While the impacts of global warming will reach across the planet, some countries and populations are more vulnerable to environmental changes than others.  What's more, physical climate changes will vary widely from region to region, exposing human and natural systems to different hazards.  Although global warming impacts are difficult to predict and to summarize, scientists anticipate a 1 to 6 degree increase in global temperature by the year 2100 (based on range of greenhouse gas emission scenarios), and can extrapolate some regional impacts from these predictions.  Below are just a few of the major predicted impacts on humans, plants and animals, followed by a comprehensive list of web resources. 

Impacts on humans:

Sea level rise.  The oceans expand as they absorb heat, causing sea levels to rise.  However, the largest contribution to rising sea levels is expected to be melting polar ice sheets and sea ice, particularly in the Arctic zone.  Researchers at the University of Arizona's Environmental Studies Laboratory have created these incredible maps, depicting sea level rise scenarios along the world's coastlines.  They predict that "the earth will be warm enough in less than 150 years (assuming no reduction in greenhouse gas emissions) to melt the Greenland Ice Cap", leading a 4 to 6 meter rise in sea level.  That rise is more than enough to flood nearly half of Florida and inundate cities along the U.S. eastern seaboard. (image courtesy of University of Arizona's Environmental Studies Laboratory)

Interruption of the Gulf Stream.  Global ocean currents, of which the Gulf Stream is part, run like a giant conveyor belt (the Thermohaline Circulation).  The system is driven by the sinking of heavy, salty, cold water at specific high-latitude locations, particularly the North Atlantic.   As ocean water sinks in the North Atlantic, warm Gulf Stream waters rush north to fill the void.  Increasing regional precipitation may dilute North Atlantic waters, and stop or slow the sinking -- thereby stopping or slowing the Gulf Stream.  If that happens, England and other parts of northern Europe will be much cooler, because the Gulf Stream keeps the region 5 to 8 degrees warmer than it normally would be for its latitude .

Agriculture. Temperature increases may cause agricultural zones to shift northward, opening up new crops for some areas, while limiting them in others, where crops and livestock may be threatened by heat stress and drought.  For example, food productivity in the tropics is likely to decline because many crops are already grown at their maximum temperature tolerance.  Agriculture is also quite vulnerable to floods, droughts and hail, though these will vary regionally from year to year. 

Human Health. Some of the health impacts of global warming include deaths from more frequent temperature extremes (particularly heat waves) and an expanded range of vector-borne illnesses (those transmitted by rodents and insects).  For example, there is a fear that diseases like malaria could become common in the United States and Europe.  

Impacts on biological systems:

Extinction.  Swaths of species could disappear if warming exceeds their ability to relocate or adapt to changing conditions.  Corals and coral reefs are at great risk because they are both immobile and highly sensitive to changes in water temperature.

Shifts in range.  Most plant and animal species are expected to shift poleward with optimum temperatures.  While many alpine species will simply rise in elevation (toward cooler zones), those already at high elevations are vulnerable to extinction.  

Habitat disappearance.  As the natural environment changes, habitats could shrink or disappear entirely, threatening the species that depend on them.  For example, the melting of permafrost (permanently frozen ground) near the Arctic is causing lakes to simply drain into the porous, thawed soil.  The complete disappearance of some lakes, as some scientists are observing, will affect local bird and aquatic species.  

Early Warning Signs

Evidence that global warming is already affecting many regions

EPA Global Warming Impacts Page

World View of Global Warming

Photos of record weather events from around the world

NRDC Consequences of Global Warming

Well-organized, accessible presentation of the basics

WWF Global Warming Impacts

Global warming impacts on wildlife and ecosystems