Full response from the Climate Council for an article on heatwaves and hot days in Australia

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Climate Council CEO Amanda McKenzie, speaking on Q&A.

Lucinda Beaman, The Conversation and Michael Courts, The Conversation

In relation to this article responding to Climate Council CEO Amanda McKenzie’s claim that heatwaves are “worsening” and “hot days” have doubled in Australia in the last 50 years, a spokesperson for the Climate Council gave the following responses. Questions from The Conversation are in bold.

Could you please provide a source, or sources, to support Ms McKenzie’s statement that heatwaves are “worsening” and hot days have doubled in the last 50 years?

Climate change is making hot days and heatwaves more frequent and more severe. Since 1950 the annual number of record hot days across Australia has more than doubled and the mean temperature has increased by about 1°C from 1910.

Specifically, there has been an increase of 0.2 days/year since 1957 which means, on average, that there are almost 12 more days per year over 35°C.

What did Ms McKenzie mean by the terms “heatwaves” and “hot days”?

Hot days – the number of hot days, defined as days with maximum temperatures greater than 35°C.

Heatwaves – three days or more of high maximum and minimum temperatures that is unusual for that location.

Furthermore, heatwaves have several significant characteristics. These include (i) frequency characteristics, such as the number of heatwave days and the annual number of summer heatwave events; (ii) duration characteristics, such as the length of the longest heatwave in a season; (iii) intensity characteristics, such as the average excess temperature expected during a heatwave and the hottest day of a heatwave; and (iv) timing characteristics, including the occurrence of the first heatwave event in a season.

Is there any other comment you would like us to include in the article?

Climate change – driven largely by rising atmospheric carbon dioxide concentrations from the burning of coal, oil and gas – is increasing temperatures and cranking up the intensity of extreme weather events globally and in Australia.

The accumulating energy in the atmosphere is affecting all extreme weather events. Climate change is driving global warming at a rate 170 times faster than the baseline rate over the past 7,000 years.

Temperature records tumbled yet again during Australia’s ‘Angry Summer’ of 2016/17. In just 90 days, more than 205 records were broken around Australia.

Heatwaves and hot days scorched the major population centres of Adelaide, Brisbane, Canberra, Melbourne and Sydney, as well as the rural and regional heartlands of eastern Australia. The most severe heatwave of this Angry Summer began around January 31 and continued until February 12, with the highest temperatures recorded from February 9-12.

This heatwave was made twice as likely to occur because of climate change, while the extreme heat in New South Wales over the entire summer season was at least 50 times as likely to occur because of climate change.

The severe heatwave of February 2017 that spread across much of Australia’s south, east and interior caused issues for the South Australian and New South Wales energy systems. In New South Wales around 3,000MW of coal and gas capacity was not available when needed in the heatwave (roughly the equivalent of two Hazelwood Power Stations).

In South Australia, 40,000 people were left without power for about half an hour in the early evening while temperatures were over 40°C. This heatwave highlights the vulnerability of our energy systems to extreme weather.

The ConversationRead the article here.

Lucinda Beaman, FactCheck Editor, The Conversation and Michael Courts, Editor, The Conversation

This article was originally published on The Conversation. Read the original article.

Are heatwaves ‘worsening’ and have ‘hot days’ doubled in Australia in the last 50 years?

Andrew King, University of Melbourne

The release of the Finkel report has refocused national attention on climate change, and how we know it’s happening.

On a Q&A episode following the report’s release, Climate Council CEO Amanda McKenzie said we’ve seen:

… worsening heatwaves, hot days doubling in Australia in the last 50 years.

Excerpt from Q&A, June 12, 2017. Quote begins at 2:12.

Her comment provides the perfect opportunity to revisit exactly what the research says on heatwaves and hot days as Australia’s climate warms.

Examining the evidence

When asked for sources to support McKenzie’s assertion, a Climate Council spokesperson said:

Climate change is making hot days and heatwaves more frequent and more severe. Since 1950 the annual number of record hot days across Australia has more than doubled and the mean temperature has increased by about 1°C from 1910.

Specifically, there has been an increase of 0.2 days/year since 1957 which means, on average, that there are almost 12 more days per year over 35°C.

You can read full response from the Climate Council here.

How do we define ‘heatwaves’?

