Global warming poses real risks. The more energy we use, the more the planet warms up. Read about the effects of global warming.
Energy from the sun drives the Earth's weather and climate, and heats the planet's surface. In turn, the Earth radiates energy back into space. Atmospheric greenhouse gases (carbon dioxide, water vapor and other gases) trap some of the outgoing energy, retaining heat somewhat like the glass panels of a greenhouse. Without this natural "greenhouse effect", temperatures would be much lower than they are now, and life as known today would not be possible. However, problems may appear when the atmospheric concentration of greenhouse gases increases.
Since the beginning of the industrial revolution, atmospheric concentrations of carbon dioxide have increased by nearly 30%, methane concentrations have more than doubled, and nitrous oxide concentrations have risen by about 15%. These increases have enhanced the heat-trapping capability of the earth's atmosphere. Sulfate aerosols, a common air pollutant, cool the atmosphere by reflecting light back into space. However, sulfates are short-lived in the atmosphere and vary regionally.
Scientists generally believe that the combustion of fossil fuels and other human activities are the primary reason for the increased concentration of carbon dioxide. Plant respiration and the decomposition of organic matter release more than 10 times the CO2 released by human activities. These releases have generally been in balance during the centuries leading up to the industrial revolution with carbon dioxide absorbed by terrestrial vegetation and the oceans.
What has changed in the last few hundred years is the additional release of carbon dioxide by human activities. Fossil fuels burned to run cars and trucks, heat homes and businesses, and power factories are responsible for about 98% of U.S. carbon dioxide emissions, 24% of methane emissions, and 18% of nitrous oxide emissions. In 1997, the United States emitted about one-fifth of total global greenhouse gases.
Estimating future emissions is difficult, because it depends on demographic, economic, institutional, policy and technological developments. Several emissions scenarios have been developed based on differing projections of these underlying factors. By 2100, in the absence of emissions control policies, carbon dioxide concentrations are projected to be 30-150% higher than today's levels.
Global mean surface temperatures have increased 0.5-1.0°F since the late 19th century. The 20th century's 10 warmest years all occurred in the last 15 years of the century. Of these, 1998 was the warmest year on record. The snow cover in the northern hemisphere and floating ice in the Arctic Ocean have both decreased. Globally, sea level has risen 4-8 inches over the past century. Worldwide precipitation over land has increased by about one percent.
Increasing concentrations of greenhouse gases are likely to accelerate the rate of climate change. Scientists expect that the average global surface temperature could rise 1-4.5°F (0.6-2.5°C) in the next fifty years, and 2.2-10°F (1.4-5.8°C) in the next century, with significant regional variation. Evaporation will increase as the climate warms, which will increase average global precipitation. Soil moisture is likely to decline in many regions, and intense rainstorms are likely to become more frequent. Sea level is likely to rise two feet along most of the U.S. coast.
Rising global temperatures are expected to raise sea level, and change precipitation and other local climate conditions. Changing regional climate could alter forests, crop yields, and water supplies. It could also affect human health, animals, and many types of ecosystems. Deserts may expand into existing rangelands, and features of some of our National Parks may be permanently altered. Unfortunately, many of the potentially most important impacts depend upon whether rainfall increases or decreases, which can not be reliably projected for specific areas.
Today, action is occurring at every level to reduce, to avoid, and to better understand the risks associated with climate change. (Well…at least theoretically it does…). Many cities and states across the world have prepared greenhouse gas inventories and many are actively pursuing programs and policies that will result in greenhouse gas emission reductions.
The largest cities in the world are likely to be hit by rising sea levels - which could eventually flood large areas by more than a metre. Some countries will be turned to desert. Hundreds of millions of people will be short of fresh water by 2050. Other parts of the world will be hit by destructive storms and floods, costing billions a year in reconstruction. 400 000 square miles of Arctic ice have already melted in the last 30 years. A quarter of all animal and plant species could be wiped out within the next thirty.
Most children alive today will find their future lives are deeply affected by new patterns of disease, extreme weather patterns, and by strict controls on energy and carbon use. Future generations will judge us by how we respond to global warming. Apocalyptic picture, isn’t it?
So please do what is in your power trying to keep our planet clean, saving energy. Everything you do like that helps a little. It's your planet...
