Earth’s degradation threatens health gains
The unprecedented degradation of Earth’s natural resources coupled with climate change could reverse major gains in human health over the last 150 years, according to a sweeping scientific review published last week in the peer-reviewed medical journal The Lancet.
Climate change, ocean acidification, depleted water sources, polluted land, overfishing, biodiversity loss — all unintended by-products of humanity’s drive to develop and prosper — “pose serious challenges to the global health gains of the past several decades”, especially in poorer nations, the 60-page report concludes.
The likely impacts on global health of climate change, ranging from expanded disease vectors to malnourishment, have been examined by the UN’s panel of top climate scientists. But the new report, entitled “Safeguarding Human Health in the Anthropocene Epoch”, takes an even broader view.
The “Anthropocene” is the name given by many scientists to the period — starting with mass industrialisation — in which human activity has arguably reshaped Earth’s biochemical make-up.
“This is the first time that the global health community has come out in a concerted way to report that we are in real danger of undermining the core ecological systems that support human health,” said Samuel Myers, a scientist at Harvard University and one of the authors.
A companion study on the worldwide decline of bees and other pollinators, led by Myers and also published in The Lancet, illustrates one way this might happen.
The dramatic decline of bees has already compromised the quantity and quality of many nutrient-rich crops that depend on the transfer of pollen to bear fruit. Pollinators play a key role in 35% of global food production, and are directly responsible for up to 40% of the world’s supply of micronutrients such as vitamin A and folate, both essential for children and pregnant women.
The complete wipeout of pollinating creatures, the study concludes, would push a quarter of a billion people into the red-zone of vitamin A or folate deficiency, and cause an increase in heart disease, stroke and some cancers, leading to some 1.4 million additional deaths each year. A 50% loss of pollination would result in roughly half that impact, the researchers found.
Scientist are still debating exactly why pollinators are dying off, but there is no disagreement that all the possible causes — pollution, insecticides, land-loss — are related to human activity.
A second companion study examines for the first time the impact of decreased zinc levels in staple crops such as wheat, rice, barley and soy caused by higher levels of carbon dioxide in the atmosphere, the main driver of global warming.
Already, nearly a fifth of the world’s population is at risk of zinc deficiency, which can cause premature delivery, reduce growth and weight-gain in children, and compromise immune functions. By 2050, projected CO2 emissions could place an additional 150 million people at risk, according to the study published in Lancet Global Health.