The World Today: ABC RN 12:10:00 31/03/2014
‘Disturbing picture’ of climate change impact on oceans in latest IPCC report
A coordinating lead author of the latest report by the Intergovernmental Panel on Climate Change says it paints a disturbing picture of how the earth’s oceans are being affected by climate change. Professor Ove Heough-Guldberg says as the oceans warm, fish and plankton are migrating towards the poles, which could cause food security issues for many nations in the tropics. He says the report also finds that carbon dioxide absorption is changing the chemistry of the ocean, making it more difficult for corals to build skeletons, and even affecting the ability of fish to navigate.
In this interview, Lynchpin notes that Professor Ove Heough-Guldberg highlights features raised in the ex Oceano science narrative.
ELEANOR HALL: The Intergovernmental Panel on Climate Change has just released its latest report at a meeting in Japan and it paints a disturbing picture of the impact of global warming on the Earth’s oceans. The report finds that carbon dioxide absorption is changing the chemistry of seawater and the distribution of fish, and that this could generate food security issues for many nations in the tropics. And despite the attacks on the UN climate body even before the report was released, lead author Professor Hoegh-Guldberg warns that, far from exaggerating the problems, the IPCC report is more conservative than the reality.
SARAH DINGLE: The IPCC is into its fifth round of reports, authored by more than 830 experts around the world. Late last year Working Group I presented a number of different scenarios for how human-induced climate change may unfold this century.
Now, Working Group Two II released a report on the impacts of climate change already taking place, with one of its chapters delving into the state of the oceans. The chapter’s coordinating lead author, Australian Professor Ove Hoegh-Guldberg says the chemistry and also the temperature of oceans is being altered, which in turn is having a dramatic impact on marine species.
OVE HOEGH-GULDBERG: We’re seeing some major impacts on how the ocean functions.
SARAH DINGLE: The IPCC has found that the ocean is warming because it’s absorbing more than 90 per cent of the increase in energy in our climate system. Professor Hoegh-Guldberg says the oceans are vast but they can’t take that kind of radical shift without some serious consequences.
OVE HOEGH-GULDBERG: Organisms that are sensitive to temperature are essentially following that warming, and so what we’re seeing is the migration of populations towards the poles to higher latitudes. Fish and plankton, for example, which are not tied to the bottom – they’re sort of swimming above it – they’re moving quite rapidly towards the polar regions to those higher latitudes. All of those populations that are migrating are probably migrating at a rate which is sort of falling behind the very rapid rate of climate change that we’re seeing.
SARAH DINGLE: And the fish and plankton, at what rate are they moving to the higher latitudes?
OVE HOEGH-GULDBERG: Some of the studies that have been tracking plankton or fish and so on are seeing rates that are anything up to, you know, 100km per decade. And I think you just get a very sobering picture when you ask the question how fast should something like the Great Barrier Reef move if it were to keep up with, say, a two-degree change in sea temperature? The answer to that is that you’d have to have the reef – and that’s everything – would have to move at the rate of 10-20km per year and, of course, that’s an extraordinarily high for such a complex ecosystem to move at.
SARAH DINGLE: The migration of key food species like tuna rings alarm bells for some nations’ food security, according to Professor Hoegh-Guldberg.
OVE HOEGH-GULDBERG: There are a number of tuna fisheries in the western Pacific, for example, which are going to be affected by the end of the century by the fact that, as we warm seas, tuna will have migrated hundreds if not thousands of kilometres in an easterly direction in the Pacific. Now, they could be well outside where those countries can actually economically fish them.
SARAH DINGLE: Apart from changing temperatures, climate change is also having a significant impact on the chemistry of the ocean. The absorption of carbon dioxide is acidifying our seas. According to Professor Hoegh-Guldberg, the changing chemistry is making it more difficult for species like coral to build skeletons, and it’s even disorienting fish.
OVE HOEGH-GULDBERG: They’ve got seawater flowing across their sensory systems and so on. PH and carbonate ions are really important in how those systems that are exposed to the ocean act. And so once you start to sort of change the PH and the chemistry, not surprisingly, we’re starting to see some neurological impacts.
SARAH DINGLE: UNESCO’s World Heritage Committee will soon decide whether the Great Barrier Reef World Heritage Area is moved to the “in danger” list. With the oceans bearing the brunt of global warming, Professor Hoegh-Guldberg says the message of this report is nations should do everything they can to relieve local pressures on ecosystems.
OVE HOEGH-GULDBERG: By building the world’s largest coal port, by having I think a decreasing response to climate change and at the same time as disrupting a lot of the coastal systems that are protecting the Great Barrier Reef, you’d have to say that we are looking to a downgrading of our listing.
SARAH DINGLE: The IPCC says it’s likely global average temperatures will rise by more than two degrees by the end of this century in all but its most optimistic climate change scenario. Professor Hoegh-Guldberg warns that all of the current changes in the world’s oceans reported by the IPCC are taking place with around one degree of warming so far.