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SELECT COMMITTEE ON CLIMATE POLICY
23/04/2009
Emissions trading and reducing carbon pollution

CHAIR —Welcome. I invite you to make an opening statement.

Mr Gunn —Good morning. As you may know, the Antarctic Division has a science branch, in which about 130 scientists and support staff conduct research into many aspects of the environment in Antarctica and the impacts of humans on that environment. Although the boundaries of what does and does not constitute climate change research are somewhat fuzzy these days, I would estimate that somewhere around 50 per cent of the research we conduct is of direct relevance to climate change. In Hobart, we work very closely with CSIRO and the University of Tasmania. With me today are my colleagues Dr Press and Dr Hunter from the Antarctic Climate and Ecosystems CRC, of which the Antarctic Division is a very major player.

As with most of the work done on global climate change or global change and certainly all of the work done in Antarctica, our research is very collaborative; we work in large collaborative frameworks on a global scale. As for our relevance to your committee, our core expertise is in ice dynamics and the impacts of global change on the Antarctic and Southern Ocean ecosystems. I just want to differentiate primarily between CSIRO and UTAS, who focus primarily on ocean and climate change dynamics and on the extent of change in the biogeochemistry of the oceans. In terms of sharing questions and giving you the best advice today, I propose to focus AAD’s answers to questions on ice dynamics and the impacts of climate change or global change on Antarctic systems’ ecosystems. Thank you.

Dr Press —Our role is to look at the role of Antarctica and the Southern Ocean in the global climate system and in climate change. We are a collaboration of research institutions: the Australian Antarctic Division, the CSIRO and the University of Tasmania. We have collaborations internationally with the Alfred Wegener Institute, the New Zealand NIWA and Silicon Graphics. We have five major programs: climate change and variability; sea-level rise, of which John Hunter is one of the key leaders; oceans and carbon dioxide; the Antarctic marine ecosystem, much of which is done with the Australian Antarctic Division; and a small policy program, which is responsible for putting information about the role of Antarctica and climate change into the public domain. In the last couple of years we have published a paper entitled Ocean fertilisation: science and policy issues; on the IPCC AR4 Report, we have done an update on sea-level rise entitled Climate change, sea-level rise and extreme events: impacts and adaptation issues and another on CO2 Emissions and Climate Change: ocean impacts and adaptation issues; and we are about to publish two position papers, one on ice sheets and another on sea ice, which we will make available to the committee, if it wishes us to. Dr John Hunter, on my left, would like to make an opening statement at some stage.

CHAIR —We will take your opening statement now, Dr Hunter.

Dr Hunter —Thank you very much. I am an oceanographer from the Antarctic Climate and Ecosystems Cooperative Research Centre. I have handed out a two-page document, which I will just read through reasonably quickly. I might miss out a few little bits, but I will try to point you to a couple of diagrams that are on the back and will just lead you through those. I am a physical oceanographer with about 10 years experience in sea-level rise and climate change. I have worked on scientific aspects of sea-level rise and also on the policy application of this science, for example, in setting risk guidelines for sea-level rise. I will only address term of reference 1(c):

… whether the government’s Carbon Pollution Reduction Scheme is environmentally effective, in particular with regard to the adequacy or otherwise of the government’s 2020 and 2050 greenhouse gas emission reduction targets in avoiding dangerous climate change …

Dangerous climate change is generally thought to start when the global average temperature has risen by about two degrees above what it was in pre-industrial times. In addition, it is generally thought that stabilisation of greenhouse gases in the atmosphere at a 450 parts per million CO2 equivalent will give rise to a global temperature rise of about two degrees centigrade above that of pre-industrial times—in other words, the threshold temperature for dangerous climate change that I have just noted.

The issue addressed in term of reference 1(c) depends strongly on the way in which emission reductions are allocated between countries; therefore, it is not answered simply by the science. There is no way a scientist can directly answer the term of reference 1(c), because it depends on what everybody else does. Therefore, I will not comment directly on Australia-specific targets but will look instead at two significant effects that happen when you stabilise greenhouse gas at a specific level and at what it does to the sea level.

It is widely considered that stabilising below a 550 carbon dioxide equivalent will be very difficult. We may be aiming for 450, but a lot of people think we are not going to get short of 550, in fact. The attached figure, which is the first coloured figure and is page 3, indicates what we might expect if we do stabilise at 550. The second dot point indicates the expected range of global temperatures above that of pre-industrial times. Roughly, you will get within a range of two to four degrees centigrade if you stabilise carbon dioxide concentrations into the atmosphere at 550 parts per million. So that is just a graphical representation and the mauve bar represents the temperature range expected if you get to 550. All this information is from the Fourth assessment report of the Intergovernmental Panel on Climate Change. So it is slightly old data and I would suggest that it is actually conservative. Since the IPCC AR4 came out, there have been suggestions that it was certainly conservative as regards where we will be at these levels of carbon dioxide.

