The science stories that shaped 2019

From the first image of a black hole to a detailed survey of sea ice in the Arctic, scientists pick the breakthrough moments that defined the year

The world awoke to the need to combat global heating

Was 2019 the year people finally started to listen to climate scientists on global heating? The previous year, the Intergovernmental Panel on Climate Change (IPCC) had laid out the monumental challenge of limiting warming to 1.5C. Global CO2 emissions would need to halve within 12 years, and reach zero around 2050. But emissions are still rising, while UN summits make tiny steps towards agreeing how to reduce them. The “emissions gap” between target and reality grows ever wider – and becomes ever harder to close.

This struck a chord with vast numbers of people, especially the young, who are thinking ahead to what their world could look like. Greta Thunberg kickstarted a global movement of school strikers, demanding that governments “listen to the science” and “act as if the house is on fire”. Although some countries have ramped up their own emissions cuts targets – the UK now officially aims for net zero emissions by 2050 – public concern and frustration has kept growing. More and more members of the public have taken extreme steps to call for urgent action on climate, with Extinction Rebellion protesters being arrested en masse and controversially keeping the issue in the news.

What if we don’t turn things around quickly? Major impacts are already baked in, with glaciers melting worldwide, Greenland losing ice rapidly, and heatwaves and fires happening more often and more severely. Heavy rainfall is increasing, as is drought in some places. We already need to live with a different climate. Although some campaigners’ rhetoric is not scientific (we don’t seriously expect “6 billion deaths”), unchecked warming would still expose tens or even hundreds of millions to extreme heat stress conditions and flooding from the sea. The worst can still be avoided, but the longer we keep heating the planet, the harder it gets.
Prof Richard Betts, climate scientist, University of Exeter and Met Office Hadley Centre

A last-chance survey of the Arctic sea ice got under way

Researchers from the icebreaker Polarstern collect snow samples from the Arctic sea ice.
Researchers from the icebreaker Polarstern collect snow samples from the Arctic sea ice. Photograph: Melanie Bergmann/Alfred-Wegener-Institut/Science Advances

Right now, on top of the world, a ship is frozen into the Arctic sea ice at the north pole. The RV Polarstern is pirouetting on the spot in the dark, with no prospect of sunlight for months to come. This region of Earth, the Arctic Ocean, is still one of the most remote and inaccessible places on our planet. We know very little about what happens here during the polar night, when temperatures can easily drop to -30C, and thick sea ice crunches and bends in the darkness. But this region is critical to Earth’s climate, and it’s essential to understand more.

The Polarstern is here on a once-in-for-ever opportunity to fill that data gap. It’s the centrepiece of the Mosaic expedition, probably the biggest polar expedition that will ever be launched. Twenty years from now, it may not be possible to do this: to freeze into the sea ice for an entire year and to drift inside this vast cold environment to watch and learn from the inside. It’s taken 20 years to organise, and over the year of the expedition (September 2019 to September 2020), 600 scientists will rotate on and off the ship, supported by many more in research institutes around the world. There is no question that the data being gathered now will drive a revolution in our understanding of the north pole and our climate, and every one of us will be affected by what they find.
Helen Czerski, physicist and oceanographer

The first image of a black hole will have huge ramifications

The image of the black hole at the centre of galaxy M87 taken by the Event Horizon Telescope in April.
The image of the black hole at the centre of galaxy M87 taken by the Event Horizon Telescope in April. Photograph: UPI/Barcroft Images

The laws of physics can be expressed in a handful of compact equations, but their reach is simply breathtaking. A stunning demonstration of this came with our first picture of a black hole, captured by the Event Horizon Telescope.

The black hole is situated at the centre of the Messier 87 galaxy, 54m light years away. The glowing ring of radiation, emitted by tortured matter spinning through warped space-time, is already iconic. The matter is plunging towards an event horizon as big as the solar system, containing the mass of 6.5bn suns.

Remarkable aspects of the image abound. The theory of general relativity, published by Einstein a hundred years ago, predicted the existence and features of this beast remarkably well. The cataclysmic whirlpool may be beyond our imagination, but it is not beyond our mathematics.

The singularity predicted at the heart of a black hole is a different story though. That is where quantum mechanics and relativity conflict and break down. We would love to know what answers lie there, and we will be scouring the image for any clues.

