QUESTION

What are the key arguments for and against global warming?


curated by 259 crowd contributors

We pulled together 12 of the most popular web sites to create this page, including www.theguardian.com, www.aproundtable.org, www.skepticalscience.com. We've organized their information into the most commonly discussed topics below, ranging from C02 to There is general support, although it can be masked by lobbying efforts.. A total of 48 crowdworkers were involved during the process, of which 23 of them gathered the information, 25 of them organized the information by different topics, and 0 of them synthesized the information into this article.


Overview

C02: Global warming remains controversial among scientists. There is not doubt that human activities increase the production of "greenhouse gasses" Whether or not these gasses are harmful is still in question.

Uncertainty: Predictions of climate change are based on computer models more than historical data. The computer models can be incorrect and are sometimes even manipulated by the scientists creating them. This can make it difficult for scientists to predict the cause and extent of global warming accurately.

Evidence for global warming: Humans are contributing to global warming and it is happening at a quicker pace now than it was before 1981.

Earth's climate is difficult to predict: There is no global warming.The earth has been cooling.

Evidence against climate change: The earth is cooling. There is no global warming.

Human impact opinion: Science says: Negative impacts of global warming on agriculture, health, and environment far outweigh any positives.

Global warming is natural and historic: Humans may, or may not, be causing global warming.

There is general support, although it can be masked by lobbying efforts.: Many westerners believe that global warming is a serious threat. However, Cote believes that the issue is more political than scientific. In contrast, organizations like The Climate Group, are looking for ways to prevent disasters caused by global warming.


C02

C02

Global warming remains controversial among scientists.

There is long-term correlation between CO2 and global temperature; other effects are short-term.

The effects of enhanced CO2 on terrestrial plants are variable and complex and dependent on numerous factors

The ocean is absorbing massive amounts of CO2, and is becoming more acidic as a result.

1. Many scientists do not believe human activities threaten to disrupt the Earth’s climate. More than 17,000 scientists have signed a petition circulated by the Oregon Institute of Science and Medicine saying, in part, “there is no convincing scientific evidence that human release of carbon dioxide, methane, or other greenhouse gases is causing or will, in the foreseeable future, cause catastrophic heating of the Earth’s atmosphere and disruption of the Earth’s climate.” (Go to www.oism.org for the complete petition and names of signers.) Surveys of climatologists show similar skepticism.

The hypothesis is that Earth's atismosphere is warming because of the release of "greenhouse gases," such as carbon dioxide. These gases are released into the air from burning gas, oil, coal, wood and other resources which then hold heat in an action similar to the walls of a greenhouse. - Source, Public Broadcasting Service

Human activities release greenhouse gases such as carbon dioxide (CO2), methane (CH4), and nitrous oxide (NO2), into the atmosphere. As of Apr. 2010, CO2 levels were 389 parts per million (ppm) - reportedly higher than at any time in the last 650,000 years when levels fluctuated between 180 and 300 ppm

Carbon dioxide (CO2) is released and absorbed in the global carbon cycle.

The amount of carbon dioxide absorbed by the upper layer of the oceans is increasing by about 2 billion tons per year

How did carbon dioxide, necessary for life on Earth and only 4 parts in 10,000 of our atmosphere, get rebranded as some sort of dangerous gas? Carbon dioxide itself is not "bad." Water is also necessary for life. Too much water will kill you. Too much carbon dioxide causes dangerous climate change. Greenhouse gases were determined to be pollutants as defined in the US Clean Air Act . This was a ruling of the (politically conservative at the time) US Supreme Court.

Uncertainty

Uncertainty

Predictions of climate change are based on computer models more than historical data.


Alarmists frequently quote the executive summaries of reports from the United Nations's Intergovernmental Panel on Climate Change (IPCC) to support their predictions about climate change. The IPCC’s latest report, Climate Change 2001, says this about predicting the future climate: “The Earth’s atmosphere-ocean dynamics is chaotic: its evolution is sensitive to small perturbations in initial conditions. This sensitivity limits our ability to predict the detailed evolution of weather; inevitable errors and uncertainties in the starting conditions of a weather forecast amplify through the forecast. As well as uncertainty in initial conditions, such predictions are also degraded by errors and uncertainties in our ability to represent accurately the significant climate processes.”

Errors accurately representing the significant climate processes are a key reason why the science behind theories of Global Warming may be flawed.
Predictions of global warming are based on computer models, not historical data. To get models to produce predictions that are close to their designers’ expectations, modelers resort to “flux adjustments” that can be 25 times larger than the effect of doubling carbon dioxide concentrations, the supposed trigger for global warming. Richard A. Kerr, a writer for Science, says “climate modelers have been ‘cheating’ for so long it’s almost become respectable.”

Essentially, scientists make assumptions about how much of an impact different factors will have; they guess how much of a change there will be and then they use models to project changes over time. Unfortunately, almost all of these models showing huge temperature gains have turned out to be wrong.
For the past 40 years, radiosonde temperature data from around the world has been collected twice each day, once during the day and once at night. While nighttime radiosonde measurements were consistent with climate models and theories showing a general warming trend, daytime measurements showed the atmosphere to be cooling since the 1970's.

Evidence for global warming

Evidence for Global Warming

Humans are contributing to global warming and it is happening at a quicker pace now than it was before 1981..

In the scientific literature, there is a strong consensus that global surface temperatures have increased in recent decades and that the trend is caused primarily by human-induced emissions of greenhouse gases.

