Every so often I get to the point where I feel I just need a break from Blogging and the like, to rest, to regroup, to recharge and to catch-up on work requirements – so that is what I am currently doing. I am physically exhausted at the moment and that often brings on more serious issues with my health (which I am beginning to sense), so the wiser course is to rest for a little – to just ease off for a bit, take the foot of the throttle, etc. So I am taking a break for a bit – I think I’m about 2, 3 or 4 days into it at the moment and when I return it will be a gradual return, not an all in and at it approach.
How long will the break be? That I’m not sure about – there are some pressing issues around my work at the moment, some medical appointments, etc – and these all over the next week or so – which also means the break will be less of a break and more of a short-term refocus I suppose. I don’t expect it to be more than 2 weeks, probably less.
A new United Nations report shows the world’s major fossil fuel producing countries, including Australia, plan to dig up far more coal, oil and gas than can be burned if the world is to prevent serious harm from climate change.
The report found fossil fuel production in 2030 is on track to be 50% more than is consistent with the 2℃ warming limit agreed under the Paris climate agreement. Production is set to be 120% more than is consistent with holding warming to 1.5℃ – the ambitious end of the Paris goals.
Australia is strongly implicated in these findings. In the same decade we are supposed to be cutting emissions under the Paris goals, our coal production is set to increase by 34%. This trend is undercutting our success in renewables deployment and mitigation elsewhere.
It reviewed seven top fossil fuel producers (China, the United States, Russia, India, Australia, Indonesia, and Canada) and three significant producers with strong climate ambitions (Germany, Norway, and the UK).
The production gap is largest for coal, of which Australia is the world’s biggest exporter. By 2030, countries plan to produce 150% more coal than is consistent with a 2℃ pathway, and 280% more than is consistent with a 1.5℃ pathway.
The gap is also substantial for oil and gas. Countries are projected to produce 43% more oil and 47% more gas by 2040 than is consistent with a 2℃ pathway.
Nine countries, including Australia, are responsible for more than two-thirds of fossil fuel carbon emissions – a calculation based on how much fuel nations extract, regardless of where it is burned.
Prospects for improvement are poor. As countries continue to invest in fossil fuel infrastructure, this “locks in” future coal, oil and gas use.
US oil and gas production are each projected to increase by 30% to 2030, as is Canada’s oil production.
Australia’s coal production is projected to jump by 34%, the report says. Proposed large coal mines and ports, if completed, would represent one of the world’s largest fossil fuel expansions – around 300 megatonnes of extra coal capacity each year.
The expansion is underpinned by a combination of ambitious national plans, government subsidies to producers and other public finance.
In Australia, tax-based fossil fuel subsidies total more than A$12 billion each year. Governments also encourage coal production by fast-tracking approvals, constructing roads and reducing royalty requirements, such as for Adani’s recently approved Carmichael coal mine in the Galilee Basin.
Ongoing global production loads the energy market with cheap fossil fuels – often artificially cheapened by government subsidies. This greatly slows the transition to renewables by distorting markets, locking in investment and deepening community dependency on related employment.
In Australia, this policy failure is driven by deliberate political avoidance of our national responsibilities for the harm caused by our exports. There are good grounds for arguing this breaches our moral and legal obligations under the United Nations climate treaty.
Protestors locked themselves to heavy machinery to protest the Adani coal mine in central Queensland. Frontline Action on Coal
Cutting off supply
So what to do about it? As our report states, governments frequently recognise that simultaneously tackling supply and demand for a product is the best way to limit its use.
For decades, efforts to reduce greenhouse gas emissions have focused almost solely on decreasing demand for fossil fuels, and their consumption – through energy efficiency, deployment of renewable technologies and carbon pricing – rather than slowing supply.
While the emphasis on demand is important, policies and actions to reduce fossil fuels use have not been sufficient.
It is now essential we address supply, by introducing measures to avoid carbon lock-in, limit financial risks to lenders and governments, promote policy coherence and end government dependency on fossil fuel-related revenues.
Policy options include ending fossil fuel subsidies and taxing production and export. Government can use regulation to limit extraction and set goals to wind it down, while offering support for workers and communities in the transition.
Several governments have already restricted fossil fuel production. France, Denmark and New Zealand have partially or totally banned or suspended oil and gas exploration and extraction, and Germany and Spain are phasing out coal mining.
Australia is clearly a major contributor in the world’s fossil fuel supply problem. We must urgently set targets, and take actions, that align our future fossil fuel production with global climate goals.
The possibilities presented by hydrogen are the subject of excited discussion across the world – and across Australia’s political divide, notoriously at war over energy policy.
