stop..stop..STOP!

How You Can Stop Global Warming
Healing the planet starts in your garage, in your kitchen, and at your dining-room table.
Nations around the world are upping their game in the fight against climate change. At the Paris climate summit in 2015, 195 countries signed a historic agreement to reduce their carbon emissions, with the goal of limiting future warming to well below 2 degrees Celsius.

It was a big step in the right direction. But it’s important to remember the equally vital contributions that can be made by private citizens—which is to say, by you. “Change only happens when individuals take action,” Aliya Haq, deputy director of NRDC’s Clean Power Plan initiative, says. “There’s no other way, if it doesn’t start with people.”

The goal is simple. Carbon dioxide is the climate’s worst enemy. It’s released when oil, coal, and other fossil fuels are burned for energy—the energy we use to power our homes, cars, and smartphones. By using less of it, we can curb our own contribution to climate change while also saving money. Here are 10 easy, effective ways each one of us can make a difference:

1. Speak up!
What’s the single biggest way you can make an impact on global climate change? “Talk to your friends and family, and make sure your representatives are making good decisions,” Haq says. By voicing your concerns—via social media or, better yet, directly to your elected officials—you send a message that you care about the warming world. Encourage Congress to enact new laws that limit carbon emissions and require polluters to pay for the emissions they produce. “The main reason elected officials do anything difficult is because their constituents make them,” Haq says. You can help protect public lands, stop offshore drilling, and more here.

2. Power your home with renewable energy.
Choose a utility company that generates at least half its power from wind or solar and has been certified by Green-e Energy, an organization that vets renewable energy options. If that isn’t possible for you, take a look at your electric bill; many utilities now list other ways to support renewable sources on their monthly statements and websites.

3. Weatherize, weatherize, weatherize.
“Building heating and cooling are among the biggest uses of energy,” Haq says. Indeed, heating and air-conditioning account for almost half of home energy use. You can make your space more energy efficient by sealing drafts and ensuring it’s adequately insulated. You can also claim federal tax credits for many energy-efficiency home improvements.

4. Invest in energy-efficient appliances.
Since they were first implemented nationally in 1987, efficiency standards for dozens of appliances and products have kept 2.3 billion tons of carbon dioxide out of the air. That’s about the same amount as the annual carbon pollution coughed up by nearly 440 million cars. “Energy efficiency is the lowest-cost way to reduce emissions,” Haq says. When shopping for refrigerators, washing machines, and other appliances, look for the Energy Star label. It will tell you which are the most efficient.

5. Actually eat the food you buy—and make less of it meat.
Approximately 10 percent of U.S. energy use goes into growing, processing, packaging, and shipping food—about 40 percent of which just winds up in the landfill. “If you’re wasting less food, you’re likely cutting down on energy consumption,” Haq says. And since livestock products are among the most resource-intensive to produce, eating meat-free meals can make a big difference, too.

6. Buy better bulbs.
LED lightbulbs use up to 80 percent less energy than conventional incandescents. They’re also cheaper in the long run: A 10-watt LED that replaces your traditional 60-watt bulb will save you $125 over the lightbulb’s life.

7. Drive a fuel-efficient vehicle.
Gas-smart cars, such as hybrids and fully electric vehicles, save fuel and money. And once all cars and light trucks meet 2025’s clean car standards, which means averaging 54.5 miles per gallon, they’ll be a mainstay. For good reason: Relative to a national fleet of vehicles that averaged only 28.3 miles per gallon in 2011, Americans will spend $80 billion less at the pump each year and cut their automotive emissions by half. Before you buy a new set of wheels, compare fuel-economy performance here.

8. Maintain your ride.
If all Americans kept their tires properly inflated, we could say 1.2 billion gallons of gas each year. A simple tune-up can boost miles per gallon anywhere from 4 percent to 40 percent, and a new air filter can get you a 10 percent boost.

