Even with all humanity’s carbon emissions to date, there’s a lot less carbon dioxide in Earth’s atmosphere than Venus, and Earth is further away from the Sun. But if carbon emissions continue at the current rate, is there any risk of reaching a tipping point at which a runaway greenhouse effect takes over, making Earth uninhabitable for any form of life?
When sunlight enters the Earth’s atmosphere, some is reflected back to space by clouds, some is reflected by bright surfaces such as ice and snow and some is absorbed by the land surface and ocean.
To maintain a balance, the Earth emits energy back to space in the form of infrared, or longwave, radiation. Some longwave radiation is absorbed in the atmosphere by heat-trapping gases, such as carbon dioxide.
One consequence of increasing atmospheric carbon dioxide concentrations is that, as the atmosphere warms, it can contain more water vapour. Since water vapour is itself a greenhouse gas, this can create an amplifying effect.
In general, as surface temperature increases, the Earth emits more longwave radiation to space to maintain the energy balance. But there is a limit to how much longwave radiation can be emitted.
If the atmosphere becomes completely saturated with water vapour, the Earth’s surface and lower atmosphere warm up, but further increases in emission of longwave radiation are not possible.
The runaway greenhouse
This is termed a runaway greenhouse and would mean the Earth would become lethally hot and unable to cool itself by emitting heat to space.
Ultimately, this is the fate of the Earth. In billions of years from now the Sun will become brighter and grow into a Red Dwarf. As the Sun’s luminosity increases, the Earth will become hotter and its oceans will evaporate.
The hot and steamy atmosphere will ensure the Earth is just as uninhabitable to current life-forms as Venus is today.
But could we bring such a situation about on a shorter timeframe through continued carbon dioxide emissions? The good news is, probably not.
We’re safe, for now
Previous research has found that, due to differences in the properties of water vapour and carbon dioxide as greenhouse gases, adding carbon dioxide to the atmosphere is likely insufficient to trigger a runaway greenhouse.
In geological terms, this is a very large increase to take place over a short period of time. Yet human emissions of carbon dioxide are considered insufficient to trigger a runaway greenhouse, given the fossil fuel reserves available.
The caveat to all the above is that the models scientists use to study future climate are built based on past, known conditions. It is therefore difficult to predict how certain parts of the climate system might operate under extremely high greenhouse gas emissions scenarios.
For example, clouds can reflect sunlight back to space, or they can trap heat emitted by the Earth. In a warming world, scientists are still unclear on the role clouds will play.
While a runaway greenhouse would make Earth completely uninhabitable to life as we know it, the losses that may accrue from just a few degrees Celsius of global warming are serious and must not be discounted.
Global rates of warming are lower due to the inclusion of the oceans in the global average, with the oceans experiencing a relatively slower rate of warming than continental areas.
The long-term warming trend increases the likelihood of extreme events beyond our historical experience. In 2019, natural climate phenomena that drive our weather, including a strong Indian Ocean Dipole and a negative Southern Annular Mode, added to the local warming trend, setting a record for the Australian average annual temperature.
This annual temperature for Australia is similar to what we might expect in an average year if the world reaches the +1.5℃ warming since pre-industrial times.
The long-term warming trend is also increasing the frequency of extreme warm days. We have seen a rise in the number of days when the Australian average temperature is within the top 1% ever recorded.
The long-term temperature trend is also lowering the frequency of cooler years. The annual mean temperatures of Australia in the seven years from 2013 to 2019 all rank in the nine warmest years since national records began in 1910.
Barring unpredictable events such as major volcanic eruptions, projections show Australia’s average temperature of 2020-2040 is very likely to be warmer than the average in 2000-2020, as the climate system continues to warm in response to greenhouse gases that are already in the atmosphere.
What’s driving our changing climate?
Australia’s Cape Grim atmosphere monitoring station, in north-west Tasmania, is one of several critical global observing sites for detecting changes in the gas concentrations that make up our atmosphere.
The increase in greenhouse gas concentrations has been the predominant cause of global climate warming over the last 70 years.
In 2019 the global average CO₂ concentration reached 410ppm, while all greenhouse gases combined reached 508ppm CO₂-equivalent, levels not seen for at least 2 million years.
Emissions of CO₂ from burning fossil fuels are the major source of the increase, followed by emissions from changes to land use. While the ocean and land have absorbed more than half the extra CO₂ emitted, the rest remains in the atmosphere.
Similar to surface temperatures over the continents, the State of the Climate report says sea surface temperatures are showing a warming trend that is contributing to an increase in marine heatwaves and the risk of coral bleaching.
Important changes are also happening below the ocean’s surface. The global oceans have a much higher heat capacity than either the land surface or atmosphere. This means they can absorb much more of the additional energy from the enhanced greenhouse effect, while warming at a relatively slower rate.
Currently, the oceans are absorbing around 90% of the excess energy in the Earth system associated with increasing greenhouse gases. The related increase in total heat content provides another important way to monitor long-term global warming.
Warmer temperatures cause the water in our global oceans to expand. This expansion, combined with the additional water from melting ice sheets and glaciers, is causing sea levels to rise.