On Friday Australia’s chief scientist Alan Finkel will present a national strategy on hydrogen to state, territory and federal energy ministers. Finkel is expected to outline a plan that prioritises hydrogen exports as a profitable way to reduce emissions.
It is to be hoped the strategy is aggressive, rather than timid. Ambition is key in lowering the cost of energy. Australia would do better aiming for 200% renewable energy or more.
It’s likely the national strategy will feature demonstration projects to test the feasibility of new technology, reduce costs, and find ways to share the risk of infrastructure investment between government and industry.
There are still a number of barriers. Existing gas pipelines could be used to transport hydrogen to end-users but current laws are prohibitive, mechanisms like “certificates of origin” are required, and there are still key technology issues, particularly the cost of electrolysis.
These issues raise questions of what a major hydrogen economy really looks like. It may prompt suspicions this is just the a latest energy pipe dream. But our research at the Australian-German Energy Transition Hub argues that an ambitious approach is better than a cautious one.
Aggressively pursing hydrogen exports will reduce costs of domestic energy supply and provide a basis for new export industries, such as greens steel, in a carbon-constrained world.
We used optimisation modelling to examine how a major hydrogen industry might roll out in Australia. We wanted to identify where major plants for electrolysis could be built, asked whether the existing national electricity market should supply the power, and looked at the effect on the cost of the system and, ultimately, energy affordability.
Australian Hydrogen export locations.
Our results show the locations for future hydrogen infrastructure investment will be mainly determined by their capital costs, the share of wind and solar generation and the capacity of electrolysers to responsively provide energy to the system, and the magnitude of hydrogen production.
If we assume electrolysers remain expensive, around A$1,800 per kilowatt, and need to run at close to full-load capacity all the time, the result is large hydrogen exporting hubs across the country, built near high quality solar and wind power resources. Ideal locations tend to be remote from the national energy grid, such as in Western Australia and Northern Territory, or at relatively small-scale in South Australia or Tasmania.
There is much debate around the current cost of electrolysis, but consensus holds that economies of scale will substantially reduce these costs – by as much as an order of magnitude. This is akin to the cost reductions we have seen in solar power and batteries.
200 per cent renewables scenario
This infrastructure requires some major investment. However, our modelling shows that if Australia produces 200% of our energy needs by 2050, exporting the surplus, we see major drops in system costs and lower costs of energy for all Australia. If Australia can produce 400 Terrawatt-hours of hydrogen energy for export, modelling results show the average energy cost could be reduced by more than 30%.
Hydrogen ambition reduces costs of electricity supply.
The driving factor is our level of ambition. The more we lean into decarbonising our economy with green energy, the further the costs fall. The savings from the integrated and optimised use of electrolysers in a renewable-heavy national electricity market outweigh the cost of building large renewable resources in remote locations.
A large hydrogen export industry could generate both substantial export revenue and substantial benefits to the domestic economy.
Hydrogen export economy versus true RE economy
To sum up, the picture above shows two possible hydrogen futures for Australia.
In the first, Australia lacks climate actions and electrolyser costs remain high with limited economies of scale, and we export from key remote hubs such as the Pilbara.
In the other, ambition increases and costs drop, and the hydrogen export industry connects to the national grid, providing both renewable exports and benefits to the grid. This also promotes the use of hydrogen in the domestic market. Australia embraces a true renewable economy and a new chapter of major energy exports begins.
Either way, Australia is primed to become a hydrogen exporting superpower.
Temperatures across many regions of Australia are set to exceed 40℃ this week, including heatwaves forecast throughout parts of eastern Australia, raising the spectre of more devastating bushfires.
We have already heard warnings this fire season of the possibility of firestorms, created when extreme fires in the right conditions form their own weather systems.
Firestorms are the common term for pyrocumulonimbus bushfires – fires so intense they create their own thunderstorms, extreme winds, black hail, and lightning.
While they are very rare, our research published earlier this year, found climate change is making it likely they will become more common in parts of southeast Australia.
We also identified certain regions in southern and eastern Australia, including near Melbourne’s fringe, that in the second half of this century will be far more vulnerable to these events than others.
How firestorms happen
The 2003 Canberra bushfires, devastating on a grand scale, saw a Canberra resident film a fire tornado for the first time ever. Six years later, the ferocious Black Saturday bushfires in Victoria created three separate pyrocumulonimbus events.
More recently, fire storms devastated California in November 2018.
