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Case Studies

RED RIVER OF THE NORTH FLOOD GRAND FORKS, APRIL 19971

Description

Flooding is a common problem during the spring in many of the western U.S. river basins. The Red River of the North Basin, located in North Dakota and Minnesota in the United States and southern Manitoba in Canada, routinely experiences various levels of floods. The Red River flows north into Canada through Winnipeg and empties into the Hudson Bay. The region is exceptionally flat and consequently prone to flooding. Conditions that contribute to the region’s flooding include soil moisture, snow cover, water equivalent, depth of frost, rate and timing of snow cover melt, spring precipitation, river ice conditions, and base hydrologic flows.

During 1997 almost all of these categories were above average, setting the stage for severe flooding. Winter records for snowfall were recorded, and the rate of melt was erratic beginning in late March. Flooding began in the southern part of the basin in March, and following a brief hiatus during a freeze, proceeded northward. Grand Forks, North Dakota, and East Grand Forks, Minnesota, which had experienced a major flood in 1979 with a river crest of 48.8 feet, prepared for the flood by raising dikes, seeking to survive a possible crest of 52 feet. Those dikes broke through on April 18, and the two cities suffered catastrophic damage.

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This case is documented in the National Weather Service’s document Service Assessment and Hydraulic Analysis: Red River of the North 1997 Floods (NWS 1998).



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A Workshop Summary Communicating Uncertainties in Weather and Climate Information 2 Case Studies RED RIVER OF THE NORTH FLOOD GRAND FORKS, APRIL 19971 Description Flooding is a common problem during the spring in many of the western U.S. river basins. The Red River of the North Basin, located in North Dakota and Minnesota in the United States and southern Manitoba in Canada, routinely experiences various levels of floods. The Red River flows north into Canada through Winnipeg and empties into the Hudson Bay. The region is exceptionally flat and consequently prone to flooding. Conditions that contribute to the region’s flooding include soil moisture, snow cover, water equivalent, depth of frost, rate and timing of snow cover melt, spring precipitation, river ice conditions, and base hydrologic flows. During 1997 almost all of these categories were above average, setting the stage for severe flooding. Winter records for snowfall were recorded, and the rate of melt was erratic beginning in late March. Flooding began in the southern part of the basin in March, and following a brief hiatus during a freeze, proceeded northward. Grand Forks, North Dakota, and East Grand Forks, Minnesota, which had experienced a major flood in 1979 with a river crest of 48.8 feet, prepared for the flood by raising dikes, seeking to survive a possible crest of 52 feet. Those dikes broke through on April 18, and the two cities suffered catastrophic damage. 1   This case is documented in the National Weather Service’s document Service Assessment and Hydraulic Analysis: Red River of the North 1997 Floods (NWS 1998).

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A Workshop Summary Communicating Uncertainties in Weather and Climate Information In East Grand Forks the crest was 54.4 feet on April 22. Total estimated damages were approximately $4 billion with $3.6 billion in losses in Grand Forks and East Grand Forks alone. These losses were the greatest per capita in U.S. history. Nearly 90 percent of the area was flooded and three neighborhoods were completely destroyed. Eleven buildings in downtown Grand Forks were destroyed by water and fire. In a region of 5,000 homes, fewer than 20 escaped damage. Widespread evacuation occurred and potable water was unavailable. Fortunately no deaths were attributed to the flood in the Grand Forks area. By February 1997 the National Weather Service (NWS) knew of the potential for record flooding in this region and disseminated information through the standard suite of products that included weather data and forecasts, hydrology data, hydrology outlooks (narrative and numerical), hydrology forecasts (at least twice a day), and flood statements and warnings. Leading up to the event, the NWS was the main voice speaking with the communities. After the event, during a post-analysis (NWS 1998), two other potential sources were identified that could have provided information that would have been beneficial leading up to the flooding. Following the disaster, considerable finger-pointing by the public and elected officials focused on the role of NWS flood predictions (see Figure 2–1). (Detailed timelines for this weather event are given in Appendix C.) FIGURE 2–1 An example of the public reaction to the flood event. SOURCE: Barry Reichenbaugh, National Weather Service.