Internationally, organisations use different definitions for

In Australia, the most commonly used definition (and the one used by the Climate Council) is from the Bureau of Meteorology (BOM). It provided the first national definition of a heatwave in January 2014, describing it as:

A period of at least three days where the combined effect of excess heat and heat stress is unusual with respect to the local climate. Both maximum and minimum temperatures are used in this assessment.

The BOM uses a metric called the “excess heat factor” to decide what heat is “unusual”. It combines the average temperature over three days with the average temperature for a given location and time of year; and how the three day average temperature compares to temperatures over the last 30 days.

We can also characterise heatwaves by looking at their their intensity, frequency and duration.

Researchers, including Australian climate scientist Dr Sarah Perkins-Kirkpatrick, are trying to standardise the definitions of “heatwaves” and “hot days” and create a framework that allows for more in-depth studies of these events.

Are heatwaves ‘worsening’?

There’s not a large body of research against which to test this claim. But the research we do have suggests there has been an observable increase in the frequency and intensity of heatwaves in Australia. Research published in 2013 found a trend towards more heat waves in Australia between 1951 and 2008.

A review paper published in 2016 assessed evidence from multiple studies and found that heatwaves are becoming more intense and more frequent for the majority of Australia.

The following chart shows heatwave days per decade from 1950 to 2013, highlighting a trend toward more heatwave days in Australia over time:

We’ve seen a trend towards more heatwave days over Australia. Trends are shown for 1950-2013 in units of heatwave days per decade. Stippling indicates statistical significance at the 5% level.
Adapted from Perkins-Kirkpatrick et al. (2017)

Have hot days ‘doubled’ in the last 50 years?

While the number of “hot days” (as defined by the BOM) has not doubled over the last 50 years, as McKenzie said, the number of “record hot days” certainly has. “Record hot days” are days when the maximum temperature sets a new record high.

Given that McKenzie made her statement on a fast paced live TV show, it’s reasonable to assume she was referring to the latter. Let’s look at both figures.

The BOM defines “hot days” as days with a maximum temperature higher than 35°C. The BOM data show there were more hot days in Australia in 2013, 2014, 2015 and 2016 than in any of the 50 years from 1966 to 2016 (the last year for which data are available).

In fact, there were more hot days in the years 2013-2016 than in any other year as far back as 1910. If we compare the decades 1966-76 and 2006-16, we see a 27% increase in the number of hot days.


The following map shows the trend in the number of days per year above 35 °C from 1957–2015:

Bureau of Meteorology

A 2010 Bureau of Meteorology/CSIRO report found record hot days had more than doubled between 1960 and 2010. That data was collected from the highest-quality weather stations across Australia.

Number of record hot day maximums at Australian climate reference stations, 1960-2010.
Bureau of Meteorology 2010
Number of days in each year where the Australian area-averaged daily mean temperature is extreme. Extreme days are those above the 99th percentile of each month from the years 1910-2015.
Bureau of Meteorology

Why are heatwaves worsening, and record hot days doubling?

The trend in rising average temperatures in Australia in the second half of the 20th century is likely to have been largely caused by human-induced climate change.

Recent record hot summers and significant heatwaves were also made much more likely by humans’ effect on the climate.

The ConversationThe human influence on Australian summer temperatures has increased and we can expect more frequent hot summers and heatwaves as the Earth continues to warm.

Andrew King, Climate Extremes Research Fellow, University of Melbourne

This article was originally published on The Conversation. Read the original article.

Volcanoes under the ice: melting Antarctic ice could fight climate change

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Furious winds keep the McMurdo Dry Valleys in Anarctica free of snow and ice. Calcites found in the valleys have revealed the secrets of ancient subglacial volcanoes.
Stuart Rankin/Flickr, CC BY-NC

Silvia Frisia, University of Newcastle

Iron is not commonly famous for its role as a micronutrient for tiny organisms dwelling in the cold waters of polar oceans. But iron feeds plankton, which in turn hold carbon dioxide in their bodies. When they die, the creatures sink to the bottom of the sea, safely storing that carbon.

How exactly the iron gets to the Southern Ocean is hotly debated, but we do know that during the last ice age huge amounts of carbon were stored at the bottom of the Southern Ocean. Understanding how carbon comes to be stored in the depth of the oceans could help abate CO2 in the atmosphere, and Antarctica has a powerful role.

