25/06/2020

Climate Explained: What Earth Would Be Like If We Hadn’t Pumped Greenhouse Gases Into The Atmosphere

The Conversation - 

OSORIOartist/Shutterstock

 is Senior Lecturer in Environmental Physics, University of Canterbury
Earth’s atmosphere is a remarkably thin layer of gases that sustain life.

The diameter of Earth is 12,742km and the atmosphere is about 100km thick. If you took a model globe and wrapped it up, a single sheet of tissue paper would represent the thickness of the atmosphere.

The gases that make up Earth’s atmosphere are mostly nitrogen and oxygen, and small quantities of trace gases such as argon, neon, helium, the protective ozone layer and various greenhouse gases – so named because they trap heat emitted by Earth.

The most abundant greenhouse gas in Earth’s atmosphere is water vapour - and it is this gas that provides the natural greenhouse effect. Without this and the naturally occurring quantities of other greenhouse gases, Earth would be about 33℃ colder and uninhabitable to life as we know it.

Changing Earth’s atmosphere

Since pre-industrial times, human activities have led to the accumulation of greenhouse gases such as carbon dioxide, methane and nitrous oxide in the atmosphere. The concentration of atmospheric carbon dioxide has risen from about 280 parts per million (ppm) before the first industrial revolution some 250 years ago, to a new high since records began of just over 417ppm. As a result of continued increases, the global average temperature has climbed by just over 1℃ since pre-industrial times.

While these long-lived greenhouse gases have raised Earth’s average surface temperature, human activities have altered atmospheric composition in other ways as well. Particulate matter in the atmosphere, such as soot and dust, can cause health problems and degrades air quality in many industrialised and urban regions.

Particulate matter can partially offset greenhouse gas warming, but its climate effects depend on its composition and geographical distribution. Climate in the southern hemisphere has also been affected by chlorofluorocarbons (CFCs), which led to the development of the Antarctic ozone hole.

If people had not altered the composition of the atmosphere at all through emitting greenhouse gases, particulate matter and ozone-destroying CFCs, we would expect the global average temperature today to be similar to the pre-industrial period – although some short-term variation associated with the Sun, volcanic eruptions and internal variability would still have occurred.

In a world that is about 1℃ warmer than during pre-industrial times, New Zealand is already facing the environmental and economic costs associated with climate change. The former head of the UN Framework Convention on Climate Change (UNFCCC), Christiana Figueres, argues that with trillions of dollars being spent around the world in economic stimulus packages following the COVID-19 pandemic, we need strong commitments to a low-carbon future if the world is to limit warming to 1.5℃ above pre-industrial levels.

What needs to happen

Greenhouse gases have long lifetimes – about a decade for methane and hundreds to thousands of years for carbon dioxide. We will need to reduce emissions aggressively over a sustained period, until their abundance in the atmosphere starts to decline.

When New Zealand entered the Level 4 coronavirus lockdown in March 2020, almost two weeks passed (the incubation period of the virus) before the number of new cases started to decline. Waiting for atmospheric carbon dioxide concentrations to decrease, even while we reduce emissions, will be similar, except we’ll be waiting for decades.

It is very unlikely that we could ever reduce greenhouse gas concentrations to the point that it becomes dangerous for life as we know it. Doing so would involve overcoming the natural greenhouse effect.

Recent research into greenhouse gas emission scenarios provides guidance on what will need to happen to stabilise Earth’s temperature at 1.5℃ above pre-industrial levels. A rapid transition away from fossil fuels toward low-carbon energy is imperative; some form of carbon dioxide capture to remove it from the atmosphere may also be necessary.

Short-term and scattered climate policy will not be sufficient to support the transitions we need, and achieving 1.5℃ will not be possible as long as global inequalities remain high.

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(AU) Australia’s Shifting Mood On Climate Change

The Lowy Institute - Bec Strating

This year’s intense bushfires seemed like the event that would finally move climate policy. Then came Covid-19.

A dust storm on a drought-stricken Australian sheep paddock (Klae Mcguinness/Getty Images)

At the beginning of 2020, Australia’s national conversation was dominated by the catastrophic bushfires raging throughout the country.

