Its not a hoax, and you dont need to be smart understand that,
Look for example on Israel, 50 years ago it was raining much much more and it was even snowing on Tel aviv, a think that will never happen again (unless there is a nuclear winter : P)
Europe is getting hotter and hotter every year,
The Ice on Antartica is melting down with each year.
Its all because of the modern life, the massive CO2 pollution that is caused by cars, industry, sprays, power plants etc...