Total global average sea level has now risen around 25cm since 1880, with half of this rise occurring since 1970. The rate of sea level rise varies around Australia, with larger increases observed in the north and the southeast.
The oceans are also acidifying due to changes in the chemistry of seawater, related to excess CO₂. The effect of this pH change is detectable in areas such as the Great Barrier Reef and the Southern Ocean.
The wetter and drier parts of Australia
The State of the Climate report shows the trend in recent decades has been for less rainfall over much of southern and eastern Australia, particularly in the cooler months of the year.
The longer-term drying trend is likely to continue, particularly in the southwest and southeast of the continent. Most areas of northern Australia have had an increase in average rainfall since the 1970s.
Natural variability has always been, and will continue to be, part of Australia’s rainfall patterns.
Fire seasons: longer and more intense
The fires of 2019-20 are still very much on everyone’s minds, and the State of the Climate report puts the weather component of fire risk into a longer-term perspective.
Since the middle of last century there has been a significant increase in extreme fire weather days, and longer fire seasons across many parts of Australia, especially in southern Australia.
The 2020 report highlights many recent changes in Australia’s climate. Most are expected to continue and include:
warmer air and sea temperatures
increased numbers of very hot days
ongoing sea level rise
more periods of dangerous fire weather
longer and warmer marine heatwaves.
When these extremes occur consecutively within a short timeframe of each other, or when multiple types of extreme events coincide, the impacts can compound in severity.
Fossil fuels and agriculture are driving a dangerous acceleration in methane emissions, at a rate consistent with a 3-4℃ rise in global temperatures this century.
Our twopapers published today provide a troubling report card on the global methane budget, and explore what it means for achieving the Paris Agreement target of limiting warming to well below 2℃.
Methane concentration in the atmosphere reached 1,875 parts per billion at the end of 2019 – more than two and a half times higher than pre-industrial levels.
Once emitted, methane stays in the atmosphere for about nine years – a far shorter period than carbon dioxide. However its global warming potential is 86 times higher than carbon dioxide when averaged over 20 years and 28 times higher over 100 years.
In Australia, methane emissions from fossil fuels are rising due to expansion of the natural gas industry, while agriculture emissions are falling.
Balancing the global methane budget
We produced a methane “budget” in which we tracked both methane sources and sinks. Methane sources include human activities such as agriculture and burning fossil fuels, as well as natural sources such as wetlands. Sinks refer to the destruction of methane in the atmosphere and soils.
Our data show methane emissions grew almost 10% from the decade of 2000-2006 to the most recent year of the study, 2017.
Atmospheric methane is increasing by around 12 parts per billion each year – a rate consistent with a scenario modelled by the Intergovernmental Panel on Climate Change under which Earth warms by 3-4℃ by 2100.
From 2008-2017, 60% of methane emissions were man-made. These include, in order of contribution:
agriculture and waste, particularly emissions from ruminant animals (livestock), manure, landfills, and rice farming
the production and use of fossil fuels, mainly from the oil and gas industry, followed by coal mining
biomass burning, from wood burning for heating, bushfires and burning biofuels.
The remaining emissions (40%) come from natural sources. In order of contribution, these include:
wetlands, mostly in tropical regions and cold parts of the planet such as Siberia and Canada
lakes and rivers
natural geological sources on land and oceans such as gas–oil seeps and mud volcanoes
smaller sources such as tiny termites in the savannas of Africa and Australia.
So what about the sinks? Some 90% of methane is ultimately destroyed, or oxidised, in the lower atmosphere when it reacts with hydroxyl radicals. The rest is destroyed in the higher atmosphere and in soils.
Increasing methane concentrations in the atmosphere could, in part, be due to a decreasing rate of methane destruction as well as rising emissions. However, our findings don’t suggest this is the case.
Measurements show that methane is accumulating in the atmosphere because human activity is producing it at a much faster rate than it’s being destroyed.
Source of the problem
The biggest contributors to the methane increase were regions at tropical latitudes, such as Brazil, South Asia and Southeast Asia, followed by those at the northern-mid latitude such as the US, Europe and China.
In Australia, agriculture is the biggest source of methane. Livestock are the predominant cause of emissions in this sector, which have declined slowly over time.
The fossil fuel industry is the next biggest contributor in Australia. Over the past six years, methane emissions from this sector have increased due to expansion of the natural gas industry, and associated “fugitive” emissions – those that escape or are released during gas production and transport.
Tropical emissions were dominated by increases in the agriculture and waste sector, whereas northern-mid latitude emissions came mostly from burning fossil fuels. When comparing global emissions in 2000-2006 to those in 2017, both agriculture and fossil fuels use contributed equally to the emissions growth.
Since 2000, coal mining has contributed most to rising methane emissions from the fossil fuel sector. But the natural gas industry’s rapid growth means its contribution is growing.
Some scientists fear global warming will cause carbon-rich permafrost (ground in the Arctic that is frozen year-round) to thaw, releasing large amounts of methane.