Pyrocumulonimbus events begin with the intense heat of a very big and fast-burning wildfire, which causes a large and rapidly rising smoke plume. As the plume rises, low atmospheric pressure causes it to expand and cool. Moisture can condense into a type of cloud known as a pyrocumulus – not pyrocumulonimbus, yet. This type of cloud can be common in large fires.
However, with the right environmental conditions the plume goes much higher and pyrocumulonimbus clouds can form, towering up to 15km in some cases. As it rises, the plume cools, and the upper part of the clouds form ice particles that collide and can produce lightning.
These thunderstorms can create erratic and dangerously strong wind gusts. These can drive blizzards of embers that ignite spot fires beyond the fire font.
Lightning from the plume can start new fires, well ahead of the main fire. In one case, lightning generated in a pyrocumulonimbus cloud has been recorded starting new fires up to 100km ahead of the main fire.
How climate change makes firestorms more likely
One of the key elements to a firestorm forming is the precondition of the atmosphere above it. We wanted to investigate how a changing climate might affect the likelihood of firestorms happening.
Previous research has found there is more dynamic interaction between a large fire and the atmosphere when the air about 1.5km above the surface is relatively dry, and when there are larger temperature differences across increasing altitudes.
The larger the temperature difference, the more unstable the atmosphere may become. When higher altitudes get cold more quickly than normal, and are also very dry at low levels, it can become more likely that a pyrocumulonimbus event will develop during a large fire.
We used high-resolution climate modelling of projected lower atmospheric instability and dryness conditions to assess the risk of pyrocumulonimbus in southeastern Australia between 2060 and 2079, compared with 1990-2009. We then overlaid this information with the forest fire danger index to identify particularly dangerous fire days.
We were then able to identify how often dangerous fire weather days occurred at the same time as a dry and unstable atmosphere. Verifying our models against past observations, we then examined how often these two characteristics coincided in the future under climate change, should our greenhouse gas emissions remain on their current trajectory.
The results were startling. From 2060 onwards, we saw sharp increases in dangerous fire days across southeast Australia that coincided with atmospheric conditions primed to generate firestorms.
These extremely dangerous days also shifted across seasons, starting to appear in late spring, whereas historically Australian pyrocumulonimbus wildfires have typically been summer phenomena.
Across large areas of Victoria and South Australia, on average, we saw four or five more days every spring that were conducive to pyrocumulonimbus events.
These were sobering findings, even in a land of extremes like Australia. Our research suggests human-caused climate change has already resulted in more dangerous weather conditions for bushfires in recent decades for many regions of Australia. These trends are very likely to increase due to rising greenhouse gas emissions.
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I saw an article claiming that “king tides” will increase in frequency as sea level rises. I am sceptical. What is the physics behind such a claim and how is it related to climate change? My understanding is that a king tide is a purely tidal effect, related to Moon, Sun and Earth axis tilt, and is quite different from a storm surge.
This is a good question, and you are right about the tides themselves. The twice-daily tides are caused by the gravitational forces of the Moon and the Sun, and the rotation of the Earth, none of which is changing.
A “king” tide occurs around the time when the Moon is at its closest to the Earth and Earth is at its closest to the Sun, and the combined gravitational effects are strongest. They are the highest of the high tides we experience.
But the article you refer to was not really talking about king tides. It was discussing coastal inundation events.
During a king tide, houses and roads close to the coast can be flooded. The article referred to the effects of coastal flooding generally, using “king tide” as a shorthand expression. We know that king tides are not increasing in frequency, but we also know that coastal flooding and coastal erosion events are happening more frequently.
As sea levels rise, it becomes easier for ocean waves to penetrate on to the shore. The biggest problem arises when storms combine with a high tide, and ride on top of higher sea levels.
The low air pressure near the centre of a storm pulls up the sea surface below. Then, onshore winds can pile water up against the coast, allowing waves to run further inshore. Add a high or king tide and the waves can come yet further inshore. Add a bit of sea level rise and the waves penetrate even further.
This means that 10cm of sea level rise will turn a one-in-100-year coastal flood into a one-in-33-year event. With another 10cm of sea level rise, it becomes a one-in-11-year event, and so on.
Retreating from the coast
The occurrence rates change so quickly because in most places, beaches are fairly flat. A 10cm rise in sea levels might translate to 30 or 40 metres of inland movement of the high tide line, depending on the slope of the beach. So when the tide is high and the waves are rolling in, the sea can come inland tens of metres further than it used to, unless something like a coastal cliff or a sea wall blocks its way.
