Thanks for responding in a civil manner and I’ll try to do the same.
So, I’ve never actually seen that graph before about the diminishing effect of CO2, but let me explain why I don’t buy that for a second, and if anything I think that graph should be flipped (i.e. higher concentrations should lead to a greater warming effect).
First, even if we assume that graph is correct, the increase in temperature from pre-industrial times to now doesn’t match up to reality. If you go by the graph, it would assume that the global average temperature has risen by about 0.6 degrees while in reality it has risen by about 1.1 degrees.
Second, if the graph were true, then we would not expect to continuously be breaking all-time high temperature records in recent years. The past five years have been the hottest on record (in nearly 140 years), July of this year was the hottest on record, and there have been 42 consecutive years that have been warmer than the 20th-century average.
Third, as CO2 emissions have risen, so too have temperatures in a somewhat linear manner with natural variability in temperature accounted for.
Lastly, I expect the warming effect from continued CO2 emissions to actually increase because of the diminishing effect of the oceans to absorb CO2. Currently, oceans are absorbing approximately 35% of our CO2 emissions (and 90% of the excess heat caused by all greenhouse gases). However, as ocean acidification increases, the oceans will begin to lose their ability to be a carbon sink (just as we lose more forests due to wildfires and deforestation, we lose more of our land carbon sinks). All this means that the CO2 being absorbed by these carbon sinks currently will eventually create an even greater warming effect in the atmosphere when the CO2 is no longer being absorbed as effectively.
Now, as far as why sea levels aren’t that high already, good question. The answer has partially due to the latency warming effect of CO2 (i.e. it takes a decade to fully experience the warming effect of CO2 emissions) and the delayed effects from glaciers melting and thermal expansion of ocean water. As Dahr Jamail talks about in “The End of Ice”, the melting occurring in Antarctica and Greenland will already raise sea levels up to 10 feet by 2050. And that’s just from Greenland and Antarctica. He also talks about how in Alaska, they’re losing about 50 glaciers every year, which isn’t just a threat to coastal cities in terms of sea level rise but also for access to drinking water.
The one thing you’re right about is that some level of carbon dioxide in the atmosphere is necessary for life on Earth, because as I said, organisms in the ocean as well as the trees, plants, and soil, all use carbon dioxide in some way to survive and thrive, and if there’s an abundance of those things on Earth then more carbon dioxide, in theory, seems like a benefit. Except, as I also mentioned, these carbon sinks are losing their ability to do their job because the carbon cycle is so out of whack thanks to CO2 emissions primarily from fossil fuels (which a fellow writer just wrote about in my publication in case you want to learn more: https://medium.com/climate-conscious/understanding-the-climate-crisis-through-the-carbon-cycle-fa5dd6668757).
And finally, please stop using what people say out of context like you did with Elon Musk. He believes the same thing that I do, that the vast majority of scientists do (11,000 scientists just backed a study stating that we face a climate emergency), and that the vast majority of people do: human activity is absolutely and unequivocally causing drastic changes to our environment and climate via greenhouse gas emissions that will only continue to get worse if we don’t rapidly move towards carbon neutrality which means getting off of fossil fuels as well as a host of other changes we will have to make if we want to maintain a habitable world for future generations.
One last thing I’ll say is that if I’m wrong, and all the scientists are wrong, about the climate crisis, then we still get a much cleaner environment that will drastically cut down on the number of deaths due to air pollution and other climate-related factors, we’ll create millions of jobs in the process of transforming our economy, our energy costs will be much cheaper as renewables continue to become cheaper than fossil fuels, and we may even be able to avoid wars and conflict in the Middle East by removing our reliance on oil.
But, what if you’re wrong? That’s a scary thought, isn’t it?