WASHINGTON — Global warming is hurting people’s health a bit more than previously thought, but there is hope that the Earth — and populations — can heal if the planet kicks its coal habit, a group of doctors and other researchers said.
The poor and elderly are most threatened by worsening climate change, but there remain ‘‘glimmers of progress’’ especially since the 2015 Paris agreement to limit heat-trapping carbon dioxide emissions, according to a big study published Monday in the British medical journal Lancet.
Comparing the report to a health checkup, four researchers and several outside experts described Earth’s prognosis as ‘‘guarded.’’
‘‘There are some very severe warning signs, but there are some hopeful indicators too,’’ said coauthor Dr. Howard Frumkin, a professor of environmental health at the University of Washington. ‘‘Given the right treatment and aggressive efforts to prevent things from getting worse, I think there’s hope.’’
In a separate development Monday, the World Meteorological Organization, the UN’s weather agency, said human activity and a strong El Nino event, caused by warm ocean currents, combined to increase the level of carbon dioxide in the atmosphere in 2016.
Last year’s increase was 50 percent higher than the average of the past 10 years, the agency said.
In addition to rising world temperatures, El Nino affects the amount of carbon dioxide in the atmosphere by causing droughts that cut the ability of plants and trees to absorb it.
Because of air bubbles preserved in ice in places like Greenland and Antarctica, researchers have reliable measurements of CO2 concentrations going back 800,000 years. Using those measurements, the bulletin said that the last time CO2 concentrations were at similar levels was three to five million years ago, when the sea level was 66 feet higher than today.
It said 2016 saw average concentrations of CO2 hit 403.3 parts per million, up from 400 ppm in 2015. That does not include carbon dioxide absorbed by oceans and plants.
This year’s greenhouse gas bulletin produced by the WMO is based on measurements taken in 51 countries. Research stations around the globe measure concentrations of global warming gases including carbon dioxide, methane, and nitrous oxide.
The Lancet report on climate highlighted health problems stemming from more frequent heat waves, disease spread by insects, air pollution, and other woes.
While the disasters have been costly, deaths haven’t been increasing because society is doing a better but more expensive job adjusting to the changing conditions, the researchers noted.
A team of 63 doctors, public health officials, and scientists from around the world wrote what they considered the first of a regular monitoring of the health of the planet, similar to having a ‘‘finger on the pulse of the patient,’’ said Dr. Hugh Montgomery, an intensive care specialist and director of the University College of London’s Institute for Health and Performance.
Based on 40 indicators, the study said ‘‘the human symptoms of climate change are unequivocal and potentially irreversible.’’
While other disease rates are dropping, cases of dengue fever — a mosquito-borne disease — have doubled every decade since 1990, with 58.4 million cases and 10,000 deaths in 2013. Frumkin, a former environmental health director at the US Centers for Disease Control and Prevention, said climate change, which allows mosquitoes to live in more places and stay active longer with shorter freeze seasons, is part but not all of the reason.
The same goes for the increase in tick-borne Lyme disease in the United States, Frumkin said, adding ‘‘the ticks do better with warmer weather.’’
