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.
Where: 1  r is the rate of natural increase and is usually expressed as a percentage (birth rate - death rate) 2  t a stated interval of time, and. 3  N is the number of individuals in the population at a given instant.