But in the northern high latitudes, we found no increase in methane emissions between the last two decades. There are several possible explanations for this. Improved ground, aerial and satellite surveys are needed to ensure emissions in this vast region are not being missed.
Fixing our methane leaks
Around the world, considerable research and development efforts are seeking ways to reduce methane emissions. Methods to remove methane from the atmosphere are also being explored.
Europe shows what’s possible. There, our research shows methane emissions have declined over the past two decades – largely due to agriculture and waste policies which led to better managing of livestock, manure and landfill.
The extraction, processing and transport of fossil fuels contributes to substantial methane emissions. But “super-emitters” – oil and gas sites that release a large volume of methane – contribute disproportionately to the problem.
This skewed distribution presents opportunities. Technology is available that would enable super-emitters to significantly reduce emissions in a very cost effective way.
Clearly, current upward trends in methane emissions are incompatible with meeting the goals of the Paris climate agreement. But methane’s short lifetime in the atmosphere means any action taken today would bring results in just nine years. That provides a huge opportunity for rapid climate change mitigation.
Our new study – the first worldwide assessment of heatwaves at the regional scale – found heatwaves have become longer and more frequent since 1950. And worryingly, we found this trend has accelerated.
We also examined a new metric: “cumulative heat”. This measures how much extra heat a heatwave can contribute, and the new perspective is eye-opening.
What is ‘extra heat’?
In southeast Australia’s worst heatwave season in 2009, we endured an extra heat of 80℃. Let’s explore what that means.
For a day to qualify as being part of a heatwave, a recorded temperature should exceed an officially declared “heatwave threshold”.
And cumulative heat is generally when the temperature above that threshold across all heatwave days are added up.
Let’s say, for example, a particular location had a heatwave threshold of around 30℃. The “extra heat” on a day where temperatures reach 35℃ would be 5℃. If the heatwave lasted for three days, and all days reached 35℃, then the cumulative heat for that event would be 15℃.
Another decade, another heatwave day
We found almost every global region has experienced a significant increase in heatwave frequency since 1950. For example, southern Australia has experienced, on average, one extra heatwave day per decade since 1950.
However, other regions have experienced much more rapid increases. The Mediterranean has seen approximately 2.5 more heatwave days per decade, while the Amazon rainforest has seen an extra 5.5 more heatwave days per decade since 1950.
The global average sits at approximately two extra heatwave days per decade.
The last 20 years saw the worst heatwave seasons
Since the 1950s, almost all regions experienced significant increases in the extra heat generated by heatwaves.
Over northern and southern Australia, the excess heat from heatwaves has increased by 2-3℃ per decade. This is similar to other regions, such as western North America, the Amazon and the global average.
Alaska, Brazil and West Asia, however, have cumulative heat trends of a massive 4-5℃ per decade. And, for the vast majority of the world, the worst seasons occurred in the last 20 years.
We also examined whether heatwaves were changing at a constant rate, or were speeding up or slowing down. With the exception of average intensity, we found heatwave trends have not only increased, but have accelerated since the 1950s.
Don’t be fooled by the maths
Interestingly, average heatwave intensity showed little – if any – changes since 1950. But before we all breathe a sigh of relief, this is not because climate change has stopped, or because heatwaves aren’t getting any warmer. It’s the result of a mathematical quirk.
Since we’re seeing more heatwaves – which we found are also generally getting longer – there are more days to underpin the average intensity. While all heatwave days must exceed a relative extreme threshold, some days will exceed this threshold to a lesser extent than others. This brings the overall average down.
When we look at changes in cumulative heat, however, there’s just no denying it. Extra heat – not the average – experienced in almost all regions, is what can have adverse impacts on our health, infrastructure and ecosystems.
Like nothing we’ve experienced before
While the devastating impacts of heatwaves are clear, it has been difficult to consistently measure changes in heatwaves across the globe. Previous studies have assessed regional heatwave trends, but data constraints and the spectrum of different heatwave metrics available have made it hard to compare regional changes in heatwaves.
Our study has closed this gap, and clearly shows heatwaves are on the rise. We are seeing more of them and they are generating more heat at an increasing pace.
There’s one small issue, though. Despite Taylor’s comments in which he sought to explain away Australia’s 0.7% year-on-year rise in emissions as a product of increased gas investment, actual emissions in the December quarter were in fact down relative to the September 2018 quarter. This is due mainly to the fact that people use much more energy for heating in the July-September period than they do during the milder spring weather of October-December.
Taylor, meanwhile, was discussing the “adjusted” data, which reveals an 0.8% increase between the two quarters.
This might all sound like minor quibbling. But knowing the difference between quarterly and annual figures, and raw and adjusted data – and knowing what’s ultimately the most important metric – is crucial to understanding Australia’s emissions. And it might come in handy next time you’re listening to a politician discussing our progress (or lack thereof) towards tackling climate change.
Highlighting the difference between quarters is problematic, because emissions data are what statisticians describe as “noisy”. Emissions levels jump around from period to period, which can obscure the overall trend.
