A large-scale analysis （分析）of nearly 1,000 scientific studies has shown just how closely human activity is tied to public health. The findings suggest environmental changes caused by human activities are making the risk of infectious （传染的） disease outbreaks all the more likely. The biodiversity （生物多样性） crisis—which has let some one million plant and animal species at risk of extinction—is a leading driver of disease spread, the researchers found.
"It could mean that by changing the environment, we increase the risks of future pandemics （流行病）,"said Jason Rohr, a co-author of the study and a biologist at the University of Notre Dame.
The analysis studied at least one of five "global change drivers" affecting wildlife and landscapes on Earth: biodiversity change, climate change, habitat loss and change, chemical pollution and the introduction of non-native species to new areas. The researchers collected nearly 3,000 data points related to how each of these factors might impact the seriousness of infectious disease outbreaks.
Their conclusions showed that four of the examined factors—climate change, chemical pollution, the introduction of non-native species to new areas and biodiversity loss—all increased the likelihood of spreading diseases, with the latter having the most significant impact. Disease and death rate were nearly nine times higher in areas of the world where human activity has reduced biodiversity, compared to the levels expected by Earth's natural variation in biodiversity.
One global change factor, however, actually reduced the likelihood of disease outbreaks: habitat loss and change. But here, context is key. Most habitat loss is linked to creating a single type of environment—urban （城市的） ecosystems—which generally have good sanitation（卫生）systems, reducing opportunities for disease outbreaks.
The new work adds to past research on how human activity can cause the spread of disease. The research signals the need for public health officials to remain watchful as the effects of human-caused climate change arise.
