IPCC flags risks and response options for polar and ocean environments in latest report
RESIDENTS in southern Australia may think about Antarctica only when a cold southerly wind affects their weather. But the importance of the Southern Ocean and Antarctica extends much further, especially in relation to climate change.
The Special Report on the Oceans and Cryosphere in a Changing Climate (SROCC), released today by the Intergovernmental Panel on Climate Change (IPCC), confirms years of accumulated evidence that the oceans and cryosphere are changing, and impacts will be far-reaching. But the SROCC goes further, highlighting recent research that shows the observed changes are happening faster than previously thought, and projections of future sea-level rise are more extreme.
CSIRO’s Dr Jess Melbourne-Thomas, Transdisciplinary Researcher and Knowledge Broker, is a lead author of the report’s polar regions chapter, and contributed to writing the report’s summary for policymakers. She says the report shows that ice around the world is melting, the oceans are warming and losing oxygen, and global sea level is rising.
“The SROCC is an update on the science since the IPCC Fifth Assessment Report (AR5) was published in 2014, and will help form the basis of the Sixth Assessment Report, due to be published in 2022,” she says. “It’s particularly important because of the rapid rate of change we’re seeing in the cryosphere, the importance of the oceans in regulating global climate, the threat of sea-level rise to coastal communities, and the dependence of the world’s population on ocean ecosystems.”
Scientists in the 1980s predicted that climate change would have significant impact on polar regions in the 21st century. These changes have now been confirmed, but the changes are occurring faster than expected, with ice loss from Greenland and Antarctic glaciers and ice sheets accelerating. Dr Melbourne-Thomas says the SROCC identifies there may be irreversible tipping points in these changes.
Metres of rising seas
Antarctica holds about 90 per cent of all the ice on Earth, a volume equivalent to 58 metres of sea-level rise. Dr Steve Rintoul from CSIRO’s Centre for Southern Hemisphere Oceans Research and a lead author on the AR5’s chapter on ocean observations, reviewed chapters of the SROCC and says a tipping point may be crossed in the coming decade or two that will commit us to metres of additional sea-level rise.
“Scientists have focused on West Antarctica, where rapid ice loss has been observed in recent decades, but most of the ice is in East Antarctica. The latest research reveals that East Antarctica is also exposed to warm ocean waters. This means the large East Antarctic ice sheet is also vulnerable to ocean warming and will contribute to future sea-level rise.”
He says there’s even stronger evidence now that ice sheets can change rapidly enough to contribute to sea-level rise on timescales of decades to centuries – researchers used to think it would take many centuries or thousands of years.
“The vulnerability of the Antarctic ice sheet to warming of the surrounding ocean is becoming clear. Since AR5 we’ve seen more evidence that Antarctica’s contribution to sea-level rise is accelerating as a result of warm ocean waters reaching the edge of Antarctica. The speed with which Antarctica and Greenland will contribute to sea-level rise is greater than we thought possible even five years ago.”
The problem, he explains, is ice sheets that rest on bedrock sloping up toward the coast are unstable: once retreat begins, it will continue until the ice is gone or the bedrock changes slope. This process is irreversible and will continue even if greenhouse gas emissions are reduced.
“Evidence that this marine ice sheet instability is already underway was published just after AR5, so that new science is included in the SROCC. There is evidence that there are tipping points, and we may already have passed those thresholds for some parts of the Antarctic ice sheet.”
Dr Rintoul says the more the Earth warms, the greater the risk of passing that tipping point threshold for other parts of the ice sheet.
“Metre-scale rises in sea level will take decades to centuries to occur, but we are committing ourselves to that sea-level rise within the next 20 years. If nations don’t take strong action to reduce emissions in the next decade, we will commit ourselves to warming that will cause several metres of sea-level rise. We can’t change our mind later on.”
Fast-changing poles affecting Australia
Antarctica and the surrounding ocean affect the Earth’s climate and weather. The Southern Ocean encircles the globe, connecting the Atlantic, Pacific and Indian oceans, with the world’s largest current, called the Antarctic Circumpolar Current, largely driving the resulting global circulation. The Southern Ocean also absorbs most of the extra heat and carbon dioxide released by human activities, slowing the pace of climate change.
