Australia’s hottest year was no freak event: humans caused it

The Conversation, 6 January 2014

Sophie Lewis, Postdoctoral Research Fellow at University of Melbourne,  

David Karoly, Professor of Atmospheric Science at University of Melbourne

See also  - BoM, Annual climate statement 2013,

 - The Guardian, Australia's hottest year recorded in 2013,

 - The Age, 2013 confirmed as Australia's hottest year on record,

 - ABC News, 2013 was hottest year on record in Australia

The Bureau of Meteorology has confirmed that 2013 was the hottest year in Australia since records began in 1910.

Unusual heat was a persistent feature throughout the year. For the continent as a whole, we experienced our hottest day on record on January 7. Then January was the hottest month on record, and the 2012-13 summer was the hottest recorded for the nation.

The nation-wide temperature record set for the month of September exceeded the previous record by more than a degree. This was the largest temperature anomaly for any month yet recorded.

Averaged across all of Australia, the temperature for 2013 was 1.2C above the 1961-1990 average, and well above the previous record hot year of 2005 of 1.03C above average.

What caused these extreme temperatures? Climate scientists have a problem: because climate deals with averages and trends, we can't attribute specific records to a particular cause.

But our research has made significant headway in identifying the causes of climate events, by calculating how much various factors increase the risk of extreme climate events occurring. And we have found sobering results.

We previously analysed the role human-caused climate change played in recent extremes across Australia.

For various record-breaking 2013 Australian temperatures, we investigated the contributing factors to temperature extremes using a suite of state-of-the-art global climate models. The models simulated well the natural variability of Australian temperatures.

Using this approach, we calculated the probability of hot Australian temperatures in model experiments. These incorporated human (changes in greenhouse gases, aerosols and ozone) and natural (solar radiation changes and volcanic) factors. We compared these probabilities to those calculated for a parallel set of experiments that include only natural factors. In this way, natural and human climate influences can be separated.

In our previous studies, we then applied an approach (known as Fraction of Attributable Risk) widely used in health and population studies to quantify the contribution of a risk factor to the occurrence of a disease. Health studies, for example, can quantify how much smoking increases the risk of lung cancer.

Using the climate models, the Fraction of Attributable Risk (FAR) shows how much the risk of extreme temperatures increases thanks to human influences.

In our earlier study of our record hot Australian summer of 2012-13, we found that it was very likely (with 90% confidence) that human influences increased the odds of extreme summers such as 2012-13 by at least five times.

In August 2013, Australia broke the record for the hottest 12-month period. The odds of this occurring increased again from the hottest summer. We found that human influence increased the odds of setting this new record by at least 100 times.

Recent extreme temperatures are exceeding previous records by increasingly large margins. The chance of reaching these extreme temperatures from natural climate variations alone is becoming increasingly unlikely. When we considered the 12-month record at the end of August, it was nearly impossible for this temperature extreme to occur from natural climate variations alone in these model experiments.

We have just completed a preliminary investigation of contributing factors for the record Australian temperature in the 2013 calendar year.

In the model experiments, it is impossible to reach such a temperature record due to natural climate variations alone. In climate model simulations with only natural factors, none of the nearly 13,000 model years analysed exceed the previous hottest year recorded back in 2005.

In contrast, in model simulations including both natural and human factors, such as increasing greenhouse gases, record temperatures occur approximately once in every ten years during the period 2006 to 2020. (On a mathematical note, as there is no instance in which the record hot yearly temperature occurred without human contributions, the FAR value is one.)

Clearly both natural climate variability and global warming from humans contribute to recent temperature records. Natural variability always plays a major role in the occurrence of weather and climate extremes. But in the case of our recent hottest year on record, human-caused global warming made a crucial contribution to our extreme temperatures.

Our extensive catalogue of 2013 record-breaking events in Australia occurred in a global context of increasing temperatures that must be considered. Globally, 2013 will likely rank as the 6^th hottest year recorded.