Icebergs and atmospheric dust are believed to have been the major sources of this micronutrient in the past. However, in research published in Nature Communications, my colleagues and I examined calcite crusts from Antarctica, and found that volcanoes under its glaciers were vital in delivering iron to the ocean during the last ice age.

Today, glacial meltwaters from Greenland and the Antarctic peninsula supply iron both in solution and as tiny particles (less than 0.0001mm in diameter), which are readily consumed by plankton. Where glaciers meet bedrock, minute organisms can live in pockets of relatively warm water. They are able to extract “food” from the rock, and in doing so release iron, which then can be carried by underwater rivers to the sea.

Volcanic eruptions under the ice can create underwater subglacial lakes, which, at times, discharge downstream large masses of water that travel to the ice margin and beyond, carrying with them iron in particle and in solution.

The role of melting ice in climate change is as yet poorly understood. It’s particularly pertinent as scientists predict the imminent collapse of part of the Larsen C ice shelf.

Researchers are also investigating how to reproduce natural iron fertilisation in the Southern Ocean and induce algal blooms. By interrogating the volcanic archive, we learn more about the effect that iron fertilisation from meltwater has on global temperatures.

A polished wafer of the subglacial calcites. The translucent, crystalline layers formed while in pockets of water, providing nourishment to microbes. The opaque calcite with rock fragments documents a period when waters discharged from a subglacial lake formed by a volcanic eruption, carrying away both iron in solution and particles of iron.

The Last Glacial Maximum

During the Last Glacial Maximum, a period 27,000 to 17,000 years ago when glaciers were at their greatest extent worldwide, the amount of CO2 in the atmosphere was lowered to 180 parts per million (ppm) relative to pre-industrial levels (280 ppm).

Today we are at 400 ppm and, if current warming trends continue, a point of no return will be reached. The global temperature system will return to the age of the dinosaurs, when there was little difference in temperature from the equator to the poles.

If we are interested in providing a habitable planet for our descendants, we need to mitigate the quantity of carbon in the atmosphere. Blooms of plankton in the Southern Ocean boosted by iron fertilisation were one important ingredient in lowering CO2 in the Last Glacial Maximum, and they could help us today.

The Last Glacial Maximum had winds that spread dust from deserts and icebergs carrying small particles into the Southern Ocean, providing the necessary iron for algal blooms. These extreme conditions don’t exist today.

Hidden volcanoes

Neither dust nor icebergs alone, however, explain bursts of productivity recorded in ocean sediments in the Last Glacial Maximum. There was another ingredient, only discovered in rare archives of subglacial processes that could be precisely dated to the Last Glacial Maximum.

Loss of ice in Antartica’s Dry Valleys uncovered rusty-red crusts of calcite plastered on glacially polished rocks. The calcites have tiny layers that can be precisely dated by radiometric techniques.

A piece of subglacial calcite coating pebbles. This suggests that the current transporting the pebbles was quite fast, like a mountain stream. The pebbles were deposited at the same time as the opaque layer in the calcite formed.

Each layer preserves in its chemistry and DNA a record of processes that contributed to delivering iron to the Southern Ocean. For example, fluorine-rich spherules indicate that underwater vents created by volcanic activity injected a rich mixture of minerals into the subglacial environment. This was confirmed by DNA data, revealing a thriving community of thermophiles – microorganisms that live in very hot water only.

Then, it became plausible to hypothesise that volcanic eruptions occurred subglacially and formed a subglacial lake, whose waters ran into an interconnected system of channels, ultimately reaching the ice margin. Meltwater drained iron from pockets created where ice met bedrock, which then reached the ocean – thus inducing algal blooms.

We dated this drainage activity to a period when dust flux does not match ocean productivity. Thus, our study indicates that volcanoes in Antarctica had a role in delivering iron to the Southern Ocean, and potentially contributed to lowering CO2 levels in the atmosphere.

The ConversationOur research helps explain how volcanoes act on climate change. But it also uncovers more about iron fertilisation as a possible way to mitigate global warming.

Silvia Frisia, Associate Professor, School of Environmental and Life Sciences , University of Newcastle

This article was originally published on The Conversation. Read the original article.

The Finkel Review at a glance

Madeleine De Gabriele, The Conversation; Michael Hopkin, The Conversation, and Wes Mountain, The Conversation

The long-awaited report from Chief Scientist Alan Finkel into Australia’s National Electricity Market was released today.

