Cli­mate sci­en­tist Ove Hoegh-Guld­berg.

The di­rec­tor of the Global Change In­sti­tute at the Univer­sity of Queens­land, Pro­fes­sor Ove Hoegh- Guld­berg, talks to Karen Mid­dle­ton about the grim re­al­i­ties of cli­mate change and how we must choose which reefs to save.

The Saturday Paper - - The Week | Contents - Karen Mid­dle­ton

Karen Mid­dle­ton We hear much about try­ing to con­tain tem­per­a­ture rises to 2 de­grees above pre-in­dus­trial lev­els. Why is that the magic num­ber?

Ove Hoegh- Guld­berg The 2-de­gree guardrail came out of the 2009 Copenhagen meet­ing. When you looked at how ecosys­tems were re­spond­ing, you got into an un­man­age­able area at 2 de­grees above the pre-in­dus­trial pe­riod, which was where the CO2 con­cen­tra­tion had been sta­ble for a long time. The tra­jec­tory we’re on to­day could raise tem­per­a­tures by as much as 5 or 6 de­grees on his­tory. One of the prob­lems with 2 de­grees is that gen­er­ally peo­ple have the idea that it’s a guardrail. You go up to the edge of 2 de­grees and look over it and see where you don’t want to go and it’s all very safe here. But it’s more like a slip­pery slope. Things get pro­gres­sively worse un­til they be­come un­man­age­able. At the lat­est Con­fer­ence of the Par­ties, the UNFCC [United Na­tions Frame­work Con­ven­tion on Cli­mate Change ] gov­ern­ing frame­work started to say, “well ac­tu­ally we want to keep things well be­low 2 de­grees, and hope­fully aim for 1.5 in the long term”.

KM And where are we now?

OHG We’re about a de­gree above the prein­dus­trial pe­riod.

KM So we’ve got half a de­gree’s lee­way left.

OHG: To keep to that half a de­gree would be a mas­sive de­car­bon­i­sa­tion of al­most ev­ery­thing we do – en­ergy, trans­port, food pro­duc­tion and so on. Key to this is not just the amount of tem­per­a­ture change; it’s the sys­tem’s sta­bil­ity. If we don’t take care of fos­sil fu­els we very quickly get into a sit­u­a­tion where things change. Any­thing like that puts a lot of stress on bi­ol­ogy but also on our eco­nomic sys­tems. If you’re con­stantly hav­ing in­creas­ing tem­per­a­tures and chal­lenges then you’re not go­ing to be able to build an eco­nomic sys­tem that will last 50 or 100 years.

KM What do you think of the 2015 Paris agree­ment on cli­mate change?

OHG The 2009 Copenhagen cli­mate meet­ing that came be­fore Paris had a top­down ap­proach. China had a very dif­fer­ent opin­ion to the Amer­i­cans, the small is­land states to the larger economies and so on. They didn’t reach agree­ment. The Paris 2015 deal was coun­tries pledg­ing what they could do, re­al­is­ing this was a very se­ri­ous is­sue. If you add the pledges up, we go to 3 to 4 de­grees above pre-in­dus­trial, which is clearly not enough. But ev­ery five years, coun­tries must come to­gether and ad­just their emis­sions re­duc­tions and they can only make greater cuts – you can’t go back­wards. If you want to do that, you leave the agree­ment.

KM Well, the United States pres­i­dent, Don­ald Trump, says Amer­ica is go­ing to pull out. How sig­nif­i­cant is that?

OHG Hav­ing such a big player with­draw, there’s def­i­nitely a stum­ble in the road. But I think it’s likely to be a small­ish blip and it doesn’t negate the huge amount of ac­tion at the sub­na­tional level in Amer­ica, like the state of Cal­i­for­nia.

KM Do you think we’re past ar­gu­ing about the sci­ence? And are events like the hur­ri­canes in the Caribbean and south­ern United States likely to gen­er­ate more cli­mate de­bate?

OHG The In­ter­gov­ern­men­tal Panel on Cli­mate Change is this very ar­du­ous process where sci­en­tists meet and bring all the lat­est sci­ence pub­lished in peer-re­viewed lit­er­a­ture and reach a con­sen­sus about it. That’s about as solid as you can get. Now there are parts of it we don’t know, but the fun­da­men­tal un­der­stand­ing that chang­ing green­house gas con­cen­tra­tions in the at­mos­phere is dis­rupt­ing weather pat­terns across the world is fact. You can’t un­pick that one. You might still dis­cuss whether ev­ery storm is a con­se­quence of cli­mate change. Over the last cou­ple of years we’ve be­come cer­tain that it’s not the num­ber of storms chang­ing, it’s the im­pact of each one. That’s what we’re see­ing across the Caribbean and South Asia. You’re get­ting those nor­mal storm sys­tems com­ing through but they pack a big­ger punch.

KM You pre­dicted 20 years ago that we were go­ing to be in a di­a­bol­i­cal sit­u­a­tion. Are you say­ing, “I told you so?”

OHG I wish I’d been wrong. A very sim­ple model that I put to­gether with peo­ple from the Euro­pean Union showed what tem­per­a­ture was likely to do and we knew the tem­per­a­ture at which coral reefs got into trou­ble and they crossed each other around mid-cen­tury. I re­mem­ber think­ing at the time, “I hope this one’s wrong.” In the last cou­ple of years we’ve had back-to-back bleach­ing events. Reefs have dis­ap­peared from many places – the Caribbean has been par­tic­u­larly hit hard. Corals have gone from maybe 50 to 60 per cent of the bot­tom of the ocean to less than 5 per cent in many places.

