Posts

Showing posts from July, 2022

Is Global Warming "Real, Man-made and Dangerous?"

Image
GMST in Various Datasets Since 2013 or so, it's been common to refer to global warming over the last 100 years or so as "real," "man-made" and "dangerous."[1]. To my knowledge, these terms were first used in political discussion, but I believe they can be useful categories for discussing whether it's happening (real), whether it's something we can correct (man-made) and whether it's a problem that needs correcting (dangerous). These three categories of claims do a good job of summarizing how a case can be built that we have a problem that we both can fix and need to fix. These categories are valuable because 1) we can only potentially have a climate warming problem if global warming is real. If it's 1) real and it's 2) man-made, then we have the capacity to fix it by changing what we're doing. If, however, it's mostly natural, then potentially there's nothing we could do to fix the problem, and that's really bad news

How Long Does it Take for the Earth's Climate System to Reach Equilibrium?

Image
Little Big Econ State Forest (just because it's pretty) Any given climate forcing affects the Earth's Energy Imbalance (EEI) - that is, it affects the amount of energy entering the climate system vs energy escaping into space. When a forcing occurs, such as from an increase in CO2, the imbalance is created and surface temperature increases until EEI returns to equilibrium (that is, EEI = 0). But how long does this take? That is, what is the lag between a climate forcing and the new equilibrium temperature? It turns out, this depends on sensitivity and the rate of temperature increase, but it is possible estimate the time to achieve this equilibrium with a forcing. But this is going to be rather math-intensive. Apologies in advance! We can begin with a simple energy balance equation: (1) ΔF = ΔT/ λ  + EEI, where λ is sensitivity (ECS/F2x) ECS is Equilibrium Climate Sensitivity F2x is the forcing for doubling CO2 EEI is the Earth's Energy Imbalance ΔF is the change in radiati