Hi Michiyo - are you talking about climatological disasters in particular? Or something else?

Pretty informative article out of South Africa about this.

http://www.servicepublication.co.za/index.php/magazine/climate--disaster-management/234-is-the-frequency-of-disasters-increasing

Don't know if this will help but to give you a laugh:

www.theonion.com/articles/july-was-hottest-month-ever-in-us,29124/

(you'll have to copy/paste the whole link to get to the right article)