The third dot point indicates the range of global temperatures at which snowfall over the Greenland ice sheet is exactly balanced by melting. We are looking at what will happen over Greenland. At the moment, if temperatures are lower than this—which, of course, they are—snowfall over Greenland will exceed melting. So more snow is falling on Greenland than is melting. Most of that balance then is taken up by calving of icebergs. As you warm up temperature, both snowfall and melting increases, but the melting increases faster. So you get to this limit of temperature, which again is in the range of about two to four degrees centigrade. At that temperature, melting equals the snowfall. This means that Greenland has to shrink. No matter what happens to the calving of icebergs or the flow of glaciers, you have to lose parts of the Greenland ice sheet. Once we get to that threshold, which is shown, as I say, by the third dot point as between two and four degrees, Greenland has to shrink, no matter what happens to glaciers. This is completely independent of information that you might have heard, since the Fourth assessment report came out, about the increased sliding of glaciers into the sea and the increased calving of icebergs; this is completely independent of that. This is about only the mechanisms of snowfall and melting. There is some evidence that, if you do get this shrinkage, it will be irreversible in that, if you remove the Greenland ice sheet in the future and then bring temperatures back to present day temperatures, you cannot get back the Greenland ice sheet.

The two mauve bars in the figure overlap almost symmetrically. This means that, if you stabilise at a 550 parts per million carbon dioxide equivalent, there is about a 50 per cent chance of Greenland going into this phase of what could be irreversible melting. So we are basically tossing a coin. If we go to 550 parts per million, based on what we know at the moment, we are tossing a coin for the future of the Greenland ice sheet. If that does shrink significantly, the potential sea-level rise will be about seven metres. However, the time scale for such a process is largely unknown; it could be millennia, or it could be shorter than that. That is the first point that I want to make about stabilising at levels that we quite likely will get to.

Secondly, if we stabilise greenhouse gas concentrations at the present level, relative to present levels, the global sea level will ultimately rise by at least half a metre. No matter what we do, we have half a meter of sea-level rise in the pipeline. This will lead to a significant increase in the frequency of flooding events from the sea. The second figure illustrates how, for 29 sites around Australia, the frequency of flooding events will increase with a half-metre sea-level rise. As I say, this is in the pipeline and we cannot avoid it. The map shows a series of red dots around Australia. The size of the red dots represents the factor by which the frequency of flooding events will increase after you have had half a metre of sea-level rise. You can see numbers which are large. Looking at, say, Sydney, you have a number of around 1,000. The average for Australia is about 300. This means that a flooding event—which now happens only once every 100 years—after half a metre of sea-level rise, will happen several times a year. I want to emphasise that we are now committed to such a rise in the future. We cannot avoid that, whatever we do with emissions. Thank you; that is all I want to say.

CHAIR —Thank you very much, gentlemen. Whoever wants to respond to this can do so. There was a fairly significant article in the Australian last week talking about ice in the Antarctic.

Senator IAN MACDONALD —As there was again this morning.

CHAIR —You might be able to enlighten us about that.

Dr Allison —My specialty is in ice. I have been working in glaciology for about 40 years, in both ice sheets and sea ice. I am not sure how familiar the panel is with ice in Antarctica, but a lot of misinterpretations get into the press about what is going on and why it is going on. I have a cartoon here, which I might try to talk to. I have a few copies that I will hand out. A lot of the reports that you see in the press confuse ice on the land, ice that originates from snowfall—what we call ‘meteoric ice’—which is in ice sheets, glaciers and ice shelves, with what is called sea ice, which forms largely by direct freezing of the ocean in the polar regions. I have not seen the Australian, but there has been a recent report on an increase in the extent of Antarctic sea ice. I will put that aside for a moment.

Senator CAMERON —That scientific magazine!

Dr Allison —I am happy to answer questions about that later, but I will concentrate now on ice sheets and sea level. Ice sheets are enormous masses of ice resting on land. In the Antarctic, the volume of ice is more than 50 meters of sea level equivalent. But this is a very thick piece of ice; on average, it is over two kilometres thick. Most of it is very stable on the time scales that we are talking about here of hundreds of years or so, but changes can occur.

We talk about the mass balance of ice sheets, which John Hunter mentioned before. That is the balance between how much snow is added to the ice sheets and how much is lost. It is exactly the same as with a river drainage basin: you get rainfall in the interior of the basin and the water is eventually lost—if you do not drag it all out for irrigation, as is done in some cases—when the river flows into the sea. In Antarctica and in Greenland, any imbalance between the amount of snow added and the amount that drains out and is lost means a change in sea level.

For a long time we have been trying to answer the question: what is the present balance of the great ice sheets and how will they change in the future? The first part we are now starting to get an idea of from some very sophisticated satellite systems, so we now have a reasonable idea of what is happening at present. We believe that, at present, both Antarctica and Greenland are adding water to the oceans and increasing sea level. There are differences in different parts and different ice sheets are behaving differently.

