Just as the world's most respected scientific bodies have confirmed that world is getting hotter, they have also stated that there is strong evidence that humans are driving the warming. The 2005 joint statement from the national academies of Brazil, Canada, China, France, Germany, India, Italy, Japan, Russia, the UK and the US said:
"It is likely that most of the warming in recent decades can be attributed to human activities."
Countless more recent statements and reports from the world's leading scientific bodies have said the same thing. For example, a 2010 summary of climate science by the Royal Society stated that:
"There is strong evidence that the warming of the Earth over the last half-century has been caused largely by human activity, such as the burning of fossil fuels and changes in land use, including agriculture and deforestation."
The idea that humans could change the planet's climate may be counter-intuitive, but the basic science is well understood. Each year, human activity causes billions of tonnes of greenhouse gases to be released into the atmosphere. As scientists have known for decades, these gases capture heat that would otherwise escape to space – the equivalent of wrapping the planet in an invisible blanket.
Of course, the planet's climate has always been in flux thanks to "natural" factors such as changes in solar or volcanic activity, or cycles relating the Earth's orbit around the sun. According to the scientific literature, however, the warming recorded to date matches the pattern of warming we would expect from a build up of greenhouse gas in the atmosphere – not the warming we would expect from other possible causes.
Even if scientists did discover another plausible explanation for the warming observed to date, that would beg a difficult question. As Robert Henson puts it in The Rough Guide to Climate Change:
"If some newly discovered factor can account for the climate change then why aren't carbon dioxide and the other greenhouse gases producing the warming that basic physics tells us they should be?"
The only way to prove with 100% certainty that humans are responsible for global warming would be to run an experiment with two identical Earths – one with human influence and one without. That obviously isn't possible, and so most scientists are careful not to state human influence as an absolute certainty. Nonetheless, the evidence is now extremely strong.
We'll look at more specific questions about the links between greenhouse gases and global warming separately. Check back soon for those.
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Based on a work at theguardian.com
Over the last hundred years the Earth has been warming. This warming is believed to lead to many issues such as drought, weather extremes and famine. The man made global warming theory states that man made CO2 is causing Earth to warm at an alarming rate; thus, the warming will continue. While some scientists believe CO2 is the culprit, other scientists believe the world’s warming and cooling happens in cycles due to various factors. Some of these scientists believe that Earth is starting a cooling trend after a long warming trend. Therefore, the trillion dollar question is global warming caused by CO2 or is this Earth’s natural cycle?
Carbon dioxide is the gas that is responsible for global warming under the man made global warming theory. CO2 is also a part of everyday life. Therefore, this gas should not be confused with smog, which creates a low level ozone layer that can be harmful to humans. CO2 is less than 2% of the world’s atmosphere. Meanwhile 93% of all CO2 is stored in the world’s oceans; the rest is stored the biosphere in things like plants. Oceans move CO2 into the atmosphere and then remove it as continual cycle. Warmer waters, like tropical waters, store less CO2 than colder arctic or deep waters. As CO2 increases in the Earth’s atmosphere, the oceans work harder to remove it. CO2 concentrations in the atmosphere have increased 30% since the pre-industrial era. The ocean has also increased its absorption of CO2 from roughly 2.0 Pg of CO2 in the 1980s to 2.4 Pg in the 1990s. Along with the oceans increased CO2 absorption, plants and trees also take in more CO2. This extra absorption of CO2 increases crop yields and plant growth.
The question arises if man is increasing the CO2 significantly or if the oceans are naturally warming and releasing more CO2 as a part of a cycle? Unfortunately, most graphs shown in news articles only go back 120 years, starting in the 1880s. One glance at these graphs and a person could easily deduce that man and industrialization has caused global warming. Many seem to forget that the last ice age was over 100,000 years ago, so looking at the last 120 years for temperature change seems inadequate. Archeologists have found cities under the oceans, such as the one in India that is 9500 years old. This indicates that the Earth must have been warming for some time, possibly including many warming and cooling cycles. Going back 2000 years paints a better picture than the 120 year “hockey stick” graph. In the Middle Ages the temperature deviation was the same as today. This period did not have industry that created man made CO2.
Images are from GlobalWarmingArt.com, red line is the most recent reconstructed model. Darker lines indicate older models.
Another interesting fact is that even though man made CO2 has exponentially increasing from 1950 to today, temperature from 1940 to 1980 decreased. Scientists back in the 1970s believed that pollution was causing global cooling. The real problem is that any model based off a lower point, like 1880s temperature, would make the model appear that the earth is on fire. Instead of using incomplete models, models need to include a couple of temperature cycles to fully understand how the Earth behaves.
At least 70-80% of the Earth’s warming effect comes from water vapor and clouds not CO2. CO2 traps about 10-20% of the world’s heat. Other contributors to warming include high altitude cirrus clouds and sunspots. Cirrus clouds block radiant heat from escaping the Earth’s atmosphere. Sunspots have been known throughout history to have an effect on the Earth’s temperature. From 1645 to 1715 there were very few sunspots recorded. This also was a period referred to as the little ice age. Over the last 60 years, our sun has been very active with a record number of sun spots recorded. This could also be the reason that ice caps on Mars are melting and other planets in our solar system are experiencing warming, like Jupiter.
By studying models that are more inclusive, scientists are now worried about the warming trend reversing. The Antarctic Ice Sheet is growing at a record pace. The media seems to focus on just the Wilkins ice sheet, which is only 0.01% of Antarctica’s ice cover. The rest of the ice cover is returning 60% faster than last year at 4.0 square km. Even Greenland is seeing a 15 year high in ice levels between Canada and itself. In the US this spring has been much cooler than normal for most of the country. These events are leading more and more scientists to believe the Earth is in for a cooling trend. If global cooling occurs, agricultural life could change as we know it. This could lead to a worldwide food shortage and a displacement of millions of people.
Currently, the United States Congress is debating a potential five trillion dollar energy policy. This policy will place carbon caps on corporations. This will raise cost of energy significantly. Money raised from these caps would be redistributed to more expensive renewable energy projects. The poor will suffer the most as they will have to contend with rising food prices, rising gas prices and now rising energy costs. With so many factors causing global warming, the anti- CO2 movement seems very reckless and will cause many people to suffer.
Fighting emissions from cars and factories is a very noble cause. Pollution can cause all sorts of problems like asthma. To say the world is warming because of humans is a very bold claim. Lots of factors go into warming the Earth. To focus on just one, CO2 is very naïve. It can also be very dangerous as it sacrifices our economic stability and standard of living. Doubling the price of gasoline over the last few years has caused food costs to shoot up; fishermen and truckers to be put out of business; and many low income people to suffer. Now, Congress is debating to do the same thing to electricity prices.
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