Quarterly data is important for understanding how Australia is tracking more generally towards doing its fair share on reducing its emissions. But too much stock is put on the noise, and not enough on the underlying trend.
The charts below compare our estimated actual emissions on a quarterly basis (top) with the cumulative emissions for the year leading up to that quarter (here described as the “year-to-quarter emissions” and shown in the lower chart).
These charts, both built on today’s data, make a few things clear.
Quarterly emissions are noisy
The first thing to note is that saying that our emissions are down compared with the previous quarter is hardly remarkable, or worth patting ourselves on the back for. This is especially true if we are comparing the December quarter data, released today, with the data for the preceding quarter.
September quarter emissions are almost always higher than the rest of the year. This is because, while September itself is in spring, the September quarter also covers July and August.
Our winter heating needs are generally met using fossil fuels, whether through electric heaters or natural gas, which is why the September quarter has the highest emissions. In the December quarter, which covers most of spring, our need for heating drops, and so do our emissions.
But if you look beyond the difference between quarters, as in the second chart above, you can see the underlying rising trend in our greenhouse gas emissions.
Cherrypicking the best metric
Readers who follow climate politics may remember the spectacular moment in March when Taylor appeared on ABC’s Insiders opposite Barrie Cassidy.
Many journalists, including those on the Insiders panel that day, responded at the time that Taylor’s claim that emissions had dipped over the preceding three months was true but not meaningful, in the context of an annual rising trend.
But it was not even necessarily true. As is visible in the quarterly chart, emissions were not lower in the September quarter of 2018 than they were in the preceding quarter.
Specifically, Taylor claimed that “total emissions are coming down right now”. This is only true if we are talking about “seasonally adjusted, weather-normalised total emissions”. The adjusted data are shown above. While the adjusted data went down between quarters, the actual emissions went up.
The process of adjustment is not unprincipled, and is used to see through the noise of our emissions data. “Seasonal adjustment” and “weather normalisation” are two separate processes.
Seasonal adjustment refers to the process of adjusting the emissions figures to account for the predictable seasonal fluctuations described earlier. Weather normalisation does the same, but takes into account individual temperature extremes, both hot and cold, during any given period, and adjusts accordingly.
Much as a golf handicap lets us compare the performance of golfers of differing abilities, these data adjustments tell us whether our emissions are tracking higher or lower than we might expect.
But if a golfer with a handicap of 10 goes around the course in 82 shots, we don’t declare that they have actually hit the ball only 72 times.
This is essentially what Taylor did in his interview with Cassidy. It is not correct to refer to these adjusted emissions data as our “total emissions”.
What does data adjustment mean?
Building on this, it is important to note that the adjusted data and actual data often disagree on whether emissions have increased between quarters. Since the Coalition took office in 2013, there have been 21 quarterly emissions data releases.
The actual quarterly emissions have increased nine times between quarters. The adjusted data says there have been 12 of these increases. And they have only agreed on whether there was an increase six times.
When one form of the data shows an increase and the other does not, the minister has a choice about which figure to highlight.
In the September quarter, the actual emissions gave bad news (an increase), and the adjusted emissions gave good news (a reduction). Taylor chose to refer to the adjusted data, as did the then environment minister Melissa Price, who had portfolio responsibility for emissions reduction at the time.
Today, this was flipped. The actual emissions showed good news (a reduction) and the adjusted data showed bad news (an increase).
It’s refreshing, then, to see Taylor choose to focus on the adjusted emissions data this time around, when he could have chosen the spin route and focused on the fact that the raw data showed a decrease between quarters.
So what does it all mean?
What we can say without any equivocation at all is that since 2015, in the wake of the carbon price repeal the preceding July, Australia’s greenhouse emissions have increased. On the government’s own projections , this trend is not expected to change.
Stabilisation is not enough. As the Intergovernmental Panel on Climate Change made clear in its Special Report on 1.5℃ last year, deep cuts are required to ensure a safe climate. The Paris Agreement, while calling on all nations to do their part, says rich countries such as Australia should take the lead.
The need to reduce emissions is pressing. And while the raw emissions figures may be down this quarter, this is not meaningful progress. Far more meaningful is the fact that Australia has no effective policy to limit our impact on the global climate.
Coastal wetlands don’t cover much global area but they punch well above their carbon weight by sequestering the most atmospheric carbon dioxide of all natural ecosystems.
Termed “blue carbon ecosystems” by virtue of their connection to the sea, the salty, oxygen-depleted soils in which wetlands grow are ideal for burying and storing organic carbon.
In our research, published today in Nature, we found that carbon storage by coastal wetlands is linked to sea-level rise. Our findings suggest as sea levels rise, these wetlands can help mitigate climate change.
Sea-level rise benefits coastal wetlands
We looked at how changing sea levels over the past few millennia has affected coastal wetlands (mostly mangroves and saltmarshes). We found they adapt to rising sea levels by increasing the height of their soil layers, capturing mineral sediment and accumulating dense root material. Much of this is carbon-rich material, which means rising sea levels prompt the wetlands to store even more carbon.
