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.
Best Answer: Population biologists have estimated that maintenance of human population requires at least 1.6% birth rate per year. In the US, there are about 4 million live births per year, or roughly 1.3%; this alone would lead to negative population growth if not for immigration. Worldwide population increases by about 2% per year, so the worldwide birth rate must be roughly 3.5%, or 210,000,000 annually. There are 31,556,736 seconds in a year (60 X 60 X 24 X 365.24). Rounding off a little for convenience (and because babies don't come in fractions), that comes out to about 7 per second.