Fossil Fuel Emissions, CO₂, Temperature, and Sea Level Rise

What is the connection between CO₂ and global temperature changes? Does the amount of carbon emissions tally with the CO₂ left in the atmosphere? Explore the graphs and find out. Let's start with determining if the human CO₂ from fossil fuel emissions and other sources lines up with the actual accumulation of CO₂ in the air.

When the two lines are almost identical in shape then the relationship is probably very close. The most important next step is to ask if there is a reason why they should be correlated. In this case it is obviously because the carbon added to the air in the form of CO₂ from fossil fuel emissions is clearly responsible for the added CO₂ in the atmosphere.

According to the theory of recent global warming, the most important greenhouse gas that we are adding to the atmosphere is CO2 and that causes the temperature to rise in the atmosphere and ocean by capturing and re-emitting infra-red radiation (heat) that is rising from the planet's surface. If that is true the average global temperature should be rising with the added CO₂. On an annual basis the temperature is very changeable from one year to the next, but the trend should follow the trend of increasing CO₂.

Another part of the theory of global warming is that the sea level should go up as the ocean warms. It goes up for two main reasons. First as the water warms up it expands, and second as the world warms up the ice that is sitting on the land melts and drains into the ocean raising the sea level. If that part of the theory is correct, then the increasing temperature should cause the sea level to rise more-or-less in synchrony with the temperature.

One more thing we can expect if the theory is correct, is that the sea level and the CO₂ should also rise in a more-or-less synchronous fashion - because the CO₂ is what is causing the temperatue to rise, which in turn is causing the ocean to warm up and that is causing the sea level to rise.

Sure enough, the annual variaton of temperatrue does not appeqar to have an effec on the overall trend of sea level rise.

We already have seen the increasing CO₂ lines up with both the increasing temperature and the rising sea level. But we also can see that the annual variation in temperature is unaffected by the increasing temperature and also we can see that it has no effect on the rising sea level.

We could also ask if emitting larger and larger amounts of CO₂ into the air has any influence on the year to year variation (the weather). We can do this by comparing the annual variation in CO₂ increase with the annual variation in the temperature.

From the graph, we can see that there is no correlation based on trend. The temperature increments don't increase with the increasing CO₂ increments. It is tempting to see if we can find similar peaks and vallys. There are a few where they line up, but it is not consistent, so there is no correlation there either.

Given that the increasing annual increments of CO₂ do not affect the annual increments of temperature, we should check to see if the increasing annual increments of CO₂ affect the annual increments of sea level rise.

Looking at the graph there are some odd things happening. The variation in sea level on an annual basis looks like it suddenly was much less after about 1880. We could ask if this was due to the increasing CO₂ level or was it developing a more accurate method of measuring sea level? Using tide guages has some potential errors because in some places in the world, the land is sinking, while in others it is rising. These are due to geological changes or rebounding from the released pressure of ancient glaciers during the ice ages. That could explain part of the difference. Once satellite measurements were possible, the sea leel is measured against the known altitude of the satellite, so that automatically corrects for sinking or rising land.

We still have one more test we can try by comparing the annual increments of sea level with the annual increments of temperature. It is important to remember that both the sea level and the temperature are rising together, but we are going to compare just the annual variation or increments on a year by year basis.

So while there is no real effect from the annual variations in temperature on sea level rise nor is there any effect from CO₂ increments on annual temperature variations, the story is quite different when we look at the trends. The increasing amounts of CO₂ line up with the rising temperature trend which in turn lines up with the rising sea levels.

If we put all this together, what we see is that the annual changes from year to year in both temperature and sea level rise are due to local and short-term effects, whereas the long term CO₂ increase has caused a long term incease in the temperatures at which the sme amount of variaiton takes place.

This next graph is a "depiction" of what is already happening and what will happen as the global average temperature rises in response to the rising CO₂ levels.