We investigated how saltmarshes have responded to variations in “relative sea level” over the past few millennia. (Relative sea level is the position of the water’s edge in relation to the land rather than the total volume of water within the ocean, which is called the eustatic sea level.)
Global variation in the rate of sea-level rise over the past 6,000 years is largely related to the proximity of coastlines to ice sheets that extended over high northern latitudes during the last glacial period, some 26,000 years ago.
As ice sheets melted, northern continents slowly adjusted elevation in relation to the ocean due to flexure of the Earth’s mantle.
For much of North America and Europe, this has resulted in a gradual rise in relative sea level over the past few thousand years. By contrast, the southern continents of Australia, South America and Africa were less affected by glacial ice sheets, and sea-level history on these coastlines more closely reflects ocean surface “eustatic” trends, which stabilised over this period.
Our analysis of carbon stored in more than 300 saltmarshes across six continents showed that coastlines subject to consistent relative sea-level rise over the past 6,000 years had, on average, two to four times more carbon in the upper 20cm of sediment, and five to nine times more carbon in the lower 50-100cm of sediment, compared with saltmarshes on coastlines where sea level was more stable over the same period.
In other words, on coastlines where sea level is rising, organic carbon is more efficiently buried as the wetland grows and carbon is stored safely below the surface.
Give wetlands more space
We propose that the difference in saltmarsh carbon storage in wetlands of the southern hemisphere and the North Atlantic is related to “accommodation space”: the space available for a wetland to store mineral and organic sediments.
Coastal wetlands live within the upper portion of the intertidal zone, roughly between mean sea level and the upper limit of high tide.
These tidal boundaries define where coastal wetlands can store mineral and organic material. As mineral and organic material accumulates within this zone it creates layers, raising the ground of the wetlands.
New accommodation space for storage of carbon is therefore created when the sea is rising, as has happened on many shorelines of the North Atlantic Ocean over the past 6,000 years.
To confirm this theory we analysed changes in carbon storage within a unique wetland that has experienced rapid relative sea-level rise over the past 30 years.
When underground mine supports were removed from a coal mine under Lake Macquarie in southeastern Australia in the 1980s, the shoreline subsided a metre in a matter of months, causing a relative rise in sea level.
Following this the rate of mineral accumulation doubled, and the rate of organic accumulation increased fourfold, with much of the organic material being carbon. The result suggests that sea-level rise over the coming decades might transform our relatively low-carbon southern hemisphere marshes into carbon sequestration hot-spots.
How to help coastal wetlands
The coastlines of Africa, Australia, China and South America, where stable sea levels over the past few millennia have constrained accommodation space, contain about half of the world’s saltmarshes.
A doubling of carbon sequestration in these wetlands, we’ve estimated, could remove an extra 5 million tonnes of CO₂ from the atmosphere per year. However, this potential benefit is compromised by the ongoing clearance and reclamation of these wetlands.
Preserving coastal wetlands is critical. Some coastal areas around the world have been cut off from tides to lessen floods, but restoring this connection will promote coastal wetlands – which also reduce the effects of floods – and carbon capture, as well as increase biodiversity and fisheries production.
In some cases, planning for future wetland expansion will mean restricting coastal developments, however these decisions will provide returns in terms of avoided nuisance flooding as the sea rises.
Finally, the increased carbon storage will help mitigate climate change. Wetlands store flood water, buffer the coast from storms, cycle nutrients through the ecosystem and provided vital sea and land habitat. They are precious, and worth protecting.
The authors would like to acknowledge the contribution of their colleagues, Janine Adams, Lisa Schile-Beers and Colin Woodroffe.
When the Pacific Islands Forum is held in Nauru from September 1, one of the main objectives will be signing a wide-ranging security agreement that covers everything from defence and law and order concerns to humanitarian assistance and disaster relief.
The key question heading into the forum is: can the agreement find a balance between the security priorities of Australia and New Zealand and the needs of the Pacific Island nations?
Even though new Prime Minister Scott Morrison is not attending the forum, sending Foreign Minister Marise Payne instead, the Biketawa Plus security agreement remains a key aim for Canberra.
The original Biketawa Declaration was developed as a response to the 2000 coup in Fiji. It has served Australia and the region well, providing a framework for collective action when political tensions and crises occur. However, in the face of rapid change, it looks narrow and dated.
Why act now? The rationale is clear. Much has happened to alter the security landscape in the Pacific since 2000. But despite the commentary in Australia, security in the Pacific is not all about geopolitics. While Australia may be most worried about China’s rising influence in the region, it would be a mistake to think this is the primary preoccupation of Pacific leaders, too.
A focus on climate change as a security issue
One key reason for updating Biketawa is to realign Australia’s security interests with those of Pacific Island countries that have grown more aware of their shared interests and confident in expressing them in international relations. This growing confidence is clear in the lobbying of Pacific nations for climate change action at the United Nations and in Fiji’s role as president of the UN’s COP23 climate talks.
