PCC FAQ's - Climate Change

Fundamentals of the Greenhouse Effect, Global Warming, and Our Changing Climate :

 Q. What is the greenhouse effect?

A. Earth's greenhouse effect is a natural phenomenon that helps regulate the temperature of our planet. Simply put, the sun heats the Earth and some of this heat, rather than escaping back to space, is trapped in the atmosphere by clouds and greenhouse gases, such as water vapor and carbon dioxide. If all of these greenhouse gases were to suddenly disappear, our planet would be 60°F colder and uninhabitable.

Q. Are human activities responsible for the warming?

A. Separating out the impact of human activity from natural climate variation is extremely difficult. Nonetheless, the IPCC concluded there is a 'discernible human influence' on climate. This means the observed global warming is unlikely to be the result of natural variability alone and that human activities are at least partially responsible.

Q. What are the most important greenhouse gases? Where are they coming from?

A. Many greenhouse gases occur naturally, but human activities are adding gases to the natural mix at an unprecedented rate. Water vapor is the most abundant greenhouse gas; it occurs naturally and makes up about two thirds of the natural greenhouse effect. Fuel burning and other human activities, however, are adding large amounts of greenhouse gases to the atmosphere the most important ones being carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), hydro fluorocarbons (HFCs), per fluorocarbons (PFCs) and sulfur hexafluoride (SF6). Since preindustrial times atmospheric concentrations of CO2, CH4 and N2O have climbed by over 30%, 145% and 15%, respectively. Scientists have confirmed this is primarily due to human activity. Burning coal, oil and gas, and cutting down forests are largely responsible.

Q. What will happen to Earth's climate if emissions of these greenhouse gases continue to rise?

A. Because human emissions of CO2 and other greenhouse gases continue to climb, and because they remain in the atmosphere for decades to centuries (depending on the gas), were committing ourselves to a warmer climate in the future. The IPCC projects an average global temperature increase of 26°F by 2100, and greater warming thereafter. Temperatures in some parts of the globe (e.g., the Polar Regions) are expected to rise even faster. Even the low end of the IPCC's projected range represents a rate of climate change unprecedented in the past 10,000 years.

Q. What are the potential impacts of global warming and a changing climate?

A. Our health, agriculture, water resources, forests, wildlife and coastal areas are vulnerable to global warming and the climatic changes it will bring. The IPCC concluded that 'climate change' is likely to have wide ranging and mostly adverse impacts on human health, with significant loss of life. A few degrees of warming increases the chances of more frequent and severe heat waves, which can cause more heat-related death and illness. Greater heat can also mean worsened air pollution, as well as damaged crops and depleted water resources. Warming is likely to allow tropical diseases, such as malaria, to spread northward in some areas of the world. It will also intensify the Earth's hydrological cycle. This means that both evaporation and precipitation will increase. Some areas will receive more rain, while other areas will be drier. At the same time, extreme events like floods and droughts are likely to become more frequent. Warming will cause glaciers to melt and oceans to expand. The IPCC projects that sea level will raise one half foot to three feet over the next century. This threatens low-lying coastal areas. Scientists are also concerned that warming could lead to more intense storms.

Q. How can we talk about climate change over the next 100 years when we can't be sure of tomorrow's weather?

A. Weather and climate are different. The methods used to forecast changes in weather and climate differ as well. Because the weather changes from day to day, current weather forecasts are reliable for roughly ten days. Climate, on the other hand, can be thought of as average weather, including weather's variability over much longer time horizons (e.g., from year to year). Natural changes in our planet's climate happen over the course of years, centuries and many millennia. Long-term climate forecasts are possible because scientists understand many of the factors that influence climate over such long periods, such as changes in the sun's energy and the level of greenhouse gases in the atmosphere. Climate scientists do not claim to know how to predict day-to-day fluctuations (weather) over the 21st century. Rather, they are predicting how they think average temperature and precipitation (climate) will change due to human activities.

Q. How might global warming affect my business?

A. As a business owner, your costs, competition, and planning decisions may be affected. Your health care costs could increase if the public health sector is burdened by increases in heat and climate-related mortality and illness. Like homeowners, your business's energy costs will reflect the need for greater cooling in the summer and less heating in the winter. Your property insurance premiums could go up due to more droughts and floods and possibly more intense storms. If your business is located along the coast, sea level rise may also affect property insurance, not to mention how rising seas may directly impact your business. If your business depends on waterways for transportation, those shipping costs could increase in some areas due to reduced river flow and lower lake levels, though in northern areas shipping could be eased by a longer ice-free season. If you're in the agricultural or food industry, changing climatic and growing season conditions will require adaptations. Your competitors in this sector may experience either more or less favorable climatic change than you. The same is true if you're in a forestry-related business. Some of global warming's impacts may be most severe in other nations less capable of adapting. This may create social and economic disruptions that ripple across the globe to affect your business. For all of these reasons, long-term business planning will increasingly have to consider the changing nature of our planet's climate.