Monthly Archives for June 2019
Sydney declares a climate emergency – what does that mean in practice?
Late on Monday night, the City of Sydney became the first state capital in Australia to officially declare a climate emergency. With climate change considered a threat to human life, Sydney councillors unanimously supported a motion put forward by Lord Mayor Clover Moore to mobilise city resources to reduce carbon emissions and minimise the impact of future change.
The decision sees Sydney join a variety of local and national governments around the world, in a movement that is increasingly gaining momentum. In total, some 658 local governments around the world have made the same declaration, with the UK and Canada committing their national governments to the global movement in just the past two months.
An official declaration of climate emergency puts a government on a “wartime mobilisation” that places climate change at the centre of policy and planning decisions.
Read more:
UK becomes first country to declare a ‘climate emergency’
While interpretations differ on what a “climate emergency” means in practice, governments have established a range of measures to help meet the targets set by the Paris climate agreement. Under this agreement, 197 countries have pledged to limit global temperature rise to less than 2℃ above pre-industrial levels, and ideally no more than 1.5℃.
With 2018 having brought all manner of record-breaking climate extremes, and global average temperatures projected to reach 3.2℃ above the pre-industrial average based on current national pledges and targets for greenhouse emissions, Sydney’s recognition of a national emergency is both highly appropriate and also a major turning-point for Australia.
Although a signatory to the Paris Agreement, Australia’s greenhouse emissions have risen over the past four years since the repeal of the carbon price. With Australian emissions most notably increasing around transport, the United Nations climate discussions currently being held in Bonn have raised concerns over the nation’s ability to meet its Paris commitments.
Economic impacts
With the global cost of inaction on climate change projected to reach a staggering US$23 trillion a year by the end of the century (equivalent to around five 2008 global financial crises every year), several nations are already ramping up their Paris Agreement commitments ahead of schedule. The UK recently announced its intention to be carbon-neutral by 2050.
Australia is particularly vulnerable to the future financial costs of climate change, with economic models suggesting losses of A$159 billion a year through the impact of sea level rise and drought-driven collapses in agricultural productivity. The cost for each household has been put at about A$14,000.
Read more:
Cutting cities’ emissions does have economic benefits – and these ultimately outweigh the costs
After Sydney’s declaration, 150 faith leaders on Tuesday signed an open letter endorsing the decision, and describing the climate issue as a moral challenge that transcends religious belief. They have called for an urgent mobilisation to reach 100% renewable energy by the year 2030, and for an end to the approval of any new coal and gas projects, including Adani’s controversial Carmichael coal mine in Queensland.
The recent court ruling against the proposed Rocky Hill coal mine in the New South Wales Hunter Valley – a decision made partly on climate grounds – could mark a crucial turning point in the fortunes of future mining projects.
Read more:
Landmark Rocky Hill ruling could pave the way for more courts to choose climate over coal
As part of its emergency declaration, Sydney has also called on the federal government to establish a “just transition authority” to support Australians currently employed in fossil fuel industries. This is an urgent issue and a crucial part of the transition to a low-emissions economy.
A major nationwide training program will be needed to help re-skill the estimated 8,000 people who work in fossil-fuelled electricity production, and to help fill the tens of thousands of new jobs in renewable energy-related fields.
With the scale of change required to decarbonise the global economy and hopefully avoid a 2℃ warmer world, the need to support communities across Australia and overseas will likely become an increasing challenge for governments around the world. Putting ourselves on an emergency footing could help provide precisely the impetus we need.
Chris Turney, Professor of Earth Science and Climate Change, ARC Centre of Excellence for Australian Biodiversity and Heritage, UNSW
This article is republished from The Conversation under a Creative Commons license. Read the original article.
The Northern lights
Scotland
‘Sadness, disgust, anger’: fear for the Great Barrier Reef made climate change feel urgent
Matt Curnock, Author provided
Matt Curnock, CSIRO and Scott Heron, James Cook University
Media coverage of mass coral bleaching on the Great Barrier Reef may have been a major tipping point for public concerns around climate change, according to research published today.
Severe and extensive bleaching during the summers of 2016 and 2017 has been directly attributed to human-caused climate change. Much of the ensuing media coverage used emotional language, with many reports of the Reef dying.
Read more:
Back-to-back bleaching has now hit two-thirds of the Great Barrier Reef
While the physical effects of the bleaching have been well documented, we wanted to understand the social and cultural impact.