In the absence of direct military threats, the Pacific Island nations are most concerned about security of a different kind. Key issues for the region are sustainable growth along a “blue-green” model, climate change (especially the increasing frequency and intensity of natural disasters and rising sea levels), illegal fishing and over-fishing, non-communicable diseases (NCDs), transnational crime, money laundering and human trafficking.
Some of these security issues can be addressed by redirecting more Australian military forces to the region. Indeed, “disaster diplomacy” has been an effective method of connecting Australia’s security interests with those of Pacific Island nations in the past.
However, other priorities for the Pacific seem to run counter to Australia’s current policies toward the region. For example, the Pacific’s sustainable “blue-green” development agenda seems incompatible with an export-oriented growth model that is often touted by Australia as an “aid for trade” solution to Pacific “problems”.
Climate change adaptation and mitigation must also be elevated to the top of the agenda in Australia’s relations with the region. It is the most pressing problem in the Pacific, but for political and economic reasons, it hasn’t resonated to the same extent with Canberra.
In fact, Australia has recently been identified as the worst-performing country in the world on climate action. This has not gone unnoticed in the Pacific. Fiji’s prime minister, in particular, has been clear in highlighting that Australia’s “selfish” stance on climate change undermines its credibility in the region.
These shifting priorities in the Pacific present a greater challenge for Australia, especially now that there are more players in the region, such as China, Russia and Indonesia. Australia may see these “outsiders” as potential threats, but Pacific nations are just as likely to view them as alternative development partners able to provide opportunities.
New Coalition team on the Pacific
Making matters even trickier is the leadership shake-up in Canberra. What’s perhaps most problematic is Julie Bishop’s departure as foreign minister. Bishop did more to engage with Pacific countries than any foreign minister in recent memory. The [2017 Foreign Policy White Paper], for example, prioritised increased Pacific engagement and led to the region receiving the lion’s share of Australia’s latest aid budget.
Payne will attend the Pacific Islands Forum on her first overseas visit as foreign minister. As the former defence minister, she lobbied for Australia to be seen as a “security partner of choice” in the Pacific. What remains to be seen is whether she can maintain the momentum on Biketawa Plus.
So the challenge for the new Coalition leadership is to find a way to push through a new Pacific security agreement that caters to both Australia’s security concerns about Chinese influence in the region and the Pacific Island countries’ focus on climate change and sustainable growth.
There are lessons that can be drawn from the decade-long negotiations between Australia, New Zealand and the Pacific Island nations over the Pacer Plus free-trade agreement, which was finally signed last year (without the region’s two largest economies, Papua New Guinea and Fiji). Australia must not underestimate the diplomatic skills of Pacific leaders or offer benefits that are perceived as being more attractive to it than the Pacific states.
Australia must also avoid allowing the leadership spill to impact its Pacific agenda at this sensitive time. Bishop’s focus on labour mobility between the Pacific islands and Australia has been most welcome, but there can be no authentic engagement with the region without addressing climate insecurity as well.
King tides occur several times a year when the Moon is slightly closer to the Earth (so they’re sometimes called perigean spring tides). This means king tides are predictable, as are rising sea levels. The combination, along with sporadic storm events, will lead to increasing flooding of our coastal cities.
Higher sea levels, whether creeping (associated with anthropogenic climate change) or transient (episodic storm events), have impacts on both private and public property and assets. What is now mostly nuisance flooding will become more problematic, and the ever-increasing global damage bill from disaster will continue to mount.
According to the global re-insurer Munich Re, losses from natural disasters in 2017 totalled US$330 billion, the second highest on record. Almost half of these losses (41%) were uninsured.
Who’s responsible for adaptation plans?
In keeping with the theory that risk is best managed by those closest to the risk, local government in Australia is the level of government best suited to managing such local risks. In response to the increasing threat from rising sea levels, many local government councils around Australia have developed coastal climate adaptation plans.
Federal and state governments clearly also have roles to play in managing coastal inundation. The federal government is often the insurer of last resort, especially for public infrastructure.
In Queensland, the state government has implemented the successful QCoast2100 program. This is helping local governments to develop adaptation plans all along the state’s coastline.
It is increasingly recognised that many of the plans developed in the past contain overcomplicated analyses of oversimplified adaptation options. Instead, we need less complicated ways of determining the most suitable adaptation option and assessments that consider more tailored and considered options, which will then be more readily implementable.
What are the options?
Coastal climate adaptation options tend to fall into one of three categories:
retreat – relocate assets and structures inland or to higher ground
protect – mostly by building engineered seawalls, although green infrastructure can also be implemented
accommodate – live with the hazard but reduce the vulnerability of structures and assets.
The third adaptation option, accommodating sea-level rise, is becoming the most popular approach in many nations, including the low-lying Netherlands. However, this approach is probably the least understood in Australia and rarely appears as the preferred option in Australian coastal adaptation plans.
This option includes making existing structures less vulnerable. This might involve relocating electrical and air-conditioning services and switchboards higher in existing buildings. Over time, vulnerable sites can be repurposed with less vulnerable land uses and structures.
This is different from pre-emptively evicting and relocating entire communities from vulnerable locations – the retreat option. The retreat option is most easily implemented immediately after major flooding that has led to significant damage.
