- 195 sovereign nations (participants in the Intergovernmental Panel on Climate Change). That is every country on earth including the Democratic People's Republic of Korea. It also includes countries whose economies are heavily dependent on fossil fuel extraction, such as Saudi Arabia and Qatar. The Saudis are planning to leave much of their oil in the ground.
- Exxon Mobil Corporation (although they lied about it for decades)
- Former Exxon CEO and current U.S. Secretary of State Rex Tillerson
- Virtually every scientist who works in a relevant field. (The commonly cited figure is actually 97% but the work of the 3% has been discredited.)
How do we know this is true? Actually, scientists have understood since the late 19th Century that the lower atmosphere is as warm as it is because of the presence of carbon dioxide. Arrhenius published this conclusion in 1896, and he later noted that burning fossil fuel would increase the CO2 in the atmosphere, presumably warming the climate. This is completely understood and it is quite straightforward. The atmosphere is largely transparent to visible and UV light. The sun's light warms the ground which then radiates heat back as infrared, to which CO2 is opaque. The CO2 absorbs the light and gets warmer, and it transfers this warmth to the other gases in the atmosphere. That's what keeps the earth warm. More CO2=more warmth. There is no doubt of this whatsoever.
Since reliable records started being kept in the 1880s, the atmosphere has warmed by about 2 degrees Fahrenheit, while the amount of CO2 in the atmosphere has increased by 43%. This is entirely consistent with model predictions. The extra CO2 is coming from humans burning fossil fuel, which is confirmed by radioactivity analysis, and also because there is no other plausible source for it. The warming is accounted for entirely by human activity. Yes, the climate has changed in the past, but over geologic time scales of thousands of years. This very abrupt change is unprecedented, as far as we know.
Most of the excess heat has been absorbed by the ocean, or the atmosphere would already be warmer. Coral reefs are dying and, as you may have noticed, storms are getting stronger. Warmer oceans make stronger hurricanes, and warmer air holds more water vapor so that rain events are more intense. At the same time, warmer places dry out faster, exacerbating the effects of droughts. And as global rainfall patterns change, some areas are becoming drier anyway. The result has been famine, and civil unrest. The collapse of Syria began with the migration of starving farmers to the cities and attendant social stresses. Agriculture has also collapsed in parts of Africa.
Sea level is now rising at a rate of about 1 foot per century, but it appears to be accelerating. Coastal areas are already experiencing more flooding, even in fair weather, just from the tides, and it's just going to get worse.
The only reason sane people deny this is because they are blinded by ideology. The Free Market™ can do no wrong. If this is really happening, we need to tax fossil fuels or otherwise find ways to reduce their use through regulation. But that can't possibly be necessary because Ayn Rand said so. Other people, such as the Koch brothers, deny it out of insatiable greed, even though they probably know that it is actually true. And some people are just easily fooled by propaganda. The tobacco companies did the same thing when it came to smoking and lung cancer, and they were just as evil.
I will not tolerate denial of anthropogenic climate change here, just as I will not tolerate holocaust denial or for that matter, a claim that the earth is flat and the sun revolves around it. This is not a matter that is open to dissent, or disagreement, or debate. It is a fact. People who refuse to believe it are not worthy of my time or attention.
P.S. If you don't want me to call you a moron, don't be a moron.