Relative to the rest of Earth’s history, the climate at the moment is pretty cold as Earth is just coming out of an ice age. So over time the gradual increase in temperature is quite normal. The Earth’s climate has undergone these ups and downs in global temperature throughout its entire lifetime with different species flourishing at different times. But even with these ups and downs the Earth’s temperature has been pretty stable and consistently habitable when compared to Venus or Mars.
So how does Earth maintain this consistent habitability?
It’s all about the exchange of elements and molecules! And this is what I learnt last term in the geochemistry module.
CO2 is important: Too much in the atmosphere and Earth’s gets too warm (like Venus) and not enough in the atmosphere and it freezes (like Mars). Earth is like the ‘Goldilocks planet’ not too hot, not too cold, but just right
How to maintain CO2 (a very basic model): Earth produces a lot of CO2, from respiration, volcanic emissions, dissolving limestone in the ocean etc. You’d think the latter was of least importance, but really it is the crux of the matter – limestone (CaCO3) is where the Earth stores most of the CO2 so as not to have it catching the sun’s rays in the atmosphere and warming the Earth up. As global temperatures increase more weathering occurs, shaving off bits of mountains and sending more elements, such as Calcium into the oceans. If there is more Calcium (Ca) in the oceans the Earth can make more Limestone (CaCO3) and thus remove more CO2 from the atmosphere which in turn decreases global temperatures. Et voila: a perfect self-sustaining global temperature cycle (which happens much the same the other way around too).
Obviously lots of other things factor into this cycle as well such as photosynthesis of trees and algae, ocean pH, how many mountains there are, the changes in shape of the orbital path the Earth takes around the sun, how quickly the tectonic plates are moving and much more.
So the Earth is very good at dealing with CO2 when considering only natural sources – the question is; do human emissions thrust the amount of CO2 out of the manageable range? Will we spiral into a global oven complex from which there is no return?
Perhaps when we consider that normal CO2 concentration in the atmosphere (what the Earth system strives for) is around 270ppm and the number we have today is 400ppm, there is cause for concern.
So to answer whether or not humans are causing global warming is: no we are certainly not causing it as it is a natural cycle and would be warming anyway. BUT we are in grave danger of meddling with it too much for Earth to recover and do need to think seriously of how not to further upset the preciously delicate balance of the Earth’s global temperature system.
Subscribe to Eleri's posts
An unfunded engineer discovered the two primary drivers of average global temperatures that explain the reported up and down measurements since before 1900 with 90% accuracy and provide credible estimates back to 1610.
The science is settled, CO2 change is NOT one of the drivers. http://agwunveiled.blogspot.com/
Of course, the Sun and sun spots have a huge effect on global temperatures and there is a lot of evidence linking changes in Earth’s orbit, rotation and axis tilt (Milankovitch cycles) to global temperature change – in fact these things are the drivers for global warming. CO2 and the other greenhouse gases are simply amplifiers but since there isn’t much we can do about the Earth’s orbit and sun spots, we are left with simply trying not to amplify warming further. That is why a lot of research has gone into the effect of greenhouse gases in the atmosphere.
However, I disagree that this paper settles the science because there has been 4.5 billion years of Earth’s history, whereas this study is only over 400 years. The reported ups and downs over the last 400 years are extremely minor considering that the climate over the last 10000 years has been eerily stable anyway. Besides the volcanic eruptions that this paper describes as coincidentally changing global temperatures are relatively small compared to those in history.
Still, you make a very good point, thank you!
That was very interesting, and I have a few questions:
Do environmentally friendly behaviours make any difference?
eg: recycling, eating less meat, using less petrol, putting on layers not heating, turning off electrical appliances when not in use etc.
Does this make any difference? Is there any point in it? Or is the Earth going to heat up naturally so we might as well enjoy all the things?
Yes, the Earth is just heating up naturally. But, with the addition of greenhouse gases from human activities we run the risk of it heating up too quickly and too much beyond the point which the Earth can control. I.e. usually when the Earth gets a bit too hot there are systems in place to cool it down again. If human activities meddle with this too much the Earth might not be able to cool down again and will just end up like Venus with an average surface temperature of 460 degrees Celsius. So there is point in trying to reduce the impact of human activities on these natural systems.
As for one person?
This webpage has a great pie chart on it showing where all of the emissions come from: http://www.epa.gov/climatechange/ghgemissions/global.html (note this is not just CO2 but all greenhouse gases).
Clearly there are a few things that us as ordinary people cannot change such as industry, energy supply, forestry and agriculture. Those are things that the governments across the globe must (and I’m sure do) think about. As for the changes we can make? Investing in renewable energy, transport – making more use of public transport, residential buildings – switching off lights, using less heating etc, and waste and waste water – recycling, using less water. If everyone thought – well there’s no point, things would never change and we run the risk of losing planet Earth. So yes, I think just one person doing these things makes a difference, maybe not in cold cut numerical ways – its just one drop in an ocean after all. But, quote here from cloud atlas; ‘what is an ocean but a multitude of drops’.
Hope this helps 🙂