Plans must consider the politics
Early coastal adaptation plans commonly advocated mass pre-emptive coastal retreat, but local government often ended up shelving or rejecting such recommendations. Instead, councils simply commissioned the construction of small local seawalls in areas at risk of erosion.
More developed and recent coastal adaptation plans consider finer spatial scales. What they still often don’t do is consider more sophisticated and politically informed adaptation options and approaches.
Hence adaptation planning is still often best characterised as the “plan and forget” approach. These plans typically lack monitoring and evaluation and a realistic implementation strategy.
Increased flooding of our coastline is inevitable and happening. Therefore, adaptation planning needs to consider more nuanced options that are likely to be more politically palatable and implementable.
A major challenge for managing such a large increase in sea level is our limited understanding of what impact this scale of change might have on humanity.
While there are excellent online resources to model the local physical impacts of sea level rise, the recent geological past can provide important insights into how humans responded to dramatic increases in sea level.
The last ice age
At the height of the last ice age some 21,000 years ago, not only were the Greenland and Antarctic ice sheets larger than they are today, but 3km-high ice sheets covered large parts of North America and northern Europe.
This sucked vast amounts of water out of our planet’s oceans. The practical upshot was sea level was around 125m lower, making the shape of the world’s coastlines distinctly different to today.
As the world lurched out of the last ice age with increasing temperatures, the melting ice returned to the ocean as freshwater, dramatically increasing sea levels and altering the surface of our planet.
Arguably nowhere experienced greater changes than Australia, a continent with a broad continental shelf and a rich archaeological record spanning tens of millennia.
A bigger landmass
For most of human history in Australia, lower sea levels joined mainland Australia to both Tasmania and New Guinea, forming a supercontinent called Sahul. The Gulf of Carpentaria hosted a freshwater lake more than twice the size of Tasmania (about 190,000km2).
Our study shows that lower sea levels resulted in Australia growing by almost 40% during this time – from the current landmass of 7.2 million km2 to 9.8 million km2.
The coastlines also looked very different, with steep profiles off the edge of the exposed continental shelf in many areas forming precipitous slopes and cliffs.
Imagine the current coastline where the Twelve Apostles are on Victoria’s Great Ocean Road and then extend them around much of the continent. Many rivers flowed across the exposed shelf to the then distant coast.
When things warmed up
Then between 18,000 and 8,000 years ago, global climate warmed, leading to rapid melting of the ice sheets, and seeing sea levels in the Australian region rising from 125m below to 2m above modern sea levels.
Tasmania was cut off with the flooding of Bass Strait around 11,000 years ago. New Guinea was separated from Australia with the flooding of Torres Strait and creation of the Gulf of Carpentaria around 8,000 years ago.
We found that 2.12 million square km, or 20-29% of the landmass – a size comparable to the state of Queensland – was lost during this inundation. The location of coastlines changed on average by 139km inland. In some areas the change was more than 300km.
Much of this inundation occurred over a 4,000-year period (between 14,600 and 10,600 years ago) initiated by what is called Meltwater Pulse 1A, a period of substantial ice sheet collapse releasing millions of cubic litres of water back into the oceans.
During this period, sea levels rose by 58m, equivalent to 14.5mm per year. On the ground, this would have seen movement of the sea’s edge at a pace of about 20-24m per year.
Impacts of past sea level rise
The potential impacts of these past sea-level changes on Aboriginal populations and societies have long been a subject of speculation by archaeologists and historians.
Most tribal groups on the coast 18,000 years ago must have slowly lost their entire territory […] a succession of retreats must have occurred. The slow exodus of refugees, the sorting out of peoples and the struggle for territories probably led to many deaths as well as new alliances.
Archaeologists have long recognised that Aboriginal people would have occupied the now-drowned continental shelves surrounding Australia, but opinions have been divided about the nature of occupation and the significance of sea-level rise. Most have suggested that the ancient coasts were little-used or underpopulated in the past.
Our data show that Aboriginal populations were severely disrupted by sea-level change in many areas. Perhaps surprisingly the initial decrease in sea level prior to the peak of the last ice age resulted in people largely abandoning the coastline, and heading inland, with a number of archaeological sites within the interior becoming established at this time.
During the peak of the last ice age, there is evidence on the west coast that shows people continued to use marine resources (shellfish, fish etc) during this time, albeit at low levels.
A shrinking landmass
With the onset of the massive inundation after the end of the last ice age people evacuated the coasts causing markedly increased population densities across Australia (from around 1 person for every 355 square km 20,000 years ago, to 1 person every 147 square km 10,000 years ago).
Rising sea levels had such a profound impact on societies that Aboriginal oral histories from around the length of the Australian coastline preserve details of coastal flooding and the migration of populations.
We argue that this squeezing of people into a landmass 22% smaller – into inland areas that were already occupied – required people to adopt new social, settlement and subsistence strategies. This may have been an important element in the development of the complex geographical and religious landscape that European explorers observed in the 18th and 19th centuries.
