"Impact of Regional Climate Change on Human Health," a new report in the latest edition of Nature, makes for sobering reading. A combined effort from the University of Wisconsin, Madison, and the World Health Organization, the report reviews the evidence connecting changes to climate conditions and threats to human health. The study looked at both empirical data from past observations and model-based simulations of future interactions. Unusually, the full report is available to non-subscribers; a good summary can be found at SciDev.net.

The nations that have been, and will be, hardest-hit by climate-related health effects are those least able to respond; they're also the least responsible for the global temperature increases both over the past century and (with the arguable exceptions of India and China) likely over the next. This is not a happy article, or a study full of solutions; it does, however, underscore why global warming is so dangerous -- and why the need to respond to environmental risks can't be disconnected from the need to respond to global poverty.

The World Health Organization now estimates that at least 150,000 deaths each year are directly attributable to the effects of climate disruption. Over the next 25 years, that risk will rise substantially:

[WHO] estimates that the climate-change-induced excess risk of the various health outcomes will more than double by the year 2030. Large increases are predicted for the relative risk of flooding and more modest changes in diseases such as malaria, malnutrition and diarrhoea. However, it is important to note that these small relative changes may actually cause far greater aggregate disease burdens. In sub-Saharan Africa, for example, flooding currently kills less than one person per million annually, while malaria kills over 1,600 per million and diarrhoea kills over 1,000 per million.

Broadly speaking, the causes of death fall into two categories: non-infectious health effects, such as heatwaves and crop failures; and infectious diseases such as malaria, dengue fever, and even salmonella. In particular, there's a strong correlation between patterns of infectious diseases and the El Niño-Southern Oscillation (ENSO) weather pattern. To the degree that global warming exacerbates ENSO, it boosts the likelihood of related epidemics.

Some of the health effects, such as heat waves, could hit anywhere, but the ENSO-related diseases disproportionately affect the South Asia/Pacific region and South America; there's some evidence that ENSO affects diseases in Africa, as well. Developing nations are hardest hit by climate-related health problems for reasons of both geography and politics. The map displayed above (larger version here) shows the climate-related mortality rates per million by 2000, and the mortality rates closely correlate to the overall degree of poverty.

As the study's lead author, Dr. Jonathan Patz, put it, ""Those least able to cope and least responsible for the greenhouse gases that cause global warming are most affected. Herein lies an enormous global ethical challenge."

Global development and environmental sustainability are interconnected. Efforts like the Millennium Development Goals, which aim to reduce poverty and improve health care in the world's poorest nations, are demonstrably critical tools for environmental response, as well. Similarly, the need to slow the pace of global warming and avoid its harshest results is as much an issue of humanitarian responsibility as it is environmental stewardship.

This study is a clear reminder of what we face in a world where worldchanging solutions are ignored or dismissed. Careful readers will note that one of the study's authors is Dr. Jon Foley. Dr. Foley is a regular WorldChanging reader, and he frequently comments on the posts. I'm very happy that he chooses to spend time here -- and I'm proud to call him our ally.

This article is sobering and, as you mention, raises a significant global ethics dillemma. Click the small map above you'll link to a page with that map as well as another that displays the GHG emissions for each country. The two maps are almost opposite with the most GHGs coming from the countries that are least effected by Climate Change and those with the least emissions the most severely effected. This is unconscionable and amounts to environmental tyranny and is yet another grevious case of North-South inequality.

Posted by: Jesse Jenkins on November 17, 2005 10:10 PM

This is a good comment on the study.

When you boil it down, that's the whole point of our study. Countries in the North (especially the U.S.) are some of the biggest CO2 polluters, but burden of disease resulting from climate change is likely to be felt by the world's poorest people -- mostly in the South.

Of course, we've been asked by some more skeptical folks why this should matter to people in the North (especially in the U.S.). After all, we export lots of environmental problems to the South already, so why is this any different? Why should we worry in the U.S.? Isn't this another "feel guilty" story? What's in it for us?

Well, in an age of global disease pathways (when a microbe can hop on an airplane and be *anywhere* in about 24 hours), global economic opportunities, and global terrorism, this may ultimately come back to bite us. Do we really want to exacerbate tensions between North and South, between rich and poor, and between those who pollute and those who die?

I'll let others expand on this idea, but we're touching upon a common theme discussed at WorldChanging: you can't have real security without sustainability. A secure world will require a viable and healthy environment, with an improved sense of equity and environmental justice. And I think it's in *all* of our interests, even taking an "enlightened" selfish view.

