Contra o costume, transcrevo um texto do TreeHugger explicando o fenómeno:

The 4 Stages of Global Warming Denial

June 6, 2006 09:00 AM - Michael G. Richard, near Ottawa

1. Global Warming doesn’t exist. It’s not happening.

We’ve all heard people claim as fact, without citing sources (or at least not credible ones), that “actually, the Earth is cooling” and such things.

Facts: Every year since 1917 has been warmer than 1917. Here’s a report by NASA with this choice cut about record-breaking 2005: “Record warmth in 2005 is notable, because global temperature has not received any boost from a tropical El Niño this year.”

2. Okay, it’s happening, but humans are not causing it.

Here we have all the “sun getting brighter” and “natural warming cycle” theories. They are all real possibilities, but have been discarded by scientists who looked at the evidence and concluded that they were not the causes of the current warming of the thin atmosphere of our planet.

Facts: It’s not the sun (”According to PMOD at the World Radiation Center there has been no increase in solar irradiance since at least 1978 when satellite observations began. This means that for the last thirty years, while the temperature has been rising fastest, the sun has shown no trend.”) and it’s not a natural cycle (if it was, it would be incredibly slower than what we’re seeing now and it would still need a cause).

Here is some evidence of a scientific consensus:

“The scientific consensus is clearly expressed in the reports of the Intergovernmental Panel on Climate Change (IPCC). [...] In its most recent assessment, IPCC states unequivocally that the consensus of scientific opinion is that Earth’s climate is being affected by human activities: ‘Human activities … are modifying the concentration of atmospheric constituents … that absorb or scatter radiant energy. … [M]ost of the observed warming over the last 50 years is likely to have been due to the increase in greenhouse gas concentrations’ IPCC is not alone in its conclusions. In recent years, all major scientific bodies in the United States whose members’ expertise bears directly on the matter have issued similar statements. [...]
That hypothesis was tested by analyzing 928 abstracts, published in refereed scientific journals between 1993 and 2003, and listed in the ISI database with the keywords “climate change” (9).

The 928 papers were divided into six categories: explicit endorsement of the consensus position, evaluation of impacts, mitigation proposals, methods, paleoclimate analysis, and rejection of the consensus position. Of all the papers, 75% fell into the first three categories, either explicitly or implicitly accepting the consensus view; 25% dealt with methods or paleoclimate, taking no position on current anthropogenic climate change. Remarkably, none of the papers disagreed with the consensus position. [...]

This analysis shows that scientists publishing in the peer-reviewed literature agree with IPCC, the National Academy of Sciences, and the public statements of their professional societies. Politicians, economists, journalists, and others may have the impression of confusion, disagreement, or discord among climate scientists, but that impression is incorrect.

3. Okay, humans are causing it, but there’s nothing we can do about it, we can’t go back to the stone age, it would ruin our economy, it’s worse to act than not to act, etc.

Or in the words of the new anti-Kyoto Canadian “Environment” Minister Rona Ambrose: “that would mean that today we would have to take every train, plane and automobile off the streets of Canada. That is not realistic.”

What do these people think Global Warming will do to the planetary economy? We can’t look into the future and know exactly what the consequences would be, but what we can deduct doesn’t sound good: Potentially millions of eco-refugees, disruptions in food supplies, heat waves and weird climate phenomenons, stronger hurricanes, flooded coastal areas, the possible cascading of species extinction (remember, animals can’t turn on the air conditioning - when their environment changes rapidly, they can’t artificially “adapt” like humans, and if the bottom of the food chain is affected, it will have effects on everything above), major changes in oceans, etc. Acting now is clearly the cheaper and better choice and countries that took important steps in reducing greenhouse gas emissions, like Germany, are hardly “ruined”. Some big businesses like insurance companies understand that, but a much broader consensus on action is needed among the powerful corporate players of the world.

The Apollo Alliance has been pushing a plan to create cleaner infrastructures and systems and eventually eliminate our dependence on fossil fuels. The Chicago Climate Exchange has been doing really good things too. Many others, like the folks at WorldChanging, have been putting together a vision of a “bright green future”, working on solutions that would actually stimulate the creation of a better tomorow and improve things on most if not all levels of society. There are lots of good ideas and solutions available right now. We’ve waited long enough. Lets act.

4. Okay, it is possible with technology, efficiency/conservation and smart planning to do something about it, but it’s going to hurt the bottom line of “dirty” corporations.

Well, a pusher is never happy when an addict is trying to get rid of him, and the end of slavery hurt the bottom line of slave owners. But very few people will say that these aren’t the right things to do.

Frankly, we can live with a few big companies making less money, especially considering the alternative. The stone age didn’t end because there was no stones left, and we didn’t keep blacksmiths in business forever after they weren’t needed anymore. But even the Exxons and Shells of this world have a choice: they have huge resources and could - if they wanted to - become pioneers in clean technology and profitably survive the transition our society now has to go through. We’re not talking about investing 1% of their benefits in clean technologies and doing massive PR campaigns; we’re talking about a real commitment, something proportional to their scale. But lets not wait for them to move… If they don’t, others will fill that role.