The annual review of extreme weather and climate events published in the Bulletin of the American Meteorological Society today highlights how climate change is influencing the events that affect us the most. This table summarises each event and whether climate change played a role.
Across the globe, extreme heat events are linked with climate change, although El Niño provided a boost in 2015 leading to more records being broken. The human influence on rainfall and drought is less strong but we can see it in many events that were studied.
Our influence on the climate extends beyond temperature and rainfall. In the UK, the chance of very sunny winters (which sounds like an oxymoron!) has increased due to climate change. The record low sea ice extents, which have continued into 2016, are strongly associated with human influences.
While the majority of studies have been done on the developed world, more analyses of developing countries are included this year than in the past. Through collaborations between local experts and teams in the United States and Europe, a greater emphasis on extreme events in the developing world was possible.
This is important because the impacts of extreme events are often more severe in these areas than in wealthier regions.
The effects of climate change on extremes spread far and wide as human activities have radically altered our climate. We can expect to see more extreme events with a clear fingerprint of human-caused climate change in the coming years and decades.
Generation Y has grown up in a rapidly warming world. According to the US National Climate Data Centre, every month since February 1985 has seen above average global temperatures, compared with the twentieth century. I have no memories of a “normal” month.
The question now is what the future will look like. At some point in the decades to come, these record-breaking temperatures will not be rare; they will become normal. But when exactly?
In a new study just released in the Bulletin of the American Meteorological Society, I (together with co-authors Andrew King and Sarah Perkins-Kirkpatrick) find that on the current greenhouse gas emissions trajectory, global temperatures like 2015 will by normal by 2030, and Australia’s record-breaking 2013 summer will likely be an average summer by 2035.
While we still have time to delay some of these changes, others are already locked in – cutting emissions will make no difference – so we must also adapt to a warmer world. This should be a sobering thought as world leaders gather in Marrakech to begin work on achieving the Paris Agreement which came into force last week.
What is a new normal for our climate? The term has been used broadly in the media and in scientific literature to make sense of climate change. Put simply, we should get used to extremes temperatures, because our future will be extreme.
But without a precise definition, a new normal is limited and difficult to understand. If 2015 was a new normal for global temperatures, what does it mean if 2017, 2018, or 2019 are cooler?
In our study we defined the new normal as the point in time when at least half the following 20 years are warmer than 2015’s record breaking global temperatures.
We examined extreme temperatures in a number of state-of-the-art climate models from an international scientific initiative. We also explored how different future greenhouse gas emissions impact temperatures.
We used four different greenhouse gas scenarios, known as Representative Concentration Pathways, or RCPs. These range from a business-as-usual situation (RCP8.5) to a major cut to emissions (RCP2.6).
It is worth emphasising that real-world emissions are tracking above those covered by these hypothetical storylines.
Our findings were straightforward. 2015’s record-breaking temperatures will be the new normal between 2020 and 2030 according to most of the climate models we analysed. We expect within a decade or so that 2015’s record temperatures will likely be average or cooler than average.
By 2040, 2015’s temperatures were average or cooler than average in 90% of the models. This result was unaffected by reducing greenhouse gas emissions or not – we are already locked in to a significant amount of further warming.
We also looked at the timing of a new normal for different regions. Australia is a canary in the coal mine. While other regions don’t see extreme temperatures become the new normal until later in the century, Australia’s record-breaking 2013 summer temperatures will be normal by 2035 – according to the majority of the models we looked at.
At smaller spatial scales, such as for state-based based temperature extremes, we can likely delay record-breaking temperatures becoming the new normal by committing to significant greenhouse gas cuts. This would clearly reduce the vulnerability of locations to extreme temperatures.
Living in a warmer world
If you like heading to the beach on hot days, warmer Australian summers seem appealing, not alarming.
But Australia’s position as a hot spot of future extremes will have serious consequences. The 2013 summer, dubbed the “angry summer”, was characterised by extreme heatwaves, widespread bushfires and a strain on infrastructure.
Our results suggest that such a summer will be relatively mild within two decades, and the hottest summers will be much more extreme.
My co-authors, Andrew and Sarah, and I all grew up in a world of above-average temperatures, but our future is in a world were our recent record-breaking temperatures will be mild. Our new research shows this is not a world of more pleasantly hot summer days, but instead of increasingly severe temperature extremes.
These significantly hotter summers present a challenge that we must adapt to. How will we protect ourselves from increases in excess heat deaths and increased fire danger, and our ecosystems from enhanced warming?
While we have already locked ourselves into a future where 2015 will rapidly become a new normal for the globe, we can still act now to reduce our vulnerability to future extreme events occurring in our region, both through cutting emissions and preparing for increased heat.
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.
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.
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.
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.
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.
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.
Environmental news, as a rule, doesn’t deal in triumphs. So the sight of leaders holding their arms aloft in celebration after clinching the historic Paris climate agreement will stand as a defining image of 2015 – a moment of cartharsis after more than two decades of infuriatingly sluggish climate diplomacy.
After two weeks of round-the-clock negotiations (and years of work beforehand), the Paris climate summit has delivered the first binding treaty under which all nations, rich and poor, will join the bid to limit global warming to “well under 2℃”, and possibly no more than 1.5℃.
Earlier in the year it held its first reverse auction for the Emissions Reduction Fund, which will use public money to invest in emissions-reducing projects without a carbon tax. Doubts still remain over whether it is fit for purpose.
One of the reasons green groups oppose the Carmichael mine is the fact that the coal will be shipped across the Great Barrier Reef. Australia faced the prospect of international embarrassment as the UN World Heritage Committee weighed up whether to add the Reef to its official list of world heritage in danger – an ignominy generally reserved for heritage sites in war-torn places like Iraq and the Congo.
In the event Australia was reprieved after persuading the UN that it now has policies in place to safeguard the Reef. Progress will be reviewed in 2019, and as our Reef threats series pointed out, the problems are many and complex.
Speaking of heat, you wouldn’t have wanted to be sitting in Volkswagen’s boardroom as the news broke about the company’s systematic gaming of vehicle emissions testing, bringing worldwide condemnation. It’s still not clear how widespread the issue will turn out to be, but Australian diesel drivers will face a rough road ahead regardless – 2016 is the year that Australia’s lax vehicle emissions standards will finally be brought into line with much of the rest of the developed world, potentially wiping out much of the financial advantage of driving a diesel.
Of course you could always catch a tram – or at least you might in a few years, if the many light rail projects planned for Australia come to fruition. After two years of roads-only infrastructure policy under Abbott, Turnbull has changed course and will invest in public transport too. Along with the appointment of cities minister Jamie Briggs, it’s a sign that the Canberra government might finally be starting to understand cities, which after all is where most of us live.
One car company whose star was definitely on the rise was Tesla, which branched out from electric sports cars to unveil an affordable power storage battery for use with home solar panels. It has been hailed as a game-changer in the bid to wean households off fossil-fuelled electricity, although it’s still early days in in figuring out how to smooth out the intermittency issues that still beset renewable energy.
The uncertainty over renewables and the growing urgency about getting away from fossil fuels are two reasons why nuclear is still getting attention, even in Australia where the prospect of nuclear power is politically unpalatable.
In March, South Australia launched a Royal Commission on nuclear power, uranium mining and nuclear waste, to the bafflement of those who thought we’ve had all these debates already.
True, Australia does eventually need somewhere to store its current stockpile of low-level nuclear waste from sources such as medical scans – and to that end the government shortlisted six sites ahead of a decision next year.
You might also spare a thought for Australia’s animals – and on that front there has been some encouraging news amid the usual environmental concerns.
While things look grim for many species, like Leadbeater’s possum or orange-bellied parrots, this year conservationists declared victory for Australia’s humpback whale population – more evidence that environmentalism can still conjure up the odd moment of triumph.
Despite robust global economic growth over the past two years, worldwide carbon emissions from fossil fuels grew very little in 2014, and might even fall this year.