The worry is that beaches are likely to remain fairly flat, so anything within 40 metres of the current high tide mark is likely to be eroded away as storms occur and we experience another 10cm of sea level rise. If a road or a house is on an erodible coast (such as a line of sand dunes), it is not the height above sea level that matters but the distance from the high tide mark.
Another 30cm of sea level rise is already “baked in”, guaranteed over the next 40 years, regardless of what happens with greenhouse gas emissions and action on climate change. By the end of the century, at least another 20cm on top of that is virtually certain.
The 30cm rise multiplies the chances of coastal flooding by a factor of around 27 (3x3x3) and 50cm by the end of the century increases coastal flooding frequency by a factor of around 250. That would make the one-in-100-year coastal flood likely every few months, and roads, properties and all kinds of built infrastructure within 200 metres of the current coastline would be vulnerable to inundation and damage.
These are round numbers, and local changes depend on coastal shape and composition, but they give the sense of how quickly things can change. Already, key roads in Auckland (such as Tamaki Drive) are inundated when storms combine with high tides. Such events are set to become much more common as sea levels continue to rise, to the point where they will become part of the background state of the coastal zone.
To ensure cities such as Auckland (and others around the world) are resilient to such challenges, we’ll need to retreat from the coast where possible (move dwellings and roads inland) and to build coastal defences where that makes sense. The coast is coming inland, and we need to move with it.
Sweden’s central bank ways it will no longer invest in assets from governments with large climate footprints, even if the yields were high. Shutterstock
Suddenly, at the level of central banks, Australia is regarded as an investment risk.
On Wednesday Martin Flodén, the deputy governor of Sweden’s central bank, announced that because Australia and Canada were “not known for good climate work”.
As a result the bank had sold its holdings of bonds issued by the Canadian province of Alberta and by the Australian states of Queensland and Western Australia.
Central banks normally make the news when they change their “cash rate” and households pay less (or more) on their mortgages.
But central banks such as Australia’s Reserve Bank and the European Central Bank, the People’s Bank of China and the US Federal Reserve have broader responsibilities.
Reserve Bank deputy governor Guy Debelle. Extreme events not cyclical. DAVID MOIR/AAP
As an example, the new managing director of the International Monetary Fund Kristalina Georgieva warned last month that the necessary transition away from fossil fuels would lead to significant amounts of “stranded assets”.
Those assets will be coal mines and oil fields that become worthless, endangering the banks that have lent to develop them. More frequent floods, storms and fires will pose risks for insurance companies. Climate change will make these and other shocks more frequent and more severe.
In a speech in March the deputy governor of Australia’s Reserve Bank Guy Debelle said we needed to stop thinking of extreme events as cyclical.
We need to think in terms of trend rather than cycles in the weather. Droughts have generally been regarded (at least economically) as cyclical events that recur every so often. In contrast, climate change is a trend change. The impact of a trend is ongoing, whereas a cycle is temporary.
And he said the changes that will be imposed on us and the changes we will need might be abrupt.
The transition path to a less carbon-intensive world is clearly quite different depending on whether it is managed as a gradual process or is abrupt. The trend changes aren’t likely to be smooth. There is likely to be volatility around the trend, with the potential for damaging outcomes from spikes above the trend.
Australia’s central bank and others are going further then just responding to the impacts of climate change. They are doing their part to moderate it.
No more watching from the sidelines
Peter Zöllner of the Bank for International Settlements launched the Green Bond Fund. BIS
Its purpose is to enhance the role of the financial system in mobilising finance to support the transitions that will be needed. The US Federal Reserve has not joined yet but is considering how to participate.
One of its credos is that central banks should lead by example in their own investments.
They hold and manage over A$17 trillion. That makes them enormously large investors and a huge influence on global markets.
As part of their traditional focus on the liquidity, safety and returns from assets, they are taking into account climate change in deciding how to invest.
The are increasingly putting their money into “green bonds”, which are securities whose proceeds are used to finance projects that combat climate change or the depletion of biodiversity and natural resources.
Over A$300 billion worth of green bonds were issued in 2018, with the total stock now over A$1 trillion.
Central banks are investing, and setting standards
While large, that is still less than 1% of the stock of conventional securities. It means green bonds are less liquid and have higher buying and selling costs.
It also means smaller central banks lack the skills to deal with them.
In September it launched a green bond fund that will pool investments from 140 (mostly central bank) clients.
Its products will initially be denominated in US dollars but will later also be available in euros. It will be supported by an advisory committee of the world’s top central bankers.
