Are you an ocean optimist or pessimist?

Helen: So, given all we know about the impacts human lives are having on the oceans, and predictions that it could all get a lot worse, can we be optimistic about the future of the oceans? Or is it all doom and gloom?

这里是海洋探险家保罗罗se who we originally spoke to at the Reefs at Risk Revisited launch in 2011 - that was the latest report to document the global status of coral reefs and forecast what lies in store for them in the years to come. I caught up with Paul to find out how he's feeling about the oceans:

Paul: Most of us live in urban environments and its beginning to bite, it's beginning to tell and its beginning to hurt and what that's means it people have actually started to realize how important it is that we understand and protect our ecosystems and biodiversity. Now I've seen the next generation and they're flipping fantastic. They're bright people. So I think in the next 30 years we really are going to do some clever things. We're going to work out how we're going to control our population growth, we're going to make some sensible adaptations to climate change that's already occurring. And most importantly we're going to learn to understand and protect our ecosystem services and biodiversity and we can't do that without understanding the ocean.

We've had this historical view of us all living on land and the seas out there somewhere, but we're finally coming to the realization that the earth is 99% water and we're living on little bits of land so it's time to understand the greatest, most important ecosystem on the planet. So I'm incredible optimistic and I recon in 30 years I'm going to be having a glass of whisky and celebrating with the youngsters.

Helen: John Bruno shares Paul's optimism although for slightly different reasons:

John: People, especially my PhD supervisor, always called me a pathological optimist. And sometimes my grad students think that too in terms of optimism about what can be accomplished during a field season or field trip. And I tend to have an optimistic outlook about the oceans. I don't think I'm in denial about how much has changed and the threats to ocean ecosystems but I still have a lot of optimism.

I've been discussing this a lot with friends and colleagues and a lot of them point out that there's just no scientific basis to be optimistic about coral reefs or any other ecosystem. I kind of dispute that. But ultimately I think optimism comes more from a perception, a feeling, it's almost a philosophical outlook rather than scientific. We don't really form emotions based on scientific evidence for or against them. So I think that really just again come from my outlook.

Helen: Mark Spalding's outlook isn't quite as cheery, but, as he says, all is not yet lost:

Mark: Reflecting on it I'd probably describe myself as a gloomy optimist, or a pragmatist, something like that. The oceans have changed so much in the last decades, beyond recognition in many places. And I think we've got to live with that. We're not going to get everything back to pristine, there's too many people and we've got too many needs. That can make you very pessimistic. You can dive on a coral reef in the Caribbean and if you know what it used to be like you can be pretty depressed about it. But actually if you look at the eyes of a person who does their first dive on a coral reef today, they're totally thrilled by what they see. I think we have to keep that in balance. Nature is still fantastic. Maybe it was better once but we're still getting wonders out there, and enjoying them. And I guess that's optimistic.

John: I do go to plenty of places in the world that are still obviously not pristine but are still wondrous and so full of life. There's big fish, living corals and other benthic invertebrates, and there's just so much left out there. We're so far still, luckily, from an ocean dominated just by jellyfish and slime although I understand we maybe be headed in that direction. I think we're many decades or many centuries from getting there. So I do think we have a lot of time to turn things around.

Helen: I also spoke with ocean explorer Sylvia Earle. WE first met at the Census of Marine Life. Her optimism comes form knowing about the impacts humans are having on the oceans and the fact that now is the time to do something about it.

Sylvia: There are a lot of smart creatures on the planet. Not just humans. Including squids and octopuses, and quite a few fish that are clearly intelligent. I think about stomatopods. Most people don't think about stomatopods, but I do because they're just amazing creatures in their ability to solve problems and figure things out in extraordinary ways. We think we're the only ones but we're not. But we are the only ones, in fact this is the only time in history that even humans have been able to look at the skies above and realize that we are within this universe of largely inhospitable places and that earth itself could be very inhospitable to us unless we take deliberate measures now on our watch. Because not only is this the first time that we have begun to connect the dots and see ourselves in perspective and see that our actions alter the nature of nature. And it's the last time perhaps that we'll have an opportunity to do something about it. The last little window of time. How long? Is it 10 years? Is it 20 or 50? Whatever it is the window is closing. But it isn't too late to reverse these trends that should have everyone's wrapped attention. We should be paying attention as if our lives depended on it because they do.

Helen: One reason that a lot of people are hopeful about the future of the oceans is the positive effect of protecting areas of the sea: Here's Enric Sala...

Enric: I'm a cautious optimist. There are things that we're not going to be able to bring back. But there are bright spots, success stories, like marine reserves that are protected from fishing where marine life comes back. And these success stories give me some hope.

Helen: But there are limitations to the protected areas we currently have in the sea:

John: I think we need more reserves, maybe 20-30% or more, but more importantly they have to be enforced. We rarely enforce the marine reserves that we designate. That's what we need to do. In fact I'm moving towards literally armed enforcement, the way we protect rhinos and African elephants. We need people out there protecting this invablable resource for all the people that depend on it economically. We protect banks with alarm system and weapons and people, and other valuable resources and a coral reef is worth millions and millions of dollars every years, even a small part of it. So I think we need to move forward in our enforcement of our marine reserves, so that's one big hope.

Helen: So it might strike you as a bit of a militant approach, but maybe what we'll need are heavily armed ocean patrols to protect valuable parts of the sea.

And while MPAs are no doubt vital for ocean conservation, as Mark Spalding points out, what about all the rest of the ocean that doesn't and never will lie within marine protected areas?

Mark: We're gradually heading towards 10% of the worlds oceans which will mean 90% isn't even thought about by those people who think marine protected areas are the answer. We've got to get beyond that. We've got to think about the entirety of ocean space and that means working with everyone and trying to get them all to share a vision, to at least be willing to take a cut rather than try and get everything for themselves all the time.

Helen: As well as efforts to protect remaining areas of healthy habitat, advances are also being made in our abilities to restore marine ecosystems.

Mark: We've known for quite a while that we can restore mangrove forests and of course there have been some pretty spectacular failures, but there's also been huge areas, about 3% of all the worlds mangroves are replanted by people. So we can put nature back and we can enhance and encourage recovery. We're doing lots of oyster reefs in North America and there's talk about doing that in Europe, that'll be really exciting. It's a habitat that's extinct, really, in Europe, but it could come back. It used to be incredibly important. And there's even talk now about being able to restore coral reefs at largish scales and that's a point of hope. This is in the Caribbean where the big reef building corals, two species only in the Caribbean, which used to grow the reefs, the structures on which so much depends, and are virtually extinct thanks to various combinations of threats. There's now 30,000 of these little corals being growing up in nurseries across the Caribbean and they're starting to plant them out in the wild. It feels a little bit hopeless.