The fires killed at least 34 people, burned through more than 11 million hectares and destroyed nearly 6000 buildings.

In March, the first scientific assessment of the role of climate change found that global warming increased the risk of hot dry weather, raising the risk of bushfires by at least 30%.

Some analysts – myself included – wondered whether the particularly intense bushfire season might present the kind of national crisis that Australia needs to shake it from its climate malaise. The Liberal-National Coalition government found its credibility and authority under challenge as it struggled to craft a coherent and effective response to the fires.

Australians are more likely to view environmental threats as more critical than “traditional” security issues such as military conflict between great powers and foreign interference in Australian politics.

Then came the novel coronavirus. The federal government’s handling of the pandemic saw Prime Minister Scott Morrison regain his lead as preferred prime minister ahead of Labor leader Anthony Albanese, and the new national and global emergency turned Australia’s attention away from the bushfires.

The 2020 Lowy Poll, which was conducted just as states began going into lockdown, highlights the ways in which environmental issues have been hijacked by Covid-19 and its global economic implications, at least in the short term.

The poll results highlight that environmental threats continue to concern Australians. Three of the top five critical threats to Australia’s vital interests related to the environment, and – consistent with the past five years of Lowy polling – 9 out of 10 participants accepted the need for Australians to act on climate change. At the top of the list of perceived critical threats was drought and water shortages, with 3 of 4 people (77%).



Yet, the coronavirus and other potential epidemics (76%) and a severe downturn in the global economy (71%) were ranked more highly as critical threats than environmental disasters such as bushfires and floods (67%). In the 2019 Lowy Poll, only 51% of respondents saw global economic downturn as a cause for concern, and pandemics did not even feature.

The results again shed light on one of the biggest conundrums for modern Australian governments: how to “act” on climate change without incurring significant costs. Importantly, Covid-19 appears to have played a role here, as the percentage of people who viewed global warming as a serious and pressing problem, and that steps should be taken even if it involves significant costs, fell five points from 2019 to 56% in 2020.

While this is still 20 points higher than it was in 2012, what was a favourable trend towards substantial climate action is now in retreat. The numbers of people who want global change addressed gradually increased from 28% to 34%, while people who argue that no economic costs should be born remained stagnant at 10%.



There is a gap between those worried about environmental security threats and those concerned about climate change specifically. Climate change only ranked the fifth highest (59%) critical threat to Australia’s vital interests, compared with 77% for drought and water shortages – a difference of nearly 20%. This suggests that a segment of the Australian community concerned about environmental security issues do not view climate change as a major contributor to drought, water shortages and environmental disasters such as bushfires and floods.

When next summer approaches, bushfires will be back on the minds of people, particularly those who live in susceptible landscapes – although the poll finds only 50% of Australia’s regional and remote population saw global warming as a serious and pressing problem, reflecting a rural/urban divide in political attitudes.

There were also some surprising results regarding climate change action and international reputation. While only 19% of respondents approved of the Trump administration withdrawing the US from international climate change agreements, less than half of respondents saw Australia’s lacklustre climate policies as having an adverse effect on its global reputation. Curiously, a decent proportion considered Australia’s reputation to be positively enhanced by its responses to climate change, despite considerable evidence to the contrary.



The prioritisation of Covid-19 as a pressing security issue may be temporary. In mid-April, an Essential Report poll found 45% of surveyed respondents were “very concerned” about Covid-19, which two months later had dropped to only 28%.

The silver lining is that Australians are more likely to view environmental threats as more critical than “traditional” security issues such as military conflict between great powers and foreign interference in Australian politics.

These public attitudes are not adequately reflected in dominant debates and discussions about Australian security among elite government and defence circles. For example, despite public narratives over the past year highlighting deepening suspicions of the influence of People’s Republic of China in Australia, this has not necessarily resonated with the electorate.

The numbers of surveyed participants who viewed “foreign interference in Australian politics” as a critical threat dropped seven points from last year to 42%, considerably lower than “non-traditional” environmental security threats.

