GRA wrote: ↑
Wed Apr 14, 2021 9:48 pm
WetEV wrote: ↑
Sun Apr 11, 2021 10:50 am
Greenhouse gas reductions are necessary. Things get bad eventually. Important, not urgent.
There isn't any specific known threshold we need to avoid. The next 20 to 30 years isn't any more or less critical than the past 20 or 30 years.
The oceans provide about 50 years of thermal inertia. To be more precise, the "mixed layer" of the ocean. So in about 50 years, we will know what we have done to the climate today. Right now, we see about what we were committed to in 1970, about when I heard about this issue first, from a high school physics teacher.
With the GHG's already released or very likely to be released, Greenland will melt to bare rock over thousands of years. A big chunk of West Antarctic Ice shelf might collapse over hundreds to tens of thousands of years.
Climate change is slow. However, it is a beast, and we need to stop whacking it over the head. Sooner rather than later, if we can. But years or even decades do not change the outcome all that much.
Humans just don't deal well with important but not urgent issues.
You are far more sanguine about the pace of needed change than I, or most climate scientists FTM.
Sanguine? An interesting word. And probably not correctly applied. Remember the driving with the rearview mirror we are doing, seeing the impact of what we did 50 years ago. What have we already done??
Consider the WAIS and some similar ice elsewhere. A pile of ice resting on the ocean floor. Piled up so high and deep that it is dynamically unstable. If it starts to melt in a serious way it will collapse into a huge number of burgy bits. If we warm up the climate enough, it goes crack splash kerplunk and the oceans rise by over 1 meter/3 feet and as much as 3 meter/10 feet in a matter of a few decades at most. What holds it together is ice shelves limiting flow from exit glaciers such as the Pine Island Glacier, aka the PIG. These should delay the collapse by decades to a century or more. We are making the PIG unhappy now. 50 years of warming are more or less locked in. Feeling sanguine yet?
So how much warming is too much? Fine question. Might be too late already. Might take another 2C. If this was D&D, time to roll some dice. We don't and can't know how much warming is too much, as there are too many unknowns. We might be able to provide a decade or more of warning once the process starts. The above statement could have been written in 1970, back when I first started to follow CO2 climate change. The dynamics of ice collapse are too hard to model, the geologic record shows they happen and these facts both haven't changed and are unlikely to change until we see an example in real time. Which might be in my lifetime. Feeling sanguine yet?
So how much does a decade matter? At 0.2C/decade, very roughly 10% on the odds eventual collapse, and some unknown number of decades more delay.
There are other issues like this, most are regional in impact, such as the drying of California. Areas becoming too hot for human survival. And so on.
Personal transportation isn't the big problem in CO2. Even without subsidies/mandates/incentives, most driving will likely be electric in 50 years or so. And electric power can be mostly non-fossil fueled in 40 years or so. And while we could and have already speed this up, the other problems that need more attention will likely suffer if there is too much governmental focus on this.
Steel? Concrete? Home heating, especially in colder areas? These are harder to solve.
GRA wrote: ↑
Wed Apr 14, 2021 9:48 pm
Personally, I figure we've probably already lost the chance to hold to a 1.5 deg. C increase,
We lost the chance for 1.5C increase 30 years ago, or more. When announced as a goal, it was already impossible. Without magic CCS and/or sulfate injection into the stratosphere or other drastic and risky climate interventions.