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.

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.

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We could reduce pest carp in Australian rivers using a disease that came from Israel

Susan Lawler, La Trobe University

Everyone wants to give Australian carp the herpes virus. That’s right, introduced carp are a serious pest species and research suggests that a viral control agent may be the most effective solution.

I love stories like this one, where groups that would normally disagree come together in an “unlikely coalition”. That is to say, fishers, conservationists, irrigators, scientists and farmers agree on the desirability of an environmental release of the carp-specific virus.

After all, it worked for rabbits. The release of the myxomatosis virus in the 1950s and the more recent release of calicivirus have permanently decreased rabbit numbers on our continent. Using viral pathogens to control vertebrate pests can be extremely effective because it does not require ongoing human intervention.

Like rabbits, carp were introduced to Australia deliberately. The first introductions in the 1800s did not cause problems, but a strain bred for European aquaculture escaped from farm dams near Mildura in the 1960s and spread throughout the Murray Darling Basin. The impact of carp on our rivers has been well documented, including increasing turbidity (making the water muddy), destroying aquatic vegetation, and contributing to the decline of native fish.

In other parts of the world, carp are an important food species, often raised in fish farms. When I worked on a kibbutz in Israel in 1980 we caught and sorted carp from geothermal pools near the Sea of Galilee. The fish were a desirable food item and water from the fish ponds was used to fertilise banana crops via drip irrigation. I admired the sustainable farming practice that was then ahead of its time.

Twenty years later while participating in a fish survey at Horseshoe Lagoon near Albury, I remember pulling dozens of giant carp out of our nets, lamenting the lack of native fish. Because we were not allowed to return the carp to the water due to its pest status, we had to kill each one, resulting in a large pile of stinky dead fish that nobody wanted to eat.

The only similarity between these two memories was the method of death: although it looks brutal and cruel, hitting carp on the back of the head with a heavy wooden stick dispatches them instantly and humanely. On those two occasions this peaceful vegetarian turned into a lethal killing machine.

Ironically, at about the time I was whacking pest carp in Australia, the carp industry in Israel was affected by a new disease. The koi herpesvirus, or Cyprinid herpesvirus 3 (CyHV-3) appeared in Israel in 1998 and was so contagious that it soon spread throughout Europe and Asia. The carp industry was devastated.

While this virus is bad news for carp farming, it could be good news for managing feral carp in Australia. With an expected mortality rate of 70-80%, CyHV-3 may be just what we need to curb the plague of carp in our rivers.

Of course, given our sometimes disastrous experience with biological control species, caution is warranted. That’s why scientists have spent the last eight years doing research to ensure that the herpes will not affect other species. Ken McColl is a leader of the team that has examined the host specificity of the virus in an Australian context.

The good news is that CyHV-3 has no impact on other native fish, yabbies and trout. It cannot infect mammals, amphibians or reptiles. In other words, it looks safe.

The bad news is that it will affect ornamental carp (koi) which are highly valued, so people who keep koi will need to monitor their water and food sources. I see this as something like vaccinating your pet rabbits against calicivirus, an inconvenient but reasonable impost given the benefit for the nation and our environment.

What happens now? There are a number of government organisations that are responsible for biosecurity. Getting approval to introduce a virus into our waterways will probably take a few years, so the research will continue as the Invasive Animals Cooperative Research Centre goes through the application process.

There is also research underway to identify locations suitable for early releases, and this is where members of the public can get involved. Hotspots for invasive fish species will be identified by gathering data from concerned citizens at a new website called Feral Fish Scan. Anyone interested in learning how to identify invasive fish and record observations of their local waterways can do so at this link.

Other conventional approaches to reducing carp are still underway, from the development of traps that target carp to better ways for Charlie Carp to turn those feral fish into fertiliser. But harvesting tons of carp and turning them into pellets will never reduce the impact of this noxious pest as effectively as a carp-specific disease.

This is why virtually everyone is excited about the possibility of giving herpes to Australian carp. And even though I think it sounds like a good idea, I am also grateful that we have robust regulations about biocontrol, because there was a time when cane toads seemed like a good idea, too.

We can wait a couple of years to ensure that we do not regret our decision, but then we may enjoy a great irony: a disease that caused huge financial losses overseas could save freshwater environments in Australia.

Susan Lawler, Senior Lecturer, Department of Ecology, Environment and Evolution, La Trobe University

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