John spoke about the difference between melt and snowfall. One way you can take the ice or the water in the ice out of the ice sheets and add it to the ocean is simply by raising the temperature and melting that ice. To a certain extent, that is what is happening in Greenland. That is one of the causes for Greenland losing mass at the moment: there is more melt around the edges than there is snowfall at high elevations. That is not happening in Antarctica, although it is happening in the Antarctic Peninsula. The main ice sheets are very much colder. Their typical surface temperatures are below minus 20. So, even if you raise the temperature five degrees, it still will not melt. East Antarctica is fairly stable in that respect. But, as we raise the temperature in Greenland, there will be increased melt, which will overwhelm the amount of snowfall and Greenland will lose mass. That effect is included in the last IPCC assessment report projections. That wide range of an 18 centimetre to 59 centimetre sea-level rise, which depends upon emission scenarios and the models used to calculate that range, includes warming and that simple increased melt over snowfall, which is accounted for in the estimates.

There is another way that ice sheets can lose mass to the ocean—that is, by the discharge from the large ice streams with an increase in the breaking off of icebergs or floating tongues of ice. We are seeing an increased discharge of ice in Greenland from the many streams around the edge, particularly Jakobshavn, which is the fastest glacier in the world. In about a five- to six-year time span, the speed at the front of that has increased from a bit under 10 kilometres a year to over 13 kilometres a year. We are also seeing increased discharge from West Antarctica. Antarctica is losing mass not because of surface melt. Greenland is losing it from a combination of melt and increased discharge; Antarctica is losing it from the West Antarctic by increased discharge. I probably should stop there, in order to see which direction you want me to go in and whether you have any questions.

Senator MILNE —Perhaps I can clarify. I think what is really being put is that your comments have been reported in the sense of suggesting—this contributes to the arguments of the sceptics—that global warming is not really happening, because there is a build-up in East Antarctica and that, therefore, negates the notion that there is global warming.

CHAIR —I am not sure that it is necessarily a sceptics’ argument; I was after clarification from the witness—

Senator MILNE —No, I was not necessarily reflecting that. That was reported was as though from a scientific journal, as Senator Cameron suggested, contributing to the argument of that particular media outlet. We just want some clarification: because there is more ice in East Antarctica and the west is melting does not mean that you cannot draw a conclusion that global warming is not happening. We want your response to that.

Dr Allison —In my opinion, the newspaper article that you are talking about was selective. It concentrated on a rise in ice in East Antarctica. There is a very much greater loss of ice from West Antarctica. There is clear evidence now that overall the Antarctic ice sheet is losing ice at a rate of somewhere between 0.2 and 0.3 millimetres of sea level per year. The East Antarctic is very close to imbalance. There may be a slight increase, but it is more than offset by the loss of ice from West Antarctica by discharge and from the Antarctic Peninsula.

Senator MILNE —I will continue with a few questions on the science. Dr Hunter, I know that you said you were not particularly interested in commenting on the government’s targets, but the five to 15 per cent is something that we have to vote on. If the world adopted, let us say, a maximum 15 per cent reduction in greenhouse gases against ‘businesses as usual’ by 2020 on 1990 levels, what does that mean for ocean acidification? Perhaps someone could talk to me about what that means in terms of the food chain, and so on, and the haline conveyor, saline density and ocean currents and so on.

Dr Hunter —Martin Riddle will talk about the acidification issue.

Dr Riddle —I will talk to your question of ocean acidification. I will not link the emission standards but will tell you what an atmospheric CO2 level would mean to ocean chemistry and some of the biota. At 450 parts per million, wintertime—

Senator MILNE —Could you just be clear about whether that is CO2 or CO2 equivalent?

Dr Riddle —That is 450 parts per million CO2 because we are talking about ocean acidification. Ocean acidification is independent of the modelling of climate change. Ocean acidification is a direct effect of the chemistry of CO2, carbon dioxide, and its dissolution in sea water. Carbon dioxide dissolving in sea water shifts the chemistry of the sea water; it changes carbonate to bicarbonate, which shifts the balance of carbonate ions. Under current conditions, at the sea surface, carbonate is saturated, which means that it is a saturated solution of carbonate. Saturated solutions cannot take up more carbonate. For that reason, seashells do not dissolve at the ocean’s surface. If you decrease the amount of carbonate—that is, if the carbonate ions become under saturated—simple thermodynamics force the carbonate to dissolve. So the saturation of carbonate is an important threshold. It is a switching in the chemistry of calcium carbonate from stable to unstable.

The latest research from CSIRO and the universities is that, based on modelling, at 450 parts per million, during the wintertime, the surface of the Southern Ocean will become undersaturated. That is a shift from how it is currently, switching the threshold to undersaturation. The models predict that, under current emission scenarios, that will happen somewhere within the next 30 years—around 2030 to 2038.

Senator MILNE —What does that mean?