Launching the fund in Basel, Switzerland, the bank’s head of banking Peter Zöllner said he was
confident that, by aggregating the investment power of central banks, we can influence the behaviour of market participants and have some impact on how green investment standards develop
It’s an important role. Traditionally focused on keeping the financial system safe, our central banks are increasingly turning to using their stewardship of the financial system to keep us, and our environment, safe.
Concrete is the most widely used man-made material, commonly used in buildings, roads, bridges and industrial plants. But producing the Portland cement needed to make concrete accounts for 5-8% of all global greenhouse emissions. There is a more environmentally friendly cement known as MOC (magnesium oxychloride cement), but its poor water resistance has limited its use – until now. We have developed a water-resistant MOC, a “green” cement that could go a long way to cutting the construction industry’s emissions and making it more sustainable.
Producing a tonne of conventional cement in Australia emits about 0.82 tonnes of carbon dioxide (CO₂). Because most of the CO₂ is released as a result of the chemical reaction that produces cement, emissions aren’t easily reduced. In contrast, MOC is a different form of cement that is carbon-neutral.
MOC is produced by mixing two main ingredients, magnesium oxide (MgO) powder and a concentrated solution of magnesium chloride (MgCl₂). These are byproducts from magnesium mining.
Magnesium oxide (MgO) powder (left) and a solution of magnesium chloride (MgCl₂) are mixed to produce magnesium oxychloride cement (MOC). Author provided
Many countries, including China and Australia, have plenty of magnesite resources, as well as seawater, from which both MgO and MgCl₂ could be obtained.
MOC also has many superior material properties compared to conventional cement.
Compressive strength (capacity to resist compression) is the most important material property for cementitious construction materials such as cement. MOC has a much higher compressive strength than conventional cement and this impressive strength can be achieved very fast. The fast setting of MOC and early strength gain are very advantageous for construction.
Although MOC has plenty of merits, it has until now had poor water resistance. Prolonged contact with water or moisture severely degrades its strength. This critical weakness has restricted its use to indoor applications such as floor tiles, decoration panels, sound and thermal insulation boards.
How was water-resistance developed?
A team of researchers, led by Yixia (Sarah) Zhang, has been working to develop a water-resistant MOC since 2017 (when she was at UNSW Canberra).
Adding industrial byproducts fly ash (above) and silica fume (below) improves the water resistance of MOC. Author provided
To improve water resistance, the team added industrial byproducts such as fly ash and silica fume to the MOC, as well as chemical additives.
Fly ash is a byproduct from the coal industry – there’s plenty of it in Australia. Adding fly ash significantly improved the water resistance of MOC. Flexural strength (capacity to resist bending) was fully retained after soaking in water for 28 days.
To further retain the compressive strength under water attack, the team added silica fume. Silica fume is a byproduct from producing silicon metal or ferrosilicon alloys. When fly ash and silica fume were combined with MOC paste (15% of each additive), full compressive strength was retained in water for 28 days.
Both the fly ash and silica fume have a similar effect of filling the pore structure in MOC, making the cement denser. The reactions with the MOC matrix form a gel-like phase, which contributes to water repellence. The extremely fine particles, large surface area and high reactive silica (SiO₂) content of silica fume make it an effective binding substance known as a pozzolan. This helps give the concrete high strength and durability.
Scanning electron microscope images of MOC showing the needle-like phases of the binding mechanism. Author provided
Although the MOC developed so far had excellent resistance to water at room temperature, it weakened fast when soaked in warm water. The team worked to overcome this by using inorganic and organic chemical additives. Adding phosphoric acid and soluble phosphates greatly improved warm water resistance.
Examples of building products made using MOC. Author provided
Over three years, the team has made a breakthrough in developing MOC as a green cement. The strength of concrete is rated using megapascals (MPa). The MOC achieved a compressive strength of 110 MPa and flexural strength of 17 MPa. These values are a few times greater than those of conventional cement.
The MOC can fully retain these strengths after being soaked in water for 28 days at room temperatures. Even in hot water (60˚C), the MOC can retain up to 90% of its compressive and flexural strength after 28 days. The values remain as high as 100 MPa and 15 MPa respectively – still much greater than for conventional cement.
Will MOC replace conventional cement?
So could MOC replace conventional cement some day? It seems very promising. More research is needed to demonstrate the practicability of uses of this green and high-performance cement in, for example, concrete.
When concrete is the main structural component, steel reinforcement has to be used. Corrosion of steel in MOC is a critical issue and a big hurdle to jump. The research team has already started to work on this issue.
If this problem can be solved, MOC can be a game-changer for the construction industry.