Satellite observations reveal that the amount of spring snow cover in the Northern Hemisphere has decreased over the past five decades and that the snow is melting earlier

According to Santer, the only group to previously analyze satellite data on the troposphere - the lowest layer in Earth's atmosphere - was a research team headed by Roy Spencer from University of Alabama in 1992

Ocean measurements, decreases in snow cover, reductions in Arctic sea ice, longer growing seasons, balloon measurements, boreholes and satellites all show results consistent with records from surface weather stations. The urban heat island effect is real but small; and it has been studied and corrected for.

Most of this warming has occurred since the 1970s, with the 20 warmest years having occurred since 1981 and with all ten of the warmest years occurring in the past twelve years. Even though the 2000's witnessed a solar output decline resulting in an unusually deep solar minimum during 2007-2009, surface temperatures continue to increase.

Earth's climate is difficult to predict

Earth's climate is difficult to predict

There is no global warming.The earth has been cooling..

Since 1998 - more than a decade - the record, as determined by observations from satellites and balloon radiosondes, shows no discernible warming.

Instruments show there has been some warming of the Earth's surface since 1979, but the actual value is subject to large errors. Most long-term data comes from surface weather stations. Many of these are in urban centres which have been expanding and using more energy. When these stations observe a temperature rise, they are simply measuring the "urban heat island effect".

Over the last 30 years of global warming, the sun has shown a slight cooling trend. Sun and climate are going in opposite directions. This has led a number of scientists independently concluding that the sun cannot be the cause of recent global warming.

While surface thermometers have clearly shown that the Earth's surface is warming, satellite and weather balloon data have actually suggested the opposite, that the atmosphere was cooling.

Evidence against climate change

There hasn't been any global warming since 1997: If nothing changes in the next year, we're going to have kids who graduate from high school who will have never seen any "global warming" during their lifetimes.

Arctic ice is up 50% since 2012: The loss of Arctic ice has been a big talking point for people who believe global warming is occurring. Some people have even predicted that all of the Arctic ice would melt by now because of global warming. Yet, Arctic ice is up 50% since 2012

Sherwood explains these discrepancies by pointing out that the older radiosonde instruments used in the 1970's were not as well shielded from sunlight as more recent models. What this means as that older radiosondes showed warmer temperature readings during the day because they were warmed by sunlight.

Predictions about the impact of global warming have already been proven wrong: The debate over global warming has been going on long enough that we've had time to see whether some of the predictions people made about it have panned out in the real world.

The Earth's climate has changed throughout history. Just in the last 650,000 years there have been seven cycles of glacial advance and retreat, with the abrupt end of the last ice age about 7,000 years ago marking the beginning of the modern climate era — and of human civilization.

Human impact opinion

So, there is this transition from one model of 'serving science on a plate' to 'everyone come join us in the kitchen.' Fights are bound to burst when there is no agreement on how to proceed."

Dr. Mitch Taylor, told the Frontier Centre for Public Policy that data he has seen does not appear to prove polar bears as a species are threatened or that their populations are in decline. He does, however, say that "some populations do seem to be experiencing deleterious effects from climate change."

Natural or Manmade? If we don't know how much of recent warming is natural, then how can we know how much is manmade?

Science says: Negative impacts of global warming on agriculture, health, and environment far outweigh any positives.

Global warming is natural and historic

Global Warming is Natural and Historic

Humans may, or may not, be causing global warming..

The beginning of the last Millennium saw a "Medieval Warm Period" when temperatures, certainly in Europe, were higher than they are now. Grapes grew in northern England. Ice-bound mountain passes opened in the Alps. The Arctic was warmer in the 1930s than it is today.

The fossil fuels lobby and free market think tanks have often been accused of overtly or covertly supporting efforts to undermine or discredit the scientific consensus on global warming.

A common skeptic argument is that climate has changed naturally in the past, long before SUVs and coal-fired power plants, so therefore humans cannot be causing global warming now.

The year 1998 was exceptionally warm because of a strong El Nino event, while 2008 was unusually cold because of La Nina conditions. Variability from year to year is expected, and picking a specific warm year to start an analysis, or a cold one to end with is "cherry-picking".

There is general support, although it can be masked by lobbying efforts.

There is general support, although it can be masked by lobbying efforts.

Many westerners believe that global warming is a serious threat.

One of the authors' main arguments is that most prominent scientists who have been voicing opposition to the near-universal consensus are being funded by industries, such as automotive and oil, that stand to lose money due to government actions to regulate greenhouse gases.

A 2009 survey found that Europeans rated climate change as the second most serious problem facing the world, between "1. poverty, the lack of food and drinking water" and "3. a major global economic downturn". 87% of Europeans considered climate change to be a very serious or serious problem, while ten per cent did not consider it a serious problem.

Forty-five percent of Americans believe the country will be harmed by global warming in the next 50 years, with only 16 percent saying that global warming will never harm the U.S.

Cote believes that the issue is more political than scientific, in large part due to some of these regulatory plans. For many, government intervention and raised taxes are highly contested issues. The imposition of taxes to prevent climate change creates a situation to which many are opposed. Some climate skeptics, fight against the actual concept and the science of climate change in order to argue that additional taxes and regulations are not necessary. Cote himself states that he's "just not interested in tax raisers."

Those who seek to prevent further climate change, such as the international non-profit organization The Climate Group, believe that slowing climate change will help the economy and improve overall qualities of life. Climate-conscious groups see climate change as a threat to global standards of living. They prediction that weather extremes will be more common, ecosystems will be challenged and ice melt will cause sea-level rise that will lead to flooding. Many of the issues that are cited as causes for global warming, such as an increase in greenhouse gases, also have adverse health effects on people living in polluted areas.