Dr Riddle —Many marine organisms use calcium carbonate for shells, both planktonic organisms and organisms that live on the seabed. For those that live on the seabed, if the saturation horizon passes them—if it moves towards the surface—at the point of moving past them, they will have to invest metabolic energy in maintaining their skeletons, which means that they will have to put energy into maintaining something that was previously done at a lower energy cost; however, they may not be able to do that. We do not know. Scientists do not know the full effects of that. A similar thing will happen for those animals in the plankton. They have the option of possibly migrating upwards but, clearly, they cannot migrate beyond the surface. This is why the point when undersaturation reaches the surface is clearly important because those planktonic organisms have nowhere else to go.

There is an extra level of complexity in this, as there are two types of calcium carbonate: aragonite and calcite. The important point here is that the aragonite form is more soluble. So the aragonite form and the organisms that use aragonite will be more sensitive to this change than the forms that use calcite. There are some important organisms in the Southern Ocean that are key to food chains: the tetrapods that use the aragonite form. That group will be more vulnerable than other types. The reef-building corals use the aragonite form, so they will be more sensitive.

Senator MILNE —So, at 450 parts per million of CO2, we have a chemical change that threatens the food chain and coral reefs.

Dr Riddle —No. At 450 parts per million, we have a change that certainly threatens the food chain in the Southern Ocean and we also have a change that threatens cold water corals in the Southern Ocean, but I cannot extrapolate that to tropical coral reefs or reefs in other parts of the world—certainly not to that level. That is not my area of expertise.

Senator MILNE —Yes, but in the Southern Ocean.

Senator CASH —Gentlemen, I am not a scientist, so please excuse my next question being a basic one. I have listened to you and you obviously say that we need to take action. However, in talking about taking action, do you mean the need for global action in the context that it has been put to us: that, without meaningful global action, any action taken by Australia in isolation or relative isolation to reduce carbon emissions would have no impact on total global emissions whilst costing Australian jobs? Putting the jobs issue aside, are you talking about taking action in the context of global action, or are you saying that, by Australia taking action, there will be a meaningful impact on the reduction of carbon emissions?

Mr Gunn —I think there is absolutely no doubt that the scientific consensus is that this is a global problem that needs to be fixed up globally. I do think it is inappropriate, sitting in a public servant’s chair, to comment more broadly on policy within Australia, but—

Senator CASH —That is why I asked that political issues be put aside.

Mr Gunn —It is a very simple question. This is a global problem and needs to be addressed globally.

Senator CASH —If it is not addressed globally and Australia, with 1.4 per cent of the world’s total emissions, goes ahead and introduces its scheme, will there be a meaningful impact on the reduction of carbon emissions?

Mr Gunn —That question goes to how long is a piece of string. I do believe that, as long as the targets are met on a global scale, you would see the projected impacts or lessening of impacts.

Senator CASH —But it gets back to our needing a global response.

Mr Gunn —How you engineer that is really up to policy and governments.

Senator CASH —But we need a global response.

Mr Gunn —You need to reduce global emissions of carbon.

Dr Hunter —Perhaps I can answer that as well. To a certain extent, the response of the climate system will be proportional to the emissions and over small ranges. If the emissions turn out to be 1½ per cent smaller than they would be otherwise because Australia reduced its emissions, say, to zero, that would have a significant effect on the climate. I do not like people saying that there will not be any effect. There will be an effect. There is a lot of uncertainty in these things. It is a bit like the weather. We are used to the weather being variable from year to year but, on average, we certainly know when it is getting hotter overall and we know if it is going to get colder overall.

Senator CASH —I am a little bit confused now. You have now stated that, if Australia were to reduce its emissions to zero, it would have a significant effect; therefore, why do we need global action?

Dr Hunter —It would have an effect that would be 1½ per cent of the effect there would be if everybody reduced their emissions. Think of the response of the climate system as being approximately proportional to the emissions. From things like the ICCP report, the Stern report and the Garnaut review, everybody accepts that the cost of climate change will be huge if we do not do anything about it. However, doing 1½ per cent of that will have some significant effect.

Senator CASH —On the basis that Australia at present is not going to reduce its carbon emissions to zero, we obviously still need a global response to get the significant effect that you refer to.

Dr Hunter —I do not think it is one thing or the other. We are going to have damage that, to a certain extent, is proportional to emissions. The more we reduce those emissions, the more we reduce the damage.

Senator XENOPHON —I have questions for Drs Riddle and Hunter. Dr Riddle, further to Senator Milne’s questioning in relation to the 450 parts per million and the changes that could cause in the oceans, at what level could we avoid the sorts of potential changes you are talking about? Is it 350 parts per million or some other figure?

Dr Riddle —I cannot tell you of a specific level that would avoid any of these changes. However, I can tell you that the change in CO2levels that has occurred so far—that is approximately a change from pre-industrial of 280 parts per million to 380 parts per million—is already seeing, through the process of ocean acidification, detectible effects in some parts of the Southern Ocean. A recent study showed that the weights of foraminifera shells—these are small planktonic organisms that are about the size of a grain of sand—are 30 to 40 per cent lower than they were in pre-industrial times. That data was based on measuring the weights of shells that were captured in sediment traps recently and measuring the weights of shells that are preserved in Holocene weights in recent but pre-industrial sediments in the sea floor in the same environment. So the increase that we have seen so far from 280 parts per million to 380 parts per million has already brought about a change in the calcification of these planktonic organisms.