Our research, including a study published today in Nature Climate Change, has compared survey responses from thousands of Australians and international visitors, before and after the bleaching event.
Reef grief
Our research team conducted face-to-face interviews with 4,681 visitors to the Great Barrier Reef region, in 14 coastal towns from Cooktown to Bundaberg, over June to August in both 2013 and 2017. We asked more than 50 questions about their perceptions and values of the Reef, as well as their attitudes towards climate change.
We found a large proportion of respondents, including Australians and overseas visitors, expressed forms of grief in response to loss and damage to the iconic ecosystem. Negative emotions associated with words given in short statements about “what the Great Barrier Reef means to you”, included sadness, disgust, anger and fear.
Read more:
Hope and mourning in the Anthropocene: Understanding ecological grief
Emotional appeals are widely used in media stories and in social media campaigns, and appealing to fear in particular can heighten a story’s impact and spread online.
However, a side-effect of this approach is the erosion of people’s perceived ability to take effective action. This is called a person’s “self-efficacy”.
This effect is now well documented in reactions to representations of climate change, and is actually a barrier to positive community engagement and action on the issue.
In short, the more afraid someone is for the Great Barrier Reef, the less they may feel their individual efforts will help to protect it.
While our results show a decline in respondents’ self-efficacy, there was a corresponding increase in how highly they valued the Reef’s biodiversity, its scientific heritage and its status as an international icon. They were also more willing to support action to protect the Reef. This shows widespread empathy for the imperilled icon, and suggests greater support for collective actions to mitigate threats to the Reef.
Matt Curnock, Author provided
Changing attitudes
We observed a significant increase in the proportion of people who believe that climate change is “an immediate threat requiring action”. In 2013 some 50% of Australian visitors to the Great Barrier Reef region agreed climate change is an immediate threat; in 2017 that rose to 67%. Among international visitors, this proportion was even higher (64% in 2013, rising to 78% in 2017).
This represents a remarkable change in public attitudes towards climate change over a relatively short period. Previous surveys of Australian climate change attitudes over 2010 to 2014 showed that aggregate levels of opinion remained stable over that time.
Comparing our findings with other recent research describing the extent of coverage and style of reporting associated with the 2016-2017 mass coral bleaching event, we infer that this event, and the associated media representations, contributed significantly to the shift in public attitudes towards climate change.
Moving beyond fear
As a source of national pride and with World Heritage status, the Great Barrier Reef will continue to be a high profile icon representing the broader climate change threat.
Media reports and advocacy campaigns that emphasise fear, loss and destruction can get attention from large audiences who may take the message of climate change on board.
But this does not necessarily translate into positive action. A more purposeful approach to public communication and engagement is needed to encourage collective activity that will help to mitigate climate change and reduce other serious threats facing the Reef.
Examples of efforts that are underway to reduce pressures on the Reef include improvements to water quality, control of crown-of-thorns starfish outbreaks, and reducing poaching in protected zones. Tourism operators on the Reef are also playing an important role in restoring affected areas, and are educating visitors about threats, to improve Reef stewardship.
Clearly there remains an immediate need to reduce greenhouse gas emissions to ensure the Reef’s World Heritage qualities are maintained for future generations.
However, maintaining hope, and offering accessible actions towards attainable goals is critical to engaging people in collective efforts, to help build a more sustainable future in which coral reefs can survive.
The authors would like to acknowledge Nadine Marshall, who co-wrote this article while employed by CSIRO. We thank our other co-authors of the Nature Climate Change paper, including Lauric Thiault (National Center for Scientific Research, PSL Université Paris), Jessica Hoey and Genevieve Williams (Great Barrier Reef Marine Park Authority), Bruce Taylor and Petina Pert (CSIRO Land and Water) and Jeremy Goldberg (CSIRO & James Cook University). The scientific results and conclusions, as well as any views or opinions expressed herein, are those of the authors and do not necessarily reflect those of the Australian Government or the Minister for the Environment, or the Queensland Government, or indicate commitment to any particular course of action.
Matt Curnock, Social Scientist, CSIRO and Scott Heron, Senior Lecturer, James Cook University
This article is republished from The Conversation under a Creative Commons license. Read the original article.
Australian Extinction Crisis
Curious Kids: why do spiders need so many eyes but we only need two?
Flickr/Thomas Shahan, CC BY-NC-ND
Samantha Nixon, The University of Queensland and Andrew Walker, The University of Queensland
Curious Kids is a series for children. If you have a question you’d like an expert to answer, send it to curiouskids@theconversation.edu.au You might also like the podcast Imagine This, a co-production between ABC KIDS listen and The Conversation, based on Curious Kids.
