Stuttering occurs when the natural flow of speech is interrupted. When the child involuntarily prolongs sounds, is unable to produce certain sounds, or repeats a sound, we can say he or she is at risk for stuttering. Stuttering will usually begin between the ages of three and six.
It is significant that so much carbon dioxide stays in the atmosphere because CO 2 is the most important gas for controlling Earthâs temperature. Carbon dioxide, methane, and halocarbons are greenhouse gases that absorb a wide range of energyâincluding infrared energy (heat) emitted by the Earthâand then re-emit it.
As you can see from the graphs, the amount of carbon dioxide in the atmosphere has increased steadily over the past 150 years, and so has the average global temperature. Some of this is due to human activity. Along with other gases such as methane and water vapour, carbon dioxide is a greenhouse gas. It absorbs heat energy and prevents it escaping from the Earthâs surface into space. The greater the amount of carbon dioxide in the atmosphere, the more heat energy is absorbed and the hotter the Earth becomes.