9. Rethink planes, trains, and automobiles.
Choosing to live in walkable smart-growth cities and towns with quality public transportation leads to less driving, less money spent on fuel, and less pollution in the air. Less frequent flying can make a big difference, too. “Air transport is a major source of climate pollution,” Haq says. “If you can take a train instead, do that.”

10. Shrink your carbon profile.
You can offset the carbon you produce by purchasing carbon offsets, which represent clean power that you can add to the nation’s energy grid in place of power from fossil fuels. But not all carbon offset companies are alike. Do your homework to find the best supplier.

www.nrdc.org/stories/how-you-can-stop-global-warming

It's too hard
"The fact is that there is no one in the world who can explain how we could cut our emissions by four fifths without shutting down virtually all our existing economy. What carries this even further into the higher realms of lunacy is that such a Quixotic gesture would do nothing to halt the world’s fast-rising CO2 emissions, already up 40 per cent since 1990. There is no way for us to prevent the world’s CO2 emissions from doubling by 2100" (Christopher Booker).
In order to avoid dangerous global warming, we need to reduce global greenhouse gas (GHG) emissions by about 50% by the year 2050.  Skeptics often make the argument that we simply don't have the technology necessary to reduce emissions this much, this quickly.

Pacala and Socolow (2004) investigated this claim by examining the various technologies available to reduce GHG emissions.  Every technology they examined "has passed beyond the laboratory bench and demonstration project; many are already implemented somewhere at full industrial scale."  The study used the concept of a "stabilization wedge", in which "a wedge represents an activity that reduces emissions to the atmosphere by a certain amount. The study identifies 15 current options which could be scaled up to produce at least one wedge:

• Improved fuel economy

• Reduced reliance on cars

• More efficient buildings

• Improved power plant efficiency

• Substituting natural gas for coal

• Storage of carbon captured in power plants

• Storage of carbon captured in hydrogen plants

• Storage of carbon captured in synthetic fuels plants

• Nuclear power

• Wind power

• Solar photovoltaic power

• Renewable hydrogen

• Biofuels

• Forest management

• Agricultural soils management

This is not an exhaustive list, and there are other possible wedges, such as other renewable energy technologies they did not consider.   The study notes that "Every one of these options is already implemented at an industrial scale and could be scaled up further over 50 years to provide at least one wedge."  Implementing somewhere between 7 and 14 wedges would be necessary to avoid dangerous climate change.
www.skepticalscience.com/global-warming-too-hard.htm

STOP Global Warming

Global warming is primarily a problem of too much carbon dioxide (CO2) in the atmosphere—which acts as a blanket, trapping heat and warming the planet. As we burn fossil fuels like coal, oil and natural gas for energy or cut down and burn forests to create pastures and plantations, carbon accumulates and overloads our atmosphere. Certain waste management and agricultural practices aggravate the problem by releasing other potent global warming gases, such as methane and nitrous oxide. To put this in perspective, the carbon we put in the atmosphere today will literally determine not only our climate future but also the future generations as well.

          There is no single solution to global warming, which is primarily a problem of too much heat-trapping carbon dioxide (CO2), methane and nitrous oxide in the atmosphere. To bring down the emissions of these gases by at least 80 percent by mid-century. Use the following:

⦁ Boosting energy efficiency: The energy used to power, heat, and cool our homes, businesses, and industries is the single largest contributor to global warming. Energy efficiency technologies allow us to use less energy to get the same—or higher—level of production, service, and comfort. This approach has vast potential to save both energy and money, and can be deployed quickly.

⦁ Greening transportation: The transportation sector's emissions have increased at a faster rate than any other energy-using sector over the past decade. Switching to low-carbon fuels, and reducing vehicle miles traveled through smart growth and more efficient mass transportation systems.

⦁ Revving up renewables: Renewable energy sources such as solar, wind, geothermal and bioenergy are available around the world. Renewable technologies can be deployed quickly, are increasingly cost-effective, and create jobs while reducing pollution.

⦁ Phasing out fossil fuel electricity: Dramatically reducing our use of fossil fuels—especially carbon-intensive coal—is essential to tackle climate change.

