A new climate model, which is based on the global energy balance, has recently given many scientists more proof to believe that the climate changes Earth has been experiencing are due to humans. The model the researchers created tells us that at least 74% of the global warming that has been occuring since 1950 has been caused by humans.
Before this model was created, scientists used “optical fingerprinting” to try and find what exactly is causing global warming. Optical fingerprinting is when they use many complex models to get a response that tells where different “forcings”, or sources of global warming, are coming from. These incluse greenhouse gases, aerosols and ozone, which are caused by humans, and then volcanic eruptions, water vapor, solar cycles and cosmic rays, which are the natural ones. After these forcings are located, each“is then assessed by a statistical comparison of the model outputs to the real-life warming pattern.” Unfortunately, the optical fingerprinting method relies on the ability of climate models to precisely create the response patterns back to its forcing, and it also assumes that the responses can be scaled and added. This means that the changes in energy balance aren’t totally reliable.
Recently though, two researchers, Reto Knutti and Markus Huber, made a model based only on the fact that Earth’s energy must be conserved. When the Earth is in equilibrium, the thermal energy it gives off is equal to the amount of energy the Sun gives off. However, evidence has shown that this energy balance has somehow gotten messed up, and less energy being given back into space. So this means that the energy trapped in the climate system ends up heating our planet, which is why our global temperature has been rising.
The model was used to find out the cause and size of this warming. The model, which works because of records of climate forcings, surface temperature and the heat the ocean takes up, was run thousands of times with different parameter groupings. The ones that matched the best went through the model a second time in order to create the climate response to each individual forcing. The model ended up predicting that that earths global temperature increased 0.51 degrees Celsius since the 1950s. It concluded that the largest thing that contributes to global warming is greenhouse gasses, “these gases act as a shield that traps heat in the earth’s atmosphere.” However, the amount of the natural solar and volcanic forcing was extremely close to zero.
When they used the model to predict what will happen in the future to our climate, they found a temperature increase of 1.29 degrees Celsius very well may happen between the years 2050-2059. Almost all of the blame for that goes to greenhouses gases with carbon dioxide being the most prominent contributor. That means it is mostly humans fault.
With evidence like this, I don’t see how anyone can believe anything differently than the fact that global warming is occurring because of humans and the choices we make for our environment. How much fossil fuel I burn by myself each day is overwhelming… by starting my car, turning on my air conditioning or heater, using hairspray. I believe that global warming is very serious, and we need to face the facts now, that we humans are the reason for it, before it is too late for anything to be done about it.
Lloyd, James. “Energy balance points to man-made climate change.” physicsworld.com. Physicsworld.com. Dec 7th, 2011. Web. February 8th, 2012.
McIntire, Jeff. ” Top Global Warming Causes – Natural or Human?” sustainablog.org. Sustainablog.org. June 18th, 2009. Web. February 8th, 2012.
Gable, Scott. “What are greenhouse gases?” about.com. About.com. Web. February 8th, 2011.