The canary in the coal mine died long ago.

There have been 5 great extinctions in earth's long history- in all but the last one (the famous KT extinction event brought on by asteroid impact) dramatically changing CO2 levels (rising and falling leading to heating or cooling) have been implicated as the culprit. Even the KT event may have been exacerbated by CO2 release from the Deccan Traps.

The fact that anthropogenic CO2 could lead to warming has been understood for well over a century- the basic science there is no mystery. Increasing atmospheric CO2 WILL lead to warming, it MUST lead to warming.

The argument that it is hubris to think that human activity could play a role in the atmospheric composition crumbles when the facts are considered:

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According to the U.S. Geological Survey (USGS), the world’s volcanoes, both on land and undersea, generate about 200 million tons of carbon dioxide (CO2) annually, while our automotive and industrial activities cause some 24 billion tons of CO2 emissions every year worldwide. Despite the arguments to the contrary, the facts speak for themselves: Greenhouse gas emissions from volcanoes comprise less than one percent of those generated by today’s human endeavors.

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The science has been clear for decades- increasing CO2 WILL lead to warming, humans ARE increasing the CO2 rapidly, and we ARE now seeing warming. We also now have the knowledge needed to make estimates of the degree of warming we can expect with high confidence. Those estimates (lets only consider the conservative estimates for now) are painting an increasingly grim picture of the future. The conservative estimates that assume IMMEDIATE and drastic action still leave us with warming that will challenge our civilization's ability to survive.

Yet Humanity has dumped more CO2 into our atmosphere SINCE Al Gore wrote the book that so upset conservatives, than it had in all its history before. And our nation refuses to even acknowledge the science and our president slanders the scientists. There will be no immediate action taken. The goal of limiting the warming to 2 degrees C is fantasy, even IF we were to take immediate action. Our best case scenario is looking to be more like 3 degrees warming by 2100.

The Trump Administration is blithely assuming 7 degrees warming by 2100 and using that to argue that fuel economy standards won't make much difference:

The draft statement, issued by the National Highway Traffic Safety Administration (NHTSA), was written to justify President Trump’s decision to freeze federal fuel-efficiency standards for cars and light trucks built after 2020. While the proposal would increase greenhouse gas emissions, the impact statement says, that policy would add just a very small drop to a very big, hot bucket.

Business as usual estimates for warming- assuming no significant action- give us 4-8 degrees of warming by 2100:
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Now two degrees is our goal, per the Paris climate accords, and experts give us only slim odds of hitting it. The U.N. Intergovernmental Panel on Climate Change issues serial reports, often called the “gold standard” of climate research; the most recent one projects us to hit four degrees of warming by the beginning of the next century, should we stay the present course. But that’s just a median projection. The upper end of the probability curve runs as high as eight degrees — and the authors still haven’t figured out how to deal with that permafrost melt. The IPCC reports also don’t fully account for the albedo effect (less ice means less reflected and more absorbed sunlight, hence more warming); more cloud cover (which traps heat); or the dieback of forests and other flora (which extract carbon from the atmosphere). Each of these promises to accelerate warming, and the history of the planet shows that temperature can shift as much as five degrees Celsius within thirteen years. The last time the planet was even four degrees warmer, Peter Brannen points out in The Ends of the World, his new history of the planet’s major extinction events, the oceans were hundreds of feet higher.

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The degree of warming we are facing will bring us areas of our planet that are uninhabitable.

1 million Syrian refugees created an excuse for fascist demagogues to gain power in Europe. In the next 3 decades the most optimistic estimates for the number of climate refugees is in the 10s of millions, with high-end estimates approaching a billion. The refugee flux from Africa, South America, and south Asia will grow by orders of magnitude.

Food production will fall- perhaps drastically and suddenly. By 2050 it seems certain that wars will be fought over water access as the glaciers rapidly vanish. The seas are acidifying, coral reefs are dying at an accelerating pace and are expected to be largely gone by 2050- eliminating a source of food for many impoverished populations.

The next 30 years will probably see death on a scale we have never seen in the history of our species.

Those that conspired to obscure and slander the science are the greatest criminals of all- and will be remembered as such as long as the study of history manages to survive.