⦁ Managing forests and agriculture:  We can fight global warming by reducing emissions from deforestation and forest degradation and by making our food production practices more sustainable.

⦁ Exploring nuclear: Because nuclear power results in few global warming emissions, an increased share of nuclear power in the energy mix could help reduce global warming.

⦁ Developing and deploying new low-carbon and zero-carbon technologies: Research into and development of the next generation of low-carbon technologies will be critical to deep mid-century reductions in global emissions.
⦁ Ensuring sustainable development: A successful global compact on climate change must include financial assistance from richer countries to poorer countries to help make the transition to low-carbon development pathways and to help adapt to the impacts of climate change.

⦁ Adapting to changes already underway: The impacts of a warming world are already being felt by people around the globe. If climate change continues unchecked, these impacts are almost certain to get worse. Developed countries must take a leadership role in providing financial and technical help for adaptation.
Global warming promises a frightening future, and it's too late to turn back the clock. We've already taken care of that by pumping a century's worth of pollution into the air nearly unchecked. Even if we stopped all carbon dioxide emissions tomorrow, we'd still see some effects. But, we can avoid a lot of the severe consequences that climate change would otherwise bring.
Our earth is our responsibility, your action can greatly affect it in a positive or negative way. It's not too late, ''If you do things now, you will have a better life tomorrow".

Who's to BLAME

How are humans responsible for global warming?
              Deforestation and burning fossil fuels are chief culprits
Scientists have closed the case: Human activity is causing the Earth to get hotter.

How? Primarily by two actions: Burning fossil fuels, with a smaller contribution from clear cutting forests, known as deforestation.

Greenhouse gases trap heat

When we extract and burn fossil fuels such as coal or petroleum, we cause the release of carbon dioxide and other heat-trapping “greenhouse gases” into the atmosphere.

Though natural amounts of carbon dioxide have varied from 180 to 300 parts per million (ppm), today’s levels are around 400 ppm. That’s 40% more than the highest natural levels over the past 800,000 years.

We also can tell that the additional carbon dioxide in the atmosphere comes mainly from coal and oil because the chemical composition of the carbon dioxide contains a unique fingerprint.

Losing forests makes it worse

Clearing forests also releases large amounts of carbon dioxide. On top of that, plants and trees use it to grow. Worldwide deforestation means we don’t have as many trees to absorb the extra carbon dioxide.

This means more of it stays in the atmosphere, trapping more heat.

Scientists are more confident than ever that humans are responsible.

Ilissa Ocko
Climate Scientist

/www.edf.org/climate/human-activity-is-causing-global-warming

Global Warming is Human Caused
Scientists have concluded that most of the observed warming is very likely due to the burning of coal, oil, and gas. This conclusion is based on a detailed understanding of the atmospheric greenhouse effect and how human activities have been tweaking it. At the same time, other reasonable explanations, most notably changes in the Sun, have been ruled out.

The atmospheric greenhouse effect naturally keeps our planet warm enough to be livable. Sunlight passes through the atmosphere. Light-colored surfaces, such as clouds or ice caps, radiate some heat back into space. But most of the incoming heat warms the planet's surface. The Earth then radiates some heat back into the atmosphere. Some of that heat is trapped by greenhouse gases in the atmosphere, including carbon dioxide (CO2).
Human activity--such as burning fossil fuels--causes more greenhouse gases to build up in the atmosphere. As the atmosphere "thickens" with more greenhouse gases, more heat is held in. Fossil fuels such as oil, coal and natural gas are high in carbon and, when burned, produce major amounts of carbon dioxide or CO2. A single gallon of gasoline, when burned, puts 19 pounds of carbon dioxide into the atmosphere.


