In the past 20 years, media reports of climate issues have largely focused on global challenges, such as greenhouse gases or catastrophic storms like hurricanes Hugo, Andrew, and Fran. Beyond the headlines and behind the scenes, however, tens of thousands of economic decisions are made each day with the aid of climatic information. Reliable climate information and data are necessary-directly or indirectly-to achieve sustainable economic advantages in virtually every enterprise in America.

What's the Difference Between Weather and Climate?
Weather chiefly concerns the present and near-term future state of the atmosphere. Should you wear a jacket? Will it rain tomorrow? Will we go to school tomorrow if this snow continues? Media outlets such as newspapers, radio, and television help you answer these and similar questions by reporting on atmospheric conditions gathered from American government sources.

Climate accounts for all past weather events and for future climate predictions. If we assume that climate is not changing rapidly, then high-quality, long-term climate data can tell us the qualitative range of weather events we might expect in the future. Accurate climate data collected over a long period can also provide useful quantitative assessments of the likelihood of various weather conditions in the next several years.

Who Uses Climate Information?
Nearly all economic activities are sensitive to climate. Some endeavors, like construction, aviation, and agriculture, are more sensitive than others, such as medicine or accounting. But at some level, almost everything depends upon the weather and, hence, climate. There are many practical day-to-day uses for climate information.

Business is a large consumer of climatic information. Effective marketing strategies target advertising when potential demand is greatest. That means selling rain gear when it's rainy, snow gear when it's snowy, and recreation products when it's sunny. Businesses also use climate data to help answer questions such as these: Why did the truckload of candy melt? What caused the large price increase of Georgia peaches in 1992? Why did we sell so many boats in 1988? And, of course, businesses use climate information when choosing relocation sites, just as individuals do when moving or retiring.

In agriculture and horticulture, the needs for climate information are obvious. The duration of the growing season depends on plant type and air temperature. Both livestock and crops depend on the availability of water, which is usually derived from local or watershed precipitation. Even the time of day when precipitation occurs is important to efficient water use. The heat tolerance of plants and animals determines what climates are favorable for different species. Less obvious dependencies, such as the number of cool days required for apples and peaches to mature properly, are climatic in nature.

Architects and structural engineers need to know factors such as wind loading; snow loads for roofing; precipitation for drainage and lawn watering systems; temperature statistics for heating, air conditioning, and frost penetration for foundations and water pipes; icing for wires and other exposed structures; and flood frequency to ensure safe construction at elevations above oceans, lakes, or streams. These factors are particularly important when large, expensive structures are built and when large communities of new homes are constructed. Virtually every professionally installed heating and air conditioning system is engineered using climatic tabulations to determine size and approximate operating costs.

The transportation industry is a large consumer of climatic data. Commercial aviation has been one of the primary forces for standardized and improved national weather and climate services worldwide. Indeed, strong aviation interest in weather was the principal reason for transferring the U.S. Weather Bureau (today's National Weather Service) from the Department of Agriculture to the Department of Commerce in the 1930s. At that time, flight schedules and safety considerations were even more critical for aviation than they are today. Climate data are used extensively in airport design and aeronautical engineering. Wind direction and speed, visibility, air pressure, temperature, icing frequency, cloud cover, humidity, the character of the air (fog, haze, smoke, and dust storms for example), and other elements are significant. There are also many uses for climate information in the shipping industry and in recreational boating.

You may not realize that athletics is another field where climate planning, implicitly or explicitly, can lead to enhanced economic advantages. Races must be run and games played so that participants are not overcome by heat or cold and sports fans are reasonably comfortable. The weather can also determine whether a new athletic record can be certified or not. For example, sprinters cannot be assisted by a tailwind above a certain speed for their time to be considered as a new record. Hence, planners try to hold events at locations where the climate is favorable for those events.

The legal profession is one of the larger segments of the climatic data user community in the United States. Attorneys and insurance companies often use official Federal Government weather records to help settle claims that may have resulted partly or entirely from adverse weather. Conversely, the absence of adverse weather may be used to argue against the validity of a claim. Insurance companies also use climatic data to establish actuarial statistics for determining premiums on policies that include a weather risk. Weather characteristics at a particular time and place have been used to corroborate or refute testimony and to help pinpoint the time and location of an event.

The application of climatic science to legal questions is called forensic climatology. This is just one specialty of the large and healthy field of private meteorological consulting. The Bulletin of the American Meteorological Society (AMS) now lists about 200 corporation members and over 120 paid advertisements for meteorological consultants, a significant increase from the 100 corporation members and 39 advertisements of 20 years ago. When the AMS began publishing these statistics in 1948, there were just 10 ads and 24 corporation members. Obviously, the private sector has seen the economic advantages to be gained by the use of climatology, but there are other aspects to consider also.

Climate, Science, and Record Keeping
Global change research is one of the most important contemporary applications of climate data. Historical records are used to document trends and test climate prediction models. One of the most challenging aspects of climate change detection is distinguishing natural long-term variations from trends caused by human activity. Many other research disciplines also depend upon climate records. These include most major branches of the life sciences, and many applied aspects and some pure research topics in the physical and geophysical sciences, such as geology.

Climate is an integral part of the geological and biological history of planet Earth. In this sense, the value of climate records transcends pure economics and adds an aesthetic dimension that cannot be easily quantified. The spirit of this assertion is implicit in the name that the early climatologists gave to periodic summaries of weather statistics: The Decennial Census of the Climate.

Just as the U.S. Constitution mandates a socioeconomic census, the World Meteorological Organization mandates 10-year calculations of Climatic Normals. And like the conventional census, the climate census has immediate and long-term economic applications, as well as scientific and historical value.

The National Climatic Data Center (NCDC), headquartered in Asheville, North Carolina, is the official repository for the United States' collection of global weather records. In addition to the varied information and data services provided by the NCDC, research is conducted to meet challenges ranging from assessing global warming to helping local ferry services.