Anthropogenic global warming (AGW) refers to an unprecedented rate of increase in temperatures of our planet Earth, and the corresponding climate system perturbations, as a result of significantly increased greenhouse gas emissions from human activities. A simple search will reveal a vast amount of material on this topic. The problem of AGW is associated with other associated problems caused to the Earth system due to human activities, and it is difficult, and perhaps unwise to separate it. Others have attempted to address by creating a multidimensional concept of planetary boundaries that humanity can and should thrive within, and is unlikely to thrive if it crosses them.
I myself think the positive feedback process that represents the tipping point for AGW is reached when Arctic ice has completely melted away at least for a brief period during the summer (the first canary in the coal mine dying), and then through the entire year (the entire flock of canaries going the way of the first). The first canary's death, and corresponding consequences, is imminent from observations of the Northern cryosphere. As the ice melts due to warmer waters from the gulf stream and rivers that drain into the Arctic ocean, as well as warmer global and hemispheric atmospheres, a greater amount of methane (from warming subsea hydrates as well as permafrost) is released. These high levels of methane then spread through the rest of the planet as a consequence of wind and water currents, which are further destabilised by the very same phenomena causing the increased loss of ice and methane concentrations. Temperatures are also further increased by decreased albedo from the loss of ice, causing further amplification of the self-reinforcing feedbacks described in this paragraph.
In an ideal world, the issue of AGW would be amenable to two kinds of solutions that are applicable correspondingly: a global solution that works globally, and an individual solution that works at an individual level. The global solution, which is political, I believe first requires agreement between most peoples of the world to certain limits and penalties. Once agreement is achieved, failure to adhere to these agreements must be treated the same way rogue nations are treated on this planet (incrementally, of course). Once we're locked into 2 degrees C of warming (a generous limit), this solution starts to become increasingly unlikely---we are extremely close to doing so, and there's no indication that we're going to do anything to stop this from happening. Once we're locked into 4 degrees C of warming (also a generous limit), this solution becomes no longer available to us.
Individual solutions, which still require some technical hurdles to be crossed, are things like constructing self-contained biospheres that allow small numbers of people to survive indefinitely. A country capable of constructing nuclear powered submarines should be able to cross these hurdles. Once a global solution becomes unavailable, this is the only way available for humanity to survive as a species.
Overall, I believe nothing done at an individual level matters in terms of AGW unless most people in the world agree to the limits that can be discerned from various analyses put out by climate scientists. I also believe that this is a fascinating experiment being conducted by humanity with regards to its own survivability. Hospice care of human populations becomes more relevant as global solutions become completely untenable.
These are random thoughts that haven't been integrated properly yet, but when they are, they will be moved up.
The prospect of near term human extinction (NTHE) within the next 100-200 years is very real in my view. What can one do about it? For me to figure out what to do, I had to ask the question: what are the most important and most urgent things I could do in my life. Before I started my own family, the answer was very clear: art, science, philosophy (all the same thing to me) were my passions and still are. I also started my own family, which is one of the most important things in my life. Spending time with them engaging in my passions is what I'd be doing with or without NTHE. The prospect of NTHE only serves to emphasise how right those choices are for me. In the end, what matters? When you die, you can't take your material possessions with you. Your intellectual contributions remain but only for a while and eventually they are supplanted. What matters is how I live. I feel anything I do can't change what happens and in fact, I don't want such a responsibility or power. I don't want to be in such a position where what I do matters to anyone else except people I care about. I'd rather be a curious scientific observer: to see if humanity can get it together to survive the challenge So spending time with my family and engaging in my passions are how I plan to live my life.