This is why the science is settled that the Earth is warming and CO2 is the cause:
So if you look at the chart it shows roughly 20x10^22 joules of energy stored in the ocean over and above what was there in 1960.
Just for comparisons sake that is equal to:
- ~5 times the energy in all fossil fuel reserves
- ~48000 Gigatons of TNT
- ~40% the estimated impact energy of the Chicxulub meteor (the one that hit the Yucutan Pennisula and killed the dinosaurs)
(Thanks Wolfram Alpha!)
It is a metric shit ton of energy and quite frankly the 800lb gorilla in the room. Any hypothesis as to what the climate is doing must explain this energy increase.
That increase in energy must have come from some where. There are really only 3 options:
- Retained Solar Energy
- Decay Heat from Radioactive Minerals
- Latent Heat from the Formation of the Earth
Decay heat makes no sense as it's been slowly decreasing since the Earth was formed. Same with the latent heat of formation.
That leaves retained solar energy.
So as you said what's our contribution? And as you also rightly pointed out we were warming after the last ice age.
Let's look at some possible natural reasons why retained solar radiation is increasing.
- Orbital variation has moved the Earth closer to the sun. Nope our orbit and inclination to the sun hasn't changed appreciably in the last 100 years.
- Solar output has increased. Nope. I've posted this chart already in this thread and you can see a steady cyclic oscillation going back several decades with a small but meaningful decrease in the 00's
So if it's not solar input the issue must be with the Earth. For the atmosphere and oceans to increase their retention of energy there must be more energy incoming than leaving. We just showed it's not due to an increase in incoming energy so that leaves us with a decrease in outgoing energy.
And that brings us to greenhouse gases. So what's the makeup of the atmosphere?
So which of these gases including H20 can trap heat?
Methane, water vapor and CO2 are the heavy hitters.
Methane seems to be leveling off.
Water Vapor has been increasing but it increases due to temperature increases as higher temperature means more evaporation and more ability for the air to hold water. So increasing water vapor is symptom not a primary cause of heating.
So that leaves us with CO2 and the infamous hockey stick plot. We know exactly how much we've been putting into the air based on fossil fuels sold and burned.
While pre-industrial levels of CO2 already grabbed most of the energy the excess CO2 traps a few more percentages of energy leaving the earth. It also continues to block IR energy leaving at higher and higher altitudes as the concentration increases, driving higher temperatures if I understand correctly.
The imbalance ends up being a fraction of a percent of the energy that hits the earth, less than 1W/m^2 out of the approximately 1300W/m^2 that hit the earth. But the earth is a big place and that imbalance ends up being an extra dinosaur killer asteroid worth of energy siting in our ocean and air over time.
So that in a nut shell is how we know the earth is warming and man is the primary cause.
I hope some of this was useful.
(From the other thread)