Anyway, I'd love to see what others think of this study...

Posted by: Jon Foley on November 17, 2005 10:29 PM

Recent scientific evidence shows that major and widespread climate changes have occurred with startling speed.

This new paradigm of an abruptly changing climatic system has been well established by scientific research, but this new thinking is little known and scarcely appreciated in the wider community.

Asked about the discovery of abrupt climate change, many climate experts today would put their finger on one moment: the day they read the 1993 report of the analysis of Greenland ice cores.

The most recent abrupt climate change, known as the “Younger Dryas,” took place on earth roughly 11,400 years ago. At that point the earth was warming rapidly, but was abruptly plunged into cold, dry, and windy glacial conditions. It remained frigid for twelve centuries before abruptly warming again.

Warm interglacial periods are generally subject to big swings of temperature lasting for centuries. The last 10,000 years, known as the “Holocene,” has been by far the longest stable warm period during the past half million years.

The entire rise of human civilization since the end of the Younger Dryas has taken place during a period of warm and stable climate that is unique in the long record. Temperatures as high as those of the Holocene have only occurred about 10% of the time during the past half million years.

Why do large and rapid changes in climate periodically overtake the planet?

Technically, an abrupt climate change occurs when the climate system is forced to cross some threshold, triggering a transition to a new state. Whenever pushed, it didn’t lead to smooth changes in earth’s climate, but rather to jumps from one state to another.

The earth’s climate does not respond to forcing in a smooth and gradual way. Complex systems like the atmosphere and ocean currents are known to move from one steady state to another with only very brief transitions in between.

Abrupt climate changes are especially common in history when the climate system was being forced to change most rapidly. Thus, greenhouse warming and other human alterations of the earth system may increase the possibility of large, abrupt, and unwelcome regional or global climatic events.

Changes in temperature differences alter the circulation of the atmosphere-this is what is most important to societies: not the temperature changes themselves, but how these changes affect precipitation patterns over time-where in the world it rains or snows and how little or how much.

Dramatic changes in water resources have enormous consequences on human populations, generating famines, migrations, civilizations foundations and collapses. Abrupt climate change took hold of many of humanity’s great civilizations and shook them until they collapsed. Year-in and year-out, over the long haul, drought extracts the most from humanity.

The earth has experienced large and rapid climate oscillations on a scale that human agricultural and industrial activities have not yet faced.

Finally, it is now clear that climate variability in many regions of the world was significantly greater during the last 10,000 years than during the last 150 years. Many of these past Holocene events appear to have been large enough that, if they were to recur in the future, they would have major impact on humans.

Posted by: Brad Arnold on November 18, 2005 12:17 AM

What has seemed more clear to me is that world climate seems to be warming (at least partially and increasingly from human causes) and that there are effects that we desire to avoid or mitigate as a result. Energy sources that do not contribute to global warming should be accelerated to slow the global warming trend. In particular ... nuclear power should be developed. Conservation, efficiency, solar, wind should also be developed as well as research and development of Molecular Nanotechnology. It is clearly possible for a country to get almost all of its electricity from nuclear (France) plus it can be used to replace natural gas and other sources for many other applications. The risks of nuclear energy (meltdown, storage of waste, terrorism, proliferation are well known and researched) that have been feared since the 70's and 80s are greatly reduced in new designs. Nuclear power should be part of the solution (along with carbon sequestoring, reforestation projects etc...)

Posted by: brian wang on November 18, 2005 8:58 AM

Nice to see how the effects of our industrial life-style are "externalized" once again, in another form. This is the crucial dynamic of modernity and capitalism: make money by externalizing the real costs and dump those on others.
Indirectly if possible (climate change), directly if necessary (slaughter inobedient Iraqis for oil).

Welcome to the arseholes of humanity, our own lives.

Posted by: Lorenzo on November 18, 2005 9:21 AM

Thanks for these comments on global warming. The virtual mountain of data identifying this phenomenon seems to have escaped many politicians, economists and policy-makers in the USA.

Posted by: Steven Earl Salmony, Ph.D., M.P.A. on November 18, 2005 10:39 AM

The history of recorded climates is so short that I feel overwhelmed with anecdotal evidence..."Doesn't this summer feel warmer than last..." Good factual article.

Posted by: Jeremy on November 19, 2005 5:51 PM