So to return to our question, what caused the 2013 record hot year across Australia? Simply put, our climate has changed due to human activities. Recent extremes, such as this hot year, are occurring well outside the bounds of natural climate variations alone.

Climate change models underestimate likely temperature rise, report shows

Forecasts predicting less global warming fail to properly take into account cloud formation, say scientists

Oliver Milman 

theguardian.com, Wednesday 1 January 2014

See also - Climate change: Planet to warm by 4 degrees by 2100, The Age, and 

Climate study paints even uglier picture of the future, ABC AM 

The Earth's climate is far more sensitive to carbon dioxide emissions than previously thought, heightening the likelihood of a 4C temperature rise by 2100, new Australian-led research of cloud systems has found.

The study, published in Nature, provides new understanding on the role of cloud formation in climate sensitivity – one of the key uncertainties in predictions of climate change.

Report authors Steven Sherwood, Sandrine Bony and Jean-Louis Dufresne found climate models which show a low global temperature response to CO2 emissions do not factor in all the water vapour released into the atmosphere.

Models typically simulate water vapour as rising to 15km and forming clouds, rather than updraughts of water vapour that rise only a few kilometres and pull away the cloud-forming vapour. This prediction of cloud cover is important because clouds reflect sunlight, lessening the impact of global warming.

The report, conducted between the University of New South Wales and the Université Pierre et Marie Curie in Paris, finds "real world observations" show the accepted models are wrong.

In reality, the study found, water vapour is distributed to different heights in the atmosphere, causing fewer clouds to form as the climate warms.

In turn, this increases the amount of sunlight entering the atmosphere, making the level of warming far more sensitive to heat-trapping gases such as CO2.

As a result, the world can expect a temperature increase of "at least" 4C by 2100 if, as predicted, there is a doubling of CO2 in the atmosphere. This could then rise by more than 8C by 2200.

This is beyond the lower range of predictions and double the 2C limit, compared with pre-industrial times, agreed by countries to prevent the impact of runaway climate change. By comparison, average temperatures have risen 0.8C over the past 100 years.

"Mixing inferred from observations appears sufficiently strong to imply a climate sensitivity greater than 3C for a carbon dioxide doubling," the report states. "This is significantly higher than the currently accepted lower bound of 1.5C, thereby constraining model projections toward relatively severe future warming."

The issue of how sensitive the climate is to CO2 was a contentious one following the release of the latest climate report in September by the Intergovernmental Panel on Climate Change (IPCC). Some sceptics have claimed a so-called warming "pause" over the past 15 years shows the climate does not react strongly to high concentrations of carbon emissions, which continued to escalate to a new average high of393.1ppm in 2012.

"Climate sceptics like to criticise climate models for getting things wrong, and we are the first to admit they are not perfect, but what we are finding is that the mistakes are being made by those models which predict less warming, not those that predict more," said Professor Sherwood, lead author of the report at the UNSW centre of excellence for climate system science.

"Our research has shown climate models indicating a low temperature response to a doubling of carbon dioxide from pre-industrial times are not reproducing the correct processes that lead to cloud formation.

"When the processes are correct in the climate models the level of climate sensitivity is far higher. Previously, estimates of the sensitivity of global temperature to a doubling of carbon dioxide ranged from 1.5C to 5C," he said.

"This new research takes away the lower end of climate sensitivity estimates, meaning that global average temperatures will increase by 3C to 5C with a doubling of carbon dioxide.

"Rises in global average temperatures of this magnitude will have profound impacts on the world and the economies of many countries if we don't urgently start to curb our emissions."

Climate change will double need for fire fighters by 2030, Climate Council says

The Age, December 9, 2013 

The Climate Council report is available at - http://www.climatecouncil.org.au/bushfirereport/

Australian fire services will need to double their boots on the ground by 2030 to cope with the increased bushfire risk caused by climate change, a new report says.

Be Prepared: The Changing Climate and Australia's Bushfire Threat is the first major report from the publicly-funded Climate Council, born out of the axed Climate Commission.

At the report's launch in Sydney, co-author Professor Lesley Hughes warned the "context" of fire in Australia was changing.

"We've had since the 1960s ... a doubling in the number of extreme hot days," she said.

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"And when we get extreme hot days the risk of bushfires is greater."

Australia's southeast and southwest was experiencing "a long-term pattern of drying" putting large populations living near bushland at particular risk, she said.

According to the report, Australia has experienced its hottest 12 months on record and the annual fire season will continue to expand into October and March in coming years.

The report says that by 2030 the number of professional firefighters should double 2010 numbers in order to keep pace with the growing population and bushfire risk.

Fire Brigade Employees' Union NSW Secretary Jim Casey said Prime Minister Tony Abbott must better resource firefighters and act on climate change.

He said Mr Abbott was prepared to "drape himself in the flag of firefighters" during the recent Blue Mountains bushfires but wasn't prepared to act on the root cause of the blaze.

Co-author Professor Will Steffen said that in the short term, governments must ensure fire services were adequately resourced to fight an increased number of fires.

In the long term Australia needed to stop using fossil fuels and develop renewable energies to reduce carbon emissions, he said.

Dr Christine Finlay, who has a PhD in bushfire research, says the "incredible surge of catastrophic fire activity" was due to policies that made it difficult to do preventative burns."

"You have to hire an environment impact assessment consultant ... to make sure there's no threatened or endangered species," she said.

AAP

Just 90 companies caused two-thirds of man-made global warming emissions

Chevron, Exxon and BP among companies most responsible for climate change since dawn of industrial age, figures show 

 • Interactive - which fossil fuel companies are most responsible?

Suzanne Goldenberg, US environment correspondent

theguardian.com, Thursday 21 November 2013

The climate crisis of the 21st century has been caused largely by just 90 companies, which between them produced nearly two-thirds of the greenhouse gas emissions generated since the dawning of the industrial age, new research suggests.

The companies range from investor-owned firms – household names such as Chevron, Exxon and BP – to state-owned and government-run firms.

The analysis, which was welcomed by the former vice-president Al Goreas a "crucial step forward" found that the vast majority of the firms were in the business of producing oil, gas or coal, found the analysis, which has been accepted for publication in the journal Climatic Change.

"There are thousands of oil, gas and coal producers in the world," climate researcher and author Richard Heede at the Climate Accountability Institute in Colorado said. "But the decision makers, the CEOs, or the ministers of coal and oil if you narrow it down to just one person, they could all fit on a Greyhound bus or two."

Half of the estimated emissions were produced just in the past 25 years – well past the date when governments and corporations became aware that rising greenhouse gas emissions from the burning of coal and oil were causing dangerous climate change.

Many of the same companies are also sitting on substantial reserves of fossil fuel which – if they are burned – puts the world at even greater risk of dangerous climate change.

Climate change experts said the data set was the most ambitious effort so far to hold individual carbon producers, rather than governments, to account.

The United Nations climate change panel, the IPCC, warned in September that at current rates the world stood within 30 years of exhausting its "carbon budget" – the amount of carbon dioxide it could emit without going into the danger zone above 2C warming. The former US vice-president and environmental champion, Al Gore, said the new carbon accounting could re-set the debate about allocating blame for the climate crisis.

Leaders meeting in Warsaw for the UN climate talks this week clashed repeatedly over which countries bore the burden for solving the climate crisis – historic emitters such as America or Europe or the rising economies of India and China.

Gore in his comments said the analysis underlined that it should not fall to governments alone to act on climate change.

"This study is a crucial step forward in our understanding of the evolution of the climate crisis. The public and private sectors alike must do what is necessary to stop global warming," Gore told the Guardian. "Those who are historically responsible for polluting our atmosphere have a clear obligation to be part of the solution."

Between them, the 90 companies on the list of top emitters produced 63% of the cumulative global emissions of industrial carbon dioxide and methane between 1751 to 2010, amounting to about 914 gigatonne CO2 emissions, according to the research. All but seven of the 90 wereenergy companies producing oil, gas and coal. The remaining seven were cement manufacturers.

The list of 90 companies included 50 investor-owned firms – mainly oil companies with widely recognised names such as Chevron, Exxon, BP , and Royal Dutch Shell and coal producers such as British Coal Corp, Peabody Energy and BHP Billiton.

Some 31 of the companies that made the list were state-owned companies such as Saudi Arabia's Saudi Aramco, Russia's Gazprom and Norway's Statoil.

Nine were government run industries, producing mainly coal in countries such as China, the former Soviet Union, North Korea and Poland, the host of this week's talks.

Experts familiar with Heede's research and the politics of climate change said they hoped the analysis could help break the deadlock in international climate talks.

"It seemed like maybe this could break the logjam," said Naomi Oreskes, professor of the history of science at Harvard. "There are all kinds of countries that have produced a tremendous amount of historical emissions that we do not normally talk about. We do not normally talk about Mexico or Poland or Venezuela. So then it's not just rich v poor, it is also producers v consumers, and resource rich v resource poor."

Michael Mann, the climate scientist, said he hoped the list would bring greater scrutiny to oil and coal companies' deployment of their remaining reserves. "What I think could be a game changer here is the potential for clearly fingerprinting the sources of those future emissions," he said. "It increases the accountability for fossil fuel burning. You can't burn fossil fuels without the rest of the world knowing about it."

Others were less optimistic that a more comprehensive accounting of the sources of greenhouse gas emissions would make it easier to achieve the emissions reductions needed to avoid catastrophic climate change.

John Ashton, who served as UK's chief climate change negotiator for six years, suggested that the findings reaffirmed the central role of fossil fuel producing entities in the economy.

"The challenge we face is to move in the space of not much more than a generation from a carbon-intensive energy system to a carbonneutral energy system. If we don't do that we stand no chance of keeping climate change within the 2C threshold," Ashton said.

"By highlighting the way in which a relatively small number of large companies are at the heart of the current carbon-intensive growth model, this report highlights that fundamental challenge."

Meanwhile, Oreskes, who has written extensively about corporate-funded climate denial, noted that several of the top companies on the list had funded the climate denial movement.

"For me one of the most interesting things to think about was the overlap of large scale producers and the funding of disinformation campaigns, and how that has delayed action," she said.

The data represents eight years of exhaustive research into carbon emissions over time, as well as the ownership history of the major emitters.

The companies' operations spanned the globe, with company headquarters in 43 different countries. "These entities extract resources from every oil, natural gas and coal province in the world, and process the fuels into marketable products that are sold to consumers on every nation on Earth," Heede writes in the paper.

The largest of the investor-owned companies were responsible for an outsized share of emissions. Nearly 30% of emissions were produced just by the top 20 companies, the research found.

By Heede's calculation, government-run oil and coal companies in the former Soviet Union produced more greenhouse gas emissions than any other entity – just under 8.9% of the total produced over time. China came a close second with its government-run entities accounting for 8.6% of total global emissions.

ChevronTexaco was the leading emitter among investor-owned companies, causing 3.5% of greenhouse gas emissions to date, with Exxon not far behind at 3.2%. In third place, BP caused 2.5% of global emissions to date.

The historic emissions record was constructed using public records and data from the US department of energy's Carbon Dioxide Information and Analysis Centre, and took account of emissions all along the supply chain.

The centre put global industrial emissions since 1751 at 1,450 gigatonnes.

Greenhouse emissions at record levels with China the leading contributor

Tom Arup, Environment editor

The Age, November 20, 2013

Global greenhouse gas emissions from burning fossil fuels reached the highest levels in human history last year, driven predominantly by Chinese growth, and are projected to surge even further in 2013.

New data from the Global Carbon Project - a team of scientists who track global emissions - finds carbon dioxide released from burning fossil fuels and making cement grew 2.2 per cent in 2012 from the previous year. In 2013 a further 2.1 per cent rise is expected.

But the latest data suggests the world's emissions could be slowing. The approximate 2 per cent growth in 2012 and 2013 falls short of the 3.1 per cent average annual rise since 2000.

CSIRO climate scientist Dr Pep Canadell - who is also executive director of the Global Carbon Project - told Fairfax Media the emissions rates of the past two years could be the tentative signs of a global slowdown.

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''But it is important to understand it is only a slowdown in growth - emissions every year are still higher than the previous one. Two per cent growth is still a very large number,'' he said.

Dr Canadell said that if current emissions trends continued the world would reach 2 degrees of global warming in about 30 years, a threshold regarded by scientists as triggering the worst impact of climate change.

The data comes as countries are meeting in Warsaw in the latest round of United Nations negotiations towards a new climate change treaty. Through the UN, countries have already agreed to the aim of keeping warming below 2 degrees.

If the Global Carbon Project projections hold the world will emit 36 billion tonnes of CO2 from fossil fuels and making cement during 2013, up 61 per cent from the 1990 levels for those sources.

Fossil fuels and cement making are responsible for 92 per cent of global greenhouse gas emissions, with the rest coming from changes in land use - such as cutting down forests.

Land-change emissions are harder to calculate due to a lack of data in some countries, but the trend since the late-1990s has been improvement. The Global Carbon Project reports 3.1 billion tonnes of CO2 were emitted from land-use change in 2012, a rise on 2011.

China was found to be responsible for 71 per cent of the global rise in fossil fuel emissions in 2012. Chinese CO2 emissions grew 6 per cent in 2012, and its annual total is now almost double the next largest contributor, the United States.

But the 6 per cent rise is slower than China's growth in recent years, which hit 10 per cent in 2011.

Greenhouse gases rise to record, will drive climate change, world body says

Peter Hannam

The Age,  November 7, 2013 

Greenhouse gases in the atmosphere are rising at an accelerating pace to record levels, a trend that will drive climate change and endanger future generations, according to the World Meteorological Organisation Greenhouse Gas Bulletin No. 9 (pdf).

Carbon dioxide, the most important greenhouse gas linked to fossil fuel burning and deforestation, rose by an average of 2.2 parts per million (ppm) in 2012 to 393.1. That increase compared with 1.5 ppm in the 1990s and 2 ppm in the past decade, and brings atmospheric levels to 41 per cent more than pre-industrial times, the WMO said in its annual Greenhouse Gas Bulletin.

Methane emissions, 60 per cent of which come from human activities such as cattle breeding and fossil fuel extraction, also reached a new high at 1819 parts per billion (ppb) in 2012, rising by 6 ppb. The gas resumed its increase after a pause between 1999 and 2006.

Nitrous oxide, another important gas with almost 300 times the impact on climate as carbon dioxide and is linked to fertiliser use among other sources, rose 0.9 ppb to 325.1 ppb, quickening from the 0.8 ppb average increase over the previous decade.

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Between 1990 and 2012 there was a 32 per cent increase in radiative forcing - the warming effect on our climate - because of the increase in these long-lived greenhouse gases, the WMO said.

Michael Raupach, a team leader in CSIRO's Marine and Atmospheric Research division, said the rise in atmospheric temperatures from the additional greenhouse gases had been temporarily limited by the oceans absorbing much of the extra heat trapped by those gases.

That pause, though, will end and "we'll see a return to significant rates of warming," he said.  

While reducing carbon emissions won't stop the build-up of heat in the earth's biosphere, reductions now reduce the magnitude of the future task.

"The reduction in emissions over the [near term] is absolutely essential," Dr Raupach said. Failure to do so will mean the size of future cuts required will "become completely impossible if we are to avoid any reasonable definition of dangerous climate change."