The role of atmospheric carbon dioxide (CO2) in warming the Earth's surface was first demonstrated by Swedish scientist Svante Arrhenius more than 100 years ago. Scientific data have since established that, for hundreds of thousands of years, changes in temperature have closely tracked with atmospheric CO2 concentrations. Since the Industrial Revolution, the burning of coal, oil and natural gas has emitted roughly 500 billion tons of CO2, about half of which remains in the atmosphere. This CO2 is the biggest factor responsible for recent warming trends.

https://www.nwf.org/Wildlife/Threats-to-Wildlife/Global-Warming/Global-Warming-is-Human-Caused.aspx

Why should we CARE

       Going forward, since the world has failed to implement meaningful abatement of emissions, the more severe warming of the earth that is foreseen will require ever greater spending for adaptation just to stay even with progressive growth in climatic harms and damages, as well as more intensive mitigation measures.

Why care about global warming?  Suppose a homeowner in America or a villager in Asia notices the first drips indicating a leaky roof.  She/he needs to repair and maintain her/his roof right away in order to minimize damage to the home’s contents.  The proverb, “a stitch in time saves nine” applies perfectly here.  Preventive investment in the integrity of the roof, undertaken before serious leaks develop, ensures that the home remains dry and undamaged.  If the roof is not repaired, damage to the home will continue indefinitely, requiring continued spending just to fix the ongoing damage.

In a similar fashion we, the people of the world, should be investing in steps to minimize the progress of global warming now in order to limit the need for emergency remedies later.  As the effects of warming become more severe the projects needed to adapt to new, harsher realities become more extensive and more costly.  Just as with the home and its roof, if we fail to abate GHG emissions “now” the damages from extreme weather and climate will continue, requiring that we provide emergency relief and build stopgap projects more or less indefinitely.

Global warming will affect our wallets, now and in the future.  Regardless of whether we agree that global warming is an issue of reason (based on sound science), a moral issue (the justice of accounting for its effects on the poor and on our children and grandchildren), a health issue, or a lifestyle issue, it clearly is a financial and economic issue.

We, the people of the entire world, would derive clear financial benefit by undertaking meaningful abatement measures to reduce GHG emissions at the present time, rather than delay.  By waiting it is certain that we will need to spend increasing resources in the future to adapt to the damages that warming brings, as well as investing more intensively in mitigation projects.

Why should we care about Global Warming?

After hearing the term ‘Environment’ what are the things that strike our mind? Stuff about trees, water, biotic factors, our surroundings, etc. roam in our brains. But do we find our current environment as green as its definition is in reality? The answer is negative. This dream environment existed in primordial time. The literal meaning of the word environment is the thing which surrounds an item. Now-a-days, we find our surroundings in a very pitiable state. The word pollution which was unfamiliar decades ago came into fame. Air pollution, Water pollution, Noise pollution, etc. are some proverbial enemies of our dear environment. Mother Nature has provided us with all our necessities. The services which could once only be dreamt are now available in reality. Mother Nature has granted all the wishes of the human race.

 But have we protected our environment? No, we haven’t. We have carelessly utilized the resources of our nature .This has led to the devastation of environment. The destruction of nature has given rise to the universal crisis named ‘Global Warming’. This term is probably familiar to everyone. We have seen organizations working at various levels to bring down the intensity of Global Warming. But what is this Global Warming? Global Warming is the increase in temperature on the earth’s surface due to the greenhouse gas emission. There are innumerable causes of this catastrophe. Some of them are deforestation, Greenhouse gas emission, overuse of fuels, etc. The effects of Global warming are deadlier than our imagination. Global Warming is the root cause of many diseases. Some of these diseases are incurable. The effects of Global Warming prove to be destruction to the human race. The most hazardous effect of Global Warming is increase in world temperature. The weather in summer season is extreme arid. Temperatures touch to 40`C. The highest temperature ever recorded is 57`C in Death Valley. Another major effect of this global crisis is rise in sea-level. This could result in flooding in low-lying areas. Some tiny island might even vanish completely! One more major problem is change in weather pattern. Many countries experience rainfall at unexpected times. Natural calamities such as hurricanes, storms, floods, etc. are now a routine to people residing in disaster prone areas. The aquatic life is endangered due to change in the temperature of oceanic waters. Chemical industries which release dangerous gases such as CFC, CO2, CO mix up with the atmosphere. This causes the depletion of ozone layer. Greenhouse gases mix up with the rain clouds which give rise to acidic rains. Today, innumerable trees are lying lifeless due to acidic rain. Fire-Brigade personnels control the flumes of fire. Trees perform the same task by lowering the risk of Global Warming. Today hardly 30% of the earth’s surface is covered by trees which is an alarm to the residents of the earth.

