Global warming is the increase in the average temperature of Earth's near-surface air and oceans since the mid-20th century and its projected continuation. According to the 2007 Fourth Assessment Report by the Intergovernmental Panel on Climate Change (IPCC), global surface temperature increased by 0.74 ± 0.18 °C (1.33 ± 0.32 °F) during the 20th century.Most of the observed temperature increase since the middle of the 20th century has been caused by increasing concentrations of greenhouse gases, which result from human activities such as the burning of fossil fuel and deforestation.

An increase in global temperature will cause sea levels to rise and will change the amount and pattern of precipitation, probably including expansion of subtropical deserts.Warming is expected to be strongest in the Arctic and would be associated with continuing retreat of glaciers, permafrost and sea ice. Other likely effects of the warming include more frequent and intense precipitation events, extreme weather events, species extinctions due to shifting isotherms, and changes in agricultural yields. Warming and related changes will vary from region to region around the globe, though the nature of these regional changes is uncertain. As a result of contemporary increases in atmospheric carbon dioxide, the oceans have become more acidic, a result that is predicted to continue.

PRECAUTIONS

1. Educate yourself about global warming. The more facts that you have, as to what mainstream science says about it, the more you can persuade others to make simple yet effective changes in daily behavior. Energy-saving techniques either are initially expensive (for example, solar power) or take extra time (for example, recycling), so many people need to be convinced that their efforts matter. Always keep in mind that you are aiming to demonstrate the benefits of these activities and highlight how each person can play a vital role in helping to reduce global warming. Remember that "civil society does not respond at all well to moralistic scolding.Use education to enlighten, not frighten.

2. Vote and influence your government with telephone calls, e-mails, letters and meetings with those who represent you in government. Learn as much as possible about the policies that you advocate before doing so; solving one problem often creates others. For example, replacing incandescent light bulbs with compact fluorescent light (CFL) bulbs has increased the hazard of mercury contamination in homes and landfills. Fluorescent light bulbs are still preferable to incandescent bulbs, but one must be careful to recycle them and to not break them, if not mercury would be released.

3. Choose vegetarian or vegan meals. Livestock are responsible for more greenhouse gas emissions than transportation is. This is due to the large amounts of petroleum used in creating ammonium nitrate fertilizer (for the corn that they are fed) plus the cost of shipping that corn to the cattle and then shipping the cattle to slaughter and grocery. If one eats meat it should always be from a local source. Choosing vegetarian foods also drasticallyreduces agricultural water consumption and land use, and favorably impacts biodiversity.Vegetarian diets have been shown to promote good health and in most developed countries, eliminating meat from one's diet is as easy as making responsible choices at stores and restaurants.

4. Recycle more by using recycling bins, composting, etc. Encourage neighbors, supervisors, colleagues, and businesses to do likewise (15-25% of people do not recycle).

5. Use compact fluorescent bulbs. Replace three frequently used light bulbs with compact fluorescent bulbs and save 300 lbs. of carbon dioxide. A standard compact fluorescent bulb will save around one third of a tonne of greenhouse gas, along with the cost of six or more incandescent globes.

6. Fill the dishwasher. Run your dishwasher only with a full load. Save 100 lbs. of carbon dioxide and US$40 per year, or do them by hand with minimal water.

7. Use recycled paper. Make sure that your printer paper is 100% post consumer recycled paper. Save 5 lbs. of carbon dioxide per ream of paper. Recycle your paper only when it has been thoroughly used up!

8. Buy locally made and locally grown products. Buy locally to reduce the energy required to transport your goods. If you successfully encourage neighbors to do this, store owners will be encouraged to stock local goods. Shop at farmers' markets.

9. Buy minimally packaged goods. Less packaging could reduce your garbage significantly.

10. Insulate anything that uses energy to stay a different temperature from its environment.

11. Replace old appliances and reduce reliance on them.

12. Use a push mower to mow the lawn. Use your muscles instead of fossil fuels and get some strength-building exercise. Save 80 lbs of carbon dioxide per year.

13. Grow fast growing plants. Plants like bamboo grow faster and produce 35% more oxygen than trees like oak or birch, and require fewer chemicals and care. Bamboo, for example, can be very invasive in most of the US.

14. Use public transportation. Taking the bus, the train, the subway or other forms of public transportation lessens the load on the roads and reduces one's individual greenhouse gas emissions by an average of 1600 pounds per year.

15. Ride a bicycle. Taking the bike instead of the car is a very simple solution. However, if you experience such problems as lack of suitable bike paths, having to deal with congested traffic or hilly terrain, you are faced with a few challenges.

16. Use your vehicle as a tool against global warming. If you can't live without a car, then use it in a way that minimizes global impact.

17.Use Refills. Try using refills instead of buying new jars or bottles each time. This reduces your consumption and is usually cheaper, too.