“Sea ice formation in Antarctica is an important driver of the big ocean conveyor belt called the thermohaline circulation, where water sinking in Antarctica stores and distributes heat and carbon,” says Dr Melbourne-Thomas. “Substantial change in sea ice formation has implications for that mechanism, and could ultimately influence climate patterns in Australia.”
She says the SROCC describes an observed increasing intensity and frequency of marine heatwaves. “The concept of a marine heatwave only emerged recently, but they are now becoming common and are found worldwide. Australia has been hit by marine heatwaves that have caused bleaching on the Great Barrier Reef, caused loss of sea grass beds off Western Australia, and impacted kelp forests and the aquaculture industry in Tasmania.”
The rapid increase in marine temperatures is also causing species to move towards polar regions, which affects fisheries and has subsequent impacts on the marine resources that people depend on.
“The increasing rates of species redistribution driven by climate change that we’re seeing in the marine environment is a key theme coming out of the SROCC,” says Dr Melbourne-Thomas. “With a general trend of species moving from tropical regions to the poles, the Southern Ocean is likely to gain species and we may see new fisheries emerging as fish stocks move south. This has important implications for management.”
“However, Antarctic species adapted to cold habitats don’t have a lot of space to move into. For example, the habitat for Antarctic krill is contracting southwards, which affects krill populations and hence the numbers of penguins, seals and whales that feed on krill. These ecosystems are complex, so it’s not just the individual species moving; it’s the effect on food webs and ecosystem function in ways that we’re only just beginning to understand. So it can be difficult to say how it will play out.”
What can we do?
Dr Melbourne-Thomas says the SROCC summarises options to reduce the impacts on polar and ocean environments, and how to adapt to the changes already happening. “There are key findings regarding timescales for responses, and the scales of decision making. That will link to the specific assessments of risk and response in the Sixth Assessment Report.”
She says developing ecosystem models to explore adaptation options is one area where CSIRO science helps understand how we can respond. “Governments, industries and communities need to manage direct human impacts from fishing and coastal runoff along with these emerging climate change challenges. CSIRO scientists provide end-to-end ecosystem modelling, risk assessment and adaptation frameworks to assess different options under different scenarios, the costs and benefits of different kinds of actions, and the consequences of the choices we make. CSIRO is really ahead of the game in developing frameworks to help respond to these challenges.”
Dr Rintoul adds that another important aspect of CSIRO research is observing the climate system to track how it’s evolving. “This guides decisions as it gives confidence in understanding whether changes are natural or caused by human activity. CSIRO scientists are also studying how we can reduce emissions by changing energy systems and other aspects of how we live, and how we can adapt to the changes we can’t avoid.”
He says there is optimism that it’s not too late. “We have time to reduce emissions and the consequences of climate change that we want to avoid. But we do need to act quickly. If we do, there are many opportunities for the Australian economy that involve helping us and others transition to a low-carbon future.”
September 30, 2019 at 1:53 pm
How are we to curb greenhouse gas emissions resulting from infrastructure improvement, such as roads, bypasses, large houses et cetera? Can we afford to forego weapons of war and avoid warfare itself? Whom can we trust as an agent of peace?
December 2, 2019 at 1:20 pm
Thanks for your comment. CSIRO researchers contributed to the WMO Greenhouse Gas Bulletin, released this week: https://library.wmo.int/doc_num.php?explnum_id=10100
The report explains that globally, cement production is a big contributor to carbon dioxide emissions. The UNFCC’s Paris Agreement addresses this challenge ad has outlined that the cement industry will need to dramatically cut its emissions to meet the Agreement’s temperature goals (2 degrees C or less). CSIRO is also contributing science solutions to lower emissions in the built environment, through smart home design and energy efficient systems. Our Australian Housing Data Portal is one example of what we’re doing: https://ahd.csiro.au/
October 16, 2019 at 11:42 am
Why is it our political leadership appear not to understand this issue? Either they don’t understand or, if they do but are failing to act that really amounts to being evil, and I struggle to believe they are evil people, but equally I struggle to see how they don’t understand the consequences of inadequate action.
October 16, 2019 at 12:21 pm
Are these peer reviewed reports as there are conflicting reports about the polar regions?
Climate has always changed and that is why the ancient people built Dams to store water, Silos to store grain, etc. If they also had jumped up and down every time the climate changed and blamed it on ‘others’ and did nothing to tide through changes in climate, we will not be here today.