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A Workshop Summary Communicating Uncertainties in Weather and Climate Information Communication Summary Because this region has had considerable experience dealing with floods, and many residents remembered a major 1979 flood, communication channels were well established. This context helped set the expectations of the public. Below is a summary of the communication process. Who? Leading up to the event, the NWS’s North Central River Forecast Center and the Grand Forks Weather Forecast Office were the primary voices providing information about river levels. The media was a secondary voice. A representative of the NWS held a press conference in Washington, D.C., that was covered on national network news. Said what? The message was one of potential for severe record-breaking flooding for the spring season. On February 28 the NWS issued a quantitative outlook with two potential river crest levels: one for 47.5 feet, which did not take into account future precipitation, and the other for 49 feet under average precipitation conditions. As the flood progressed, the NWS issued flood crest forecasts of 50 feet, 52 feet, and 54 feet on April 14, 17, and 18, respectively. None of the forecasts provided any numerical measure of uncertainty, although some general words indicating uncertainty and severity were used. The NWS headquarters press conference included a qualitative statement indicating that the level of flooding would be “more water than you’ve ever seen before.” When? The North Central River Forecast Center and the Grand Forks Weather Forecast Office issued narrative and numerical outlooks periodically from February 14 to March 28, 1997, for the entire river basin. Deterministic operational hydrology forecasts for the Grand Forks area were made twice a day after April 14, 1997. There was plenty of lead time to develop mitigation and adaptation strategies for handling the flood. The NWS press conference in Washington, D.C., was held on March 18, 1997. To whom? The primary communication was between the NWS and emergency managers in the region and to local officials responsible for flood preparedness. The secondary communication was made through the media to the general public. How? The dissemination of the information was done through regular media outlets, including television, radio, and print. Information was also conveyed through the National Oceanic and Atmospheric Administration (NOAA) weather radio, wire services, Internet, emergency manager weather information network, weather hotline phone, and amateur radio.

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A Workshop Summary Communicating Uncertainties in Weather and Climate Information With what effect? Based on available information, city officials decided to prepare the city for a 52-foot river crest. This level was chosen based on the 49-foot forecast and adding a 3-foot buffer. But in reality the forecast was not meant to be taken with such certainty. The NWS thought it was conveying real urgency by using the 49-foot measure because this was above the past instrumented flood record in 1979. Instead, the message received was one of perceived certainty, in part due to the experience of the 1979 flood when the NWS forecast a flood crest of 49 feet, a forecast that came within two-tenths of a foot of the actual flood level. The effect was misplaced certainty in the outlook/forecast product. At another level, however, the communication to the public was effective. After the press conference held by the NWS representative in Washington, D.C., there was a dramatic increase in the purchase of residential Federal Emergency Management Agency (FEMA) flood insurance policies. The fact that there was a spike in flood insurance sales after the remarkably clear statement “more water than you’ve ever seen before” was made indicates that many people were paying attention to the forecasts, the warning was communicated effectively, and people understood the implication of the warning and took action to protect themselves. Better follow-on information would have helped local officials to evaluate the specifics of the developing situation and plan more sufficient protective action. The forecasts were accurate, better than in many previous flooding situations, but the uncertainties were neither communicated nor understood. Analysis of the Case The magnitude of the disaster prompted the NWS to conduct a detailed analysis of the event (NWS 1998). This report identified problems in the scientific information that was disseminated, in institutional arrangements, and in communication. The first problem was that the scientific information did not contain uncertainty information. The hydrologic models did not produce probabilistic information. In part this lack of information was due to “guessing” how to extend the rating curve on the hydrograph beyond the 48.8-foot limit of the instrumental record. In reality there are multiple methods to extend a rating curve. After the event it was learned that the U.S. Army Corps of Engineers had been using a rating curve different from the one the NWS forecast offices were using, and in hindsight the Corps of Engineers’ method gave a more accurate estimate of the flood crest. Although making precise predictions of the Red River at these extreme levels may not be possible, better information about the uncertainty of the forecast could have been useful to the decision makers. Quantification of the uncertainty could also have been done empirically by analyzing the success of historical forecasts and events. For example, records indicate that earlier floods at East Grand Forks had a 10-percent error (5 feet for the 1997 flood). From a forecast verification perspective, the Red River flood

