Human Driven Climate Change

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There is quite possibly not a more contentious debate going on in America than global warming and its causes. The science is clear with 97% (based on 11,944 abstracts of research papers) of climate scientists worldwide declaring that human influence is the dominant force driving global warming. The consensus position is articulated by the Intergovernmental Panel on Climate Change (IPCC) statement that “human influence has been the dominant cause of the observed warming since the mid-20th century”. The National Academies of Science from 80 countries have issued statements endorsing the consensus position. Nevertheless, the existence of the consensus continues to be questioned.

A dumbed down (i.e. No math) summary of the theory of the Greenhouse effect:

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Energy from the Sun that makes its way to Earth can have trouble finding its way back out to space. The greenhouse effect causes some of this energy to be waylaid in the atmosphere, absorbed and released by greenhouse gases.

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Without the greenhouse effect, Earth’s temperature would be below freezing. It is, in part, a natural process. However, Earth’s greenhouse effect is getting stronger as we add greenhouse gases to the atmosphere. That’s is warming the climate of our planet.

Solar energy absorbed at Earth’s surface is radiated back into the atmosphere as heat. As the heat makes its way through the atmosphere and back out to space, greenhouse gases absorb much of it. Why do greenhouse gases absorb heat? Greenhouse gases are more complex than other gas molecules in the atmosphere, with a structure that can absorb heat. They radiate the heat back to the Earth’s surface, to another greenhouse gas molecule, or out to space.

Even though only a tiny amount of the gases in Earth’s atmosphere are greenhouse gases, they have a huge effect on climate. Sometime during this century, the amount of the greenhouse gas carbon dioxide in the atmosphere is expected to double. Other greenhouse gases like methane and nitrous oxide are increasing as well. The quantity of greenhouse gases is increasing as fossil fuels are burned, releasing the gases and other air pollutants into the atmosphere. Greenhouse gases also make their way to the atmosphere from other sources. Farm animals, for example, release methane gas as they digest food. As cement is made from limestone, it releases carbon dioxide.

With more greenhouse gases in the air, heat passing through on its way out of the atmosphere is more likely to be stopped. The added greenhouse gases absorb the heat. They then radiate this heat. Some of the heat will head away from the Earth, some of it will be absorbed by another greenhouse gas molecule, and some of it will wind up back at the planet’s surface again. With more greenhouse gases, heat will stick around, warming the planet.

What can be done?

“Humans have caused major climate changes to happen already, and we have set in motion more changes still. Even if we stopped emitting greenhouse gases today, global warming would continue to happen for at least several more decades if not centuries. That’s because it takes a while for the planet (for example, the oceans) to respond, and because carbon dioxide – the predominant heat-trapping gas – lingers in the atmosphere for hundreds of years. There is a time lag between what we do and when we feel it.

In the absence of major action to reduce emissions, global temperature is on track to rise by an average of 6 °C (10.8 °F), according to the latest estimates. Some scientists argue a “global disaster” is already unfolding at the poles of the planet; the Arctic, for example, may be ice-free in the summer within just a few years. Yet other experts are concerned about Earth passing one or more “tipping points” – abrupt, perhaps irreversible changes that tip our climate into a new state.

But it may not be too late to avoid or limit some of the worst effects of climate change. Responding to climate change will involve a two-tier approach: 1) “mitigation” – reducing the flow of greenhouse gases into the atmosphere; and 2) “adaptation” – learning to live with, and adapt to, the climate change that has already been set in motion. The key question is: what will our emissions of carbon dioxide and other pollutants be in the years to come? Recycling and driving more fuel-efficient cars are examples of important behavioral change that will help, but they will not be enough. Because climate change is a truly global, complex problem with economic, social, political and moral ramifications, the solution will require both a globally-coordinated response (such as international policies and agreements between countries, a push to cleaner forms of energy) and local efforts on the city- and regional-level (for example, public transport upgrades, energy efficiency improvements, sustainable city planning, etc.). It’s up to us what happens next.”

“Global Climate Change: Evidence.” NASA Global Climate Change and Global Warming: Vital Signs of the Planet. Jet Propulsion Laboratory / National Aeronautics and Space Administration, 15 June 2008. Web. 14 Jan. 2015. <http://climate.nasa.gov/evidence/&gt;.

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