Finally, the global collaboration necessary to capture the image shows we can work together on a worldwide scale to a common goal – something that our science tells us we need to do more of, if we want to survive as a species and continue our exploration of the amazing universe in which we find ourselves.
Jon Butterworth, professor of physics, University College London

Progress was made in the fight against Ebola in DRC

A WHO nurse with a bottle of Ebola vaccine, Mbandaka, Democratic Republic of the Congo.
A WHO nurse with a bottle of Ebola vaccine, Mbandaka, Democratic Republic of the Congo. Photograph: Junior D Kannah/AFP via Getty Images

Ebola in 2019 highlights both the achievements of scientific progress and the persistent deep-rooted challenges of improving health in the most difficult settings. The 2014 Ebola outbreak in west Africa killed more than 11,000 people and alerted the world to its dangers. It highlighted the rich world’s neglect of research and development for infectious diseases that only rarely present a global risk.

At the end of 2019 we have a licensed Ebola vaccine, another hopefully soon to be licensed, and two effective therapeutic drugs. We can now treat those infected as well as prevent spread of the disease, allowing us to move from reactive containment to primary prevention, as a result of large and innovative collaborations that demonstrate how to help develop new and effective technologies, now and in the future.

But the current outbreak in eastern Democratic Republic of Congo has lasted more than 15 months and killed more than 2,000 people. Treatment and control continues to be hugely difficult in a setting characterised by political, economic and social fragility. Effective vaccines and drugs are part of what is needed for epidemic prevention, but we must continue to strive to address the fundamental causes of ill health in these settings.
Anne Mills, professor of health economics and policy, London School of Hygiene & Tropical Medicine

A computer model (left) and reconstruction (right) of one of two skulls found in a cave in Greece, the earliest modern human remains found outside Africa.
A computer model (left) and reconstruction (right) of one of two skulls found in a cave in Greece, the earliest modern human remains found outside Africa. Photograph: Katerina Harvati/AFP/Getty Images

We found our earliest European ancestors

Remember that time when we were young, and we had those nice neat family trees about human evolution? Lucy, Homo erectus, skip a few, Neanderthals and finally us? That whole scheme has been thoroughly binned in the last decade, with more fossil discoveries and the addition of ancient DNA to the armoury. We now have less confidence in the relationships between many more members of the human family, apart from the ones whose legacy we can see in our own DNA – our Neanderthal and Denisovan ancestors. Others will be found soon enough.

We remain an African species. Homo sapiens evolved in multiple places in Africa, and a few thousand left some 70,000 years ago to populate the rest of the world. But now we know that there were earlier diasporas from the motherland. This year, we discovered that we had made it all the way to Greece. Embedded in the roof of a cave in the southern Peloponnese, two crushed skulls were found by Katerina Harvati and her team, one a sprightly 170,000-year-old Neanderthal, but the other is us, Homo sapiens, and is more than 210,000 years old. This is far older and much farther afield than we had previously found. The revolution in the story of how we got here shows no signs of calming down.
Dr Adam Rutherford is a geneticist and author. His book How to Argue With a Racist is out in February (W&N, 12.99)

The promise and fears around gene editing ratcheted upwards

A microplate of human embryos altered by Chinese scientist He Jiankui, Shenzhen, Guangdong Province.
A microplate of human embryos altered by Chinese scientist He Jiankui, Shenzhen, Guangdong Province. Photograph: Mark Schiefelbein/AP

Although announced in November 2018, the shock waves from the announcement by the Chinese scientist He Jiankui that two girls had been born from embryos that were genetically modified using genome editing have been reverberating throughout 2019, and will no doubt continue to do so for years to come. This was a misguided and badly conducted attempt to make children resistant to infection by HIV, the virus that causes Aids, by mutating the CCR5 gene, which encodes a protein expressed on the surface of white blood cells that the virus uses to gain entry. He showed disregard for normal scientific and clinical practice, ignored risks to the children born and potentially to subsequent generations.

But the work made the prospect of altering our genetic makeup more immediate rather than theoretical. It also raised concerns about where to draw the line with the possibility of not just avoiding genetic and perhaps infectious disease, but ultimately carrying out forms of enhancement. However, it had the positive benefit of stimulating debate worldwide and it has led to the launch of international efforts, notably a science academies panel to judge the science, clinical need, and the conditions that would have to be met for germline (potentially heritable) genome editing to be carried out; and a WHO-appointed committee to develop a framework of governance that can be adopted to control the use of the genome editing methods in treating or avoiding disease. Both of these efforts will report next year.

