February 1, 2006 While raising average global temperatures, climate change could also bring more snow, harder rain, or heat waves, meteorologists say. Computer models based on climate data from nine countries indicate every place on the planet will be hit with extreme weather events, including coastal storms and floods.
ORLANDO, Fla.-- f you don't like the weather now ... Just wait, huge changes could be in store. Some scientists predict severe weather events will be even more extreme over the next few decades -- more snow, harder rain, and hotter heat waves.
People everywhere are noticing the changes in climate. Susan Decker, from Broomfield, Colo., says, "It seems warmer. Not as cold. We don't get the snow anymore." Rob Topolski, from Paducah, Ky., says, "We also don't have not nearly as much snow as we used to in Kentucky." Abbie Pumarejo, from Augusta, Ga., says, "It just seems like every summer gets a little bit warmer."
Gerald Meehl, from the Climate and Global Dynamics Division at the National Center for Atmospheric Research (N-CAR) in Boulder, Colo., tells Ivanhoe, "We see the biggest increase in heat waves in the Pacific Northwest where we don't presently have heat waves."
Computer models based on nine different countries' climate data indicate every country will be hit with climate change throughout this century. Meehl says: "If extreme heat bothers you that can be a problem. It could affect your utility bill. You might have to think about getting air conditioning if you don't have it."
The potential effects are far reaching; the computer models have accurately simulated past weather events and now some experts believe these simulations of future climates are likely to be correct. Scientists, however, disagree on what can or should be done, but know something needs to be done.
N-CAR scientists expect the average global temperature to increase by three degrees over this century. Three degrees may not seem like a large amount, but in a heat wave, a three-degree difference could be dangerously hot for more people and create one-foot higher storm surges.
BACKGROUND: Storms will dump heavier rain and more snow around the world as earth's climate continues to warm in the next 100 years, according to several leading computer models. A new study by scientists at the National Center for Atmospheric Research (NCAR) explains how and where warmer oceans and atmosphere will produce more intense precipitation. Such information could help communities better manage water resources and anticipate possible flooding.
ABOUT GLOBAL WARMING: Global warming refers to an average increase in the earth's temperature -- which has risen about 1 degree Fahrenheit over the past 100 years -- which in turn causes changes in climate. A warmer earth may lead to changes in rainfall patterns, and a rise in sea level, for example, as polar glaciers melt. Some of this rise is due to the greenhouse effect: certain gases in the atmosphere trap energy from the sun so that heat can't escape back into space. Without the greenhouse effect, the earth would be too cold for humans to survive, but if it becomes too strong, the earth could become much warmer than usual, causing problems for humans, plants and animals.
WHAT NCAR FOUND: Both the oceans and the atmosphere are warming as greenhouse gases build. Warmer sea surfaces boost evaporation, while warmer air holds more moisture. As this soggy air moves from the oceans to the land, it dumps extra rain per storm. The greatest increases will occur over land in the tropics because that is where water vapor most tends to increase, according to the NCAR study. However, extra moisture combined with changes in sea-level pressures and winds means that northwestern and northeastern North America, northern Europe, northern Asia, the east coast of Asia, and southwestern Australia will also experience heavier rain or snowfall.
WHAT CAUSES RAIN AND SNOW: Rain and snow are two forms of precipitation, along with sleet, hail, dew and fog. Rising warm air carries water vapor high into the sky, where it cools and condenses into water droplets. Some vapor freezes into tiny ice crystals, which can attract cooled water drops to form snowflakes. As snowflakes fall, they meet warmer air and melt into raindrops, unless temperatures are below freezing close to the ground: then we get snow.
The American Meteorological Society contributed to the information in the TV portion of this report.