Up to one fifth of the Amazon rainforest is emitting more carbon dioxide (CO₂), than it absorbs, new research suggests. Results from a decade-long study of greenhouse gases over the Amazon rainforest appear to show around 20% of the total area has become a net source of CO₂ in the atmosphere. One of the main causes is deforestation. While trees are growing, they absorb CO₂ from the atmosphere; dead trees release it again. However, the fact is that millions of trees have been lost to logging and fires in recent years.

The results of the study, which have not yet been published, have implications for the effort to combat climate change. They suggest that the Amazon rainforest, a vital carbon “store”, or “sink”, that slows the pace of global warming may be turning into a carbon source faster than previously thought. Every two weeks for the past 10 years, a team of scientists led by Professor Luciana Gatti, a researcher at Brazil’s National Institute for Space Research (INPE), has been measuring greenhouse gases by flying aircraft fitted with sensors over different parts of the Amazon basin. What the group found was startling: while most of the rainforest still retains its ability to absorb large quantities of CO₂ — especially in wetter years — one portion of the forest, which is especially heavily deforested, appears to have lost that capacity.

Gatti’s research suggests this south-eastern part of the forest, about 20% of the total area, has become a carbon source. “Each year is worse,” she told Newsnight. “We observed that this area in the south-east is an important source of carbon. And it doesn’t matter whether it is a wet year or a dry year. 2017 was a wet year, but it didn’t make any difference.”

A forest can become a source of carbon rather than a “store”, or “sink”, when trees die and emit carbon into the atmosphere. Areas of deforestation also contribute to the Amazon’s inability to absorb carbon.

Carlos Nobre, who co-authored Prof Gatti’s study, called the observation “very worrying” because “it could be showing the beginnings of a major tipping point”. He believes the new findings suggest that in the next 30 years, more than half of the Amazon could transform from rainforest into savanna (稀树草原).

Living in the USA today is to gain an appreciation for Dahrendorf’s words there are social changes everywhere. Technology, the application of knowledge for practical ends, is a major source of social change.

Yet we would do well to remind ourselves that technology is a human creation; it does not exist naturally. A spear(矛) or a robot is much a cultural as a physical object. Until humans use a spear to hunt game or a robot to produce machine parts, neither is much more than a solid mass of matter. For a bird looking for an object on which to rest, a spear or robot serves the purpose equally well. The explosion of the Challenger space shuttle and the Russian nuclear accident Chernobyl drive home the human quality of technology; they provide cases in which well-planned systems suddenly went wrong and there was no ready hand to set them right. Since technology is a human creation, we are responsible for what is done with it. Pessimists(悲观主义者) worry that we will use our technology eventually to blow our world and ourselves to pieces. But they have been saying this for decades, and so far we have managed to survive and even flourish. Whether we will continue to do so in the years ahead remains uncertain. Clearly, the impact of technology on our lives deserves a closer examination.

Few technological developments have had a greater impact on our lives than the computer revolution. Scientists and engineers have designed specialized machines that can do the tasks that once only people could do. There are those who say that the switch to an information-based economy is in the same camp as other great historical milestones, particularly the Industrial Revolution. Yet when we ask why the Industrial Revolution was a revolution, we find that it was not the machines. The primary reason why it was a revolution is that it led to great social change. It gave rise to mass production and, through mass production, to a society in which wealth was not confined to the few.

In somewhat similar fashion, computers promise to revolutionize the structure of American life, particularly as they free the human mind and open new possibilities in knowledge and communication. The Industrial Revolution supplemented and replaced the muscles of human and animals by mechanical methods. The computer extends this development to supplement and replace some aspects of the mind of human beings by electronic methods. It is the capacity of the computer for solving problems and making decisions that represents its greatest potential and that poses the greatest difficulties in predicting the impact on society.

If you’ve ever felt “butterflies in your stomach” when nervous, you’re likely getting signals from an unexpected source: your second brain. Hidden in the walls of the digestive system, this “brain in your gut (肠道) ” is revolutionizing medicine’s understanding of the links between digestion, mood and health. Scientists call this little brain the enteric nervous system (ENS 肠神经系统).

The ENS is two thin layers of more than 100 million nerve cells lining your gut. Unlike the big brain in your head, the ENS can’t calculate or compose a love note. “Its main role is controlling digestion,” explains Jay Pasricha, M.D., director of the Johns Hopkins Center. “The enteric nervous system doesn’t seem capable of thought as we know it, but it communicates back and forth with our big brain.” For decades, researchers and doctors thought that anxiety and depression contributed to gut problems. But Pasricha’s research shows that it can also be the other way around.

Our two brains “talk” to each other, so treatments that help one may help the other. In a way, doctors who treat digestive conditions are like advisors looking for ways to comfort the second brain. Psychological approaches also help to improve communications between the big brain and the brain in our gut.

Pasricha says the research suggests that digestive-system activity may affect thinking skills and memory, too. “This is an area that needs more research, something we hope to do here at Johns Hopkins,” he says.