Nitrous oxide (N₂O) (more commonly known as laughing gas) is a powerful contributor to global warming. It is 265 times more effective at trapping heat in the atmosphere than carbon dioxide and depletes our ozone layer.
Human-driven N₂O emissions have been growing unabated for many decades, but we may have been seriously underestimating by just how much. In a paper published today in Nature Climate Change, we found global emissions are higher and growing faster than are being reported.
Although clearly bad news for the fight against climate change, some countries are showing progress towards reducing N₂O emissions, without sacrificing the incredible crop yields allowed by nitrogen fertilisers. Those countries offer insights for the rest of the world.
N₂O concentrations (parts per billion) in air from Cape Grim Baseline Air Pollution Station (Tasmania, Australia) and air contained in bubbles trapped in firn and ice from the Law Dome, Antarctica. N₂O concentrations from these two sites reflect global concentrations, not local conditions. Source: BoM/CSIRO/AAD.
The Green Revolution
There are a number of natural and human sources of N₂O emissions, which have remained relatively steady for millennia. However, in the early 20th century the Haber-Bosch process was developed, allowing industry to chemically synthesise molecular nitrogen from the atmosphere to create nitrogen fertiliser.
This advancement kick-started the Green Revolution, one of the greatest and fastest human revolutions of our time. Crop yields across the world have increased many times over due to the use of nitrogen fertilisers and other improved farming practices.
But when soil is exposed to abundant nitrogen in its active form (as in fertilizer), microbial reactions take place that release N₂O emissions. The unrestricted use in nitrogen fertilisers, therefore, created a huge uptick in emissions.
N₂O is the third-most-important greenhouse gas after carbon dioxide and methane. As well as trapping heat, it depletes ozone in the stratosphere, contributing to the ozone hole. Once released into the atmosphere, N₂O remains active for more than 100 years.
Tracking emissions from above
Conventional analysis of N₂O emissions from human activities are estimated from various indirect sources. This include country-by-country reporting, global nitrogen fertiliser production, the areal extent of nitrogen-fixing crops and the use of manure fertilisers.
Our study instead used actual atmospheric concentrations of N₂O from dozens of monitoring stations all over the world. We then used atmospheric modelling that explains how air masses move across and between continents to infer the expected emissions of specific regions.
We found global N₂O emissions have increased over the past two decades and the fastest growth has been since 2009. China and Brazil are two countries that stand out. This is associated with a spectacular increase in the use of nitrogen fertilisers and the expansion of nitrogen-fixing crops such as soybean.
We also found the emissions reported for those two countries, based on a methodology developed by the Intergovernmental Panel on Climate Change, are significantly lower than those inferred from N₂O levels in the atmosphere over those regions.
This mismatch seems to arise from the fact that emissions in those regions are proportionally higher than the use of nitrogen fertilizers and manure. This is a departure from the linear relationship used to report emissions by most countries.
There appears to be a level of nitrogen past which plants can no longer effectively use it. Once that threshold is passed in croplands, N₂O emissions grow exponentially.
N₂O emissions from agriculture estimated by using the emissions factors approach of the IPCC (blue), the calculated emission factor in this study (green), and the average of the atmospheric inversions in this study (black). Thompson et al. 2019 Nature Climate Change
Reversing the trends
Reducing N₂O emissions from agriculture will be very challenging, given the expected global growth in population, food demand and biomass-based products including energy.
However, all future emission scenarios consistent with the goals of the Paris Agreement require N₂O emissions to stop growing and, in most cases, to decline – between 10% and 30% by mid-century.
Interestingly, emissions from the USA and Europe have not grown for over two decades, yet crop yields across these regions increased or remained steady. Both regions have created strong regulations largely to prevent excess accumulation of nitrogen in soils and into waterways.
These areas and other studies have demonstrated the success of more sustainable farming in reducing emissions while increasing crop yields and farm-level economic gains.
A whole toolbox of options is available to increase nitrogen use efficiency and reduce N₂O emissions: precision applications of nitrogen in space and time, the use of N-fixing crops in rotations, reduced tillage or no-tillage, prevention of waterlogging, and the use of nitrification inhibitors.
Regulatory frameworks have shown win-win outcomes in a number of countries. With intelligent adaptions to different nations’ and regions’ needs, they can also work elsewhere.
For more than 3.5 billion years, living organisms have thrived, multiplied and diversified to occupy every ecosystem on Earth. The flip side to this explosion of new species is that species extinctions have also always been part of the evolutionary life cycle.
But these two processes are not always in step. When the loss of species rapidly outpaces the formation of new species, this balance can be tipped enough to elicit what are known as “mass extinction” events.