A report released today by the Global Carbon Project has found that fossil fuel emissions of carbon dioxide grew by only 0.6% in 2014, breaking with the fast emissions growth of 2-3% per year since early 2000s. Even more unexpectedly, emissions are projected to decline slightly in 2015 with continuation of global economic growth above 3% in Gross Domestic Product.
This is the first two-year period in a multi-decade record where the global economy shows clear signs of decoupling from fossil fuel emissions. In the past, every single break or decline in the growth of carbon emissions was directly correlated with a downturn in the global or regional economy.
This time is different.
However, it is quite unlikely that 2015 is the much-sought-after global peak in emissions which will lead us down the decarbonisation path required to stabilise the climate.
In a separate paper published today in Nature Climate Change, we look in more detail at the possibility of reaching global peak emissions.
What caused it?
The principal cause of this unexpected lack of growth in emissions is the slowdown in the production and consumption of coal-based energy in China in 2014, followed by a decline in 2015.
This has taken China’s emissions growth from close to double digits during the past decade to an extraordinary low of 1.2% growth in 2014 and an unexpected decline by about 4% projected for 2015.
Although China is only responsible for 27% of global emissions, it has dominated the growth in global emissions since early 2000s. Therefore, a slowdown in China’s emissions has an immediate global impact.
Further adding to this main cause, emissions from industrialised economies, including Australia, Europe and the United States, have declined by 1.3% per year on average over the past decade, partially supported by extraordinary growth of renewable energy sources.
Have we reached global peak emissions?
Most likely not. One key uncertainty in answering this question is the future of coal in China. But China is pushing to achieve peak carbon consumption as early as possible (and emissions by 2030), and to phase out the dirtiest types of coal from the nation’s energy mix, largely in response to a pollution crisis affecting many of its large urban areas. It is well within the possibilities that growth in coal emissions in China will not resume any time soon, and certainly not at the fast pace of the previous decade.
A strong basis for this assessment is the remarkable growth in non-fossil fuel energy sources such as hydro, nuclear and renewables. These accounted for more than half of the growth in new energy in 2014, with a very similar mix during the first three-quarters of this year. Such structural changes, if continued, could bring China’s peak emissions much earlier than anyone is anticipating and certainly well before 2030.
Although it is unlikely that we have reached global peak emissions, it is very likely that 2015 marks a new era of slower growth in fossil fuel emissions. This is perhaps the first sign of a looming peak on a not-too-distant horizon.
This might well be the future. But models used for such analysis were not that different from those that completely missed the very rapid rise of the Chinese economy in the decade of 2000 and perhaps now its rapid decarbonisation.
However, China is not alone in this game. Industrialised countries plus China, accounting for half of global fossil fuel emissions, have pledged to reduce or stabilise emissions absolutely by 2030.
But the other half belongs to less-developed nations whose pledges do not include absolute emission reductions but departures from business-as-usual scenarios (meaning emissions can increase, but not as fast). This emphasises the disproportionate importance of international climate finances required to help that “other” half of the emissions to peak and join the decline of the rest.
2015 has been an extraordinary year, and not just because of China. Emissions from Australia, Europe, Japan and Russia have all come down as part of longer or more recent trends. Installed wind capacity reached 51 gigawatts in 2014, an amount greater than the total global wind capacity just a decade ago. Solar capacity is 50 times bigger than it was ten years ago.
And emissions from land-use change, albeit with large uncertainties and high emissions from Indonesian fires this year, have been on a declining trend for over a decade. These trends are not stopping here.
Yet the current emissions path is not consistent with stabilising the climate at a level below 2℃ global warming.
If we maintain the level of 2015 emissions, the remaining carbon budget before setting the earth on a path that exceeds 2℃ is less than 30 years away, unless we bet on unproven negative emissions technologies to remove carbon from the atmosphere later in the century.
But 2015 is a historic year to galvanise further action. The trends in emissions are favourable, and countries have the opportunity to negotiate significantly higher levels of ambition to decouple economic growth from emissions.
Pep Canadell, CSIRO Scientist, and Executive Director of Global Carbon Project, CSIRO
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.