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A Workshop Summary Communicating Uncertainties in Weather and Climate Information forecast was good, with only about an error of 5 feet between predicted and actual river crest. To the public, however, this was a greater error than the 1979 flood because the dikes were overtopped and real damage ensued. Another problem was the lack of new observational information that would lead to updated river predictions. The 49-foot forecast was reiterated several times by the NWS even though no new information had been assimilated into the forecast. The forecast given immediately after an early April blizzard did not incorporate any of the blizzard’s effects. The timing of this reiterated forecast could have led to the belief that the precipitation from the blizzard had no effect on the river crest value, and in the public’s mind it reinforced the certainty of the 49-foot level. The 1998 NWS assessment also found that institutional arrangements and delineation of responsibilities were a problem. The river forecast office and the weather forecast office were not coordinated. Responsibilities between officials in Grand Forks and the forecast offices were unclear. While Grand Forks officials wanted a single number for the predicted crest, a single number was simply not justified by the state of the science. There were plenty of data and folklore to indicate river crests had high variability. Ignoring this variability and not quantifying uncertainty caused decision makers to misjudge how to handle the flood and led to a de facto handing off of responsibility from the city officials to the weather service. As an example of mitigation alternatives, the city of Fargo sacrificed certain streets to save other parts of the city. Grand Forks and East Grand Forks made the decision to try to save all of the city and neighborhoods. Communication was the final problem area. While almost everyone in the community was aware of the 49-foot forecast, very few knew how to interpret it in the context of flood-fighting decisions. Errors in interpretation were obvious in the media, yet the forecast offices did not correct the misinterpretation that was in the print/news media. Psychologically the public had a previous context in which to “anchor” this flood, that of 1979. Communication in terms of this experiential knowledge would have gone a long way in helping to understand the potential severity of the flood. Lessons Learned During the workshop, participants suggested several lessons learned from this case: Understanding the uncertainty inherent in the scientific products that are being delivered is essential to delivering an accurate message to decision makers and the public. Uncertainty measures of scientific products are needed. These measures can be of multiple forms, including probabilistic model outcomes, empirical

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A Workshop Summary Communicating Uncertainties in Weather and Climate Information verification of outlook/forecast performance, and narrative language that conveys the correct meaning of the uncertainty. Visualized presentation of the uncertainty would complement text presentation of uncertainty. A clear understanding of the roles and responsibilities of forecasters and decision makers is essential for an effective communication process. Forecasters need to convey full information to the decision makers. Maintaining the credibility of the science for the decision maker is essential. Forecasters may require training to recognize that their role is not to make decisions for decision makers or to provide prognostications that go beyond what the science can support. An understanding of the decision process by those handling weather service outreach is invaluable in determining the strategic information that needs to be disseminated. This understanding is needed in order to know where the science has the most impact and what products would be most effective. Development of new products may be a part of this process. Developing a dialog between forecasters and decision makers would be more useful than briefings. Coordination among the agencies well before any event is essential, and synthesized scientific knowledge (stream flow and precipitation) is key to preparing accurate products for decision makers. When communicating with the public, the context of the upcoming event relative to past experiential evidence of the people helps to convey the potential severity of the hazard. A personalized narrative is important and can have beneficial impact. Misinterpretation of scientific information by the media can be expected. After all, they are not scientific experts. Therefore, it is imperative that errors be corrected quickly to avoid public confusion. Follow-up Improvements The Service Assessment and Hydraulic Analysis report (NWS 1998) provided guidance for improvements, and suggestions for improvements were also provided by user communities. Several actions have been taken since the disaster in order to avoid a repeat of this experience (Anderson 2001): The North Central River Forecast Office and the Grand Forks Weather Forecast Office implemented new products under the Advanced Hydrologic Prediction Service (AHPS) capturing uncertainty and probability of a given crest level. The uncertainty is characterized by 40 years of precipitation data that are used to determine a historical probability function for precipitation. Future climate outlooks are taken from monthly Climate Prediction Center (CPC) outlooks that are then used to weight the probability density function. The information is incorporated into a new hydrology model that has been improved from a channel hydraulics model to a soil moisture/terrain model. AHPS now produces a number of different products and is experimenting with different forms of graphical presentation.

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A Workshop Summary Communicating Uncertainties in Weather and Climate Information Probability products are being tested with users, and feedback is being received and incorporated to improve products and services. Narrative outlooks are now more descriptive, contain more information, discuss uncertainty, and encourage users to contact the weather office for continual updates of meteorological conditions. Statements of how hydrologic projections are made are now included, and these projections include the current observed state of stream flow, soil moisture, and snow pack, and are coupled with future precipitation and temperature patterns and anticipated hydrologic changes due to reservoir and canal releases. Product delivery is now enhanced through an expanded outreach program and Internet and wireless delivery systems. The media and decision makers have shown a greater sophistication in the use and interpretation of outlook/forecast information, as evidenced in the tone of articles in printed and broadcast venues. Remaining Challenges Although significant improvements have been made, the workshop participants identified some challenges still to be addressed in the forecast/decision-making process: Although probabilistic information is now being produced, understanding of the different types of measures of uncertainty is still limited. In particular, regular use of empirical performance of NWS outlook and forecast products could be used to augment probabilistic outlooks/forecasts. This additional information would provide a level of calibration of the historical accuracy of particular prediction products. Given the public response to personalized narrative, this approach could be developed to help convey and interpret the products. It will be a challenge to develop appropriate language that conveys experiential meaning to the public. Reconciliation of user wants and user needs with science capabilities is important. Inherent and irreducible uncertainty cannot be ignored by the NWS even though users seek certainty because such uncertainty clearly affects the alternatives that might be available in the decision-making process. EAST COAST WINTER STORM MARCH 2001 Description In March 2001 a major winter storm brought precipitation along the East Coast from the mid-Atlantic states to the Northeast. Heavy snow (primarily inland and in New England), high winds, and coastal flooding occurred in the eastern United States. Snowfall in excess of 10 inches was commonplace from