Can you find out why spiders need six eyes but we only need two? – Amos, age 3, Newcastle.
Hi, Amos. Thanks for your excellent question.
The first thing we should say is that while it’s true that some spiders have six eyes, most actually have eight.
The short answer to your question is that animals have evolved different eyes that best suit the lives they lead.
Read more:
Curious Kids: What are spider webs made from and how strong are they?
Humans have two eyes that face forward. Our eyes are very good at seeing colours and shapes. Having two big eyes in the front of our head means they can work together to guess how far away something is (we call this “judging distance”). That makes it easier for us to catch another animal so we can eat it.
Spiders are also hunters and they need eyes that help them find and catch their food. In fact, most spiders can’t see very well, and use touch and taste to explore the world. But the kind of eyes they have tells us something about the food they eat and the lives they live.
Spider eyes for spider lives
Jumping spiders are active hunters, like tiny lions chasing down their prey (bugs). They usually have eight eyes: two very large front eyes to get a clear, colour image and judge distance, and extra side eyes to detect when something is moving. Here’s a picture of an Australian jumping spider.
Michael Duncan., Author provided
Some spiders make nets to catch their prey. These net-casting spiders also need to see clearly and judge distances. Some have developed huge, scary-looking black eyes that stare straight ahead, so they are nicknamed ogre spiders! These gigantic eyes help the spider to see a wide area and accurately throw down its spider web net to catch its prey. Here’s a picture of a net-casting spider.
Michael Duncan, Author provided
Some spiders live in caves that are completely dark, where eyes are no use at all. They have to rely on other senses to find their food in the dark. To save energy making eyes, these spiders lost their eyes during evolution, so now some of them have no eyes at all. You can see a picture of a spider like that here.
So why did most spiders end up with so many eyes?
Both human and spider eyes are the result of slowly evolving to help us survive in our different environments. One reason our human eyes are different from spiders is because our bodies and brains are also built differently.
For example, spiders don’t have necks. So they can’t turn their heads to look at things like we can. Having extra eyes around their heads is one way that spiders see more of the world around them, helping them to quickly spot prey or a potential predator.
Human eyes and spider eyes also do different jobs. Our two eyes are very complex and are good at doing many jobs at once, while spiders have different sorts of eyes that do different jobs.
For example, the large central eyes of jumping spiders are best for seeing shapes, but the simple side eyes have the important job of watching out for predators.
So a two-eyed spider or even an eight-eyed human isn’t impossible. But the two eyes we have and the eight eyes most spiders have are perfectly suited to help each of us live our lives just the way they are.
Read more:
Curious Kids: why do spiders have hairy legs?
Hello, curious kids! Have you got a question you’d like an expert to answer? Ask an adult to send your question to curiouskids@theconversation.edu.au
CC BY-ND
Please tell us your name, age and which city you live in. We won’t be able to answer every question but we will do our best.
Samantha Nixon, PhD, The University of Queensland and Andrew Walker, Postdoctoral Research Fellow, The University of Queensland
This article is republished from The Conversation under a Creative Commons license. Read the original article.
The mighty mulga grows deep and lives long
Mark Marathon via Wikipedia, CC BY-SA
Gregory Moore, University of Melbourne
Sign up to the Beating Around the Bush newsletter here, and suggest a plant we should cover at batb@theconversation.edu.au.
Among the nearly 1,000 species of Australian acacias, there are few with a reputation for hardiness, resilience and endurance to match mulga. Once the higher rainfall of the coastal fringes of the continent diminishes, from west to east and south to north, the mulga prevails.
It grows over the vast expanse of about 20% of our continent and is often the dominant woody species of the grassland communities that are themselves known as the mulga. It is also an important shrub component of inland woodlands, such as those dominated by poplar box, Eucalyptus populnea.
Any species that covers 1.5 million km² of any landmass is clearly a vital part of its ecosystems.
The scientific name of mulga is Acacia aneura, which refers to the lack of a prominent mid-rib in their leaves (a means “no” and neura means “nerve”). Interestingly, like most Australian acacias, mulga lacks spines which their African relatives possess in abundance on their foliage, and they don’t actually have leaves.
