It's no longer a question of if sea levels will rise or when, but how to protect coastal cities and towns before they do, the Ecologist reported.

Based on a new study published in the Proceedings of the National Academy of Sciences, the damages caused by storms and flooding will reach $100 trillion per year this century if current measures don't change. The current figures are between $10 and $40 billion per year.

"If we ignore this problem, the consequences will be dramatic," said lead author Jochen Hinkel of the Berlin-based think-tank, Global Climate Forum (GCF).

According to his co-author, professor Robert Nicholls form the University of Southampton, focusing governments (and people in general) on long-term protective measure is a challenge because " coastal development tends to be dominated by short-term interests of, for example, real-estate and tourism companies, which prefer to build directly at the waterfront with little thought about the future.

With proper investment -- about $10 - $70 billion per year worldwide -- the global economy would be able to contain damages to a significantly more manageable $80 billion annually by 2100, according to the report.

Not only must countries invest for themselves, but they must help other countries in need - and not just after a major storm has struck. By aiding the defenses of economically developing countries, richer countries may actually be saving money down the line they won't have to send as storm relief.

"Poor countries and heavily impacted small-island states are not able to make the necessary investments alone, they need international support," said Hinkel

Proactive measures, according to Hinkel and Nicholls, include "building or raising dikes, planning higher defenses, flood proofing buildings and strategically planning coastal land use."

Hinkel also pointed to one of the underlying causes of rising sea levels, greenhouse gases.

"If we do not reduce greenhouse gases swiftly and substantially, some regions will have to seriously consider relocating significant numbers of people in the longer run."