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A Workshop Summary Communicating Uncertainties in Weather and Climate Information West Virginia to Maine, with 40 inches recorded in southeastern New Hampshire near Manchester. Figure 2–2 shows snowfall amounts and the track of the storm. The storm had major impacts: Schools were closed; many activities were canceled; and transportation was disrupted, first in anticipation of the storm and then as a result of its effects (see Figure 2–3). Air traffic was significantly disrupted in the northeast corridor as airlines canceled flights and moved aircraft out of the storm’s path days before any storm had actually formed. During the storm, downed power lines left tens of thousands without electricity, primarily in the interior of New York and New England. There were at least eight fatalities attributed directly or indirectly to the storm. Before and during the storm, a state of emergency was declared in Massachusetts and Connecticut. After the storm, Maine and New Hampshire filed for disaster relief assistance. Although this was a major storm with many impacts, it illustrates another side to the communications issue: In this case, private sector and media meteorologists and weathercasters in major metropolitan areas from New York City to Washington, D.C., criticized the NWS for over-estimating in its forecasts when, FIGURE 2–2 Snowfall total amounts (in inches) and track of the storm, March 4–7, 2001. SOURCE: National Weather Service.

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A Workshop Summary Communicating Uncertainties in Weather and Climate Information FIGURE 2–3 Snow was piled deep in many New England areas. SOURCE: National Weather Service. in fact, the storm never had the major impact on the East Coast megalopolis that it had on many inland and New England areas. One potential explanation for this over-estimation was that both media and government officials remembered the “surprise” snowstorm of January 2000, which was not well anticipated and had significant impacts on the public, and consequently they took pains to ensure against another unforecast storm. (Detailed timelines for this weather event are given in Appendix C.) Communication Summary Who? Communication of information was shared among NWS through the National Centers for Environmental Prediction’s Hydrometeorological Prediction Center (NCEP/HPC), NOAA, weather forecast offices (WFOs), private forecasting services and companies, and national and local media. Said what? NWS/HPC provided medium range forecast (MRF) computer-generated outlooks and hand drawn guidance indicating a potential developing

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A Workshop Summary Communicating Uncertainties in Weather and Climate Information FIGURE 2–4 MRF surface pressure forecast made at 0000Z, February 26, and valid at 1200Z, March 4. SOURCE: National Weather Service. major storm off the East Coast of the United States 7 days in advance of actual cyclogenesis. Figures 2–4 and 2–5 provide illustrations of 156 hour (made at 0000Z2 on Monday, February 26) and 108 hour (made at 0000Z on Wednesday, February 28) MRF model forecasts, both valid at 1200Z on March 4. Figure 2–6 is the verifying surface analysis for that time. These forecasts showed the potential development of a significant storm that, if verified, would have a major impact on the East Coast. Local and national media and private forecasting organizations began discussing the possibility of an East Coast storm for the weekend of March 3–4 as early as Monday, February 26. On Wednesday, February 28, a TV weathercaster in Philadelphia issued a statement predicting a possible 16 to 20 inches of snow for the Philadelphia metropolitan area beginning on Monday, March 5. 2   In meteorological discussions, times of data analyses and computer model valid times are usually referred to in “Z", or Coordinated Universal Time (UTC). These times are expressed in two or four digits (e.g., 0000Z or 00Z). Conventional time designations are used for press releases, etc.

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A Workshop Summary Communicating Uncertainties in Weather and Climate Information FIGURE 2–5 MRF surface pressure forecast made at 0000Z, February 28, and valid at 1200Z, March 4. SOURCE: National Weather Service. Other local and national media soon became aware of other deterministic forecasts being made 4 to 5 days in advance of the potential storm and came under increasingly competitive pressure to make some deterministic forecasts even though the timing was well in advance of what most agree is the current state of the science. By Thursday, March 1, many private weather services and local and national media began making deterministic forecasts and statements of snow amounts. On Friday, March 2, NWS/HPC hosted a storm conference call at 11:00 A.M. (See Figure 2–7 for the AVN3 model forecast made at 1200Z on March 2 and valid at 0000Z on Monday evening, March 5. This forecast indicated a major storm that would bring significant amounts of snow to the Northeast.) This conference call included all affected WFOs and NWS/HPC meteorologists. Many NWS WFOs on the call conveyed that they were feeling increasing pressure 3   The AVN is one of the major numerical weather prediction models run at NCEP. The model was originally designed to support the needs of the aviation community, hence the name AVN for aviation.

