Image credits
Image Credits:

Photos: girl drinking: Natasha Paterson / AGE Fotostock tree: Digital Vision / AGE Fotostock; polar bear: NOAA; kangaroo rat: AMNH / R. Mickens morning mist, snowflakes: J. Falk volcano: Coombs / USGS snowy streets: Image 100 / AGE Fotostock; sea ice: NSF clouds: V. Ryzin; Grand Canyon: NPS Central Park; rocks: AMNH / T. Gaud iceberg: AMNH / C. Chesek; carrying water: Digital Vision / AGE Fotostock; hamburger: Science Museum of Minnesota; dam: BPA wetland: USDA; girl drinking from water fountain: R. Friedman