What is Global Warming?

(taken from: (http://www.wecansolveit.org/)
Earth is naturally insulated by a delicate balance of heat-trapping (or "greenhouse") gases in the atmosphere. When the sun shines on the Earth, some of that heat is absorbed, keeping Earth warm enough to support life.

The problem is that over the last century, we humans have been releasing more and more carbon dioxide and other heat-trapping gases into the atmosphere when we burn fuels and cut down forests. These additional gases have upset the natural balance of our atmosphere, trapping more heat than is healthy for the Earth.

The result is human-caused global warming, which brings serious threats from increased flooding to the spread of disease to the disruption of agriculture in many parts of the world.

Scientists tell us that stopping global warming is urgent -- we have just a few years to turn around the growth of greenhouse gas emissions in order to avoid the worst effects. The good news is that we can achieve these emissions reductions with effective national policies and international treaties. We must insist that businesses and governments join individuals around the world to greatly increase energy efficiency, widely adopt renewable energy, and commit to stopping climate change. Success is possible, but we need your help.

Climate crisis

No human challenge is so potentially uniting as the climate crisis. Our human drive to invent and build has led to extraordinary advances and great technological promise. It's also had grave, unintended consequences. And unless we face the climate crisis with ingenuity, resolve, and a sense of urgency, much of the world as we know it will begin to unravel before our eyes.

The warning signs are plain to see. The 10 warmest years on record have all occurred since 1990. Mountain glaciers are fading on every continent and the sea ice is melting. The seas have begun a slow but menacing rise.

What is global warming?

The science behind global warming is often portrayed as enormously complex, but some of it is quite simple. It begins with a ray of light, shot through space from the staggering inferno of our sun. That sunbeam delivers energy to earth, giving us light and warmth and life.

As some of this energy radiates back toward space as heat, a portion is absorbed by a delicate balance of heat-trapping (or "greenhouse") gases in the atmosphere that create an insulating layer. Without the temperature control of this greenhouse effect, the Earth's average surface temperature would be 0°F (-18°C), a temperature so low that the Earth would be frozen and could not sustain human life as we know it.

The most abundant of the greenhouse gases is water vapor. In addition, there are other powerful greenhouse gases like carbon dioxide (CO2), methane, and nitrous oxide. Each of these is a natural part of the never-ending cycle of life, death, and decomposition on Earth. But since the onset of the Industrial Revolution humans have been pumping out more and more of these and other greenhouse gases. Scientists are clear: human activities are contributing to global warming by adding large amounts of heat-trapping gases to the atmosphere. Our fossil fuel use is the main source of these gases. Every time we drive a car, use electricity from coal-fired power plants, or heat our homes with oil or natural gas, we release carbon dioxide and other heat-trapping gases into the air. The second most important addition of greenhouse gases to the atmosphere is related to deforestation, mainly in the tropics, as well as other land-use changes.

The concentration of CO2 in the atmosphere is now 380 parts-per-million (ppm), 100 ppm higher than at the beginning of the Industrial Revolution. But we can look back even further. By drilling into the deepest glacial ice we can measure CO2 deep into time. And this ice library shows more carbon dioxide in the atmosphere than at any time in last 650,000 years.

As a result of the build up of gases, the temperature is beginning to rise. Adults today have already felt the average global temperature rise more than a full degree Fahrenheit (0.8°C) during our lifetimes. We expect another degree F by 2020 due to past emissions. Based on modeling by an international body of experts studying the climate crisis, the Intergovernmental Panel on Climate Change (IPCC), the temperature could increase by more than 7°F (4°C) by the end of the century in the absence of meaningful efforts to rein in global warming pollution.

What happens when the global temperature rises?

For a global system that is delicately balanced, the rise in temperatures will pose serious threats:

• Rising sea levels, leading to more coastal erosion, flooding during storms, and permanent inundation
• Increased drought and increased incidence of wildfires
• Severe stress on many forests, wetlands, alpine regions, and other natural ecosystems
• Impacts on human health as mosquitoes and other disease-carrying insects and rodents spread diseases over larger geographical regions
• Disruption of agriculture in some parts of the world due to increased temperature, water stress, and sea-level rise in low-lying areas such as Bangladesh or the Mississippi River delta

Other projected impacts include increased intensity of hurricanes; the long-term destabilization of the Greenland and West Antarctic ice sheets, leading to much greater sea level rise; the acidification of the world's oceans; and a vastly increased rate of species extinction. Wonders such as the Great Barrier Reef and the Amazon could collapse under the weight of just a few more degrees. And hundreds of millions of people may be forced from their homelands as the climate shifts, creating increased political and economic instability.

What are the economic costs of the climate crisis?

The projected economic costs of the climate crisis are extraordinary. By mid-century, extreme weather alone could cost 0.5 - 1% of the global economic production. A seminal study led by a distinguished British economist, Sir Nicholas Stern, suggests that under business-as-usual scenarios climate change could reduce overall economic activity in the range of 5 to 20%-more likely on the high side of this range. Think Great Depression, or world war.

Can we solve it?

We can - and must - act urgently if we are to limit and eventually halt the impacts of global warming on human communities and natural ecosystems. The greater the magnitude and rate of warming, the greater the chances are for truly devastating - and potentially irreversible - changes in the Earth's climate system. Even by acting today to reduce our emissions from cars, power plants, land use, and other sources, we will see some degree of continued warming for a period of time because past emissions will stay in the atmosphere for decades or more. But, the window for effective action is closing fast and responding to the climate crisis will take commitment and ingenuity. The actions we take in the next several years will determine the kind of world our children and grandchildren will inherit.

How much will it cost to solve?

The IPCC has estimated that stabilizing the concentration of greenhouse gases in the atmosphere at levels that will limit long-term temperature rise to a few degrees will slow the rate of global economic growth by only about a tenth of a percent per year. Based on the expected growth rate of the global economy, that is about equivalent to the world reaching the expected 2030 economic levels in 2031 in return for preventing the worst effects of the climate crisis.

Fortunately, we have the tools we need to start on the path to a stable climate. Fuel-efficient vehicles and higher efficiency appliances; advanced wind turbines, next-generation solar photovoltaics and other renewable energy technologies; proven strategies to protect threatened forests; communities making it easier for people to walk and bike. These are just a few of the common sense solutions that will not only reduce global warming, but can save us money and create new business opportunities.

What should I do to help?

We have lacked full global leadership and political will to implement these solutions as if our future depended on it. But now we need to insist that businesses and governments all over the world join individuals in taking the steps needed to get the job done. We need to help citizens everywhere understand how the choices they make in their daily lives can make a real difference, and we need to provide incentives for all of us to make better choices.

The climate forces we have set loose are great indeed. But the world we build as we move forward to meet this challenge will be a sight to behold. This is our opportunity to come together to make a real difference.The time to act is now.