Meanwhile, the science of genome editing and its application in both the field and clinic are progressing rapidly. A novel and ingenious new method termed prime editing, published by David Liu and colleagues, can efficiently make precise, small changes in DNA, without the problems associated with earlier methods, such as those used by He Jiankui. Given that about 85% of disease-causing mutations in humans could, in theory, be corrected by prime editing, it clearly offers great promise. Ways to make animals and plants resistant to disease and to allow plants to cope with climate change have been developed using genome editing, and this year we have seen a huge jump in the number of clinical trials using the methods to treat patients with genetic diseases (“somatic” or non-heritable gene therapy), including cancers, blindness and sickle cell disease.
Robin Lovell-Badge, group leader, the Francis Crick Institute, London

Work on batteries for the future was rightly honoured

Prof John Goodenough, the oldest person to receive a Nobel prize, for his work on lithium-ion batteries.
Prof John Goodenough, the oldest person to receive a Nobel prize, for his work on lithium-ion batteries. Photograph: Alastair Grant/AP

The rechargeable lithium-ion battery has helped power the global revolution in portable electronics, and, indeed, many of you will be reading this article on a mobile phone, laptop or tablet computer. In October this year, the three pioneers of the lithium-ion battery, John Goodenough from the University of Texas at Austin, Stan Whittingham from Binghamton University, New York, and Akira Yoshino from Japan’s Meijo University, were awarded the Nobel prize in chemistry.

For me, this award was long overdue and finally recognised an exciting area of materials chemistry. There are lots of reasons to welcome this news. For the sheer beauty of literally holding the result of their fundamental research in our hands. For the celebration of John Goodenough, who at 97 is the oldest person ever awarded any Nobel prize. For the fact that new materials lie at the heart of developing green technologies that can change the way we live and work. For spurring further development of better batteries for electric vehicles and for storing energy from wind and solar.

Perhaps most of all because it helps to shine a light on one of the most urgent challenges of our time: a low-carbon future to deal with climate change.
Saiful Islam, professor of materials chemistry at the University of Bath

Madagascar’s plight highlighted a global problem

Berthe’s mouse lemur, the world’s smallest known primate, lives only in two small areas of dry forest in western Madagascar.
Berthe’s mouse lemur, the world’s smallest known primate, lives only in two small areas of dry forest in western Madagascar. Photograph: Mark Thiessen/AP

Menabe, a dry forest in western Madagascar, is on fire. The only habitat of the world’s smallest primate (Berthe’s mouse lemur) is going up in flames as hungry people, many escaping droughts in the south, clear land for agriculture (despite the area being officially protected). Worryingly, we learned in October that this is far from an isolated problem and protected areas are less effective than previously thought.

Using a global data set of population density, night-time light and agriculture, researchers compared the changes in human pressures over time in more than 12,000 protected areas with similar unprotected areas. On average, pressures have increased faster inside than outside protected areas and those in poorer countries are particularly likely to suffer higher pressures. A decade ago, governments agreed a target to increase the proportion of the globe under conservation by 2020. Next year they gather to review progress and, potentially, commit to new targets.

The evidence is clear; when it comes to protecting sites for conservation, quality matters. Designating protected areas without effective management (including support for local communities) won’t stop the fires, hold back the expansions of farms, or, ultimately, protect species from extinction.
Julia Jones, professor in conservation science, Bangor University

Rats like playing hide-and-seek – just for fun

A rat
Rats learn to play hide-and-seek ‘for the sheer joy of playing the game’. Photograph: Eduard Lysenko/Getty Images/iStockphoto

Games of hide-and-seek are among my favourite childhood memories, and I still case novel environments for good hiding places. Researchers in Germany studied how rats can learn to play hide-and-seek with humans. All the rats learned to look for the hiding experimenter and all but one learned to hide from her. The only reward the rats received was the experimenter tickling and playing with them.

The data suggests that the rats were enthusiastically engaging in the game, looking “frantically” for the experimenter, squeaking and executing Freudensprünge (“joy jumps”) when they found her. They seemed to understand what it means to hide, preferring opaque boxes rather than clear boxes, and remaining silent (no squeals) until found. Frequently when they were found, they would tease the experimenter by running away and hiding again.

It’s worth bearing in mind how complex this hide-and-seek is – involving changes in role (hider or seeker) and theory of mind, and it’s almost alarming how well these rats learned to do this, all in the absence of classic psychological rewards like food. The experimenters conclude that the rats learn to play this game for the sheer joy of playing the game, and this is disconcertingly similar to the way human children play.
Sophie Scott, professor of cognitive neuroscience, University College London

Pioneering work on oxygen levels in the blood paid dividends

Once, during an ill-judged holiday in Borneo, I tried to climb a small mountain. While I crawled, panted and coughed on the slopes, my Malaysian guide, Miki, shuffled around politely, hands in his pockets, playing football with small rocks to slow his pace enough to match mine. Unacclimatised to altitude, it took me a day and a half to get to the summit. When I asked Miki how long it would normally take him to do the same he told me that, unencumbered by tourists like me, he could run up and down the mountain in just over three hours.