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A Workshop Summary Communicating Uncertainties in Weather and Climate Information FIGURE 2–9 Headlines illustrating the variety of forecasts available to the public. SOURCE: Changnon (2000). Used by permission of Oxford University Press, Inc.

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A Workshop Summary Communicating Uncertainties in Weather and Climate Information marily addressed initially to the scientific community. After a short period of time, however, ENSO predictions, as well as predictions of impacts of ENSO, were addressed to users and the public. Points about this case: This was the largest and warmest El Niño to develop in the Pacific Ocean during the past 100 years. The news media gave great attention to this El Niño, and it received more attention at all levels than any previous climate event. Scientists were able to use El Niño conditions to successfully predict weather conditions for the winter 6 months in advance over most of the United States. The direct impacts of the ENSO-generated weather during October 1997-April 1998 included: (1) flooding and wind damages in California, (2) increased tornadic activity in the South, (3) heavy rain events in Texas and Florida, (4) unusual winter storms in the High Plains in early fall and severe winter weather in Canada and New England in January, (5) few winter storms, above normal temperatures, and little snow over most of the northern United States, (6) no Atlantic hurricanes striking the United States, and (7) Pacific hurricanes that hit Mexico and California. The net effect of the El Nine-influenced weather on the United States was an economic benefit, after early fears and predictions of great damages. Some areas, including California and Florida, suffered major losses, but many areas, including the northern United States, realized sizable economic and health-related benefits. When? NOAA issued official, scientific-based weather forecasts for the fall, winter, and spring from July 1997 through December 1997. The various weather impact predictions were issued by government agencies such as the Federal Emergency Management Agency (FEMA) and the U.S. Geological Survey (USGS) and by numerous private sector organizations during the fall and winter of 1997–1998. To whom? The forecasts were issued to the ocean/atmosphere community, the prediction centers, relevant federal and state government agencies, the media, the public, and managers of, for example, agriculture, water, power, emergency preparedness, transportation, and insurance. How? Official NOAA predictions were disseminated through press conferences, news releases, Internet releases, and interagency memorandums. In turn, this information was interpreted by numerous government agencies, individual scientists, and the media and distributed to the public.

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A Workshop Summary Communicating Uncertainties in Weather and Climate Information With what effect? Many decisions makers took steps toward mitigating the potential impacts of the El Niño in such areas as utility operations and power purchases, agricultural planning, and water management. The media coverage created high penetration into the public consciousness of climate variability and of potential for greater skill in seasonal to interannual forecasting. The success of the forecasts improved climate forecast credibility. Awareness of the climate-weather connection was raised. One possible negative impact was an over-simplification of the complexities of climate variability resulting from a view of ENSO as sole driver. Some levels of confusion and skepticism resulted from different forecasts coming from multiple institutions. The predictive successes brought new credibility to the science of long-range prediction and, in general, acted to increase the public’s understanding of the weather-climate connection and the utility of long-term forecasts. The intensity of the 1997–1998 El Niño brought forth claims that the phenomenon was the result of anthropogenic global warming. This possibility added to the scientific-policy debates. Analysis of the Case There were notable differences in how weather-sensitive decision makers reacted to the predictions—some used them for gain, while others, fearing failure, did not. There was a progression in the media coverage. First came science stories by science writers, which included discussion of uncertainty. Then came stories with mass appeal, not always by science writers, which emphasized causality and downplayed uncertainty. The ENSO-based weather predictions were received with little debate or skepticism by the media and the public. There also was a readiness to accept predictions of impacts, although this created confusion in some regions. At some point the 1997–1998 ENSO achieved a sort of folklore status and even became the subject of jokes making it responsible for all problems. The media and the public were fascinated with El Niño, and it became a household word throughout the country. (See Figure 2–10.) It is not yet clear that the 1997–1998 ENSO created a lasting change in public perception and media treatment. The 1997–1998 ENSO was the strongest on record, and its clear secondary impacts on regional weather created opportunities to affect perceptions. There was opportunity for NOAA to take advantage of the high visibility to illustrate its capabilities and for private sector firms to produce marketable ENSO and ENSO impact products. There were shortcomings in the predictions. The rapid development of the El Niño was not predicted successfully. Basing predictions on the 1982–1983 ENSO produced poor results in some parts of the world. However, in terms of human lives and dollars saved, winners exceeded losers in the United States.

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A Workshop Summary Communicating Uncertainties in Weather and Climate Information FIGURE 2–10 Diverse forecasts together with uncertainty gave rise to the tendency to ascribe many events to the El Niño. SOURCE: Changnon (2000). Used by permission of Oxford University Press, Inc.