                  There are innumerable effects of Global Warming to discuss. But has anyone ever thought of putting a full-stop to these problems? The issue of environment destruction is a famous topic of elders for chit-chatting. But has anyone of them taken up the responsibility to stop this universal crisis? ‘Everybody’ thinks that ‘Somebody’ would do this task but in the end ‘Nobody’ does what ‘Anybody’ could have done. If we wait for everybody, we wouldn’t succeed in our task. We must take up the task of reducing Global Warming with simple precautions. At present we can see many vehicles running on the streets. Have you ever thought about the release of harmful gases by these vehicles? We certainly don’t think of such issues. But this is a very serious issue. We can’t stop travelling by vehicles but certainly we can opt for CNG as an alternative to petrol and diesel. If we travel by public transport, we can save litres of petrol and also the pollution occurring due to emission of carbon-monoxide. Tree plantation is the key to save our nature. Trees absorb the atmospheric CO2 and convert it into oxygen which is not a greenhouse gas. If every individual plants a tree per year, the population of the trees on the earth would certainly rise up. Burning of fossil fuel leads to greenhouse gas emission. Another solution of this difficult ‘Equation’ is by using less energy and recycling more products. The solution has numerous benefits.

                Lastly, I would conclude by saying that if we put efforts to stop the Global Warming, the following generations wouldn’t be familiar with this term only! We are a part of nature and not apart from it. We must take pledge to ourselves to save our dearest Mother Nature who has always cared us like her progeny. If we try to destroy nature, we’ll have to suffer double the destruction. Nature’s debt is un-repayable.

http://greencleanguide.com/why-should-we-care-about-global-warming/

Global warming is worsening

  It seems that new reports appear with increasing frequency emphasizing the worsening of global warming due to increased accumulation of man made greenhouse gases (GHG ) in the atmosphere.  They show that extreme weather or climate events already appear to be more severe and/or frequent than in the past, and will continue to worsen.  They urge that efforts be made to counter the worsening of global warming.  Most recently, the Intergovernmental Panel on Climate Change (IPCC) issued its Synthesis Report in November 2014 summarizing the more extended three-part Fifth Assessment Report dealing with the scientific basis for global warming; impacts, adaptation and vulnerability; and mitigation.  Also, a few months ago the U. S. government issued its National Climate Assessment, focusing on global warming and its effects in the U. S.

           Damages from recent extreme weather and climate events.  Effects that can be related to global warming include storms and floods (Hurricane Sandy and coastal flooding in the U. S., 2012; regular fair weather flooding from high tides in the southeastern U. S., ongoing), heat waves and droughts (Russia, 2010; U. S. Midwest and plains, 2012 and 2013; Australia, 2013), forest wildfires, and heavy rainfall and river flooding (Pakistan, 2010; England and Wales, 2014).  Such individual occurrences may be at least partly, or even entirely, caused by global warming, consistent with expected consequences of warming.

           Why should we, the public, care about these events?  These repetitive news items may seem, after a while, to be singing the same tune: “I’ve heard it all before, what’s new this time, why should I care?”  After all, at least among those of us who live in developed countries, we live in cities or other settings where we don’t directly feel the damaging effects of extreme events.  While such occurrences pass before our eyes on television and social media, our lives continue undisrupted from our normal routines.  And if a weather- or climate-driven tragedy occurs abroad, we may well ask ourselves “why does that affect me?”

