Killer health problems such as diarrhoea, malnutrition, malaria and dengue are highly sensitive to climate change and could worsen in the coming decades, health experts agree. But how, where and to what extent remains unclear.
More than 140,000 lives lost per year - that's the number of excess deaths global warming since the 1970s was causing by 2004, according to the World Health Organisation.
It's reasonable to assume the figures could be higher by now.
Health officials and aid workers in developing nations are becoming increasingly worried about how they're going to cope if the disease burden starts to rise faster.
"The situation in Africa is being worsened because of ill-preparedness... because of weak and already over-stretched health systems," Evans Tembo from Zambia's health ministry told a panel discussion at the sixth International Conference on Community-Based Adaptation to Climate Change in the Vietnamese capital Hanoi last week.
In Zambia, for example, 2007 figures show an annual 4 million cases of malaria and 50,000 deaths from the mosquito-borne disease, according to Tembo.
"Zambia is a country with a population of only 12.6 million, so if we're talking about 50,000 people dying from malaria alone, then for us, it's a disaster," he said.
Yet health concerns are often sidelined in climate change debates as people bicker over science, polar bears and responsibility. It wasn't until the most recent U.N. climate negotiations in Durban late last year that the effects of climate change on health were formally addressed.
One reason is the lack of scientific, evidence-based research on climate and health, especially in developing countries where the impacts are expected to be greatest, panellists said.
Nguyen Thi Thuan, health programme manager for the International Federation of Red Cross and Red Crescent Societies (IFRC) in Vietnam, said national data on vector-borne diseases for the past 30 years doesn't exist in most developing countries, making it difficult to draw comparisons.
TAKING ACTION NOW
The Vietnam Red Cross and IFRC are working on a dengue prevention programme, as the disease is a growing health problem for many urban and rural communities.
Household surveys point to a possible link between dengue and climate shifts, as cases are now occurring outside the rainy season, but there's no other hard data, Nguyen said.
"There probably needs to be more research to prove if dengue-fever season has changed, but for community members, the impact is already here," she added.
As there are no vaccines or cure for dengue fever, preventing infection by eliminating mosquito breeding sites is key, she said. The Red Cross is training an extensive network of volunteers to spread awareness.
In Zambia, it's not only malaria that may spread as temperatures rise. More frequent droughts, leading to crop failures and water scarcity, could hike malnutrition and diarrhoeal diseases.
Already, 2.2 million Africans die every year from diarrhoea, 3.5 million from malnutrition and about 60,000 from natural disasters, Tembo said.
The Zambian government is looking at training communities in household water treatment and storage methods, hygiene education and waste management, he added.
TALKING THE RIGHT LANGUAGE
In Laos, meanwhile, communications technology is being used to track pandemic outbreaks and raise awareness of health issues.
Cecile Lantican from FHI 360 said her organisation has been working with the Lao Women's Union, which has over 1 million members across the land-locked country of 6 million.
"We trained them to use SMS technology to monitor cases of influenza-like illness in poultry and humans... and to identify potential outbreaks," she said.
People's behaviour has since changed for the better, she said, with improved poultry hygiene practices, and better monitoring and reporting of diseases.
Communication is equally important in helping people understand the risks to their health from climate change and extreme weather, panellists said.
Even though local communities are eager to learn about climate change, they find the concept difficult to grasp, IFRC's Nguyen said.
"We need to communicate in a language they understand - (talking about) weather conditions and short-term impacts such as changes in temperature and rainfall, and how this is related to health practices," she said.