Ask a Scientist:
Freeman Dyson, retired Professor at the
Princeton Institute for Advanced Study.
The probability of a certain event is 1. This is equivalent to you being 100% sure it will happen.
With a coin toss it will fall as either heads or tails, on tossing a coin repeatedly over time this will average out so that half the time, that’s 1 in 2, it will fall as heads.
Scientists make predictions about outcomes of events according to their calculated probability level. A U.S. Environmental Protection Agency report written in 1995 by Titus and Narayanan concludes that that there is
- a 90 percent chance that global temperatures will rise by at least the 0.6°C warming of the twentieth century and
- a 10 percent chance that temperatures will rise more than 4°C in the next century.
Other scientists are more certain of a larger rise, Tom Wigley of the National Center for Atmospheric Research in Colorado, USA and Sarah Raper of the University of East Anglia in England reported in 2001 that there was a 90% probability of average global temperatures rising 1.7 to 4.9 degrees over the next 100 years.
Will it happen to me?