Here’s why: calamities driven by global warming already affect our pocketbooks, whether we were personally harmed by an event or not.  Worsening warming in future years, with even more severe extreme events, will hit our finances even more.  In the face of financial or economic consequences of global warming, we don’t even need to consider other correct and appropriate reasons for acting.  Writers appeal to our reason, based on the scientific reports (correct as they are) documenting the scientific causes and effects of global warming that appear at each turn.  Religious communities and other morals-based groups appeal to faith or our sense of morality (appropriate as those appeals are).  These stress a moral responsibility we have to both people in impoverished lands who are affected by global warming but don’t have resources to respond, and our progeny who will be affected by worsening warming, yet who will be blameless.  Others urge us to acknowledge the important health “co-benefits” arising from reducing emissions (beneficial as they would be).  Some writers encourage us to change our attitudes and behaviors that might constrain the comfortable lifestyle that we, in developed countries around the world, enjoy and value (uncomfortable as this is likely to be). We can reject or accept these reasons for climate action as we see fit.
Financial consequences arising from extreme events.  

http://www.theenergycollective.com/henry-auer/2153506/why-care-about-global-warming

Effects of Climate Change on Agriculture

            Agriculture feeds and clothes the world. Although the long-term effects of climate change are still largely unknown, scientists can observe short-term effects of climate change on crops and animals. In addition, scientists can prognosticate about the changes that are likely to occur in agriculture if global climate change causes changes in temperatures and rainfall. The National Climatic Data Center has published a FAQ on global warming that might be useful to read.

Crops
        Data have shown that levels of atmospheric CO2 are increasing. Research is being conducted to determine what types of plant responses can be expected from these changes (see section on CO2 increase below). Others worry that climate change is going to permanently alter weather patterns, temperatures, and rainfall. NOAA data show that for much of the Southeast, annual average rainfall has been relatively constant or slowly increasing; air temperatures are slightly lower than 100 years ago. However, the frequency of rainfall events greater than 2 inches is increasing, leading to longer dry periods between rain events. Crop yields are likely affected by these changes to some extent already, but it is not clear if future changes will be catastrophic or not. Plants are surprisingly resilient, and can withstand a variety of conditions while still being productive. In addition, other factors such as location, soil fertility, crop varieties, and management practices will all affect future yields. Below we list some of the effects we could expect for agriculture due to various aspects of climate change.



Temperature Increase
Many scientists project that the average temperatures throughout the US will rise in the next few decades. Much of this warming could occur at night, but the models are not clear on this. If temperatures increase, cooler areas of the country might be more habitable for some of the main food crops grown in the US – thus, expanding the areas in which certain crops could be grown or moving their ranges north. For example, less frequent freezes could allow citrus to move north from its current range in Florida to other areas of the Southeast. In areas where crops are being grown in their warmest productive temperature ranges already, heat stress or increased disease could reduce yields. However, research on new crop varieties and technological advances could improve yields in spite of reductions due to temperature increases. A report from the IPCC (Intergovernmental Panel on Climate Change) is optimistic that general crop yields for the next century could increase in a range from 5-20% during the first few decades of the 21st century, and they expect the crop yield to remain somewhat steady (but positive) through the rest of the century. If climate change reduces the global amount of arable land, however, total yields could still decrease.

Extreme Weather Events
     Some scientists believe that climate change will lead to more extreme weather events. Extreme weather events include heat waves, droughts, strong winds, and heavy rains. Climate models do not do a good job of predicting how extreme weather events might change under global warming. For example, models do not agree on whether the number of hurricanes in a warmer world would be more or less than current values, but scientists generally feel that the strength of the largest hurricanes will increase. The length of the hurricane season could also increase. Observational changes in the number of tornadoes per year we see now may be due to increases in the number of people watching the skies and the growth of urban areas rather than any strict climate changes. It is not clear if observed changes in extreme weather events we see now are part of long natural cycles, or if they are in response to climate change. Nonetheless, all of these events can be detrimental to crop growth.
Droughts are damaging because of the long-term lack of water available to the plants. Droughts have been responsible for some of the more serious famines in the world, although sociological factors are also important. Heat waves can cause extreme heat stress in crops, which can limit yields if they occur during certain times of the plants' life-cycle (pollination, pod or fruit set). Also, heat waves can result in wilted plants (due to elevated transpiration rates) which can cause yield loss if not counteracted by irrigation. Strong winds can cause leaf and limb damage, as well as "sandblasting" of the soil against the foliage. Heavy rains that often result in flooding can also be detrimental to crops and to soil structure. Most plants cannot survive in prolonged waterlogged conditions because the roots need to breathe. In addition, flooding can erode topsoil from prime growing areas, resulting in irreversible habitat damage. Heavy winds combined with rain (from events such as hurricanes and tornadoes) can down large trees, and damage houses, barns and other structures involved in production agriculture.