The key recommendation is the adoption of a Clean Energy Target. This mandates that energy retailers provide a certain amount of their electricity from “low-emissions” generators – sources that produce emissions below a threshold level of carbon dioxide per megawatt.

Crucially, Dr Finkel has not made a recommendation as to the precise threshold or the number of certificates to be issued, saying:

The Panel acknowledges that the specific emissions reduction trajectory that should be set for the electricity sector is a question for governments.

The ConversationAt a minimum, the electricity sector should have a trajectory consistent with a direct application of the national target of 26-28% reduction on 2005 levels by 2030, as per Australia’s international obligations under the Paris Agreement.

Independent Review into the Future Security of the National Electricity Market/The Conversation, CC BY-ND

Madeleine De Gabriele, Deputy Editor: Energy + Environment, The Conversation; Michael Hopkin, Environment + Energy Editor, The Conversation, and Wes Mountain, Deputy Multimedia Editor, The Conversation

This article was originally published on The Conversation. Read the original article.

Explainer: what is a ‘low emissions target’ and how would it work?

Frank Jotzo, Australian National University

The main job of the Finkel Review, to be released this week, is to set out ways to reform the National Electricity Market (NEM) to ensure it delivers reliable and affordable power in the transition to low-carbon energy. Yet most of the attention has been focused on what type of carbon-reduction scheme Australia’s chief scientist, Alan Finkel, will recommend.

The expectation is that he will advocate a “low emissions target” (LET), and it looks like industry is getting behind this.

That would be instead of an emissions intensity scheme (EIS), which had been supported by much of industry as well as regulators and analysts, but the government rejected this.

Both types of scheme are second-best approaches to a carbon price. They can have similar effects depending on their design and implementation, although an EIS would probably be more robust overall.

How a LET might work

A LET would give certificates to generators of each unit of electricity below a threshold carbon intensity. Electricity retailers and industry would be obliged to buy the certificates, creating a market price and extra revenue for low-emission power generators.

How many certificates get allocated to what type of power generator is an important design choice. Government would also determine the demand for the certificates, and this defines the overall ambition of the scheme.

At its core, the scheme would work rather like the existing Renewable Energy Target, which it would replace. But the new scheme would also include some rewards for gas-fired generators, and perhaps even for coal-fired generators that are not quite as polluting as others. The question is how to do this.

A simple but crude way of implementing a LET would be to give the same number of certificates for every megawatt hour (MWh) of electricity generated using technologies below a benchmark level of emissions intensity. In practice, that would be renewables and gas. In principle, the scheme could include nuclear power as well as coal plants with carbon capture and storage, but neither exists in Australia, nor are they likely to be built.

Such a simple implementation would have two drawbacks. One, it would create a strong threshold effect: if your plant is slightly above the benchmark, you’re out, slightly below and you’re in. Two, it would give the same reward to gas-fired generators as to renewables, which is inefficient from the point of view of emissions reduction.

A better way is to scale the amount of certificates issued to the emissions intensity of each plant.

If the benchmark was 0.7 tonnes of carbon dioxide per MWh of electricity (as some media reports have predicted), then a gas plant producing 0.5 tonnes of CO₂ per MWh would get 0.2 certificates per MWh generated. A wind or solar farm, with zero emissions, would receive 0.7 certificates per MWh generated.

The benchmark could also be set at a higher level, potentially so high that all power stations get certificates in proportion to how far below the benchmark they are. For example, a benchmark of 1.4 tonnes CO₂ per MWh would give 1.4 certificates to renewables, 0.9 certificates to the gas plant, 0.5 certificates to an average black coal plant and 0.2 certificates to a typical brown coal plant.

Including existing coal plants in the LET in this way would create an incentive for the sector to move towards less polluting generators. It would thus help to reduce emissions from the coal fleet, and perhaps pave the way for the most polluting plants to be retired earlier. But the optics would not be good, as the “low emissions” mechanism would be giving credits to coal.

Whichever way certificates are distributed, the government also has to specify how many certificates electricity retailers need to buy. Together with the benchmark and with how electricity demand turns out, this will determine the emissions intensity of overall power supply. The benchmark would need to decline over time; alternatively, the amount of certificates to be bought could be increased.

The price of LET certificates would depend on all of these parameters, together with the cost of energy technologies, and industry expectations about the future levels of all of these variables. As the experience of the RET has shown, these can be difficult to predict.

