Water, Water Everywhere (At Least Everywhere It's Not Wanted)

Let's cut to the chase. The IPCC, Intergovernmental Panel on Climate Change, has estimated sea level rise over the course of this century will be somewhere between 30 cm. to 1 metre. With the IPCC's track record for getting it wrong, understating the pace and impact of climate change, you can consider that a low ball opinion.

More recent studies of the rate at which ice caps in both hemispheres are declining suggests by 2100 we'll see between 2 and 3 metres of sea level rise. With the current rate of sea level rise of 4 mm. annually and increasing, 2 metres is probably a safe bet.

Which lends a bit of perspective to the recent study about near-term sea level rise. Here they're looking at sea level rise of 5, 10 and 20 cms.  That sort of rise may not be devastating in its own right but it can be when it combines with high tides and storm surge events and it's expected to cause havoc in the tropics first.

In those locations, just 2.5cm of sea level rise leads to extreme water levels being seen twice as often, while a 5-10cm increase means coastal floods are twice as likely across all the tropics. A rise of 20cm leaves almost every coast with twice the risk.

The rise of 5-10cm, likely to occur within a couple of decades, would mean major cities including San Francisco in the US, Mumbai in India, Ho Chi Minh in Vietnam and Abidjan in Ivory Coast facing a doubled risk of coastal floods. “The maps of increased flooding potential suggest a dire future,” write the scientists.

“This study shows how even small changes in mean sea level can significantly increase the frequencies with which critical thresholds are exceeded,” said Thomas Wahl, professor of coastal risks at the University of Central Florida, who was not part of the research team.

While coastal British Columbia is obviously not in the tropics it already experiences seawater inundation events, especially in spring, when high tides and storm surges can be compounded by early season mountain snowcap melts and runoff. British Columbia's Lower Mainland, one of the most densely populated regions in Canada, is particularly vulnerable when meltwater runoff swells the Fraser River as it nears the sea. There are some very low-lying municipalities along the way, Richmond and Surrey in particular.

[University of Illinois prof, Sean] Vitousek said: “We are going to have to [cut carbon dioxide emissions] and engineer the coastlines to stop a lot of these events from happening. We want Greenland and Antarctica to remain as ice for as long as possible.

“One metre of sea level rise is going to be a game-changer for the coastal zone. The next time you are at the beach or down by the water, think about what that area would be like in some of these sea level rise scenarios, half a metre or metre. You’ll see it’s a pretty scary proposition.”