Rising sea levels in Bangladesh appear to be leading to more pregnancy complications. The rise in carbon dioxide in the atmosphere could lead to lower levels of protein in food crops like rice and wheat. It could also translate into deficiencies in zinc and iron for millions.

The changing environment is affecting human health in all kinds of unpleasantly surprising ways — to the point that researchers are launching a new field, "planetary health," to explore them. They're holding their first annual conference this weekend in Boston, funded by the Rockefeller Foundation and also backed by Harvard, the Wellcome Trust, medical journal The Lancet and two big scientific societies.

So while marchers are out in the streets calling for action on climate change, nearly 400 conference-goers at Harvard Medical School will be discussing just what the changing environment is doing — and likely to do — to our health.

I spoke with Harvard's Dr. Sam Myers, director of the Planetary Health Alliance and lead organizer of the conference. Our conversation, edited:

So this is kind of a joining of forces of climate change scientists and medical research?

I would very carefully not say 'climate change.' The whole concept of planetary health is that human activity is increasingly disrupting all of our planet's natural systems, including the climate system but also including land use, land cover, global fisheries, freshwater systems, bio-geochemical cycles, and a variety of other natural systems. So even if our climate were entirely stable, we would be convening our community to address this growing concern that accelerating environmental change is driving a larger and larger burden of disease around the world.

So it's not specific to climate change. But it's a bringing-together of the earth and natural scientists, the ecologists and the mainstream public health professionals who have all been feeling different parts of the elephant. They've all been recognizing in their own ways — within their societies and their disciplines — that the changes that they're seeing in the earth and natural sciences are increasingly having very immediate impacts on the health of particular populations. And so this is the first meeting that is really explicitly bringing those communities together around these sorts of ideas.



There has been a lot of work about how pollution affects health. How is this different from that?

Going back to the 1800s, we have what I think of as classic environmental health, which started with occupational exposures — whether it was miners or people working in cotton factories. They were experiencing direct toxic exposures, and then a field of public health evolved to quantify those health effects at the population level. This is really different from that. This is understanding how changes in the structure and function of our planet's natural systems will ultimately impact the health of different populations across all the different dimensions of health.

Examples?

Example #1:

One example concerns biodiversity loss. It's a global problem that the insects that pollinate food crops are in decline, mostly bees but other insects as well. We wanted to understand whether the global pollinator decline may represent a health threat, so we did an analysis in which we looked at the pollinator dependence of every single food crop on the planet, and how pollinator declines would affect the yield of those food crops. And then we modeled the nutritional outcomes for the populations of 152 different countries if those pollinators were allowed to continue to decline. We found that we could see 1.4 million excess deaths annually as a result of vitamin deficiencies from Vitamin A and folate deficiencies, but also a loss of protective food groups — like fruits and nuts and seeds and vegetables — that protect us from diseases like cardio-respiratory disease and cancer.

Example #2:

Another example is the work that we've done showing that, as we add carbon dioxide to the atmosphere through burning fossil fuels, there's a direct effect of that rising carbon dioxide on the nutritional value of staple food crops. And that when you grow staple foods like rice and wheat and soy at concentrations of carbon dioxide that the world will experience in the next 40 or 50 years, those foods lose significant amounts of iron and zinc and protein. And we know that about 2 billion people around the world today are suffering from iron and zinc deficiency, at a cost of around 63 million life-years annually. So there's real concern that further reducing the amount of iron and zinc in the diet as a result of this CO2 effect on plants would significantly increase the number of people who are suffering from these deficiencies. For zinc, for example, we would expect to see on the order of 200 million people around the world pushed into zinc deficiency as a direct effect of these anthropogenic carbon dioxide emissions. That's not an effect that we would have anticipated just thinking, 'Hmmm, I wonder how adding carbon dioxide will affect our lives?' And that illustrates one of the themes of planetary health, which is that we're frequently encountering unintended consequences and surprises.

Example #3:

Another example is something that isn't my work: We were starting to see an increase in pre-eclampsia in women in Bangladesh. (Pre-eclampsia is a condition that pregnant women can get and it threatens their health and their fetus's health.) The incidence of pre-eclampsia was going up, and some researchers identified that there was a very direct relationship between the incidence of pre-eclampsia in Bangladeshi women and the salinity in the groundwater they were drinking. It turns out that what's driving that increased salinity and groundwater is probably complex, but one factor is sea level rise: an intrusion of salt water into these coastal aquifers. So again, not in a million years would we sit down and say, 'I wonder how sea level rise is going to affect our lives? We're going to see more pre-eclampsia.' But in fact, that's what we're seeing. I could rattle off more examples: how nutrient runoff from agricultural fields in Belize are creating ecological changes hundreds of miles away in the lowlands, and leading to changes in the vegetation type as a result of more nitrogen and phosphate being available. And those changes in vegetation are actually much more propitious for different anopheles mosquitoes that can breed in that different vegetation. And those anopheles mosquitoes turn out to be better vectors for malaria. So adding too much nitrogen and phosphate to your soil in upland Belize can cause increased malaria in lowland Belize. There are lots of those kinds of stories.

Can you tell me a provincial story of what we're likely to see either in New England or in the United States — what is of greatest concern?

Well, we saw things like Hurricane Sandy and Hurricane Katrina, which we associate with climate change. One can surmise that significant change to the nutrient quality of staple food crops might have some impact on nutritional outcomes for Americans as well as people in other parts of the world.

But also, I slightly bristle at the question itself. I get that question all the time. I guess I would turn that question around: What does it mean for us to live in one of the wealthiest societies in the world, where our consumption practices are putting the most vulnerable people, all over the planet, billions of them, in harm's way? What is the impact of that on us as a society? We live in a global society. Our actions have consequences. So I think it's important to think about the direct impact on our own health. But I also think it's important to understand that we have some moral responsibility as well.

And, meanwhile, you're helping to launch the field of planetary health at a time when the administration of the U.S. government seems to be going in the other direction.

Well, all the more reason that we should be doing it.

Also, this is about a lot more than the United States, and this is about a lot more than the federal government. At the meeting, we'll be highlighting work that's being done in other countries around the world and also the work of activists. Change almost never comes, really, from the top. This kind of fundamental cultural change that we think is going to be necessary to develop a new relationship between us and our natural systems is going to need to come from the bottom up, in many cases. That needs an activated global constituency, and people changing behavior, and people demanding a different way of living. And that takes time. And yes, we have an administration that's not enormously sympathetic for the next three and a half years. We'll see where we go after that.