KM Is this ir­re­versible?

OHG Un­der nor­mal, non-cli­mat­e­change cir­cum­stances, reefs might lose corals due to cy­clones for ex­am­ple. And if they’re given 10 to 20 years, they’ll bounce back. But what’s been hap­pen­ing with these bleach­ing events, which are sim­i­lar to cy­clones in killing coral en masse, is they’re now com­ing faster and faster. There’s not enough time for reefs to bounce back.

KM You’re in­volved in a project, the 50 Reefs Project, which is at­tempt­ing to ef­fec­tively triage reefs around the world and work out which ones are save­able and which ones aren’t – a po­ten­tially con­tro­ver­sial thing to do. Can you give us a progress re­port?

OHG This project came out of the cer­tainty one gets, to some ex­tent, from the Paris agree­ment. You’ve got another half a de­gree of change, then it is sup­posed to sta­bilise about mid-cen­tury. Even un­der that path­way, we still lose an aw­ful lot of coral. We’d lose 90 per cent in some places of to­day’s coral by the time we get the Paris agree­ment in place. We’ve al­ready lost maybe 50 or 60 per cent. If we can get as much of those coral re­sources through to the time when the cli­mate is sta­bilised then bi­ol­ogy will take over. Once it is con­stant again, corals will grow and do what they nor­mally do, post a dis­as­ter. Then you have to say, “Where are those reefs that have the best chance of sur­viv­ing a cli­mate in­crease of 0.5 de­grees?” The ocean isn’t heat­ing up at the same rate in all places. There are some places where the cur­rents have stalled, where it’s get­ting a lot hot­ter a lot quicker, like the equa­to­rial Pa­cific, ver­sus the coral tri­an­gle, which is this South-East Asian par­adise for corals. The num­ber of species there is some­thing like three times that of Aus­tralia. So you start to go, “Oh, well if we’re go­ing to pre­serve some­thing we wouldn’t do it at the equa­tor where it’s get­ting re­ally, re­ally hot – we should be go­ing to South-East Asia.”

You do run into what ap­pears to be triage, and I don’t think that’s the right word. I think it’s about another strat­egy be­ing added onto the great things that are al­ready go­ing on in con­ser­va­tion. We will be re­leas­ing a list later this year and you have to ask the ques­tion: “What if the Great Bar­rier Reef’s not on it?” And it’s an in­ter­est­ing one.

KM Is it go­ing to be on it?

OHG I don’t know. Peo­ple much smarter than me are work­ing on this prob­lem in a very ob­jec­tive way.

KM It’s re­ally the re­verse of triage, be­cause un­der triage the most dire in­juries are treated first. This is say­ing, “We’re go­ing to go for the ones with the best chance of sur­viv­ing and leave the ones that are worst un­til last”. OHG Yes, we’re try­ing to be smart about those in­vest­ments.

KM So what are the bench­marks for es­tab­lish­ing which are save­able?

OHG It’s got to not be chang­ing too quickly. You don’t want them in the way of storms. You want them not to be re­mote. There are a lot of reefs in the world that are in the mid­dle of nowhere, so the value of pro­tect­ing those might be high in terms of unique species but it won’t be in a good po­si­tion to re-spawn back onto dam­aged reefs. The team went through a re­ally large num­ber of data sets and came up with about five or six of these key char­ac­ter­is­tics and then ran a mod­el­ling sys­tem which is ac­tu­ally used with fi­nan­cial in­vest­ments for spread­ing in­vest­ment and risk to op­ti­mise a port­fo­lio. Let’s say a coun­try’s not on the list. That doesn’t mean it doesn’t have reefs that are worth pre­serv­ing. It just means this is a set of 50 sites where you’re try­ing to en­sure that this ecosys­tem gets through to the fu­ture.

KM What do you then do with the rest?

OHG We need to go in there and map the re­sources. On the Great Bar­rier Reef, that’s prob­a­bly not an is­sue be­cause we’ve got one of the best park sys­tems in the world. But many places will be in coun­tries that don’t have those re­sources. We’ll need to map them, the po­ten­tial threats and the po­ten­tial so­lu­tions.

KM How do you as­sess the cur­rent sta­tus of the Great Bar­rier Reef? How bad was the bleach­ing?

OHG The reef’s health has been rocky for some time. In 1998 we had 50 per cent of the reef bleached but only 10 per cent died. That’s 10 per cent of 40,000 square kilo­me­tres of coral – it’s still a large amount. Then it hap­pened again in 2002 and then we had a bit of a break and then it came roar­ing back in 2016 and 2017, where not only much of the reef bleached but we lost al­most 50 per cent of the corals over the last two years. If we con­tinue to have warm sum­mers like we had in ’16 and this year, the next one could wipe out the re­main­ing coral. Now, I don’t want to sound dooms­day, but that’s where we’re at right now. It’s still a won­der­ful place to visit. But if we con­tinue on this tra­jec­tory it won’t be, very soon – within our life­time. I think that this is the wakeup call that we need. If los­ing the Great

• Bar­rier Reef isn’t se­ri­ous stuff, what is?

This is an edited tran­script from A Month of Satur­days at the Na­tional Por­trait Gallery. This week: Clover Moore at the Na­tional Library of Aus­tralia, 2pm, Septem­ber 16.

Ove HoeghGuld­berg, the di­rec­tor of the Global Change In­sti­tute.

KAREN MID­DLE­TON is The Satur­day Pa­per’s chief po­lit­i­cal cor­re­spon­dent.

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