Senator XENOPHON —But, from a policy point of view, what do you, as a scientist, say that we should aim for? Should we aim for 350 parts per million, as some scientists in Europe are now saying? What level do you say we need to aim for to minimise that risk?

Mr Gunn —I do apologise if this sounds like a lesson in uncertainty and precaution. I understand personally that, in giving a lesson to someone, saying somewhere between 400 and 470 does not quite have the impact of stating a number. I think what Martin and science are saying is that the impacts of acidification are already happening. We are seeing those impacts on a range of systems around the world. The number 450 sits in a range of uncertainty. At the bottom of the range, we are seeing 380 already having an impact. We know that at 450, which is in the middle of a range of impact, it is starting to get very, very serious for animals that need aragonite saturation as one of their key physiological inputs. At a higher rate, we know that it will be more draconian. So, like most things—Senator Macdonald has dealt with fisheries for a long time—a number of what is sustainable is, in fact, a band of what is sustainable. With policy, you have the choice of being precautionary or less precautionary. That is the answer that I would give to your ‘how low do we go’. The question is: in a policy sense, how precautionary do you want to be in mitigating the risk of impacts?

Senator XENOPHON —Dr Hunter, your evidence is that there is roughly a 50 per cent chance or probability of irreversible Greenland melting based on 550 parts per million. What is your understanding of the possibility of that at 350 parts per million and 450 parts per million? You may want to take this on notice, if you do not have it in front of you.

Dr Hunter —I would have to take that on notice. I do not think those numbers are even in the literature at the moment. There already is an effect of sea-level rise due to carbon dioxide emissions into the atmosphere; we know that. Throughout the last century, the sea level rose by something like 17 to 18 centimetres. If we want to return to pre-industrial times, we need to bring back our greenhouse gas levels in the atmosphere to those levels; so we need to bring them back essentially to around 280 parts per million. As John Gunn says, any amount above that gives us some damage, basically, or some change to the environment. The further you go away, the worse that damage is.

Senator XENOPHON —It would be good if you could take that on notice. Thank you.

Senator CAMERON —Gentlemen, thank you for appearing before the committee. I have just had another look at the inquiry’s terms of reference. Those terms of reference do not cover a threshold issue that we have spent a lot of time debating at the inquiry, and that is whether global warming is actually taking place and needs to be dealt with along with associated issues. On that basis, we had evidence from a couple of scientists who indicated that they do not believe there is carbon-induced global warming. Given that there are some in politics who still need to be convinced of the reality, what do you say about the argument from some geologists that global warming is not taking place? Professor Stewart Franks, I think, is one; I am not sure whether you are aware of his work. Can anyone comment on that threshold issue?

Dr Press —I think now that the vast majority of scientists working on this issue believe that global warming is happening and is aided and abetted by the increased carbon dioxide that we, as humans, have put into the atmosphere since industrialisation. It is a very complicated story, but one of the things about Antarctic research is that the ice cores in Antarctica—those that we have so far that go back 860,000 years—can tell us a lot about the atmosphere, temperature and changes in climate over that period of time. Ian Allison is an expert in that area and he might like to make a comment.

Senator CAMERON —The two scientists that I have spoken of are Professor Robert Carter, an environmental geologists from James Cook University, and Associate Professor Stewart Franks, who is with the School of Engineering at the University of Newcastle. I do not want to say anything that they did not say, but I will summarise by saying that Professor Carter said that this is a natural phenomenon and not about CO2; and Professor Stewart Franks said that this argument about global warming is all rubbish. That is the evidence we have had from those two scientists and is the issue I would like you to address.

CHAIR —Perhaps it could be made fairly succinct, as we are getting close to time.

Senator IAN MACDONALD —Do not feel obligated to attack other people in the same field as you, if you do not feel comfortable in doing so.

Dr Allison —No, I cannot comment on their individual work. I will just reinforce that the last IPCC assessment report came up with the conclusion that warming is unequivocal. This is not the work of a bunch of eco-terrorists, as some would have you believe. The IPCC work relies totally on peer reviewed scientific literature, which is stuff that has already been out there. It undergoes intense peer and government scrutiny. Every word in the report is subject to review. I was involved in one chapter and it was probably one of the smallest chapters; there were something like 1,600 review comments that we had to respond to for that one chapter alone, before the final report went out. All those responses are available on the web—they are open responses—and the review comments were all published. That report is not a consensus, as you will never get a 100 per cent consensus, but it is evidence that a very clear majority of scientists active in that field hold that conclusion.

Senator IAN MACDONALD —Dr Hunter, I am going right back to the beginning because between Dr Allison and yourself, rather than clarifying it, I have become more confused. First, is there anything in today’s Australian report that has been attributed to you but that you say were not your words?

Dr Hunter —I do not think there is anything in the Australian that I have said; it is from Ian Allison, I believe.