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A Workshop Summary Communicating Uncertainties in Weather and Climate Information Highly accurate seasonal climate forecasts were based on our understanding of El Niño, and mitigation actions produced large and measurable savings. Lessons Learned The 1997–1998 ENSO brought beneficial scientific outcomes: Climate research paid off with quality predictions, and as a result, the science of climate-weather links was strengthened. Mitigation efforts paid off (e.g., California performed major maintenance on flood control systems). Although climate research was important to the success of the predictions, there were shortcomings such as linking ENSO to other scales of variability. Differing forecasts from multiple sources create a problem for users. Coordinating the forecasts or providing discussion of the various forecasts with an explanation of the uncertainty could reduce confusion in the future. There may be value in labeling some forecasts as official to show official expertise as opposed to research-based experimental forecasts. Classic ENSO patterns and impacts can be unreliable as a guide for predictions of impact of new ENSO events. The 1997–1998 ENSO event was not a repeat of the 1982–1983 ENSO event. Local experts may not be prepared to interpret regional scale events and often provide differing views. Forecasters and media should attempt to provide information on both negative and positive outcomes. Forecasts from the Climate Prediction Center mentioned the possible “good” effects of El Niño, such as lower heating bills across the North, but this perspective was often overlooked. Dire warnings hurt credibility when different outcomes occur. A skillful forecast does not directly lead to value. The decision environment plays a critical factor in the value achieved. The expectations of decision makers can be guided by the careful predictions of forecasters. It is easy to oversell climate forecasts. If the media and the public fail to understand El Niño, then chances are decreased that even skillful forecasts will have value to decision makers. Follow-up Improvements The entire weather community has worked to improve coordination of forecast releases. The National Weather Service has vetted a Web site for information and graphics to accompany forecasts. Ongoing communication of interannual to decadal modes of variability (Pacific Decadal Oscillation, Arctic Oscillation, North Atlantic Oscillation) as well as ENSO would raise the level of understanding of climate variability and thus of uncertainties related to ENSO and ENSO impact predictions.

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A Workshop Summary Communicating Uncertainties in Weather and Climate Information Study of the 1997–1998 ENSO leads to understanding of why it was not more similar to the 1982–1983 event and to the building of quantification of uncertainty in both ENSO and ENSO impact predictions. Remaining Challenges There is a need to adequately inform the media and provide them with the type of information they can understand, including names of experts they can contact. Properly managing the public and media interest to achieve education and over the long term improve understanding of uncertainty in predictions remains a significant challenge. Developing skill at seasonal prediction is needed to separate seasonal changes that are a result of extreme events from those that are a result of normal variability. Explaining complexity of seasonal to interannual prediction and impact prediction will lead to better understanding of the forecasts. It is important to respond to users and adjust forecast products to their needs. If they turn out to be largely accurate, uncertain predictions will become fact if the event’s conditions agree with the prediction. But this can inflate expectations and lead to problems if future predictions are less accurate. Seasonal forecasts can be made more useful by including more information on existing and past forecast accuracy and comparing current and past outcomes; current probabilistic information about forecast conditions; and “climate profiles” of weather conditions during a warm, cold, wet, or dry season. Agencies in the business of issuing forecasts and warnings may have to deal with unintended consequences of success, including inflated expectations of the public and other users in the future. There is an opportunity for forecasters to improve communication of probabilistic information to decision makers. CLIMATE CHANGE SCIENCE AN ANALYSIS OF SOME KEY QUESTIONS JUNE 2001 Description The importance of anthropogenic greenhouse gases as a potential mechanism for causing future climate change has been a topic of scientific investigation, political debate, and media discussion for several decades. Much of the debate focuses on the level of uncertainty associated with projections of future climate change and whether the risk warrants action to minimize potential adverse effects. President Clinton endorsed an international treaty, the Kyoto Protocol, as a mechanism for reducing U.S. and world greenhouse gas emissions as a first step in addressing the global warming problem. The election of President George W.