Following the stabilisation of the sea level after 8,000 years ago, we start to see the onset of intensive technological investment and manipulation of the landscape (such as fish traps and landscape burning).
We also see the formation of territories (evident by marking of place through rock art) that continues to propagate up until the present time. All signs of more people trying to survive in less space.
So what are the lessons of the past for today? Thankfully, we can show that past societies survived rapid sea level change at rates slightly greater than those projected in our near future, albeit with population densities far lower than today.
But we can also see that sea level rise resulted in drastic changes to where people lived, how they survived, what technology they used, and probable modifications to their social, religious and political ways of life.
In today’s world with substantially higher population densities, managing the relocation of people inland and outside Australia, potentially across national boundaries, may provide to be one of the great social challenges of the 21st century.
Fiji’s presidency of this year’s United Nations climate summit has put a renewed focus on the future of low-lying Pacific Islands. And while we should not ignore the plight of these nations, it is just as damaging to assume that their fate is already sealed.
Many people in Australia consider island nations such as Kiribati, Tuvalu and the Marshall Islands to be almost synonymous with impending climate catastrophe. After returning from Papua New Guinea in 2015, federal immigration minister Peter Dutton infamously joked that “time doesn’t mean anything when you’re about to have water lapping at your door”.
If influential and everyday Australians, and the rest of the world, hold the view that Pacific Island nations are doomed to succumb to climate change, the danger is that this will become a self-fulfilling prophecy.
When we deny the possibility of a future for low-lying small islands, we are
admitting defeat. This in turn undermines the impetus to reduce greenhouse gas emissions and find ways to help communities carry on living in their island homes. It leaves us unable to discuss any options besides palliative responses for climate refugees.
There are other consequences of this pessimistic framing of islands. It may
undermine efforts to sustainably manage environments, because a finite future is
anathema to the sustaining resources in perpetuity. It can also manifest itself in harmful local narratives of denial or self-blame. And it can lead to climate change being blamed for environmental impacts that arise from local practices, which then remain unchanged.
We would do well to listen instead to what the leaders of low-lying island nations are saying, such as Tuvalu’s Prime Minister Enele Sopoaga, who told the 2013 Warsaw climate summit:
… some have suggested that the people of Tuvalu can move elsewhere. Let
me say in direct terms. We do not want to move. Such suggestions are
offensive to the people of Tuvalu. Our lives and culture are based on our
continued existence on the islands of Tuvalu. We will survive.
Displacement is not an option we relish or cherish and we will not operate on that basis. We will operate on the basis that we can in fact help to prevent this from happening.
Determined to survive
These leaders are determined for good reasons. Small islands are likely to respond in a host of different ways to climate change, depending on their geology, local wave patterns, regional differences in sea-level rise, and how their corals, mangroves and other wildlife respond to changing temperatures and weather patterns.
Evidence suggests that even seemingly very similar island types may respond very differently to one another. In many cases it is too early to say for sure that climate change will make a particular island uninhabitable.
But perhaps even more important in the future of low-lying small islands is the
way people adapt to climate change. There are all sorts of ways in which people can adapt their environments to changing conditions. Indeed, when the first migrants arrived in the low-lying atolls of Micronesia more than 3,000 years ago they found sand islands with no surface water and little soil, and settled them with only what they had in their small boats. Modern technologies and engineering systems can transform islands even more substantially, so that people can still live meaningful lives on them under changed climate conditions.
Adapting islands to climate change will not be easy. It will involve changes in where and how things are built, what people eat, how they get their water and energy, and what their islands look like.
It will also involve changes in institutions that are fundamental to island
societies, such as those concerned with land and marine tenure. But it can be done, with ingenuity, careful and long-term planning, technology transfer, and
meaningful partnerships between governments and international agencies.
Failure so far
Frustratingly, however, the international community is so far failing island states when it comes to this crucial adaptation. Despite their acute vulnerability having been recognised for at least 30 years, low-lying atoll countries such as Kiribati, the Marshall Islands and Tuvalu are attracting only low or moderate amounts of international adaptation funding. This is mostly as part of larger regional projects, and often focused on building capacity rather than implementing actual changes.
It is we who have failed to reduce greenhouse gas emissions and to help low-lying islands adapt, and it is we who cannot imagine any long-term future for them. It seems all we can do is talk about loss, migration, and waves of climate refugees. Having let them down twice, this defeatist thinking risks denying them an independent future for a third time. This is environmental neo-colonialism.
The international community has a moral responsibility to deliver a
comprehensive strategy to minimise the risks climate change poses to remote
low-lying islands. People living on these islands have a legal and moral right to lead dignified lives in their homelands, free from the interference of climate impacts. People who live in affluent countries high above sea level have several responsibilities here.
First, as most of us agree, we should reduce our greenhouse gas emissions. We have some control over that through how we consume, invest, vote and travel. Second, we should insist that our governments do more to help low-lying states to adapt to climate change. It is our pollution, after all. And we should argue for a reversal in our declining aid budgets.
And finally, and perhaps most importantly, we should all stop talking down the future of low-lying small islands, because all this does is hasten their demise.