December 2, 2019 at 1:21 pm
Hi Rabi Gunaratnam,
Thanks for your comment. We’re not sure which conflicting report you are referring to. However, we can let you know that the SROCC IPCC report referred to in this article, as is the case for all IPCC reports, is drafted and reviewed in multiple stages to ensure rigor, objectivity and transparency.
The IPCC is the world leading body for assessing the science related to climate change – and its impacts, potential risks and possible response options. The IPCC reviews and assesses thousands of scientific papers that have already been published (and peer reviewed) from around the world.
For more information about the peer review process, we recommend you visit our Climate Change Q&A section on our website: https://www.csiro.au/en/Research/OandA/Areas/Assessing-our-climate/Climate-change-QA/Information
October 16, 2019 at 5:50 pm
1) Many have noted that Earth’s temperature is increasing (relative to long term average from 1901 to 2000) from a pre-industrial (1880) of -0.2C to +0.8C (2018).
However, a number of things have been forgotten: the Vostok ice-core data show that over about 12,000 years, global temperatures have been relatively stable – hence the classification of Holocene Epoch – but fluctuated by +/- 2C (relative to 1991 when the data were published). Temperatures have risen about 04 C since then.
Therefore, temperatures could rise by a further 1.6C naturally. No need to invoke AGW and blame Man – and we cannot do anything about it.)
2) “but the changes are occurring faster than expected,”
Actually, they increased a little faster (0.17 C/decade) in the period between 1910 to 1940, when there was less CO2 than the “Enhanced Greenhouse Era” 1950 to 2019 (0.12 C/decade).
October 16, 2019 at 6:04 pm
I read somewhere recently that the extent of winter sea ice around Antarctica was growing. Is this true? It doesn’t seem to match with everything else that is going on in the arctic ocean.
October 16, 2019 at 6:39 pm
These things are important, but may not be most urgent in Australia. Revegetation of our land so that at least 1/3 of all cleared land is returned to a natural endemic environment will reduce temperatures, increase humidity, retain rainfall, provide food for native insect, bird and animal species and would seem most urgent. Once these species are gone, that’s it! Once temperatures rise, or rainfall drops below thresholds the plants cannot be grown.
I live in Adelaide and have heard reports saying that when the average annual temperature was 3 degrees cooler than it is now, the area was covered in glaciers. The same reports forecast barren desert with 3 degree warming. I have just come back from New Zealand and seen where glaciers are now and were 100 years ago. The effects look real to me.
Yes large houses is an issue in Australia, but a bigger housing issue is the very poor environmental design – living areas on south, and those to the north receiving no sun due to large covered outdoor areas, or small to no eaves, black roofs, single window glazing, little insulation etc, etc. Then there’s build quality – or lack of it? Frankly residential construction in Australia looks like a cottage industry when compared to OECD countries. I’ve seen recent house constructions where I could look up through the gap where cornices are yet to be installed and can see gaps between the roof tiles – ino sisalation, no complete insulation throughout roof and big gaps in wall insulation. Most houses don’t seal in Australia leaking heating and cooling energy. Clearly the building code of Australia and passive design of Council Development Plans are not being complied with. Perhaps it’s time to return to Council inspections as still used elsewhere – in NZ I was told 28 hold points with inspections with work not allow to proceed until approved.
So I’m nearly done! Take the River Murray. How do we, as an intelligent species think it’s even remotely okay to disrupt a system that has evolved to a balance position over millions of years and dam it and use locks changing water flows. Divert water out of the basin through channels and pipes for irrigation over summer where evaporation insures no water return to the Murray.
I’m sure what I’ve written will be understood by some, not understood by others, agreed by some and denied by others. The point is, we are having measurable detrimental effects on the planet which is our one and only home.
October 21, 2019 at 9:24 am
With species redistribution in response to climate change, we should expect to see more birds join those migratory birds of the East Asian-Australian Flyway whose regular stopover is on the Southern Ocean-facing beaches of S.A. However, looking for the tourism dollar, South Australia allows vehicles to drive on beaches, including those on which such birds traditionally build nests. Any of these approximately 60 species are now an extremely rare sight on these beaches. I do not hold out much hope for any other birds finding their way south to look for a new home.