Human Impacts on the Biosphere

• Human activities are now changing the composition of the atmosphere in ways that most authorities conclude will be damaging or, in the long run, disastrous.

• Global warming–Changes in atmospheric composition–Average temperature of the Earth’s surface is

increasing

Carbon dioxide affects temperature

• CO2 strongly absorbs electromagnetic radiant energy at some of the wavelengths that are critical for the global heat budget.

• Greenhouse gases– CO2

– Methane– Nitrous oxide

Global temperature change has affected ecosystems in the pat and is doing so now

• Many insects and amphibians breed earlier in the year

• Many plants flower earlier• Concerns:– The rate of warming today is rapid– Natural areas no longer cover the whole landscape– As temperature increases

Global warming affects human populations as well

Rising sea levels

Other climatic effects

Effects on agriculture

Effects on human health

Solving the problem

Rising sea level

• Two effects of global warming– The melting of polar ice and glaciers, adding water to the ocean– The increase of average ocean temperature, causing an increase in volume because water expands as it warms

Other climatic effects

• Frequency or severity of extreme meteorological events– Heat waves– Droughts– Severe storms– Hurricanes– El Niño– Rainfall patterns

Effects on agriculture

• Positive side– Warmer temperatures and increase atmospheric CO2

tend to increase growth of some crops and thus may increase agricultural yields.

• Negative side– Droughts– Changes in rainfall patterns– Temperature– Pest distributions

Effects on human health

• Loss of safe drinking water– Epidemics of cholera

• Human diseases– Diseases transmitted by mosquitoes• Temperatures above 16⁰C

– Malaria

• Temperatures above 10⁰C– Yellow fever– Dengue fever

• Higher temperature– Malaria pathogens mature more rapidly

Solving the problem

• “green” technologies

• Concerted efforts from:– Citizens– Corporations– Governments