Low emissions target vs emissions intensity scheme

An emissions intensity scheme (EIS) is the proposal that in recent times had the broadest support in the policy debate. Finkel’s preliminary report referenced it and the Climate Change Authority earlier put significant emphasis on it. But it got caught in the internal politics of the Liberal-National Coalition and was ruled out.

Under an EIS, the government would set a benchmark emissions intensity, declining over time. Generators below the benchmark would be issued credits, whereas those running above the benchmark would need to buy credits to cover their excess emissions. Supply and demand set the price in this market.

Depending on how the parameters are set, the effects of a LET and an EIS on the power mix and on power prices would differ, but not necessarily in fundamental ways.

There are some key differences though. Under a LET, electricity retailers will need to buy certificates and not all power plants may be covered by a low-carbon incentive. Under an EIS, the higher-polluting plants buy credits from the cleaner ones, and all types of plants are automatically covered. The EIS market would be closely related to the wholesale electricity market, with the same participants, whereas a LET market would be separate and distinct, like the RET market now.

Further, the benchmark in an EIS directly defines the emissions intensity of the grid and its change over time. Not so for the benchmark in a LET. A LET will also require assumptions about future electricity demand in setting the total amount of credits that should be purchased – and bear in mind that the estimates used to calibrate the RET were wildly off the mark.

What’s more, an EIS might present a chance to circumvent the various special rules and exemptions that exist in the RET, and which might be carried over to the LET.

Politics vs economics

Neither a LET nor an EIS provides revenue to government. Since the demise of Australia’s previous carbon price this has often been considered desirable politically, as it avoids the connotations of “carbon tax”. But economically and fiscally it is a missed opportunity.

Globally, most emissions trading schemes generate revenue that can be used to cut other taxes, help low-income households, or pay for clean energy research and infrastructure.

An economically efficient system should make carbon-based electricity more expensive, which encourages energy consumers to invest in energy-saving technology. Both a LET and an EIS purposefully minimise this effect, and thus miss out on a key factor: energy efficiency.

Ambition and confidence

More important than the choice of mechanism is the level of ambition and the political durability of the policy.

Bringing emissions into line with the Paris climate goals will require fundamental restructuring of Australia’s power supply. Coal would need to be replaced well before the end of the lifetime of the current plants, probably mostly with renewables.

To prompt large-scale investment in low-carbon electricity, we need a reliable policy framework with a genuine and lasting objective to reduce emissions. And investors need confidence that the NEM will be governed by rules that facilitate this transition.

Of any policy mechanism, investors will ask the hard questions: what will be its actual ambition and effects? Would the scheme survive a change in prime minister or government? Would it stand up to industry lobbying? Investor confidence requires a level of predictability of policy.

The ConversationIf a LET were supported by the government and acceptable to the Coalition backbench, and if the Labor opposition could see it as a building block of its climate policy platform, then the LET might be a workable second best, even if there are better options. Over the longer term, it could be rolled into a more comprehensive and efficient climate policy framework.

Frank Jotzo, Director, Centre for Climate Economics and Policy, Australian National University

This article was originally published on The Conversation. Read the original article.

Energy solutions but weak on climate – experts react to the Finkel Review

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The Finkel Review is scientifically modest but politically deft.
Lukas Coch/AAP

Hugh Saddler, Australian National University; Alan Pears, RMIT University, and David Karoly, University of Melbourne

The keenly anticipated Finkel Review, commissioned in the wake of last year’s South Australian blackout, has made a range of recommendations aimed at delivering a reliable, secure and sustainable National Electricity Market.

Among the proposals is a new Clean Energy Target to boost investment in low-carbon electricity generation, as well as moves to require high-emitting power stations to give three years’ notice before shutting down.

Below, our experts react to the measures.

“Security and reliability are first”

Hugh Saddler, Honorary Associate Professor, Australian National University

With so much focus on the design of a mechanism to support a shift towards lower-emissions generation, it is easy to forget that the primary purpose of the Review, commissioned following the “system black” event in South Australia on September 28, 2016, was “to develop a national reform blueprint to maintain energy security and reliability”. It is thus appropriate that security and reliability are the first topics to be addressed in the main body of the report.

System security is defined as the ability of the system to tolerate disturbances. Maintaining security requires the system to be able to prevent very high rates of change of frequency. At present the system has no explicit mechanism for doing this, but relies implicitly on the inertia provided, effectively as a free service, by existing large thermal generators.

