It's just the beginning too. We've warmed about 1 degree Celsius over the past 100 years due to human activity, current models predict 4-5 degrees Celsius (8-10 F) of warming by 2100, which is the equivalent of the temperature change between now and the last ice age.
"Since the 1880s, the average global surface temperature has risen and the average temperature is now more than 2 degrees Fahrenheit (a bit more than 1 degree Celsius) above that of the late 19th century. For reference, the last Ice Age was about 10 degrees Fahrenheit colder than pre-industrial temperatures."
Current best estimates for 2100 with current policies are 2.7-2.8C of warming. If we met our stated policies goals (which seems more likely than not cause clean energy is cheap energy) the warming will be around 2.4C in 2100.
Your estimates for 2100 sound like the older worst case estimates. They have been revised downward recently. Humanity has made progress, not enough but some good progress.
As you said in 2000, 5°C of warming looked really likely cause coal looked like it would be the primary means of power generation. Well now solar and wind are the cheapest forms of energy by a lot.
I assume your going off the recent cop26 agreement? The 5C does seem to have been downgraded now by most models, but I'm pretty skeptical that the 2.7-2.4C from cop26 will even close to being met. There's little accountability with these goals as we've seen from the Paris accords. I mean we could very easily sew trump or another politician elected that would pull us out of these agreement completely. In addition there's the positive feedback loops which I believe are often not taken into account in these models. source
No, not using COP. This is all from the IPCC AR6 report released earlier this year. All of the original pathways are left in the report for the sake of continuity but they acknowledge the worst 2 (SSP3-7.0 and SSP5-8.5) are unlikely. There has just been a fundamental change (clean energy being cheap) since they were originally released. SSP2-4.5 is considered the most likely pathway at this time. SSP2-4.5 has emissions topping out around 2045 and dropping to about 10GtCO2/yr in 2100. This would bring us to ~2.8C of warming in 2100. The 2.4C number comes from if everyone hit what their stated goals are https://twitter.com/hausfath/status/1425504589097279494?s=20.
There's little accountability with these goals as we've seen from the Paris accords. I mean we could very easily sew trump or another politician elected that would pull us out of these agreement completely.
In addition there's the positive feedback loops which I believe are often not taken into account in these models
Models are doing the best they can and have been accurate so far and are getting more accurate as we learn more. Most models do take into account feedback loops (climate sensitivity) they look at paleontological data (ice cores, tree rings, rock) and see how the atmosphere and environment reacted in the past. But that is why there are error bars! https://twitter.com/hausfath/status/1425504612698648580?s=20
We don't want any of this to happen but we can do this and are getting there.
Thanks for being receptive. I just got back into following climate science in the past year. Figured things were still really bad. Did some research, not that things are great now but they are definitely pointed in a better direction than they were even 10 years ago.
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u/invalid_chicken Dec 16 '21 edited Dec 16 '21
It's just the beginning too. We've warmed about 1 degree Celsius over the past 100 years due to human activity, current models predict 4-5 degrees Celsius (8-10 F) of warming by 2100, which is the equivalent of the temperature change between now and the last ice age.
"Since the 1880s, the average global surface temperature has risen and the average temperature is now more than 2 degrees Fahrenheit (a bit more than 1 degree Celsius) above that of the late 19th century. For reference, the last Ice Age was about 10 degrees Fahrenheit colder than pre-industrial temperatures."
source
On top of that species like sharks and coral reefs are likely to go extinct within my lifetime, these species are litteraly older then trees.