Science Man and His Environment/Global Warming

Recent Climate Change
The global temperature of the Earth has increased over the last century.

Current temperatures are 0.6 &deg;C over the 1950-1980 average



In the Arctic current temperatures are 2 &deg;C higher





Natural Greenhouse Effect


The above picture shows the natural greenhouse effect in red. All objects emit heat in the form of infrared (IR) radiation. Gases in the atmosphere absorb the IR radiation from the Earth and reradiate it back to the surface. This regulates the temperature.

Natural greenhouse effect allows life to survive on Earth.

But problems occur when humans cause additional greenhouse effects.

Greenhouse Gases
Major Greenhouse Gases
 * Carbon dioxide
 * Methane
 * Nitrous Oxide

Now we can define global warming:

Carbon dioxide is by far the largest cause of global warming



Methane is at lower concentrations, but has a stronger greenhouse effect.

Largest sources of methane:
 * Agriculture, especially from cows and other ruminants
 * Disturbance of peat lands

Summary
Increasing of greenhouse gases (especially carbon dioxide) can cause an increase in the greenhouse effect, which increases the temperature of the Earth's atmosphere.

Changing of the weather
Global warming will cause shift in climate

An animation of how the Earth's climate would change can be found here

Generally, more hot days and fewer cool days. Tropics will get less precipitation. Polar regions will get more precipitation.

Temperate regions will shift north. Heat waves, droughts, wildfires, and storms will increase. Growing seasons are also moving poleward.

Melting of sea ice and glaciers
Rising temperatures causes sea ice and glaciers to decrease





Sea level rise
The melting of the sea ice causes the amount of seawater to increase. Also heating water causes it to expand.

Models estimate that sea levels will rise 0.18 - 0.59 m.

10 percent of world's population lives less than 10 m above sea level. Some island countries may no longer exist.

Wildlife
Global warming can also affect wildlife. It can affect their distribution. Some species have already migrated towards the poles.

This is a especially a threat to endangered species.

Permafrost melting
Permafrost is soil which remains frozen all year.

Melting of permafrost is a feedback mechanism. It releases methane, which increases global warming, which in turn causes more permafrost melting creating a loop.

Ocean Acidification
This effect is due to the carbon dioxide directly and not temperature change. Carbon dioxide dissolves in the ocean to create acid conditions.

This in turn has an effect on marine organisms. Acidic conditions increase the solubility of calcium carbonate in shells of shellfish, coral, etc.

Mitigation
Reducing the amount of carbon dioxide

Methods of mitigation
 * energy conservation
 * renewable energy sources
 * changing transport
 * carbon tax
 * reforestation
 * carbon sequestering ? - this is capturing CO2 and then pumping it underground
 * geoengineering ??? - mega projects to reduce effects of global warming

Adaptation
Measures to reduce the effects of global warming

Examples
 * Building sea walls
 * Changing crop types
 * Generating a fund to help low income countries (the most talked about adaptation measure)