The report recommends a series of regulatory energy security obligations to provide this service by various additional means, falling on the transmission network service providers in each of the five NEM regions (states), and also on all new generators connecting to the system.

System reliability is defined as the ability of the system to meet consumer demand at all times. In the old system, this is achieved by “dispatchable” generators, meaning coal and gas generators that can vary their output as required to meet demand.

In the new system, with large amounts of variable wind and solar generation, other supply sources are needed to meet demand at times of low wind speed and/or lack of sun – that is, to act as complements to wind and solar. Existing hydro and open-cycle gas turbine generators are ideally suited to this task, but with the growth in wind and solar generation, this capacity will very soon be insufficient for the task across the NEM (and is already insufficient in SA).

The Report recommends what it calls a Generator Reliability Obligation, which would be triggered whenever the proportion of dispatchable generation (which could include batteries and other forms of storage) in a region is falling towards a predetermined minimum acceptable level. The obligation would fall on all new renewable generators wishing to connect thereafter and, in the words of the Report “would not need to be located on site, and could utilise economies of scale” through multiple renewable generation projects “pairing” with “one new large-scale battery of gas fired generation project for example”.

If implemented, this recommendation would seem certain to greatly complicate, slow down and add to the administrative overhead cost of building new renewable generation. It would involve putting together a consortium of multiple parties with potentially differing objectives and who would otherwise be competing with one another in the wholesale electricity market.

A far better approach would be to recognise that dispatchable generation provides a distinct and more valuable product than non-dispatchable generation. There should be a separate market mechanism, possibly based on a contracting approach, to provide this service. If well designed, this would automatically ensure that economies of scale, as may be realised by pumped hydro storage, for example, would be captured. This approach would be far more economically efficient, and thus less costly to electricity consumers, than the messy processes required under the Report’s obligation approach.

“Energy efficiency is effectively handballed to governments”

Alan Pears, Senior Industry Fellow, RMIT University

The Review’s approach to the demand side is very focused. Demand response, the capacity to reduce demand at times of extreme pressure on the supply system, is addressed thoroughly. The past under-utilisation of this approach is acknowledged, and the actions of the Australian Energy Market Operator (AEMO) intended to capture some of its potential in time for next summer are outlined.

However, the deep cultural problems within the Australian Energy Markets Commission regarding demand response are not tackled. Instead, the AEMC is asked (yet again) to develop facilitation mechanisms in the wholesale market by mid-2018.

Energy efficiency is effectively handballed to governments. After making some positive comments about its valuable roles, recommendation 6.10 states that governments “should accelerate the roll out of broader energy efficiency measures to complement the reforms recommended in this Review”.

This is a disappointing outcome, given the enormous untapped potential of energy markets to drive effective energy efficiency improvement. But it clearly shows governments that they have to drive energy-efficiency initiatives unless they instruct energy market participants to act.

“It follows the wrong path on greenhouse emissions”

David Karoly, Professor of Atmospheric Science, University of Melbourne and Member, Climate Change Authority

The Finkel Review says many sensible things about ways to improve the security and reliability of Australia’s electricity sector. However, it follows completely the wrong path in what it says about lower greenhouse emissions from the electricity sector and Australia’s commitments under the Paris Agreement. This is disappointing, as Alan Finkel is Australia’s Chief Scientist and a member of the Climate Change Authority.

All economy-wide modelling shows that the electricity sector must do a larger share of future emissions reductions than other sectors, because there are easier and cheaper solutions for reducing emissions in that sector. However, this review’s vision is for “emissions reduced by 28% below 2005 levels by 2030” – exactly the same as Australia’s target under the Paris Agreement. It should be much more.

The ConversationAustralia’s commitments under the Paris Agreement are “to undertake ambitious efforts” to limit global warming “to well below 2℃ above pre-industrial levels”. The Targets Report from the Climate Change Authority in 2015 showed that this means Australia and the electricity sector must aim for zero emissions before 2050, not in the second half of the century, as suggested in the Finkel Review.

Hugh Saddler, Honorary Associate Professor, Centre for Climate Economics and Policy, Australian National University; Alan Pears, Senior Industry Fellow, RMIT University, and David Karoly, Professor of Atmospheric Science, University of Melbourne

This article was originally published on The Conversation. Read the original article.