Senator IAN MACDONALD —BAS Project Leader John Turner. I am sorry; I beg your pardon. Were you involved in that project, Dr Allison?

Dr Allison —No, I was not involved in that project. For a long time there has been some indication that the extent of sea ice—that is the area that sea ice covers in the ocean—perhaps has been slightly increasing. The last IPCC report showed that there was an increase in Antarctic sea ice.

Senator IAN MACDONALD —Who or what is John Turner?

Dr Allison —John Turner is an atmospheric scientist at the British Antarctic Survey in Cambridge. He did this work with colleagues from the US, from NASA, particularly Joey Comiso, who is one of the lead workers in the interpretation and estimation of the extent of sea ice from satellite data.

Senator IAN MACDONALD —Is that your field? Are you his counterpart?

Dr Allison —I have worked in that field and I agree with their conclusions. However, you must realise that they are not measuring the total volume of sea ice; they are measuring the area of the ocean that is covered by sea ice. That can be changed by changes in the wind. Sea ice is moved by wind and current. So, if you get a change in wind systems, the sea ice can move further out and cover a greater area of ocean; but it may be thinner. We do not know how thick sea ice is, because we cannot measure that with radar systems.

Senator IAN MACDONALD —He is quoted as saying that it got colder and there was more sea ice because of the ozone hole. Now we have fixed the ozone hole, we are going to get warmer.

Dr Allison —That opinion has been around for a couple of years. He is not saying that it is getting colder; he is saying that the wind systems have changed.

Senator IAN MACDONALD —The wind systems are getting—

Dr Allison —Stronger, so that the ice has flowed further out.

Senator IAN MACDONALD —I am not arguing in a scientific way; I am purely quoting the Australian report of what Dr Turner allegedly said.

Dr Allison —A change in the wind systems will change the ice. It can even lead to more ice. If you export or push ice at high latitude—and it is naturally cold at high latitude—further south, you will have left open ocean behind and more ice will grow there rapidly. So changing wind systems can change the movement and export of ice—remember that we are talking about sea ice and not ice on the land—which can change the extent of sea ice.

Senator IAN MACDONALD —I cannot understand what he suggests, not that I really need to—and, before my democrat colleagues criticise me for being a sceptic, I would say that I am not.

Senator BOSWELL —They are the Greens actually. The Democrats have gone.

Senator MILNE —We are the Greens; it has taken a while.

Senator IAN MACDONALD —I meant small ‘d’ democrats, those who encourage differences of opinion. If you do have a difference of opinion, you are pilloried and sneered at—but I am not one of them. However, those who do have a different point of view should not be sneered at in the way that some of my colleagues do—and you are seeing an example of it now. The suggestion is that, as we repair the ozone hole, we will make the climate warmer.

Dr Allison —Yes, that is a scientific opinion. It is based on models. We have not repaired the ozone hole yet.

Senator IAN MACDONALD —But as we do.

Dr Allison —It will take decades for high-atmospheric chemistry to restore it.

Senator IAN MACDONALD —I will be accused of urging this, but I am simply asking the question: why don’t we then leave the ozone hole to get global cooling to counter global warming?

Dr Allison —If you want to wait 100 years and swim or die of cancer tomorrow, that is your decision.

Senator IAN MACDONALD —Swim?

Dr Allison —That is with sea-level rise. Many of the climate change issues we are talking about are slow but relentless.

Senator BOSWELL —What is a good example?

Dr Allison —With changes in UV levels, we have concerns about ecosystems.

Senator IAN MACDONALD —I under the UV levels. However, we are saying that the ozone hole, because of winds or whatever, is making us cooler and, in repairing it, we are getting warmer, which is what carbon emissions are doing as well.

Dr Allison —The whole earth system is interconnected. We cannot change one part of the system, whether it is the ecosystems, the oceans or the atmospheres, without affecting another part of the system. We are affecting it at a number of different levels. We are affecting it with our carbon emissions and other greenhouse gases. We have affected it in the past with CFCs and their impact on the ozone. These processes are interrelated.

Senator IAN MACDONALD —But does it not follow then that, if something makes the globe cooler and something else makes it warmer, they balance each other out?

Dr Allison —No, not completely. The ozone effect on climate is occurring only in the immediate Antarctic region.

CHAIR —I think Dr Press has something he wants to say quickly.

Dr Press —I know that you are coming to an end, but I want to make the point that the conversation with Senator Macdonald emphasises that it is very difficult to put together the complete story by picking up little bits of information from a couple of paragraphs in a newspaper quoting a part or a summary of a scientific paper that might have been published on the internet as a prelude to the complete paper being published in a physical form. The climate change story is very complicated and has interactions with ozone, acidification of the ocean and various other things. One of the important things about the Intergovernmental Panel on Climate Change process is that, with the amount of peer review that is done, you do not chase a rabbit down a burrow.

Senator IAN MACDONALD —Are you suggesting that this BAS work was not peer reviewed?