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A Workshop Summary Communicating Uncertainties in Weather and Climate Information Bush resulted in a review of U.S. climate change policy and a decision not to endorse the Kyoto Protocol. Review of climate change policy continued amid international criticism of U.S. rejection of the protocol and the lack of an alternative action proposed by the White House. During this review of U.S. policy options, the Intergovernmental Panel on Climate Change (IPCC) released its Third Assessment, a comprehensive summary of climate change findings written by a broad spectrum of international scientists (IPCC 2001). Seventeen international scientific societies then endorsed the IPCC report and used its findings as a call for action on the Kyoto Treaty. Because President Bush was scheduled to discuss global warming with leaders from 15 European nations in June 2001, the White House requested a fast-track study by the National Research Council (NRC) to help inform the Administration’s ongoing review of the U.S. climate change policy by identifying the greatest certainties and uncertainties in the science of climate change and answering 14 key questions on climate change science. There were initial discussions within the National Academies as to whether the study should be done and whether the questions were appropriate for an NRC study. Since the original purpose of the National Academies was to provide sound scientific advice to the government, the study was accepted. The NRC completed this study in less than one month, releasing its report on June 6. Communication Summary Who? The U.S. National Academy of Sciences (NAS) communicated the findings of a special study on climate change science. The NAS committee that conducted the study was composed of 11 members chosen for their special competences and with regard for appropriate balance (and with minimal involvement in the IPCC Third Assessment report), 7 of whom were also members of the NAS. The NAS not only selected a larger than usual representation of Academy members, but (recognizing its 1863 charter to respond to government requests) it also chose to support the committee work with its own funds rather than with the more usual agency contributions. Said what? The NAS released its final report, Climate Change Science: An Analysis of Some Key Questions, on June 6, 2001. This report was based on the committee’s critical assessment of certainties and uncertainties in climate change, the accuracy and consistency of the recent IPCC assessments, and answers to 14 key questions on climate change science. The committee of U.S. senior scientists reached consensus that, among other things, Temperatures are, in fact, rising. The changes observed over the last several decades are likely due mostly to human activities, but we cannot rule out

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A Workshop Summary Communicating Uncertainties in Weather and Climate Information that some significant part of these changes are also a reflection of natural variability. The committee generally agrees with the assessment of human-caused climate change presented in the IPCC Working Group I scientific report. A warming of 3°C by the end of the twenty-first century was deemed consistent with current understanding of climate change. However, considerable uncertainties in this forecast were noted to be associated with natural variations and reactions to anthropogenic influences. Of note was that the NAS committee did not communicate any policy recommendations regarding what to do about global warming, which it viewed not to be part of its charge and not possible in the time frame. When? At 4:00 P.M. on Wednesday, June 6, the NAS posted a final draft of the report on its Web site and the NAS media officer issued a press release. To whom? The White House was the official recipient of the information in the report, but the communication was intended also for The U.S. Congress. Climate change was a topic of debate in the U.S. presidential election 6 months prior to the White House request. During the campaign, then-candidate Bush pledged to reduce CO2 emissions from U.S. power plants. Following the election and the President’s subsequent reversal (in March) of his campaign decision, Drs. Hansen and Linzden (both members of the NAS committee) testified to Congress (on April 30, 2002) on this topic. Foreign academies. Seventeen foreign academies of sciences requested that the NAS co-sign a statement supporting the Kyoto Protocol. In his letter declining the U.S. signature, NAS member and then foreign secretary Sherwood Roland noted that the NAS believes that it “can be of the most value in conducting its work on this topic through the Research Council committee process using a highly expert group of scientists; that report is expected to be issued this summer.” International policy makers and the IPCC. Despite the findings of the IPCC Third Assessment report and pressure from European and other governments, the United States had not endorsed the 1997 U.N. Kyoto treaty to restrict the emissions of CO2. The scientific community, both U.S. and international. The media, which had followed and reported climate change news for a number of decades, and with whom the scientific community had established considerable working connections. The American public. The 14 questions were typical of public enquiry of global change issues and underscored the public quest for answers. Europeans

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A Workshop Summary Communicating Uncertainties in Weather and Climate Information had protested President Bush’s reversal of his campaign promise to reduce CO2 emissions from power plants. How? A short (24-page) peer-reviewed NAS report was the source of the information that was communicated. The NAS produced this report in fast-track mode, producing a final report within 1 month of receiving the official White House request. A key aspect of communicating the report’s findings was the active involvement of an NAS media officer with the committee throughout the entire process. The media officer issued a press release, and in the following weeks, NAS personnel and committee members briefed the White House, Administration officials, Congress, and the media. Another key aspect of how the report was communicated was its release on the web, making the key information available simultaneously to all recipients. With what effect? The immediate effect of the communication was a speech by President Bush on June 11 (just prior to his European trip) acknowledging the report and thanking the NAS. The President, who had said in March that he was unsure that global warming was a real phenomenon, now suggested several ways to address the problem, including more basic climate change research and advanced computer modeling, technological innovation to help reduce CO2 emissions, and improved international cooperation. Subsequently, President Bush’s stand on environmental issues became somewhat more visible, with talk of a “new environmentalism.” The clearly received information that anthropogenic climate change was probably occurring and would likely be a significant environmental “event” of the twenty-first century was conveyed to the public by the media. The balance of scientific evidence was recognized as supporting this view, even with the caveat of significant uncertainties. Lacking in the media, for the most part, were the tones of prior reporting in which both sides of the argument were given equal weight. And unlike past media reporting, the event (i.e., real climate change expected by end of the twenty-first century) rather than the uncertainties was the focus. The recognition by both the NAS and the White House, conveyed more or less faithfully by the media, that climate change was real and likely to be a twenty-first century environmental event helped move climate change (and related research) to the forefront of Administration policy and Congressional legislation, with the challenge of providing a U.S.-based scientifically-justified plan for action. The report helped promote a more bipartisan approach to climate change policy now that the option of “doing nothing” is less viable: Senator Kerry (D-Mass) said, “It increases the imperative for them to take action,” and Senator Hagel (R-Neb) said that “the report provides us with a basis to move forward.” An unexpected effect of the communication of the NAS report was a refocusing of attention on prior climate change studies that had already identified key

