Climate Science
Climate change is a reality. Today, our world is hotter than it has been in two thousand years. By the end of the century, if current trends continue, the global temperature will likely climb higher than at any time in the past two million years.
While the end of the 20th century may not necessarily be the warmest time in Earth's history, what is unique is that the warmth is global and cannot be explained by the natural mechanisms that explain previous warm periods. There is a broad scientific consensus that humanity is in large part responsible for this change, and that choices we make today will decide the climate of the future.
How we are changing the climate
For more than a century, people have relied on fossil fuels such as oil, coal and gas for their energy needs. Burning these fossil fuels releases the greenhouse gas (GHG) carbon dioxide into the atmosphere. Other, even more potent greenhouse gases are also playing a role, as well as massive deforestation.
The scientific understanding of climate change is now sufficiently clear to justify nations taking prompt action.
Joint statement by 11 national science academies to world leaders
What we know
While there are still uncertainties, particularly related to the timing, extent and regional variations of climate change, there is mainstream scientific agreement on the key facts:
· Certain gasses in the atmosphere, such as carbon dioxide, create a "greenhouse effect", trapping heat and keeping the Earth warm enough to sustain life as we know it.
· Burning fossil fuels (coal, oil, etc.) releases more carbon dioxide into the atmosphere. Although not the most potent greenhouse gas, carbon dioxide is the most significant in terms of human effects because of the large quantities emitted.
· Carbon dioxide concentrations in the atmosphere are now the highest in 150,000 years.
· The 1990's was most likely the warmest decade in history, and 1998 the warmest year.
There is also widespread agreement that:
· A certain amount of additional warming - about 1.3 degrees Celsius (2.3 degrees Fahrenheit) compared to pre-industrial levels - is probably inevitable because of emissions so far. Limiting warming to under 2 degrees Celsius (3.6 degrees Fahrenheit) is considered vital to preventing the worst effects of climate change.
· If our greenhouse gas emissions are not brought under control, the speed of climate change over the next hundred years will be faster than anything known since before the dawn of civilization.
· There is a very real possibility that climate feedback mechanisms will result in a sudden and irreversible climate shift. No one knows how much global warming it would take to trigger such a "doomsday scenario."
CO2 emissions
Carbon dioxide and fossil fuels: where do the greenhouse gases come from, who put them in the atmosphere and what can we do about it?
The primary human source of carbon dioxide (CO2) in the atmosphere is from the burning of fossil fuels for energy production and transport. Changes in land use and deforestation also contribute significantly. Trees, for example, are natural 'carbon sinks' - they absorb carbon dioxide while alive and when they are destroyed, carbon dioxide is released into the atmosphere. Once in the atmosphere, most of the carbon dioxide stays there for 50 to 200 years, and some of it stays there indefinitely.
What are fossil fuels?
Oil, coal and natural gas are called fossil fuels because it is believed they are formed from the remains of plants and animals living millions of years ago. All fossil fuels are made up of hydrocarbons, and release carbon dioxide when burned.
How we are changing the climate
For more than a century, people have relied on fossil fuels such as oil, coal and gas for their energy needs. Burning these fossil fuels releases the greenhouse gas (GHG) carbon dioxide into the atmosphere. Other, even more potent greenhouse gases are also playing a role, as well as massive deforestation.
The scientific understanding of climate change is now sufficiently clear to justify nations taking prompt action.
Joint statement by 11 national science academies to world leaders
What we know
While there are still uncertainties, particularly related to the timing, extent and regional variations of climate change, there is mainstream scientific agreement on the key facts:
· Certain gasses in the atmosphere, such as carbon dioxide, create a "greenhouse effect", trapping heat and keeping the Earth warm enough to sustain life as we know it.
· Burning fossil fuels (coal, oil, etc.) releases more carbon dioxide into the atmosphere. Although not the most potent greenhouse gas, carbon dioxide is the most significant in terms of human effects because of the large quantities emitted.
· Carbon dioxide concentrations in the atmosphere are now the highest in 150,000 years.
· The 1990's was most likely the warmest decade in history, and 1998 the warmest year.
There is also widespread agreement that:
· A certain amount of additional warming - about 1.3 degrees Celsius (2.3 degrees Fahrenheit) compared to pre-industrial levels - is probably inevitable because of emissions so far. Limiting warming to under 2 degrees Celsius (3.6 degrees Fahrenheit) is considered vital to preventing the worst effects of climate change.
· If our greenhouse gas emissions are not brought under control, the speed of climate change over the next hundred years will be faster than anything known since before the dawn of civilization.
· There is a very real possibility that climate feedback mechanisms will result in a sudden and irreversible climate shift. No one knows how much global warming it would take to trigger such a "doomsday scenario."
CO2 emissions
Carbon dioxide and fossil fuels: where do the greenhouse gases come from, who put them in the atmosphere and what can we do about it?
The primary human source of carbon dioxide (CO2) in the atmosphere is from the burning of fossil fuels for energy production and transport. Changes in land use and deforestation also contribute significantly. Trees, for example, are natural 'carbon sinks' - they absorb carbon dioxide while alive and when they are destroyed, carbon dioxide is released into the atmosphere. Once in the atmosphere, most of the carbon dioxide stays there for 50 to 200 years, and some of it stays there indefinitely.
What are fossil fuels?
Oil, coal and natural gas are called fossil fuels because it is believed they are formed from the remains of plants and animals living millions of years ago. All fossil fuels are made up of hydrocarbons, and release carbon dioxide when burned.
Carbon dioxide emissions and the carbon cycle.
Currently, fossil fuels are the primary source for almost 80 percent of the industrial world's energy. They are a non-renewable resource, so we'll eventually run out of them. However, if we want to avoid dangerous climate change we can only afford to burn less than one-fourth of the known oil, coal and gas reserves - burning any more will almost certainly release enough carbon dioxide to change the climate dramatically.
Who burns the most?
The simple answer is that because industrialised nations have bigger economies and have been burning fossil fuels for a hundred years or more, they are responsible for most of the cumulative carbon dioxide emissions in the atmosphere. However, all nations are responsible to one degree or another.
This can, and should, change in the future. In some countries, it is changing today. Thanks to renewable energy technology and energy efficiency, economic development and fossil fuel use need not be coupled.
However, among the world's top economies, the US still stands out as the number one polluter. With less than 5 percent of the world's population, the US is the world's largest producer of greenhouse gases and is responsible for almost a quarter of global emissions of carbon dioxide.But to look at carbon dioxide emissions only by country is perhaps too narrow. The same question applies per business or even individual. Someone driving a gas-guzzler of a car is burning more fossil fuels then someone with a more efficient car, for example. Of course nations and businesses must be held accountable, but as individuals we each also make decisions that affect the climate.
Who burns the most?
The simple answer is that because industrialised nations have bigger economies and have been burning fossil fuels for a hundred years or more, they are responsible for most of the cumulative carbon dioxide emissions in the atmosphere. However, all nations are responsible to one degree or another.
This can, and should, change in the future. In some countries, it is changing today. Thanks to renewable energy technology and energy efficiency, economic development and fossil fuel use need not be coupled.
However, among the world's top economies, the US still stands out as the number one polluter. With less than 5 percent of the world's population, the US is the world's largest producer of greenhouse gases and is responsible for almost a quarter of global emissions of carbon dioxide.But to look at carbon dioxide emissions only by country is perhaps too narrow. The same question applies per business or even individual. Someone driving a gas-guzzler of a car is burning more fossil fuels then someone with a more efficient car, for example. Of course nations and businesses must be held accountable, but as individuals we each also make decisions that affect the climate.
Daniel Casique 17646876 CRF
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