A mass extinction is usually defined as a loss of about three quarters of all species in existence across the entire Earth over a “short” geological period of time. Given the vast amount of time since life first evolved on the planet, “short” is defined as anything less than 2.8 million years.
Since at least the Cambrian periodthat began around 540 million years ago when the diversity of life first exploded into a vast array of forms, only five extinction events have definitively met these mass-extinction criteria.
These so-called “Big Five” have become part of the scientific benchmark to determine whether human beings have today created the conditions for a sixth mass extinction.
An ammonite fossil found on the Jurassic Coast in Devon. The fossil record can help us estimate prehistoric extinction rates. Corey Bradshaw, Author provided
The Big Five
These five mass extinctions have happened on average every 100 million years or so since the Cambrian, although there is no detectable pattern in their particular timing. Each event itself lasted between 50 thousand and 2.76 million years. The first mass extinction happened at the end of the Ordovician period about 443 million years ago and wiped out over 85% of all species.
The Ordovician event seems to have been the result of two climate phenomena. First, a planetary-scale period of glaciation (a global-scale “ice age”), then a rapid warming period.
The second mass extinction occurred during the Late Devonian period around 374 million years ago. This affected around 75% of all species, most of which were bottom-dwelling invertebrates in tropical seas at that time.
This period in Earth’s past was characterised by high variation in sea levels, and rapidly alternating conditions of global cooling and warming. It was also the time when plants were starting to take over dry land, and there was a drop in global CO2 concentration; all this was accompanied by soil transformation and periods of low oxygen.
To establish a ‘mass extinction’, we first need to know what a normal rate of species loss is. from http://www.shutterstock.com
The third and most devastating of the Big Five occurred at the end of the Permian period around 250 million years ago. This wiped out more than 95% of all species in existence at the time.
Some of the suggested causes include an asteroid impact that filled the air with pulverised particle, creating unfavourable climate conditions for many species. These could have blocked the sun and generated intense acid rains. Some other possible causes are still debated, such as massive volcanic activity in what is today Siberia, increasing ocean toxicity caused by an increase in atmospheric CO₂, or the spread of oxygen-poor water in the deep ocean.
Fifty million years after the great Permian extinction, about 80% of the world’s speciesagain went extinct during the Triassic event. This was possibly caused by some colossal geological activity in what is today the Atlantic Ocean that would have elevated atmospheric CO₂ concentrations, increased global temperatures, and acidified oceans.
The last and probably most well-known of the mass-extinction events happened during the Cretaceous period, when an estimated 76% of all species went extinct, including the non-avian dinosaurs. The demise of the dinosaur super predators gave mammals a new opportunity to diversify and occupy new habitats, from which human beings eventually evolved.
The most likely cause of the Cretaceous mass extinction was an extraterrestrial impact in the Yucatán of modern-day Mexico, a massive volcanic eruption in the Deccan Province of modern-day west-central India, or both in combination.
Is today’s biodiversity crisis a sixth mass extinction?
The Earth is currently experiencing an extinction crisis largely due to the exploitation of the planet by people. But whether this constitutes a sixth mass extinction depends on whether today’s extinction rate is greater than the “normal” or “background” rate that occurs between mass extinctions.
This background rate indicates how fast species would be expected to disappear in absence of human endeavour, and it’s mostly measured using the fossil record to count how many species died out between mass extinction events.
The Christmas Island Pipistrelle was announced to be extinct in 2009, years after conservationists raised concerns about its future. Lindy Lumsden
The most accepted background rate estimated from the fossil record gives an average lifespan of about one million years for a species, or one species extinction per million species-years. But this estimated rate is highly uncertain, ranging between 0.1 and 2.0 extinctions per million species-years. Whether we are now indeed in a sixth mass extinction depends to some extent on the true value of this rate. Otherwise, it’s difficult to compare Earth’s situation today with the past.
In contrast to the the Big Five, today’s species losses are driven by a mix of direct and indirect human activities, such as the destruction and fragmentation of habitats, direct exploitation like fishing and hunting, chemical pollution, invasive species, and human-caused global warming.
Even considering a conservative background rate of two extinctions per million species-years, the number of species that have gone extinct in the last century would have otherwise taken between 800 and 10,000 years to disappear if they were merely succumbing to the expected extinctions that happen at random. This alone supports the notion that the Earth is at least experiencing many more extinctions than expected from the background rate.