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(NSW) State Government Banking On Coal Exports As World Chases Paris Targets

Sydney Morning Herald - Nick O'Malley | Peter Hannam

The (NSW) state government is banking on global coal demand defying the Paris climate goals of slashing carbon emissions, predicting instead only a marginal cut in consumption of the fossil fuel by mid-century.

According to the government's new Strategic Statement on Coal Exploration and Mining, to be released on Wednesday, the appetite for thermal coal burnt in power stations will only ease about one-tenth from just over 1 billion tonnes a year to about 900 million by 2050.

John Barilaro, at a solar farm near Dubbo on Tuesday, will be in the Hunter Valley on Wednesday to unveil the state's coal strategy. Credit: Janie Barrett



The modest decline is well short of the Paris goal of developed nations reaching net-zero emissions by 2050 and also out of line with NSW's own net-zero target by then.

Even so, the government forecasts "significant disruptions" for NSW communities reliant on thermal coal exports, the report states.

It plans to release maps clearly outlining where coal exploration and expansion will be allowed to continue and where it will be banned in order to give more certainty to communities and mining interests.

Deputy Premier and resources minister John Barilaro said the resilience of the coal industry has "never been more important" given the state's need to bounce back from drought, bushfires and now the COVID-19 crisis.

"We are determined to set a clear and consistent policy framework that supports investment certainty in NSW as the coal sector responds to global demand," he said.

To reduce emissions from coal mining and "support responsible coal production", the government would spend $50 million on new infrastructure projects and community programs to mining-affected towns under the Resources for Regions program, he said.

The Mount Piper power plant, near Lithgow, could be among the last coal plants in eastern Australia. It is scheduled to close in 2043. Credit: Janie Barrett



Coal was the single-largest export for NSW last year, amounting to $23.1 billion, or about 3 per cent of global coal consumption. Of NSW's exports, more than 80 per cent was thermal and the rest coking coal used to make steel.

Projections set out in the report indicate that demand for seaborne coal exports in 2050 will be slightly less than today, though demand will remain significant.

A rise in demand for coal from India in particular would counter expected falls in shipments to major markets such as China, Japan and South Korea. South-east Asian imports are predicted to rise and then plateau.

According to the strategy document, use of thermal coal in NSW itself will decline over coming decades as ageing coal-fired power plants are closed and replaced with cleaner power technologies.

The NSW government forecasts no early sunset for coal exports. Credit: Nic Walker

The release of the coal report comes a day after Mr Barilaro joined Energy and Environment Minister Matt Kean to trumpet the success of the state's first renewable energy zone. The region around Dubbo attracted investment funds the equivalent of nine times the target of 3000 megawatts, prompting Mr Kean to consider expanding the pilot scheme's size.

Over the medium term the government plans to support the mining industry to shift its focus from thermal coal to mining for metals used in high-tech industries such as copper, cobalt and rare earths, the report says.

But it acknowledges that as these metals and minerals tend to be found in the state's central and far west regions rather than in existing coal-mining heartlands, there will be "significant disruption for coal-reliant communities."

In a foreword to the plan Mr Barilaro writes that the government expects a shift away from coal in the medium term, but "during the transition, the NSW Government will continue to support the responsible development of our abundant, high-quality coal resources for the benefit of the state".

Global coal demand won't fall fast enough to meet mid-century zero-emissions goals for NSW, if the government's forecasts are correct. Credit: Louie Douvis

The NSW government prediction of coal demand is broadly in line with that of the International Energy Agency, but it is at odds with the cuts in coal use that scientists say the world will need to adopt if we are to achieve the goal of keeping global warming beneath 1.5 degrees.

In its most recent global energy analysis the IEA warned that though coal demand had decreased due to COVID-19 and climate action by some governments, new plants under construction around the world "risks increasing the locked-in emissions from coal-fired power plants that already threaten to put a sustainable energy pathway out of reach".

In recent months major institutional investors have begun abandoning their stakes in thermal coal companies due to the impact coal has on the climate, compounding pressure on businesses already facing a slump in global thermal coal prices.

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