Dr Press —No. I am just referring to the picking out of one bit. I have seen a summary of the paper. I have just come back from Washington and the 50th anniversary of the Antarctic Treaty Meeting; that paper was being discussed there and people were not disagreeing with it. Apparently, you are getting more sea ice—not glacial ice—in some parts of Antarctica, particularly around the Ross Sea, However, around the Bellingshausen Sea and the Antarctic Peninsula, you are also getting loss of sea ice on the scale that is happening in the Arctic. So, just taking one bit of the story without being able to look at all of it, you cannot be misled but form a picture in your own mind that is not as complete as the author had when he wrote the story.

Senator IAN MACDONALD —A quote there states:

While there is increasing evidence that the loss of sea ice in the Arctic has occurred due to human activity, in the Antarctic human influence through the ozone hole has had the reverse effect and resulted in more ice.

Dr Press —This is correct.

Senator IAN MACDONALD —Your point is about snippets of information but, unfortunately, most of the world relies on snippets of information about all sorts of scientific and political, I might say, life. We are disadvantaged, but that is the way life is. Thank you for that.

Dr Allison —Perhaps I could make one very brief comment. If you go to the original paper by Turner and his colleagues, the conclusion is that the increase in sea ice extent is still consistent with overall global warming.

Senator IAN MACDONALD —That the increase in sea ice—

Dr Allison —That the increase they see is not inconsistent with global warming. While any warming is occurring over the planet, these regional differences are possible.

Senator IAN MACDONALD —That is why you guys are scientists and we are but mere politicians.

Dr Allison —We can have floods in Queensland and droughts in Victoria.

Senator IAN MACDONALD —Which we have had all along. Getting back to Dr Hunter—accurately this time, I hope—you told Senator Cash that, if we shut Australia down, it would make a significant difference, being a 1.4 per cent less—

Senator CAMERON —I do not think he said that.

Senator CASH —It is exactly what he said.

Senator IAN MACDONALD —I think Dr Hunter is clever enough and brave enough to tell me if I am quoting him incorrectly; thank you, Senator Cameron. Again, for us mere mortals, are you able to somehow quantify what ‘significant’ means? I do not think we are having fewer cyclones. We are going back to the number of cyclones that we used to have 20 years ago—that is my observation, although I am not a scientist—but will we have fewer floods and fewer droughts, if Australia completely cuts out its 1.4 per cent of the world’s emissions?

Dr Hunter —I mean ‘significant’ in the scientific sense. We can tell from the physics of the problem that, if you change an input to the system, there will be a change in the output of the system. I do not mean by ‘significant’ that it will be large or important, but it will be a difference. In other words, the only way that you can predict what is going to happen in the future is basically to run things like computer models. If you change the inputs to the models, if you decrease the emissions to a certain extent by any amount, you will probably get some kind of decrease in the output of that model. That is what I mean by ‘significant’.

Senator BOB BROWN —Dr Allison, I read the Australian this morning too and went down to the beach to see how far the sea had fallen, as Antarctica sucked up the water, but I found it was a high tide. I just want to summarise what you are saying because it is very important for the committee.

CHAIR —Senator Brown, could you actually ask a question rather than make a summary? We have heard the evidence, but I really would like a question. We are over time. Please ask a question and then I have to go to Senator Boswell for a question.

Senator BOB BROWN —In exactly the same way as other senators, Chair, I will. Let me put this in question form, for the chair’s edification.

CHAIR —Thank you, Senator Brown.

Senator BOB BROWN —Is your evidence to the committee that this century there will be a two- to three-centimetre rise in sea level worldwide on the current Antarctic water discharge into the ocean?

Dr Allison —Yes. We now have evidence that both Antarctica and Greenland are adding to sea level. Together they have probably increased ice loss a little bit from the IPCC assessment, so both ice sheets are probably adding about 0.6 millimetres per year to the ocean. That 0.6 millimetres comes to six centimetres over a century. However, that is if it continues at the present rate and does not allow for accelerated discharge of glaciers. I have not included in there, of course, the other effects on sea level, which are the melting of temperate glaciers all around the world, which are contributing as much as one centimetre a year at the present, or the other important component of thermal expansion of the ocean. So the ice sheets are adding. The other important point is that we are talking about what is going to happen in the next 100 years. But, with a warmer climate, this increased contribution of the ice sheets will continue for millennia. If the world stays warmer, they will keep adding to ocean levels over thousands of years, possibly at slow rates.

Senator BOB BROWN —If we go to 450 parts per million atmospheric content, will this rate of water discharge from north and south into the oceans increase?

Dr Allison —Certainly it will increase at a level of a few tenths of a millimetre a year. However, we are uncertain about the possibilities of rapid climate change—change due to the discharge of the glaciers due to processes such as basal lubrication and the removal of buttressing from floating ice out the front. We know what will happen directly as a result of warming; we are less certain how the glacier dynamics will respond.

Senator BOB BROWN —The figures you were giving a while ago indicate that Antarctica is discharging almost the same amount of water as Greenland is.

Dr Allison —Yes. However, with Greenland we also see evidence of an increase over the last 15 years. We do not have clear evidence of that for Antarctica. I should mention that we have only been able to measure these total contributions over the last 10 to 15 years.

