in 2002 was the second hottest since record keeping began in the late 1800s (1998 was the first), and the nine warmest years on record have occurred since 1990. Most scientists agree that global warming is real. What some debate is how much humans affect temperature and climate change. However, prominent scientists from around the world at the World Meteorological Organization, the Intergovernmental Panel on Climate Change (IPCC), and the U.S. National Academy of Sciences agree that humans are the main force behind the sharp global warming trend of the past century.

The most important scientific questions about global warming today are how rapidly temperatures will increase over the coming decades and what the specific regional effects will be. The computerized climate models used by scientists include a significant range of uncertainty, but generally project that global warming will accelerate in the period ahead—leading to more extreme temperatures (hot and cold), increased storm intensity and frequency, more frequent droughts and floods, and rising sea levels.

Most scientists agree that global warming will never be completely predictable, but that it presents serious risks that warrant immediate efforts to reduce emissions from fossil fuels.

The IPCC has warned that to stabilize atmospheric concentrations of carbon dioxide at 450 parts per million (more than one and a half times the pre-industrial level), global man-made emissions must fall below 1990 levels within the next few decades. Yet, based on current projections by the International Energy Agency, the increase in fossil fuel use over the next few decades will lead to a 70 percent increase in carbon dioxide emissions between 2000 and 2030.

Q. I've read that the world average temperature fluctuates naturally over time. Is a little more climate change really something we should worry about?

The Earth's climate has changed dramatically during its geological history, which spans billions of years. But scientists warn that climate change is now occurring far faster than ever before, in recorded history. There is also growing evidence that the Earth has seen dramatic and rapid changes in climate in the past over a period of years, rather than decades or centuries, adding to concerns that we could suddenly experience very abrupt and significant, possibly irreversible, changes at any time as average global temperatures rise.

Unless global warming emissions are reduced, average U.S. temperatures could rise up to ten times faster than the average rate of global temperature change from the end of the last ice age

to the present. If this happens, sea levels will rise, flooding coastal areas. There will be more frequent and intense heat waves, floods, droughts, and wildfires. The numbers and ranges of agricultural pests will likely increase, while growing ranges for many crops will shift. Extinctions will likely accelerate, and disease-carrying mosquitoes will be able to expand their range.

Q. In areas such as Western Europe, Japan, and North America, the air is cleaner than it was in the 1960s and 1970s. Isn't this inconsistent with the notion that fossil fuel emissions are changing the climate today?

A. Environmental regulations and resultant emissions controls on automobiles, factories, and power plants that helped clean the air in recent decades have successfully limited pollutants such as sulfur and nitrogen oxides. But they have done nothing to control carbon dioxide, which is an odorless gas, emitted in far greater quantity, and is very difficult to separate and dispose of. As a result, carbon dioxide emissions have risen, even as many other emissions have declined. In addition, carbon dioxide is diffused throughout the atmosphere and its effects are global and cumulative—we are living now not just with recent carbon dioxide emissions, but also with those that have built up over the last two centuries.

Q. Which countries contribute the most to global warming?

A. Wealthier industrial countries contribute the most to global warming since they use most of the fossil fuels. Europe, Japan, and North America—with roughly 15 percent of the world's current population—are estimated to account for two-thirds of the carbon dioxide now in the atmosphere. With less than five percent of world population, the United States is the single-largest source of carbon from fossil fuels—emitting 24 percent of the world's total. U.S. automobiles (more than 128 million, or one quarter of the world's cars) emit roughly as much carbon as the entire Japanese economy, the world's fourth-largest carbon emitter. China, despite being home to one-fifth of the world's population and its heavy dependence on coal, ranks a distant second behind the U.S., emitting 12 percent of the global total. China produces less than one-eighth as much carbon dioxide per person as the United States does.

