From a new peak in carbon dioxide levels in the atmosphere to the lab-grown hamburger, it's been a big year for science. Staff from the New Zealand Science Media Centre and their Australian counterparts put together their 10 top picks for the world's biggest science stories of 2013

1. Voyager reaches the next frontier

- It's taken 36 years, but United States scientists were able to confirm this year that Nasa's Voyager 1 spacecraft has journeyed out of the solar system, making it the first man-made object to reach interstellar space.

The probe was launched in 1977 with the aim of reaching Jupiter and Saturn, but it is now more than 19 billion kilometres from the sun. Scientists listened in to vibrations in the plasma surrounding Voyager - the sound of interstellar space - after it was hit by a massive solar wave in April. The vibrations allowed them to calculate the plasma's density, which differs between our solar system and interstellar space, confirming Voyager was no longer in the solar system.

Watch the Nasa video of Voyager 1's mission.
2. Climate of concern - In a year that also saw the release of the biggest report on climate change to date, and United Nations climate talks in Warsaw that finished a long way from global resolution, the amount of carbon dioxide in the Earth's atmosphere reached a symbolic milestone. In May, the level of CO2 passed the 400 parts per million mark for the first time in human history. Months later, the leading international body for the assessment of climate change, the Intergovernmental Panel on Climate Change (IPCC), found that human influence on the climate system is clearer than ever - we are now 95 per cent certain that humans are the cause of global warming. Climate scientists from New Zealand were among the more than 600 scientists and researchers who worked on the IPCC report.


3. Human stem cells created by cloning - In May, researchers from the Oregon Health and Science University used therapeutic cloning to create human embryonic stem cells for the first time. This process involved taking the nucleus, which contains the genetic material, from a normal cell and transferring it into an unfertilised egg with its own genetic material removed. While this approach had previously been used in monkeys and mice, it had never succeeded using human cells.

This discovery could help develop personalised therapies for a range of currently untreatable diseases. However, the process requires human donor eggs, which are not easy to obtain, and raises a number of ethical issues.

4. Birth of the Franken-burger - The world's first lab-grown burger was cooked and eaten at a news conference in London in August, making headlines around the world. The burger patty, which one food critic described as "close to meat", was developed by scientists from Maastricht University in the Netherlands through research funded by Google co-founder Sergey Brin. Starting with stem cells from a biopsy of two cows - a Belgian Blue and a Blonde d'Aquitaine - the scientists grew muscle fibres in the lab. The fibres were pressed together with breadcrumbs and binding ingredients, then coloured with beetroot juice and saffron, resulting in the most expensive hamburger in history at a cost of about $400,000.

5. Wonder cure for the "Mississippi Baby" - A child born with HIV and treated with a series of antiviral drugs for the first 18 months of her life was found to be free of the virus more than 12 months after treatment ended. When the infant was 30 months of age, HIV-1 antibodies remained completely undetectable. However, the big question of whether this baby girl, known as the "Mississippi Baby", had truly been cured of HIV remains unanswered. "The best answer at the moment is a definitive maybe," HIV expert Scott Hammer wrote in a New England Journal of Medicine editorial which accompanied the research.

6. Rewriting psychiatric medicine's bible - In May, the new version of the diagnostic reference manual used by clinicians in the US and around the world to diagnose mental disorders was released. The fifth revision of the Diagnostic and Statistical Manual of Mental Disorders, better known as the DSM-5, is the first update in nearly 20 years and followed a decade of review and consultation. Its publication met with widespread controversy.

One of its major changes is to introduce a graded scale known as autism spectrum disorder combining the former four autism-related disorders: autistic, Asperger's, childhood disintegrative, and pervasive developmental disorder. Elsewhere, several new disorders were added, new suicide risk assessment scales were introduced and the threshold for diagnosing post-traumatic stress disorder (PTSD) was lowered.

Critics of DSM-5, including New Zealand experts, argue that it will lead to the over-diagnosis of mental disorders, stigmatising millions of people who are essentially normal.

7. The mouse-grown human liver - Scientists successfully transplanted tiny "liver buds" derived from human stem cells into mice with disabled immune systems, staving off the deaths of the animals.

The preliminary results, published in Nature, will need years of follow-up research and trials, but hint at a potential solution to the worldwide scarcity of human livers for transplant.

Major technical hurdles have to be overcome before the treatment is useful for humans, including mass-producing the trillions of human iPS-derived precursor cells to replace even part of a human liver.

