Transcript
REBECCA ASCH: So we did look at two climate change scenarios. One that is a warmer kind of scenario where we are getting changes. Generally between two and four degrees. There is a scenario where if everyone came together and really took mitigating climate change seriously the warming would only be about one degree. Which would be a much better situation.
JAMIE TAHANA: And on that sort of more bleak scenario a prediction of between 50 and 80 percent of species extinction or migration that is a very dramatic number how did you come to that?
RA: Well what we did is we looked at the habitat species used and where that habitat will be in the future and on a regional basis what we looked at is for each region of the ocean how much species will gain locally versus how many basically leave that area. So it is a local extinction those species still might be occurring in other parts of the ocean but not necessarily the regions where they were in the past. And so what we have been finding is that the gains for most areas are fairly low often about two to six percent of biodiversity but these losses are a lot higher and there are some areas where it does exceed 80 percent but overall all over the Pacific you kind of have losses that are kind of in the 50 to 60 percent range. And this is kind of at the end of the century under the higher climate change impact scenario.
JT: Is that largely because the Pacific is quite a static temperature and the species can't adapt to a change?
RA: Yeah that is part of it. So basically if you look at kind of the seasonal cycle how much temperature varies. The most variability over the course of the year tends to be in the mid latitudes and in the lower latitudes as well as at the poles you don't to get as much change which means that organisms are often very kind of adapted to a narrow range of temperature and that means that you know if temperatures go beyond that range we are either going to have species migrating out of an area decreasing in abundance or in some cases you could get adaptation to these changes. But the question is just as the changes are happening fairly quickly so can organisms adapt quickly enough.
JT: Yes because adaptation is a sort of really slow process isn't it and if we have had these dramatic changes in mere decades.
RA: Yes that is exactly. Like there is some cases where you can get rapid evolution but that is something that we can’t count on happening.
JT: To what extent is this affecting the species that Pacific Islanders rely on for their livelihoods or Sustenance and such?
RA: Okay the study looked at about a thousand different species because it was looking at biodiversity patterns and one of the things that was a little bit surprising is that we are then divided up into species that either have more reef fish species or open water species and surprisingly we kind of found similar patterns across a lot of different species. So it does seem like that is going to be a problem though for you know small scale fisheries you know people rely on for subsistence as well as larger scale fisheries are focussing on commercially important species like Tuna.
JT: Already we are starting to see in countries like Kiribati, Tuvalu and that fishermen reporting reduced catches or having to go out further into the sea to actually find fish and stuff is this all part of that? Is it already underway?
RA: So one of the things that is really difficult to sometimes tell is how much is due to fishing pressure as well as changes in climate and for the most part it is something where you know often times trends that we see are a bit of those and certainly that would be consistent with projections that people might see under climate change. But you know it may be a kind of a combination of historical or over-fishing as well.
JT: Is this trend reversible. You say kind of the 50 to 80 percent is sort of in the worst case scenario of global warming but say with the targets I mean we have got all the world leaders in Germany at the moment trying to thrash out some rules for climate action and stuff. If action comes together is this avoidable or reversible or anything?
RA: It think that avoidable is definitely a possibility. I think the hard thing is once we have CO2 in the atmosphere a lot of it will stick around for centuries so once it happens it is going to take a long time to reverse. But I think we are still at a point in time where we can avoid the worst impacts scenario. So like I think that this is a really important moment in history for that reason and we did find that for a lot of the climate variables if you kind of take this best case scenario where we do take action now the changes in things like temperature, Ph will be two to four times smaller than otherwise. So that is certainly going to have a positive impact compared to a business as usual scenario.
