In 2015, for example, scientists said that an ongoing drought in Californiaâthe stateâs worst water shortage in 1,200 yearsâhad been intensified by 15 percent to 20 percent by global warming. They also said the odds of similar droughts happening in the future had roughly doubled over the past century.
Definition: Birth rate is the demographic measure of the rate at which children are born. The most well known is the crude birth rate, which is the number of births that occur each year per 1,000 people in the midyear population. It is called âcrudeâ because it does not take into account the possible effects of age structure.
The total (crude) birth rate (which includes all births)âtypically indicated as births per 1,000 populationâis distinguished from an age-specific rate (the number of births per 1,000 persons in an age group). The first known use of the term birth rate in English occurred in 1859.ccording to the United Nations' World Population Prospects: The 2008 Revision Population Database, the crude birth rate is the number of births over a given period, divided by the person-years lived by the population over that period.