8. Richard III's bones discovered - In February, the bones of England's King Richard III were discovered in the inauspicious surroundings of a car park in Leicester - more than 500 years after he died. Radiocarbon dating, radiological evidence, DNA and bone analysis all helped to confirm the identity of the last Plantagenet king. As if the indignity of being dug up in a car park wasn't bad enough, further research revealed Richard was infected with roundworms in his intestines.

9. Frog's kiss of life

- Australian scientists announced in March that they had succeeded in growing early-stage embryos containing the DNA of an extinct frog. The research is the first step of Project Lazarus, which aims to bring the Australian gastric-brooding frog back to life.

The scientists took nuclei, which contain the extinct frog's DNA, from frozen tissue samples collected in the 1970s. The nuclei were injected into donor eggs from a distantly related frog, and some of the eggs went on to divide and grow into embryos, reviving hopes for an animal that has been extinct since 1983. The research was listed as one of Time magazine's top 25 inventions of this year.

10. World's largest volcano discovered - In September, scientists discovered the largest single volcano on Earth under the Pacific Ocean. The megavolcano spans 650km - but don't worry, it's been slumbering for the past 145 million years. Scientists had thought the Tamu Massif was a series of volcanoes, but the Integrated Ocean Drilling Programme, in which New Zealand is a partner - showed it is in fact a single, immense volcano, constructed from huge lava flows that emanated from the volcanic centre to form a broad, shield-like shape.

And ... the NZ Science Media Centre's pick for our own 10 biggest science stories of the year

1. The biggest dry

- The year began with the worst drought since 1946, with incredibly dry conditions that soon had farmers throughout the country struggling to feed their animals. The entire North Island was officially declared a drought zone and ongoing water restrictions were imposed in many regions.

2. Viagra for pregnant women

- Researchers from Gravida and the University of Auckland embarked on the world's first clinical trial of a new therapy that adapts sildenafil, the generic form of Viagra, for use in pregnant women whose babies have intrauterine growth restriction.

3. Capital rattled by earthquakes - A magnitude 6.5 earthquake beneath Cook Strait in July and subsequent aftershocks reminded New Zealanders of just how active a seismic region we all live in. The earthquakes caused damage to buildings in central Wellington and in Seddon, close to the epicentre. The quakes also posed a puzzle for scientists getting to grips with what happened on what faults beneath Cook Strait.

4. Fluoridation in the spotlight - Hamilton City Council's decision in July to suspend fluoridation of the town water supply sparked widespread debate about the use of the compound to combat tooth decay. The move went against Ministry of Health guidelines and was widely condemned by dental experts.

The botulism scare sparked a trade crisis and diplomatic tensions. Photo / APN
The botulism scare sparked a trade crisis and diplomatic tensions. Photo / APN

5. Fonterra's food scare

- New Zealanders became acquainted with the microbe clostridium botulinum when dairy giant Fonterra revealed its milk powder may have been tainted with the potentially deadly bacterium. Fonterra quickly moved to recall shipments of infant formula, sparking a trade crisis for the Government and diplomatic tensions.

6. The sugar babies project - A study of babies born at Waikato Women's Hospital in Hamilton between 2008 and 2010 found that a cheap and easy-to-administer dextrose gel should be used to treat low blood sugars in newborns, a condition that affects five to 15 per cent of newborns and, in severe cases, can lead to brain damage.

7. Getting to grips with Psa - The genome of Psa-V, the causal agent of bacterial canker of kiwifruit, was sequenced by a team of scientists at the University of Otago, with the results published in PLoS ONE. The study confirmed a Chinese origin for the bacteria and revealed genetic clues about why this variant of the plant disease devastated New Zealand kiwifruit crops.

8. Cosmic clues in the ice - The international IceCube research team, which includes New Zealanders working with scientific instruments buried 2km down beneath the South Pole, detected for the first time neutrinos from outside the solar system. The research published in the journal Science detailed the observation of 28 high-energy particle events that constitute the first solid evidence for astrophysical neutrinos from cosmic sources.

E-cigs are found to be more useful for those wanting to quit. Photo / NZ Herald
E-cigs are found to be more useful for those wanting to quit. Photo / NZ Herald

9. Patches and e-cigarettes

- The first trial to compare e-cigarettes with nicotine patches, undertaken by researchers from the University of Auckland, found that both methods result in comparable success in quitting, with roughly similar proportions of smokers who used either method remaining abstinent from smoking for six months after 13-week courses.

10. DNA secrets of the Wairau Bar - University of Otago researchers sequenced the mitochondrial DNA from several human samples extracted from the Wairau Bar burial site in the Northern South Island, revealing there was a greater level of genetic diversity than expected in the early settlers of New Zealand. The results cast doubt upon the theory that New Zealand was settled via small accidental or unplanned voyages.