Read more:
A detailed eucalypt family tree helps us see how they came to dominate Australia
The structures that appear to be leaves are actually flattened leaf stems called phyllodes. They function as leaves, but are very efficient in arid conditions. The narrow and rolled mulga leaves often have a sharp tip, so while they are not spiny they are still prickly.
Mulga plays an important ecological role in drier parts of Australia. It is a nitrogen-fixing species that enriches often impoverished soils, provides habitat for birds, insects, reptiles and mammals, and is important for honey production.
They drop many of their phyllodes during very dry spells, which not only reduces demand for water, but provides a vital mulch to their ecosystems during tough times. Acacia aneura is fire-sensitive, and changes to fire regimes can see it displaced by grass species. In parts of the outback, the species is not regenerating, and as the old specimens die the mulga is disappearing.
The Conversaion
Frugal lifestyle
Mulga are brilliantly designed for coping with the arid Australian interior, as they do not get too big in places where resources are limited. In good conditions they are small trees that can grow taller than 10m, but in dry conditions they may be shrubs little more than 2-3m tall. They have a very deep root system that begins with a tap root 3m or more in length when the tree is only 20cm tall, and which exploits a large volume of soil for water.
This biology often leads to individual specimens being evenly spaced in the landscape as if they were positioned by design. The roots may be considerably longer than the tree is tall!
The little apertures on the phyllodes that regulate water loss and gaseous exchange (stomata) are located at the bottom of deep pits called stomatal crypts, which further slows water loss.
It is common for gardeners to think of acacia species as being short-lived, but with nearly 1,000 different species there is great variation in the age that various species can reach. While many shrubby species might only survive for a decade or two, Acacia aneura can live for three centuries or more. It is hard to believe many of the scrubby little specimens only a metre or two high growing in the arid heart of Australia are such a venerable age.
Mulga can be very slow-growing, and its wood can be both strong and durable. It grows a light cream sapwood that surrounds a dark reddish-brown or black heartwood. The combination is ideal for wood carving, especially of ornaments, utensils, and of course prized souvenirs of a trip to the red centre. It is durable as indigenous weapons, digging sticks or modern fence posts, and its foliage can provide emergency fodder for stock during prolonged dry periods. Resin from the leaves is also used for sealing cracks and splits in cups and bowls.
Read more:
The art of healing: five medicinal plants used by Aboriginal Australians
Like many acacia species, the seeds of mulga are protein-rich and have made an excellent food source for many centuries, particularly in seed cakes. Boiling young leaves and twigs in water has been used for treating colds, and lerps – the sticky protective coverings of insects that grow on the leaves – provide a sugary treat.
Many of those who have never seen the outback of Australia imagine it to be a vast and barren red sandy desert. However, for those areas where mulga rules, it is a place of diversity and complex ecosystems. Acacia aneura typifies the resilience of a huge part of the Australian landscape, and its wonderful biology deserves to be better known.
Gregory Moore, Doctor of Botany, University of Melbourne
This article is republished from The Conversation under a Creative Commons license. Read the original article.
Memo to the environment minister: a river does need all its water
Paul Humphries, Charles Sturt University and R. Keller Kopf, Charles Sturt University
Given her new role as federal environment minister, one of Sussan Ley’s comments in an interview with Nine Newspapers was eyebrow-raising, to put it mildly. She said:
Sometimes the environment doesn’t need all its water but farmers desperately do need water.
This is inaccurate and concerning, but not all that surprising, given the attitude to water and rivers of some in the community and federal government.
In this age of water sharing and trading, and storing water in dams, it is easy to lose sight of what water is to a river, and how every drop of water that enters (or should enter) a river defines the character and function of that river.
Ultimately, the community – not scientists or even river managers – decides how much water a river should get. But it’s essential to be honest about the effects these decisions have on rivers and the ecosystems they support. This is vital for long-term environmental sustainability, upon which all our industry, agriculture and indeed our society are based.
Crises and concerns
Recently the Murray-Darling river system has suffered several crises, including fish kills, hypoxic water, acid-sulfate soils, and algal blooms. These are all wake-up calls that the way we manage rivers are not working.
But besides these disastrous incidents, there are many other ways in which river ecosystems are changing, that are not as obvious to the general public.
Contraction of native species’ ranges, local extinctions, success of invasive species and the “need” to stock non-native recreational fish species are just a few of the insidious symptoms of a general malaise.
Water to a river is like air to a balloon. Let out a little air and the balloon is still balloon-shaped, albeit less taut than before. But let out more air and there comes a point, which is hard to predict exactly, when the balloon suddenly collapses. By this analogy, the Murray-Darling Basin is very deflated indeed.