The molecular mechanisms that underpin Miki’s apparently superhuman adaptation to high-altitude life revolve around a family of proteins known as hypoxia-inducible factors (HIFs). These substances trigger alterations in a host of genes, which together help regulate oxygen levels in the human body. Their discovery helped explain how oxygen levels could be sensed and gave scientists insight into the mechanisms that allow the body to adapt and survive when demand for oxygen greatly outstrips supply.

This year Sir Peter Ratcliffe, Gregg Semenza and William Kaelin shared a Nobel prize for their part in unpicking that mystery.

Their work informs more than ill-advised summit attempts. HIFs and the regulation of oxygen levels are together central to almost all aspects of human life, whether in health or disease. The work has already been applied to develop drugs to treat anaemia and may one day lead to new treatments for stroke, spinal cord injury, chronic inflammation and even cancer.
Prof Kevin Fong is a consultant anaesthetist at University College London Hospital

The Israeli moon probe Beresheet crash-landed but broke new ground

A photograph of the lunar surface taken by the camera on board the Israeli moon probe Beresheet, which crash-landed on 11 April.
A photograph of the lunar surface taken by the camera on board the Israeli moon probe Beresheet, which crash-landed on 11 April. Photograph: AFP/Getty Images

My choice is a venture that failed – but was a heroic failure: the Israeli effort to land a small robotic vehicle on the moon. This project, named Beresheet (Hebrew for “in the beginning”), was supported by private and philanthropic funding. It attracted wide interest among the young, and showed what can be achieved with hi-tech ingenuity. To minimise the weight of fuel, it didn’t follow a direct track but was boosted into successively higher orbits around the Earth until it was captured by the moon’s gravity. It was launched on 22 February and was planned to soft-land on 10 April. But a gyroscope malfunctioned; the retro-jets didn’t ignite soon enough, and it crash-landed. I highlight Beresheet because it’s a precursor of a new style of space ventures – small scale, privately funded, and genuinely involving the public. (Indeed, Beresheet carried, as a school project, hundreds of tardigrades, microscopic “water bears”, which may have survived the impact.) We’re moving beyond an era when all space projects must involve national agencies or large commercial conglomerates.

Groups from many nations will be able to launch follow-ups similar in concept to Beresheet. Sophisticated, privately funded miniaturised probes will gather data about the moon as well as the Earth. Some may go deeper into space, using advanced robotics, and the sophisticated electronics developed for smartphones. There will still be scope for big projects – maybe even some carrying humans. But space will become an arena for independent experimenters – even hobbyists.
Martin Rees, Astronomer Royal

The kilogram was redefined using quantum physics

The standard international mass of a kilogram was redefined last month using quantum theory and caesium atoms.
The standard international mass of a kilogram was redefined last month using quantum theory and caesium atoms. Photograph: Alamy Stock Photo

There have been so many “significant” science stories in 2019 that I have been spoilt for choice. I could have gone with the climate crisis (David Attenborough’s speech at Davos or Greta Thunberg’s at the UN); or maybe the announcement of the first image of a black hole by scientists on the Event Horizon Telescope project, which seems to have already achieved iconic status. Or I could have chosen Google’s recent announcement that they had achieved quantum supremacy with their new quantum computer. But instead, I’ve gone with “quirky” rather than “significant”. In May, it was announced that the international SI units of measurement had been redefined. For example, the kilogram will no longer be compared with a cylinder of metal sitting under a bell jar outside Paris. Instead – check this out – it can be fixed just by knowing the frequency of vibration of an atom of caesium. That frequency defines the length of a second, which together with the speed of light defines the length of a metre, which in turn, together with knowing Planck’s constant of quantum theory, allows us to calculate what a kilogram is. It is so utterly cool, but probably only fascinating to geeky physicists like me. Still, I make no apology.
Jim Al-Khalili, professor of physics and public engagement in science at the University of Surrey and presenter of The Life Scientific (BBC Radio 4)


Richard Betts, Helen Czerski, Jon Butterworth, Anne Mills, Adam Rutherford, Robin Lowell-Badge, Saiful Islam, Julia Jones, Sophie Scott, Kevin Fong, Martin Rees and Jim Al-Khalili

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