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A Workshop Summary Communicating Uncertainties in Weather and Climate Information problem areas. Questions were raised about the ability of the United States to address the problem within the current framework of climate change research (disparate groups scattered among various organizations and agencies, with limited coherency or overall vision, and inadequate computer resources). Media reports pointed out that U.S. capability lagged behind that of Europe, especially in the types of effort needed to contribute to the studies on which the IPCC reports were based (implying a reduction of U.S. effectiveness in this process). Both the NRC and the National Assessment had addressed these very issues in prior reports6 whose findings and recommendations had initially received far less attention, but which now emerged anew. A particular recommendation from prior reports that received favorable attention, in addition to the urgent need for advanced computer resources, was the need for a National Climate Service, analogous to the National Weather Service. Lessons Learned The questions from the White House that became the charge to the committee were very basic in nature; they were perhaps not scientifically valid questions to ask and probably not what scientists would have asked. Nevertheless, they were the types of questions the average person might ask, and they seemed to reflect underlying controversies about whether global warming was real and whether humans were responsible for it. It is important for scientists to consider the public audience at the very beginning of a study. If part of the goal of a scientific endeavor is to communicate the findings to the public and policy makers, then the charge and findings should be written with that audience in mind from the start. Dissemination should not be an afterthought. Executive summaries and press releases are helpful, but lay language should not be confined exclusively to these documents. Along the same lines, it was very beneficial to include a “communication” person (in this case an NAS media officer) in committee deliberations. This helped the committee consider aspects of communication as an integral component of the report and resulted in much smoother public relations following the report’s release. The brevity of the climate change report seemed to play a role in its dissemination. This does not mean everything should be boiled down to a 1-page 6   For example, Climate Change Impacts on the United States: The Potential Consequences of Climate Variability and Change (U.S. Global Change Research Program 2001, Cambridge, U.K.: Cambridge University Press); Decade-to-Century-Scale Climate Variability and Change: A Science Strategy (NRC 1998); The Atmospheric Sciences Entering the Twenty-First Century (NRC 1998); Adequacy of Climate Observing Systems (NRC 1999); Global Environmental Change: Research Pathways for the Next Decade (NRC 1999); Improving the Effectiveness of U.S. Climate Modeling (NRC 2001); The Science of Regional and Global Change: Putting Knowledge to Work (NRC 2001).

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A Workshop Summary Communicating Uncertainties in Weather and Climate Information press release or a 3-page executive summary. On the other hand, if scientists are concerned about communicating to the public, it would help to keep in mind that reporters have a limited time to write their stories. Likewise, the public is much more inclined to read a 30-page report word for word than they are a 300-page report. The important lesson here is to be cognizant of time limitations, for better or worse, which impact reporters and the general public. Regarding the communication of uncertainties in general, certainties are news, while uncertainties rarely are. By making a considerable effort to communicate uncertainties, the certainties were more readily accepted. Most of the media reports acknowledged the uncertainties highlighted in the report, and they were clearly highlighted by the White House. However, the focus was the Academy telling President Bush how certain the NAS was about global temperatures rising, greenhouse gas emissions contributing to this, and future impacts. To focus attention on the scientific questions of climate change, the composition of the committee was critical to its integrity. The committee included leading scientists with a wide range of publicly recognized views, who achieved a consensus on the central issues. The process of constructing the report was made intentionally clear and public. Furthermore, by keeping the report to the science of climate change the message was clear and easier to communicate. The extension to climate change impacts and mitigation would have cluttered the message. When it was decided to release the report earlier than expected on the afternoon of June 6, the NAS was prepared to do so instantaneously by releasing electronic files of the report. Having documents in electronic versions that can be e-mailed and posted on the Academies’ Web site is key to disseminating news in today’s world of constant news cycles and the instantaneous flow of information. By posting the climate change report to the Web, it was available for anyone to read in its entirety before it could be misrepresented.