The point is that if we take water out of a river, or change the patterns of its flow, we inevitably change the nature of that river. Irrigators undoubtedly need water. But we shouldn’t kid ourselves that we’re not altering the river and its ecosystems by allowing them to take it.
Do we want healthy rivers?
Our job as river scientists is not to say what type of river the community wants. Our job is to inform people on what the actions of changing river management will do to a river and its life.
We already have seriously degraded river ecosystems. Restoring them is exceedingly unlikely under current demands and management. But if we take even more of a river’s water away, we need to acknowledge that the river will become yet a different river, and in some cases, one that we hardly recognise.
The public backlash following the fish kills earlier this year suggests that the community has decided that further degradation of our rivers is not acceptable.
Read more:
5 ways the government can clean up the Murray-Darling Basin Plan
Paul Humphries, Senior lecturer in Ecology, Charles Sturt University and R. Keller Kopf, Research fellow, Charles Sturt University
This article is republished from The Conversation under a Creative Commons license. Read the original article.
Australia’s energy exports increase global greenhouse emissions, not decrease them
Frank Jotzo, Crawford School of Public Policy, Australian National University and Salim Mazouz, Australian National University
When unveiling government data revealing Australia’s rising greenhouse emissions, federal energy minister Angus Taylor sought to temper the news by pointing out that much of the increase is due to liquefied natural gas (LNG) exports, and claiming that these exports help cut emissions elsewhere.
LNG exports, Taylor argued, help to reduce global emissions by replacing the burning of coal overseas, which has a higher emissions factor than gas. In reality, Australian gas displaces a mix of energy sources, including gas from other exporters. Whether and to what extent Australian gas exports reduce emissions therefore remains unclear. Meanwhile, Australia’s coal exports clearly do increase global emissions.
The way Australia can help clean up world energy systems in the future is through large-scale production and export of renewable energy.
Read more:
Here’s how a 100% renewable energy future can create jobs and even save the gas industry
In a statement accompanying the latest quarterly emissions figures, the Department of Environment and Energy stated:
Australia’s total LNG exports are estimated to have the potential to lower emissions in importing countries by around 148Mt CO₂-e [million tonnes of carbon dioxide equivalent] in 2018, if they displace coal consumption in those countries.
In truth, the assumption that every unit of Australia’s exported gas displaces coal is silly. The claim of a 148Mt saving is wrong and unfounded. The real number would be much smaller, and there could even be an increase in emissions as a result of LNG exports.
For the most part, exported gas probably displaces natural gas that would otherwise be produced elsewhere, leaving overall emissions roughly the same. Some smaller share may displace coal. But it could just as easily displace renewable or nuclear energy, in which case Australian gas exports would increase global emissions, not reduce them.
How much might gas exports really cut emissions?
Serious analysis would be needed to establish the true amount of emissions displaced by Australian gas. It depends on the specific requirements that importers have, their alternatives for domestic energy production and other imports, changes in relative prices, resulting changes in energy balances in third-country markets, trajectories for investments in energy demand and supply infrastructure, and so forth. No such analysis seems available.
But for illustration, let’s make an optimistic assumption that gas displaces twice as much coal as it does renewable or nuclear energy. Specifically, let’s assume – purely for illustration – that each energy unit of Australian exported LNG replaces 0.7 units of gas from elsewhere, 0.2 units of coal, and 0.1 units of renewables or nuclear.
Australia exported 70 million tonnes of LNG in 2018. A Department of Environment and Energy source told Guardian Australia that this amount of gas would emit 197 million tonnes of CO₂ when burned. We calculate a similar number, on the basis of official emissions factors and export statistics.
Under the optimistic and illustrative set of assumptions outlined above, we calculate that Australia’s LNG exports would have reduced emissions in importing countries by about 10 million tonnes of CO₂ per year. (See the end of the article for a summary of our calculations.)
They might equally have reduced emissions by less, or they might in fact have increased these countries’ emissions, if more renewables or nuclear was displaced than coal. But whatever the the actual number, it’s certainly a long way short of the 148 million tonnes of emissions reduction claimed by the government.
We also should consider the emissions within Australia of producing LNG. The national emissions accounting shows that the increase in national emissions of 3.5 million tonnes of CO₂-e compared with the year before is mostly because of a 22% increase in LNG exports. This means that LNG production in Australia overall may be responsible for 16 million tonnes of CO₂ emissions per year.