An endangered Indian wild dog, or Dhole. Before extinction comes a period of dwindling numbers and spread. from http://www.shutterstock.com
It would likely take several millions of years of normal evolutionary diversification to “restore” the Earth’s species to what they were prior to human beings rapidly changing the planet. Among land vertebrates (species with an internal skeleton), 322 species have been recorded going extinct since the year 1500, or about 1.2 species going extinction every two years.
If this doesn’t sound like much, it’s important to remember extinction is always preceded by a loss in population abundance and shrinking distributions. Based on the number of decreasing vertebrate species listed in the International Union for Conservation of Nature’s Red List of Threatened Species, 32% of all known species across all ecosystems and groups are decreasing in abundance and range. In fact, the Earth has lost about 60% of all vertebrate individuals since 1970.
Although biologists are still debating how much the current extinction rate exceeds the background rate, even the most conservative estimates reveal an exceptionally rapid loss of biodiversity typical of a mass extinction event.
In fact, some studies show that the interacting conditions experienced today, such as accelerated climate change, changing atmospheric composition caused by human industry, and abnormal ecological stresses arising from human consumption of resources, define a perfect storm for extinctions. All these conditions together indicate that a sixth mass extinction is already well under way.
Frédérik Saltré, Research Fellow in Ecology & Associate Investigator for the ARC Centre of Excellence for Australian Biodiversity and Heritage, Flinders University and Corey J. A. Bradshaw, Matthew Flinders Fellow in Global Ecology and Models Theme Leader for the ARC Centre of Excellence for Australian Biodiversity and Heritage, Flinders University
Since the Chinese plastic recycling market closed, 58% of New Zealand’s plastic waste goes to countries in South-East Asia. from http://www.shutterstock.com, CC BY-ND
Since the Chinese market closed, 58% of New Zealand’s plastic waste now goes to Malaysia, Indonesia, the Philippines, Thailand and Vietnam — all countries with weak regulations and high rankings as global sources of marine plastic pollution.
Waste-to-energy (WtE) incineration has been raised as a solution. While turning plastic waste into energy may sound good, it creates more pollution and delays a necessary transition to a circular economy.
Shipments of plastic recycling often arrive in developing countries unsorted and contaminated. Materials that cannot be easily recycled are commonly burned, releasing dioxins into air, soil and water. In response, South-East Asian countries have started returning dirty plastics to developed countries.
Several New Zealand councils have stopped collecting certain plastics for recycling offshore. They are sending them to landfill instead. Available data suggest that even before the China ban plastics made up roughly 15% of the waste in municipal landfills – about 250,000 tonnes a year. Much of this is imported plastic packaging.
In the scramble to find alternatives, waste-to-energy (WtE) incineration has become a hot topic, particularly as foreign investors look to establish WtE incinerators on the West Coast and [other centres]in New Zealand. Some local government representatives have endorsed WtE proposals, or raised WtE as an election issue.
Less plastic good for climate
Like landfills, WtE incinerators symbolise the linear “take-make-waste” economy, which destroys valuable resources and perpetuates waste generation.
Globally, countries are moving to circular approaches instead, which follow the “zero waste hierarchy”. This prioritises waste prevention, reduction, reuse, recycling and composting and considers WtE unacceptable.
Some New Zealanders say Nordic countries have proven that incineration is the environmental silver bullet to our waste woes. But a recent study found these countries will not meet EU circular economy goals unless they replace WtE incineration with policies that reduce waste generation. Such policies include packaging taxes, recycling and recovery rate targets, landfill bans on biodegradable waste, deposit return schemes and extended producer responsibility.
To address plastic pollution, it is easy to see how prevention and reduction work better than “getting rid of” plastic once produced. Many WtE proponents argue that incineration technology can be a temporary solution for the plastic waste we have already created.
The only real solution to our plastics problem is through regulation that moves New Zealand towards a circular economy. We can start by making the linear economy expensive by increasing landfill levies above the current $NZ10/tonne and expanding it to all landfills. We must also invest in better waste collection, sorting and recycling systems, including a national network of resource recovery centres.
Instead of burning or burying plastic that cannot be reused, recycled or composted, we can prevent or reduce it through targeted phase-outs. The government is proposing to regulate single-use plastic packaging, beverage packaging, electronic waste and farm plastics through mandatory product stewardship schemes. This would make manufacturers responsible for the waste they produce and provide incentives for less wasteful and toxic product design and delivery systems (e.g. refill stations).
Without a swift, brave shift to a circular economy, New Zealand will remain one of the world’s most wasteful nations. Circular economies are developing globally and WtE incineration will only set us back by 30 years.
Hannah Blumhardt, the coordinator of the NZ Product Stewardship Council, has contributed to this article.
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