Reddit reviews Physics of Climate

> The problem is that CO2 is not the most important greenhouse gas; water vapor is.

True, but irrelevant. Water vapor content in the atmosphere varies by orders of magnitude on both short time and spatial scales. However, in the global average, it doesn't really, because the balance of precipitation versus evaporation fundamentally constrains the movement of energy in the atmosphere (see Oort and Peixoto, 1992).

On the other hand, CO2 steadily rises.

If you add a sine wave and a line together, you got a sine wave tilted upwards.

> As CO2 levels increase it's ability to trap radiation acutally diminishes substantiallly.

Also true but irrelevant; atmospheric levels of CO2 are nowhere near saturating all the modes of absorption. The many overtones of ro-vibrational modes can go a long way before you should expect the simplest estimates of CO2's radiative forcing to break down.

> Water vapor is by far the biggest greenhouse gas and is incredibly poorly modeled, if at all.

Water vapor is modeled by every climate model. It's fundamental. Do you have any citation backing up your assertion that it's "poorly modeled?"

> To answer your question, we don't know and we don't have enough data. Long-term temperature records aren't that reliable, accurate, or global. We've only had satellite records for 35 years and there's been no warming for about half of that record.

Which is why we drive to understand the physics, chemistry, and dynamics of the climate system - to make progress where we're observationally-constrained. We do not have direct evidence of gravitational waves, yet we have the immensely powerful general relativity which predicts them. Until recently, we did not have direct evidence of the Higgs boson, yet we have a powerful and successful Standard Model and related theories which predicted it.

Besides, the existing temperature record unambiguously shows warming. You can do a lot more than just plot global mean temperatures if you wish to understand what caused that warming.

> Man made climate change is a hypothesis which hasn't been proven. There's no smoking gun. The satellite data is showing that there has been no appreciable warming in the last 15-18 years yet we have put 30% more CO2 into the atmosphere.

Internal variability dominates the signal in global temperature on short (less than 30 year) timescales. It's simply wrong to try to extrapolate the tendency in the climate system from such few years of data - particularly when you pin the beginning of that subset of data to a very strong El Nino, which skews any statistical analysis of the trend you might wish to do.

Why don't you use all the satellite data and re-evaluate that paragraph? I can answer for you: because then there is an unambiguous warming trend.

By the way, science doesn't deal in proof. You want /r/mathematics.

> Climate scientists projections have been wildly inaccurate over the years.

Climate scientists have never said that there is high confidence in decadal-scale climate projection. Again - on that timescale, internal variability dominates. So it's a curious benchmark for evaluating the science, kind of like asking a police officer why he failed to put out a house fire.

> The jury is still out for anyone that actually looks at the data. Others buy into it whole-heartedly because that's what they've been taught.

It's not. The science is in - human activity is leading to climate change. What you choose to do with that information is your own prerogative, but don't pretend that reality is something that it isn't.