A full analysis of global effects would also need to factor in the emissions that would be incurred from the production of alternative energy sources displaced by Australia’s LNG.
Read more:
Whichever way you spin it, Australia’s greenhouse emissions have been climbing since 2015
Coal exports unambiguously raise emissions
The picture is more clear-cut for coal. If there was no Australian thermal coal (the type used in power stations) in world markets, much of this would be replaced by more coal mined elsewhere. The remainder would be replaced by gas, renewables or nuclear. As for the case of gas, the precise substitution effects are a matter of complex interactions.
The crucial point is that all alternative fuels are less emissions-intensive than coal. In the substitution of Australian-mined coal for coal from other sources, there could be some substitution towards coal with higher emissions factors, but this is highly unlikely to outweigh the emissions savings from the substitution to nuclear, renewables and gas.
So, removing Australian coal from the world market would reduce global emissions. Conversely, adding Australian coal to the world market would increase global emissions.
Australia exported 208 million tonnes of thermal coal in 2018, which according to the official emissions factors would release 506 million tonnes of CO₂ when burned. On top of this, Australia also exported 178 million tonnes of coking coal for steel production.
If a similar “replacement mix” assumed above for gas is also applied to coal – that is, every unit of coal is replaced by 0.7 units of coal from elsewhere, 0.2 units of gas, and 0.1 units of renewables or nuclear – then adding that thermal coal to the international market would increase emissions by about 19% of the embodied emissions in that coal. As in the case of LNG, this is purely an illustrative assumption.
So, in this illustrative case, Australia’s thermal coal exports would increase net greenhouse emissions in importing countries by about 96 million tonnes per year.
This figure does not consider the coking coal exports, nor the emissions from mining the coal in Australia and transporting it.
The real opportunity is in export of renewable energy
Thankfully, there actually is a way for Australia to help the world cut emissions, and in a big way. That is by producing large amounts of renewable energy for export, in the form of hydrogen, ammonia, and other fuels produced using wind and solar power and shipped to other countries that are less blessed with abundant renewable energy resources.
Even emissions-free production of energy-intensive goods like aluminium and steel could become cost-competitive in Australia, given the ever-falling costs of renewable energy and the almost unlimited potential to produce renewable energy in the outback. Australia really could be a renewable energy superpower.
Such exports will then unambiguously reduce global emissions, because they will in part displace the use of coal, gas and oil.
Once we have a large-scale renewable energy industry in operation, the relevant minister in office then will be right to point out Australia’s contribution to solving the global challenge through our energy exports. In the meantime, our energy exports are clearly a net addition to global emissions.
Summary of data and calculations
LNG emissions and displacement – illustrative scenario
Emissions inherent in Australia’s LNG exports of 69.5 million tonnes (in calendar year 2018) are 197 million tonnes (Mt) of carbon dioxide, based on emissions factors published by the Australian government.
If the same amount of energy was served using coal, emissions would be:
197Mt CO₂ + 148Mt CO₂ = 345Mt CO₂
Emissions under the mix assumed for illustration here would be:
0.7 x 197 (LNG) + 0.2 x 345 (coal) + 0.1 x 0 (renewables/nuclear) = 207Mt CO₂
That is 10Mt higher than without Australian LNG.
Coal emissions and displacement – illustrative scenario
Australia’s thermal coal exports were 208Mt in calendar year 2018. Emissions when burning this coal were 506Mt CO₂, based on government emissions factors.
Assuming typical emissions factors for fuel use in electricity generation of 0.9 tonnes of CO₂ per megawatt-hour (MWh) from black coal and 0.5 tonnes of CO₂ per MWh from gas, the emissions intensity of electricity generation under the mix assumed for illustration here would be:
0.7 x 0.9 (coal) + 0.2 x 0.5 (gas) + 0.1 x 0 (renewables/nuclear) = 0.73 tonnes CO₂ per MWh
This is 19% lower than the emissions intensity of purely coal-fired electricity, of 0.9 tonnes CO₂ per MWh.
19% of 506Mt CO₂ is 96Mt CO₂.
Frank Jotzo, Director, Centre for Climate Economics and Policy, Crawford School of Public Policy, Australian National University and Salim Mazouz, Research Manager, Crawford School of Public Policy; and Director at EcoPerspectives, Australian National University
This article is republished from The Conversation under a Creative Commons license. Read the original article.
Kevin's Walk on the Wild Side 
You must be logged in to post a comment.