The world needs to understand that climate change is a fact, the chief financial officer of Swiss Re told CNBC, as the firm posted a $468 million nine-month net loss after several recent catastrophes.

"I think society really needs to wake up and realize that things are changing and if you continue to build in areas that are subject to flood, you need to be prepared to actually deal with the aftermath of flood," David Cole, CFO of Swiss Re, told CNBC Thursday.

The world's second-largest reinsurer said its nine-month property and casualty combined ratio, a measure of underwriting profitability, rose to 114.1 percent on the back of the heavy natural disaster claims. A figure above 100 percent indicates a loss.

Swiss Re and other reinsurers act as financial backstops for insurance companies, helping them cover the cost of claims from natural and man-made disasters.

Following disasters such as Hurricanes Harvey, Irma and Maria and Australia's Cyclone Debbie, the reinsurer expects natural catastrophe claims to reach $4 billion.

Cole told CNBC that everyone needs "to realize climate change is a fact and we need to prepare for that."

"Our role is to make people aware, to help people understand the risk they face and also to put a price on that risk. If these prices are unsustainable we need to signal that to the market," he added.