Q. What is the Kyoto Protocol and what will it do to curb climate change?

A. The Kyoto Protocol is an international agreement, initially negotiated by government representatives meeting in Kyoto, Japan in 1997, that sets targets to reduce the greenhouse gas emissions causing climate change. It requires a variety of actions by governments, including specific emission reduction requirements for industrial countries, as well as provisions to assist developing countries limit their emissions. For the Protocol to "enter into force," it must be ratified by at least 55 nations representing 55 percent of industrial-country 1990 carbon dioxide emissions. As of September 5, 2003, 117 nations including those of the European Union, Canada, Japan, and a host of developing countries have ratified the Protocol, but only if Russia ratifies the agreement, will the 55 percent threshold be crossed, allowing the Protocol to enter into force.

According to many studies, enforcing the Kyoto Protocol would protect the environment, decrease air pollution, and create jobs in energy conservation, solar energy, wind power, and hydrogen technology, all of which could become powerful growth sectors in the decades ahead.

The Kyoto Protocol, during its first phase (through 2012) is a modest, yet important first step. Perhaps its greatest contribution in the short term will be to put in place mechanisms that we can build on such as emissions trading and the transfer of clean technologies (such as renewable energy) to the developing world. Even though it hasn't yet entered into force, it is already spurring corporations and governments to action from the E.U. to Japan and many developing countries.

Q. Why won't the U.S. ratify the Kyoto Protocol?

A.The Kyoto Protocol was signed by the U.S. government during the Clinton Administration in 1997. However, in March 2001, the Bush Administration withdrew its support for the agreement due to the treaty's requirement that the U.S. cut greenhouse gases to 7 percent below 1990 levels by 2012. The Administration claimed this put too heavy a burden on the U.S. economy, arguing that there was too much uncertainty around climate change to make the economic changes that would be necessary for such emissions reductions. The administration also argued that the treaty did not require developing nations to curb their emissions.

The vast majority of governments, ranging from Great Britain to Japan, disagree with the Bush Administration, and believe that the Kyoto Protocol represents a moderate step that will not only be affordable, but will actually spur the market for cleaner and more energy efficient technologies and thereby strengthen economies. Many nations are enthusiastic about the international emissions trading system that would be created by the Protocol, which ironically is an idea that originated in the United States and was adopted due to the lobbying of the U.S. government.

Q. Can I do anything about global warming?

A. While it's impossible for any one individual to prevent global warming, we each have a direct impact on the conditions that allow warming to occur. We can pledge to do our part to conserve energy and pollute less. Whether at home, on our commute to work or school, or at the store, there are things we can do to lessen our impact on climate change.

Examples of things you can do include turning off lights and computers when not in use, using public transportation, driving less, purchasing energy star appliances and a more-efficient car, insulating your water heater and home, and choosing "green" electricity from a wind or solar company, which is now possible in many areas.

For additional practical ways to lessen your impact on global warming see The Green Ribbon Pledge at and the Center for a New American Dream'sTurn the Tide Campaign at Both sites will allow you to calculate your energy savings and track the positive impact you are having on the planet as you make better choices.

Q. What other resources are available from Worldwatch on climate change and global warming?

For statistics about climate change and the problems it induces, see

Vital Signs, 2003
Contains articles on severe weather events and more, including:
"Severe Weather Events on the Rise," Page 92
"Carbon Emissions and Temperature Climb," Page 40
"Fossil Fuel Use Up," Page 34
"Small Islands Threatened by Sea Level Rise," Page 84

State of the World 2003, "Charting a New Energy Future":
Renewable energy technologies have the potential to meet world energy demand many times over and are now ready for use on a large scale.

Unnatural Disasters Worldwatch Paper #158:
In the 1990s, natural catastrophes like hurricanes, floods and fires caused over &608 billion in economic loss worldwide. A growing share of this devastation is not natural at all but is due to ecologically destructive practices.

Reading the Weathervane, Worldwatch Paper #160:
A ten-year review of global climate policy since the Rio Earth Summit.

Hydrogen Futures, Worldwatch Paper #157:
The notion of a "hydrogen economy" is moving beyond the realm of scientists and engineers and into the lexicon of political and business leaders.

Worldwatch online climate change resources and links:

Worldwatch online energy sources resources and links: