Fossil fuel emissions hit record high after unexpected growth: Global Carbon Budget 2017


Pep Canadell, CSIRO; Corinne Le Quéré, University of East Anglia; Glen Peters, Center for International Climate and Environment Research – Oslo; Robbie Andrew, Center for International Climate and Environment Research – Oslo; Rob Jackson, Stanford University, and Vanessa Haverd, CSIRO

Global greenhouse emissions from fossil fuels and industry are on track to grow by 2% in 2017, reaching a new record high of 37 billion tonnes of carbon dioxide, according to the 2017 Global Carbon Budget, released today.

The rise follows a remarkable three-year period during which global CO₂ emissions barely grew, despite strong global economic growth.

But this year’s figures suggest that the keenly anticipated global peak in emissions – after which greenhouse emissions would ultimately begin to decline – has yet to arrive.


Read more: Fossil fuel emissions have stalled: Global Carbon Budget 2016


The Global Carbon Budget, now in its 12th year, brings together scientists and climate data from around the world to develop the most complete picture available of global greenhouse gas emissions.

In a series of three papers, the Global Carbon Project’s 2017 report card assesses changes in Earth’s sources and sinks of CO₂, both natural and human-induced. All excess CO₂ remaining in the atmosphere leads to global warming.

We believe society is unlikely to return to the high emissions growth rates of recent decades, given continued improvements in energy efficiency and rapid growth in low-carbon energies. Nevertheless, our results are a reminder that there is no room for complacency if we are to meet the goals of the Paris Agreement, which calls for temperatures to be stabilised at “well below 2℃ above pre-industrial levels”. This requires net zero global emissions soon after 2050.

After a brief plateau, 2017’s emissions are forecast to hit a new high.
Global Carbon Project, Author provided

National trends

The most significant factor in the resumption of global emissions growth is the projected 3.5% increase in China’s emissions. This is the result of higher energy demand, particularly from the industrial sector, along with a decline in hydro power use because of below-average rainfall. China’s coal consumption grew by 3%, while oil (5%) and gas (12%) continued rising. The 2017 growth may result from economic stimulus from the Chinese government, and may not continue in the years ahead.

The United States and Europe, the second and third top emitters, continued their decade-long decline in emissions, but at a reduced pace in 2017.

For the US, the slowdown comes from a decline in the use of natural gas because of higher prices, with the loss of its market share taken by renewables and to a lesser extent coal. Importantly, 2017 will be the first time in five years that US coal consumption is projected to rise slightly (by about 0.5%).

The EU has now had three years (including 2017) with little or no decline in emissions, as declines in coal consumption have been offset by growth in oil and gas.

Unexpectedly, India’s CO₂ emissions will grow only about 2% this year, compared with an average 6% per year over the past decade. This reduced growth rate is likely to be short-lived, as it was linked to reduced exports, lower consumer demand, and a temporary fall in currency circulation attributable to demonetisation late in 2016.

Trends for the biggest emitters, and everyone else.
Global Carbon Project, Author provided

Yet despite this year’s uptick, economies are now decarbonising with a momentum that was difficult to imagine just a decade ago. There are now 22 countries, for example, for which CO₂ emissions have declined over the past decade while their economies have continued to grow.

Concerns have been raised in the past about countries simply moving their emissions outside their borders. But since 2007, the total emissions outsourced by countries with emissions targets under the Kyoto Protocol (that is, developed countries, including the US) has declined.

This suggests that the downward trends in emissions of the past decade are driven by real changes to economies and energy systems, and not just to offshoring emissions.

Other countries, such as Russia, Mexico, Japan, and Australia have shown more recent signs of slowdowns, flat growth, and somewhat volatile emissions trajectories as they pursue a range of different climate and energy policies in recent years.

Still, the pressure is on. In 101 countries, representing 50% of global CO₂ emissions, emissions increased as economies grew. Many of these countries will be pursuing economic development for years to come.

Contrasting fortunes among some of the world’s biggest economies.
Nigel Hawtin/Future Earth Media Lab/Global Carbon Project, Author provided

A peek into the future

During the three-year emissions “plateau” – and specifically in 2015-16 – the accumulation of CO₂ in the atmosphere grew at a record high that had not previously been observed in the half-century for which measurements exist.

It is well known that during El Niño years such as 2015-16, when global temperatures are higher, the capacity of terrestrial ecosystems to take up CO₂ (the “land sink”) diminishes, and atmospheric CO₂ growth increases as a result.

The El Niño boosted temperatures by roughly a further 0.2℃. Combined with record high levels of fossil fuel emissions, the atmospheric CO₂ concentration grew at a record rate of nearly 3 parts per million per year.

This event illustrates the sensitivity of natural systems to global warming. Although a hot El Niño might not be the same as a sustained warmer climate, it nevertheless serves as a warning of the global warming in store, and underscores the importance of continuing to monitor changes in the Earth system.

The effect of the strong 2015-16 El Niño on the growth of atmospheric CO₂ can clearly be seen.
Nigel Hawtin/Future Earth Media Lab/Global Carbon Project, based on Peters et al., Nature Climate Change 2017, Author provided

No room for complacency

There is no doubt that progress has been made in decoupling economic activity from CO₂ emissions. A number of central and northern European countries and the US have shown how it is indeed possible to grow an economy while reducing emissions.

Other positive signs from our analysis include the 14% per year growth of global renewable energy (largely solar and wind) – albeit from a low base – and the fact that global coal consumption is still below its 2014 peak.


Read more: World greenhouse gas levels made unprecedented leap in 2016


These trends, and the resolute commitment of many countries to make the Paris Agreement a success, suggest that CO₂ emissions may not return to the high-growth rates experienced in the 2000s. However, an actual decline in global emissions might still be beyond our immediate reach, especially given projections for stronger economic growth in 2018.

The ConversationTo stabilise our climate at well below 2℃ of global warming, the elusive peak in global emissions needs to be reached as soon as possible, before quickly setting into motion the great decline in emissions needed to reach zero net emissions by around 2050.

Pep Canadell, CSIRO Scientist, and Executive Director of the Global Carbon Project, CSIRO; Corinne Le Quéré, Professor, Tyndall Centre for Climate Change Research, University of East Anglia; Glen Peters, Research Director, Center for International Climate and Environment Research – Oslo; Robbie Andrew, Senior Researcher, Center for International Climate and Environment Research – Oslo; Rob Jackson, Chair, Department of Earth System Science, and Chair of the Global Carbon Project, globalcarbonproject.org, Stanford University, and Vanessa Haverd, Senior research scientist, CSIRO

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

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2017 is set to be among the three hottest years on record


Andrew King, University of Melbourne and David Karoly, University of Melbourne

The year isn’t over yet, but we can already be sure that 2017 will be among the hottest years on record for the globe. While the global average surface temperature won’t match what we saw in 2016, it is now very likely that it will be one of the three warmest years on record, according to a statement issued by the World Meteorological Organization.

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What is more remarkable is that this year’s warmth comes without a boost from El Niño. When an El Niño brings warm waters to the tropical east Pacific, we see a transfer of heat from the ocean to the lower atmosphere, which can raise the global average temperatures recorded at the surface by an extra 0.1-0.2℃. But this year’s temperatures have been high even in the absence of this phenomenon.


Read more: Why hot weather records continue to tumble worldwide


We can already say with confidence that 2017 will end up being the warmest non-El Niño year on record, and that it will be warmer than any year before 2015. The average global temperature between January to September this year was roughly 1.1℃ warmer than the pre-industrial average.

This trend is associated with increased greenhouse gas concentrations, and this year we have seen record high global atmospheric carbon dioxide concentrations and the biggest recorded surge in CO₂ levels.

A year of extremes

Of course, none of us experiences the global average temperature, so we also care about local extreme weather. This year has already seen plenty of extremes.

Global sea ice extent continues to decline.
NASA Earth Observatory

At the poles we’ve seen a continuation of the global trend towards reduced sea ice extent. On February 13, global sea ice extent reached its lowest point on record, amid a record low winter for Arctic ice. Since then the Arctic sea ice extent has become less unusual but it still remains well below the satellite-era average. Antarctic sea ice extent also remains low but is no longer at record low levels as it was in February and March of this year.

East Africa saw continued drought with failure of the long rains, coupled with political instability, leading to food insecurity and population displacement, particularly in Somalia.

Storms and fires

This year also saw a very active North Atlantic hurricane season. Parts of the southern United States and the Caribbean were struck by major hurricanes such as Harvey, Irma, and Maria, and are still recovering from the effects.

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Other parts of the globe have seen a quieter year for tropical cyclones.

There have also been several notable wildfire outbreaks around the world this year. In Western Europe, record June heat and very dry conditions gave rise to severe fires in Portugal. This was followed by more severe fires across Spain and Portugal in October.


Read more: Wildfires are raging in the Mediterranean. What can we learn?


Parts of California also experienced severe fires following a wet winter, which promoted plant growth, and then a hot dry summer.

Australia is now gearing up for what is forecast to be a worse-than-average fire season after record winter daytime temperatures. A potential La Niña forming in the Pacific and recent rains in eastern Australia may reduce some of the bushfire risk.

The overall message

So what conclusions can we draw from this year’s extreme weather? It’s certainly clear that humans are warming the climate and increasing the chances of some of the extreme weather we’ve seem in 2017. In particular, many of this year’s heatwaves and hot spells have already been linked to human-caused climate change.

For other events the human influence is harder to determine. For example, the human fingerprint on East Africa’s drought is uncertain. It is also hard to say exactly how climate change is influencing tropical cyclones, beyond the fact that their impact is likely to be made worse by rising sea levels.

The ConversationFor much of 2017’s extreme weather, however, we can say that it is an indicator of what’s to come.

Andrew King, Climate Extremes Research Fellow, University of Melbourne and David Karoly, Professor of Atmospheric Science, University of Melbourne

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

2016 crowned hottest year on record: Australia needs to get heat smart


Liz Hanna, Australian National University; Kathryn Bowen, Australian National University, and Mark Howden, Australian National University

It’s official, 2016 set another record for being the world’s hottest. Three international agencies have confirmed today that last year was the hottest on record.

NASA reported that 2016 was 0.99℃ hotter than the 20th-century average, while the US National Oceanographic and Atmospheric Administration (NOAA) called it at 0.94℃. NOAA also calculated that global land temperatures were 1.43℃ higher. The UK Met Office, using its own data, also reported that 2016 is one of the two hottest years on record.

The figures vary slightly, depending on the baseline reference period used.

Heat records don’t linger for long any more. 2016 surpassed the 2015 record, which surpassed the 2014 record. Three record hot years in a row sets yet another record in the 137-year history of modern accurate and standardised meteorological observation.

For Australia, the Bureau of Meteorology described 2016 as a “year of extreme events” and the fourth hottest at 0.87℃ above the 1961-1990 average. The warming trend is clear.

Australia is already on average 8℃ hotter than the average global land temperature, so further warming means our heat risk is far greater than for other industrialised countries.

This dangerous warming trend sends a dire warning, as average warming delivers many more extreme heat events, as we’re currently seeing in Queensland and New South Wales. These are the killers.

As Australia lurches from heatwave to heatwave, the message is clear: extreme heat is the new norm – so Australia needs to get “heat smart”.

Rising extremes

In Australia the number of days per year over 35℃ has increased and extreme temperatures have increased on average at 7% per decade.

Very warm monthly maximum temperatures used to occur around 2% of the time during the period 1951–1980. During 2001–2015, these happened more than 11% of the time.

This trajectory of increased temperature extremes raises questions of how much heat can humans tolerate and still go about their daily business of commuting, managing domestic chores, working and keeping fit.

We can’t just get used to the heat

Air-conditioning and acclimatisation are not the answer. Acclimatisation to heat has an upper limit, beyond which humans need to rest or risk overheating and potential death. And air-conditioning, if not powered by renewable electricity, increases greenhouse gas emissions, feeding into further climate changes.

We have two key tasks ahead. The first is to stop the warming by drastically reducing emissions – the 2015 Paris Agreement was a step along this path. Several studies have shown that Australia can achieve net zero emissions by 2050 and live within its recommended carbon budget, using technologies that exist today, while maintaining economic prosperity.

Our second task is to adapt to the trajectory of increasing frequency of dangerous heat events.

A heat-smart nation

We can prevent heat-related deaths and illnesses through public health mechanisms. Australia enjoys a strong international track record of world-leading public health prevention strategies, such as our campaign against smoking.

We can equally embrace the heat challenge, by adopting initiatives such as a National Climate, Health and Wellbeing Strategy, which has the support of Australia’s health sector. Its recommendations outline a pathway to becoming a heat-smart nation.

At a recent heat-health summit in Melbourne, experts declared Australia must adopt four key public health actions to reduce heatwave deaths.

These are:

• Prevent

• Prepare

• Respond

• Educate.

These fundamental public health strategies are interlinked and operate at the government, health sector, industry and community levels.

Prevention includes reducing greenhouse gas emissions, as well as reducing exposure. The Bureau of Meteorology provides superb heat warnings that allow us to prepare. Global organisations such as the Intergovernmental Panel on Climate Change (IPCC) provide reports that can underpin greater understanding.

The next challenge is for the populace broadly to act on that knowledge. This requires having options to protect ourselves and avoid hazardous heat exposures while commuting, working and at home.

The health sector must also prepare for demand surges. Tragic outcomes will become increasingly common when, for example, ambulance services cannot meet rising demand from a combination of population growth, urbanisation and forecast heat events.

The health sector will need the capacity to mobilise extra resources, and a workforce trained in identifying and managing heat illness. Such training remains limited.

Individuals and workplaces also need to prepare for heatwaves. In a heat-smart nation, we’ll need to reschedule tasks to avoid or limit exposure, including rest periods, and to ensure adequate hydration with cool fluids.

We’ll need to think about housing. Building houses without eaves or space for trees to provide shade forces residents to rely on air-conditioning. In such houses, power failures expose residents to unnecessary heat risks, and many air-con systems struggle when temperatures exceed 40℃.

Urban planners and architects have solutions. There are many options for safe housing design, and the government should consider supporting such schemes.

We’ll need to think about our own health. Active transport, such as walking and cycling, both reduces emissions and improves fitness. Promoting active transport throughout summer requires the provision of shade, rest zones with seats, and watering stations along commuting routes. High cardio-respiratory fitness also boosts heat resilience: a win-win.

Ultimately, Australia has two options: ignore the risks of increasing heat extremes and suffer the consequences, or step up to the challenge and become a heat-smart nation.


This article was co-authored by Clare de Castella Mackay, ANU.

The Conversation

Liz Hanna, Honorary Senior Fellow, Australian National University; Kathryn Bowen, Senior Research Fellow, Australian National University, and Mark Howden, Director, Climate Change Institute, Australian National University

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

This summer’s sea temperatures were the hottest on record for Australia: here’s why


Elaine Miles, Australian Bureau of Meteorology; Claire Spillman, Australian Bureau of Meteorology; David Jones, Australian Bureau of Meteorology, and David Walland, Australian Bureau of Meteorology

The summer of 2015-2016 was one of the hottest on record in Australia. But it has also been hot in the waters surrounding the nation: the hottest summer on record, in fact.

Difference in summer sea surface temperatures for the Australian region relative to the average period 1961-1990.
Australian Bureau of Meteorology

While summer on land has been dominated by significant warm spells, bushfires, and dryness, there is a bigger problem looming in the oceans around Australia.

This summer has outstripped long-term sea surface temperature records that extend back to the 1950s. We have seen warm surface temperatures all around Australia and across most of the Pacific and Indian oceans, with particularly warm temperatures in the southeast and northern Australian regions.

Last summer’s sea surface temperature rankings for Australia.
Australian Bureau of Meteorology

In recent months, this warming has been boosted – just like land temperatures – by natural and human-caused climate factors.

Why so warm?

These record-breaking ocean temperatures around Australia are somewhat surprising. El Niño events, such as the one we’re currently experiencing, typically result in cooler than normal Australian waters during the second half of the year. So what is the cause?

The most likely culprit is a combination of local ocean and weather events, with a substantial contributor being human-caused climate change.

In the north, the recent weak monsoon season played a role in warming surface waters. Reduced cloud cover means more sunshine is able to pass through the atmosphere and heat the surface of the ocean. Trade winds that normally stir up the water and disperse the heat deeper into the ocean have also remained weak, leaving the warm water sitting at the surface.

In the south, the East Australian Current has extended further south over the summer. This warm current flows north to south down Australia’s east coast. Normally it takes a left turn and heads towards New Zealand, but this year it extended down to Tasmania, bringing warm waters to the south east.

This current is also getting stronger, transporting larger volumes of water southward over time. This is due to the southward movement of high pressure systems towards the pole.

High pressure systems are often associated with clear weather in Australia, and when they move south they prevent rain. This southward movement over time has also been linked to climate changes in our region, meaning that changes in both rainfall and ocean temperatures are responses to the same global factors.

We’ve also seen high ocean temperatures in the Indian Ocean. Around 2010, temperatures in the region suddenly jumped, likely because of the La Niña event in the Pacific Ocean. The strong events during this period transferred massive amounts of warmth from the Pacific Ocean into the Indian Ocean through the Indonesian region.

The warmer waters in the Indian Ocean have persisted since and have influenced land temperatures. The five years since the 2010 La Niña are the five hottest on record in southwest Western Australia (ranked 2011, 2015, 2014, 2013 and 2012).

What are the impacts?

The world’s oceans play a major role in global climate by absorbing surplus heat and energy. Oceans have absorbed 93% of the extra heat trapped by the Earth since 1970 as the greenhouse effect has increased. This has lowered the rate at which the atmosphere is warming – which is a good thing.

However, it also means the oceans are heating up, raising sea levels as well as leading to more indirect impacts, such as shifting rainfall patterns.

As a nation that likes to live by the coast as well as enjoy recreation activities and harvest produce from the sea, warmer-than-usual oceans can have significant impacts.

Australia derives a lot of its income from its oceans and while such impacts aren’t often seen immediately, they become apparent over time.

Warm sea temperatures this summer and in the past have seen declines in coral reef health, and strains on commercial fisheries and aquaculture. The Great Barrier Reef is currently experiencing coral bleaching amid very warm water temperatures.

Our neighbouring Pacific islands have also seen the impacts of these very high sea surface temperatures, with recent mass fish kills and coral bleaching episodes in Fiji.

The impacts of warmer ocean temperatures are also felt on land, as ocean temperatures drive climate and weather. Abnormally high sea surface temperatures may have contributed to the intensity of Cyclone Winston as cyclone potential intensity increases with ocean temperature.

What is the outlook?

The seasonal outlook from the Bureau of Meteorology shows El Niño weakening over the next few months. This typically means cooler weather and can mean more rain on land.

However, closer inspection shows surface temperatures over the entire Indian Ocean and coastal Australian waters will very likely continue to remain well above average for the next few months. There are currently signs that surface currents are moving warm El Niño waters from the eastern Pacific over to the western Pacific, towards Australia.

There is potential for the East Australian Current to continue to transport this warmth to southern waters as far as Tasmania. Warm water could also be transported through Indonesia and travel south along the Western Australian coast via the warm Leeuwin Current, potentially causing further warming of already record warm waters.

So for the near future, the waters are going to continue to be warm. That’s good news if you’re heading to the beach, but not so good for the environment.

The Conversation

Elaine Miles, Ocean Climatologist , Australian Bureau of Meteorology; Claire Spillman, Research Scientist, Australian Bureau of Meteorology; David Jones, Scientist, Australian Bureau of Meteorology, and David Walland, , Australian Bureau of Meteorology

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

It’s official: 2015 was the hottest year ever recorded


Janette Lindesay, Australian National University and Mark Howden, CSIRO

It’s official: 2015 was the hottest year on record. The US-based National Oceanic and Atmospheric Administration has confirmed overnight that 2015 saw the global average temperature climbing to 0.90°C above the 20th-century average of 13.9°C. The record has been confirmed by the UK Met Office.

It’s been only a year since the record was previously broken, but 2015 stands out as an extraordinarily hot year. 2014, the previous hottest year, was 0.74°C above the global average. December 2015 marks the first time in the NOAA record a global monthly temperature anomaly has exceeded 1°C – it reached 1.11°C.

Every month since February 1985 has been warmer than average, and 2015 is the 39th consecutive year with above-average annual temperatures in an uninterrupted run that began in the mid 1970s. Ten months in 2015 beat previous records for those months.

The evidence that the so-called “global warming hiatus” is over is compelling – if it ever existed.

https://charts.datawrapper.de/9RvfW/index.html

Air temperatures over the land rose markedly to a new record of 1.33°C above average, and ocean temperatures also reached a new record anomaly of 0.74°C in 2015. The global ocean has absorbed up to 90% of the excess heat retained or accumulated by human activities since the industrial revolution, and ocean temperatures show clear warming trends both at the surface and deep down.

In 2015/2016 a strong El Niño event is bringing some of that heat buried in the ocean back to the surface.

The “perfect storm”

Global temperatures are influenced by both natural and human factors.

2015 saw the development of an El Niño event classed as one of the three strongest on record, comparable to those of 1982/83 and 1997/98.

These events are linked to higher global air temperatures. Since 1850 many of the warmest years have also been El Niño years. El Niño events are driven by changes in the winds across the Pacific Ocean, which move warm water from the western Pacific to the east.

In 2015 central Pacific sea surface temperatures were more than 3°C above average over an area of approximately 5.5 million square kilometres, around 70% of the size of the Australian continent. Air temperatures increase during El Niño events as heat is transferred from the ocean to the atmosphere.

Sea surface temperature anomalies, Oct-Dec 2015 showing the characteristic El Niño pattern of increases across the central to eastern Pacific
NOAA

But a strong El Niño event alone is not sufficient to account for the 2015 record temperature anomaly.

In May 2015 carbon dioxide concentrations reached a monthly value of 403.9 parts per million (ppm) – the highest ever recorded. The average concentration of CO₂ in 2015 may exceed 400 pppm for the first time in human history. CO₂ is the one of the principal greenhouse gases responsible for human-induced global warming.

Since 2008 the CO₂ concentration has increased by an average of 2.1 ppm per year, largely due to fossil fuel and land-use emissions, emphasising the significant impact of human activity on the atmosphere.

CO₂ concentrations now exceed pre-industrial levels by more than 40%, and the likelihood of this increase and the associated warming being due only to natural factors is vanishingly small.

Carbon dioxide exceeded 400 ppm in 8 months in 2015.
NOAA

Climate extremes everywhere

Across the globe 2015 was characterised by weather and climate extremes from floods and severe storms to droughts and heatwaves.

In Australia climate conditions are being pushed beyond our historical experience of natural climate variability and into new territory. Global warming has increased the likelihood of record-breaking temperatures by up to 100 times.

In 2015 records were broken once again across Australia, in a series of high temperature events particularly in Western Australia (January), Queensland (March), and the south-eastern states (October, November and December).

The Bureau of Meteorology 2015 Annual Climate Statement highlights October as particularly noteworthy. October 2015 was 2.89℃ warmer than the average October inn Australia. While this doesn’t make October the hottest month overall (that title still belongs to the summer months), it is the largest margin by which a monthly record has ever been broken.

High temperatures broke the internet (literally); led to cancelled sporting events in Victoria and South Australia; and added to severe bushfire conditions in several states.

October 2015 warmest on record with largest temperature anomaly.
Australia Bureau of Meteorology

In response to concerns about this ongoing warming and the associated heat extremes, the wine industry is exploring adaptation options including changing grape varieties; cereal crop, fruit, vegetable and milk producers are trying to reduce the impact of heatwaves and droughts on yields; and we need to change our behaviour and infrastructure to deal with the health impacts of more extreme temperatures and more frequent heatwaves.

We are all affected by global warming.

The necessity of mitigation

The climate and weather impacts of 2015 in Australia are examples of what is happening around the globe, adding to the overwhelming body of evidence of the reality and impacts of global warming.

The combination of a strong El Niño event with ongoing human-induced warming of the ocean and atmosphere set up the conditions for 2015. It is unlikely to be the last such record.

El Niño events are part of natural climate variability and will continue to occur, and until greenhouse gas emissions are reduced at least in line with the Paris Climate Agreement global temperatures will continue to rise for the foreseeable future.

As agreed by the governments of the world at the Paris UNFCCC meeting, the need for effective and urgent local, national and global action to reduce emissions has never been more pointed.

The Conversation

Janette Lindesay, Professor of Climatology, Australian National University and Mark Howden, Research Scientist, Agriculture Flagship, CSIRO

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

2015 to be hottest year ever: World Meteorological Organization


Paul Yacoumis, The Conversation

2015 will likely be the hottest year on record, according to a preliminary analysis released by the World Meteorological Organization. Worldwide temperatures are expected for the first time to reach more than 1℃ above pre-industrial temperatures.

The five years from 2011-2015 will also likely be the hottest five-year period on record. Average global atmospheric CO₂ concentrations over three months also hit 400 parts per million for the first time during the southern hemisphere Autumn this year. On top of this, we are experiencing one of the strongest El Niño events ever recorded.

According to Dr Karl Braganza, head of climate monitoring at the Australian Bureau of Meteorology, these climate milestones are both symbolic and highly significant.

“One degree is half way to the 2 degree guardrail of warming that the global community is aiming for in terms of future climate change,” Dr Braganza said.

“400 parts per million of CO₂ in the atmosphere is a composition that the climate system has not likely seen in probably the past 2.5 million years.”

In Australia, 2015 is likely to fall into the top 10 warmest years on record, all of which have occurred this century.

Dr Braganza said that record breaking hot weather was now six times more likely than it was early last century. Meanwhile, the oceans continue to warm at an alarming rate.

“About 90% of the additional heat from the advanced greenhouse effect goes into warming the oceans,” he said.

This is particularly worrying as any change to sea temperature is potentially very significant in terms of impacts on Australia’s weather, from droughts to flooding rains.

Dr David Karoly, Professor of Atmospheric Science at the University of Melbourne, said that there was little doubt as to the cause of the warming.

“It is now all but certain that 2015 will be the hottest year since record keeping began.

“The new record high global temperature in 2015 is mainly due to human-caused global warming, with smaller contributions from El Niño and from other natural climate variations,” Dr Karoly said.

According to calculations by Karoly and colleagues as part of the World Weather Attribution Project coordinated by Climate Central, temperatures will likely reach around 1.05℃ above pre-industrial temperatures. Of this, about 1℃ can be attributed to the release of greenhouse gases into the atmosphere, about 0.05ºC-0.1ºC to El Niño, and about 0.02ºC to higher solar activity. The numbers don’t quite add up to 1.05℃ due to uncertainties and natural variability.

The World Meteorological Organization statement comes as world leaders are set to meet in Paris next week to begin the next round of negotiations on taking action against climate change.

Comments compiled with the assistance of the Australian Science Media Centre.

The Conversation

Paul Yacoumis, Editorial intern, Environment & Energy, The Conversation

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