Carbon Dioxide Increase
         Scientists are in agreement that the levels of atmospheric CO2 (carbon dioxide) have increased in recent years. Prior to the Industrial Revolution, they were measured at 280 parts per million by volume currently the levels are around 380 ppmv. These levels have been steadily increasing by 1.9 ppm yearly since the year 2000, largely as a result of fossil fuel burning. Carbon dioxide is critical to photosynthesis (and thus plant growth). Scientists agree that even small increases in carbon dioxide result in more plant growth. It is likely that higher levels of carbon dioxide will result in higher harvestable crop yields. However, this depends critically on the availability of sufficient water and nutrients necessary for plant growth. Some scientists believe that one drawback to this increased productivity will be crops with lower nutrient and protein levels. If true, this could have a significant, widespread impact on long-term human health if additional fertilizers were not incorporated into crop production.

http://climate.ncsu.edu/edu/k12/ClimateChange-Ag

Global Warming
             Throughout its long history, Earth has warmed and cooled time and again. Climate has changed when the planet received more or less sunlight due to subtle shifts in its orbit, as the atmosphere or surface changed, or when the Sun’s energy varied. But in the past century, another force has started to influence Earth’s climate: humanity
How does this warming compare to previous changes in Earth’s climate? How can we be certain that human-released greenhouse gases are causing the warming? How much more will the Earth warm? How will Earth respond? Answering these questions is perhaps the most significant scientific challenge of our time.
http://earthobservatory.nasa.gov/Features/GlobalWarming/page2.php

What is Global Warming?
             Global warming is the unusually rapid increase in Earth’s average surface temperature over the past century primarily due to the greenhouse gases released as people burn fossil fuels. The global average surface temperature rose 0.6 to 0.9 degrees Celsius (1.1 to 1.6° F) between 1906 and 2005, and the rate of temperature increase has nearly doubled in the last 50 years. Temperatures are certain to go up further.

Earth’s natural greenhouse effect
Earth’s temperature begins with the Sun. Roughly 30 percent of incoming sunlight is reflected back into space by bright surfaces like clouds and ice. Of the remaining 70 percent, most is absorbed by the land and ocean, and the rest is absorbed by the atmosphere. The absorbed solar energy heats our planet.
As the rocks, the air, and the seas warm, they radiate “heat” energy (thermal infrared radiation). From the surface, this energy travels into the atmosphere where much of it is absorbed by water vapor and long-lived greenhouse gases such as carbon dioxide and methane.
When they absorb the energy radiating from Earth’s surface, microscopic water or greenhouse gas molecules turn into tiny heaters— like the bricks in a fireplace, they radiate heat even after the fire goes out. They radiate in all directions. The energy that radiates back toward Earth heats both the lower atmosphere and the surface, enhancing the heating they get from direct sunlight.
This absorption and radiation of heat by the atmosphere—the natural greenhouse effect—is beneficial for life on Earth. If there were no greenhouse effect, the Earth’s average surface temperature would be a very chilly -18°C (0°F) instead of the comfortable 15°C (59°F) that it is today.
The enhanced greenhouse effect
What has scientists concerned now is that over the past 250 years, humans have been artificially raising the concentration of greenhouse gases in the atmosphere at an ever-increasing rate, mostly by burning fossil fuels, but also from cutting down carbon-absorbing forests. Since the Industrial Revolution began in about 1750, carbon dioxide levels have increased nearly 38 percent as of 2009 and methane levels have increased 148 percent.