Senator IAN MACDONALD —Thank you for your six-centimetre comment. Someone was telling us that they were going to rise by six metres.

Senator BOSWELL —That was my comment. I was just going home to sell my waterfront property. Now that I know it is only six millimetres, I will leave it for a couple of years. That was my question, Dr Hunter. I have lived on the water all my life. I have sailed boats all my life. You could throw a stone from my back veranda into the water. I am not challenging you—before I could do so, I would have to go and get some readings off tide gauges—but, from my own observations of living on the bay and sailing just about every weekend when I was a kid, I cannot see there having been any rise in water over the last 10 to 15 years. I am not saying that it is not there, but I cannot pick it.

The other matter I want you to comment on is that you said that, if we get down to the levels of CO2 going into the atmosphere pre-industrial times, we will make a significant change. I suggest that we probably would too, but we would all have to go and live in a cave. In addition, you say that, if the ice melts in Greenland, it may never recover. I am a seller of paint brushes; that was my expertise before I came to the parliament, so I am very appreciative of being able to ask you these questions and getting some scientific deliverance of an opinion. I am told that thousands or maybe hundreds of years ago there was climate change in Greenland. People were farming and growing wheat there and the climate changed and now it is changing again. But why did the ice recover then but it will not recover now? They are probably basic questions for the uninformed, but I wonder whether you could answer them for me.

Senator IAN MACDONALD —Remember the Ice Age too in Gondwanaland.

Senator BOSWELL —Yes, I take all that.

CHAIR —Perhaps we could go to the witnesses.

Dr Hunter —From satellite observations, we know that the sea level is rising at the moment at about three millimetres a year; therefore, if you are talking about the last 10 years, it will have risen about three centimetres. I suspect that, if you live by the coast, it would be quite difficult to actually notice a three-centimetre sea-level rise. We know from, as I say, satellites that the sea level has been rising at about three millimetres a year for the last couple of decades.

Senator BOSWELL —That is a bit different from six metres.

Dr Hunter —Pardon?

Senator BOSWELL —You have in your paper ‘half a metre’.

Dr Hunter —Half a metre is the amount that sea level will rise, if we stabilise at current greenhouse gas levels in the atmosphere. If we stabilise at the present level and carry on forever, we have about half a metre of sea-level rise yet to come because of the inertia in the system. But at the moment we are heading for about three millimetres a year upwards.

Senator IAN MACDONALD —Didn’t you say six centimetres in 100 years?

Dr Allison —That is the present rate.

Senator IAN MACDONALD —He is saying three centimetres in 10 years.

Dr Hunter —The sea-level rise at the moment globally is at about three millimetres a year.

Dr Allison —I was talking about just the ice sheet contribution. There are larger contributions from glaciers and thermal expansion.

Senator BOSWELL —No wonder we get confused.

Senator IAN MACDONALD —Okay; I am sorry.

Dr Hunter —The second point concerned our returning to pre-industrial levels of CO2. I am not suggesting that we do that; I am saying that, if we want to completely or partially reverse everything that we have seen since pre-industrial times, we would need to reduce carbon dioxide levels in the atmosphere back to that level. We are stuck with what we have at the moment.

The third question concerned Greenland. The reason that Greenland is cold on top is that it is high. The reason that Greenland could shrink irreversibly and not be able to build itself up again is that, by removing Greenland, essentially the surface is lowered and therefore the temperature gets warmer. You must not think of Greenland as being a mountain on which there is a bit of thin ice; it is actually a huge thick ice sheet. It is not something that you can remove in a matter of hundreds of years.

Senator BOSWELL —That was not the question I asked. The question I asked was: we have heard—I think scientifically it has been proved—that people were farming on Greenland. I do not know when; probably a thousand years ago. If at that stage the ice had melted to allow farming to take place and the ice shelf had repaired itself, why won’t the ice shelf repair itself now? You have said that, if the ice shelf goes beyond a certain point, it will not recover. It did recover.

Dr Allison —For it to disappear totally and not rebuild, it has to go past a threshold, a tipping point. The changes that occurred in the medieval warm period did not go that far. People were farming not over all of Greenland but just around the edge. The ice sheet still existed and was a little bit smaller than it is now, but it did not go below that tipping point.

Senator CAMERON —Can I ask a question?

CHAIR —Senator Cameron, please put your question in writing. We are over time.

Senator CAMERON —Can I ask—

CHAIR —No, you cannot, Senator Cameron. We are over time.

Senator CAMERON —That is ridiculous. There is one Labor senator here asking questions. I have asked only one question.

CHAIR —Senator Cameron, if your colleagues cannot come, I cannot help that.

Senator CAMERON —I have asked one question; that is all.

CHAIR —We are 20 minutes over time and I ask you to put your question on notice, in writing, and let the answer come back. Gentlemen, I thank you for your time this morning. We appreciate your evidence. There will be questions on notice and we would appreciate your assistance with them.

[10.05 am]