Global change / global warming and human health
Climate change is taking many forms around the world, which is leading to various changes affecting human health. For instance, warming trends moving north in the United States is allowing the spread of infectious diseases to spread north as well. While temperature changes are not always drastic, they can also be changes in how cold it gets (changing growing zones), changes in precipitation, etc. Furthermore, similar changes allow for the spread of invasive species to dislocate native species and alter habitat's in destructive and harmful ways, although usually affecting humans economically. Examples of this can be strictly through introductions from foreign lands, or gradual movements towards climatically changing areas.
(CC Image of invasive Japanese Kudzu by Gsmith [GFDL (http://www.gnu.org/copyleft/fdl.html), CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0/) or CC-BY-2.5 (http://creativecommons.org/licenses/by/2.5)], via Wikimedia Commons))
Other aspects of climate change on human health are: rising sea levels dislocating persons, anthropogenic pollution creating difficult breathing conditions or other health risks, increased allergies, increased refugees, and more. These difficulties have numerous health implications and increase the overall chances of pandemics, and other major health events.
Lastly, climate change and other more direct human induced problems such as deforestation are helping to make an estimated 140,000 species extinct each year around the world. Our basic human needs, as well as access to biodiversity for human health and biomimicry purposes is being reduced at an extremely unsustainable level. Biodiversity loss may be our greatest threat to human health as we deplete many possible cures and medical solutions.
(CC Image by European Environment Agency, Copenhagen, Denmark [Public domain], via Wikimedia Commons)