New report suggests sea level rise could swamp Halifax's Armdale Roundabout

On his last day in office U.S. President Barack Obama received a government report on global sea level rise.

It says by the year 2100, the oceans around us could rise by as much as 2.5 metres — with Nova Scotia being particularly hard hit by the repercussions.

Boris Worm, a marine biologist at Dalhousie University, explains what this means for Nova Scotians.

This interview has been edited for clarity and length.

Q: Who came up with this number? Who came out with the report?

The remarkable thing is this comes straight from the U.S. government, from the National Oceanic and Atmospheric Administration, which is the equivalent of our Department of Fisheries and Oceans, roughly. They authored a report called Global Regional Sea Level Rise Scenarios for the United States. 

They did this though, remarkably, on the last day of the Obama administration and you can't help but think that they felt that if they didn't release it now it wouldn't be released at all under the Trump administration. 

They came up with this upper limit of 8.2 feet or 2.5 metres and a lower limit of one foot or 0.35 metres, so it's somewhere in the range of that.

The one foot would be if we stop everything now and do anything we can to avoid further climate change and then the 2.5 metres — which right now is the more likely scenario — if we're only going to have minor adjustments and going to burn through our fossil fuels as we have.

Q: How would coast roads and landscapes in Nova Scotia cope with two and a half more metres of water? 

It's remarkable. I was driving down Quinpool Road on my way here. You're by the rotary, so that's under water. 

You see all the coastal property, very low-lying, very valuable property. That's under water. Then you have to add storm floods on top of that.

Different places are affected differently. Our region for example would experience more than the average and this has to do with the gravitational pull of the continents, the shape of the ocean basins, the lifting or sinking of land masses that are still recovering from the ice age.

For a given amount of sea level rise our region would see more than that and then the Pacific Northwest so British Columbia and Alaska for example would see less than that. So that means we're at the losing end of this game.

Q: How likely is the worst case scenario?

It's if we continue with business as usual — which the U.S. is again on track, but Canada very much so is not on track.

Nova Scotia, since they came out with that action plan [in 2009], has transformed 27 per cent of their electricity supply by renewable sources. Wind, solar, tidal, biomass and hydro. And by 2020 they're on track to have 40 per cent generated by renewable power.

We're really in a fast transition here in Nova Scotia and Canada more broadly to wean ourselves off fossil fuels. Maybe not fast enough but certainly faster than some other places.

Even a single foot of sea level rise would increase the likelihood of these floods 25-fold, meaning it doesn't happen every five years it happens five times a year. Think about that. That means all the time. And that's just a foot — and we're talking about eight feet — so really I have to say it's unimaginable what eight feet will do to New York City, to Venice, to Halifax, to all of these coastal cities.

Q: Was this report a revelation for you?

I have to say I didn't see this coming and I think most people haven't seen this coming. People are realizing that a lot of the Antarctic ice shelf is unstable now … and it really affects our daily lives here.

We really have to face that reality … the highest emission scenario is that 25-fold increase in floods will be realized by 2030 — that's 13 years away.

Under the lowest, most aggressive greenhouse gas reduction scheme it will be 2080. So not in my lifetime but certainly within our children's' lifetime.

We can buy ourselves 50 years to prepare for that one foot sea level rise and then hopefully cap the total magnitude by doing the right thing now.

• Listen to the full interview with Boris Worm