Global Climate Change: A hot topic

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The earth as we know it is changing at an alarming rate, and scientists are more certain than ever that humans are the cause of it. Climate change could be considered the most important issue we face in our lifetime, and we need to act now to change the dangerous path we are on.

Environmental issues like climate change have become politically polarized between people who think it is a hoax, and people who think immediate action is necessary. Because our political leanings have become so divided, media coverage has confused the public about the issue. I am going to present some of the evidence of human caused (anthropogenic) global warming scientists have found.

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Scientists are more certain than ever that humans are causing global warming

97% of climate scientists have shown that humans are causing the earth to warm. A recent study showed that out of 9,136 authors in peer-reviewed scientific journal articles on studies done about climate change, only one rejected man-made global warming since 2012. This means that scientists studying the mechanism and causes of global warming have come to the conclusion that humans are contributing to it, and other scientists have reviewed their methods and analysis to make sure it is sound.

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Scientific evidence shows that humans are contributing to global warming

Scientists have a multitude of ways they can show the correlation between greenhouse gases and global temperature. Greenhouse gases include carbon dioxide, which is a product of burning fossil fuels, methane, and water vapor. Greenhouse gases trap heat in the atmosphere by absorbing radiation from the sun. The greenhouse effect is the reason the earth is habitable.

Since the industrial revolution, humans have increased the amount of greenhouse gases in the atmosphere to amounts higher than those that are naturally occurring. Scientists have come to a consensus that it is extremely likely that “more than half of the observed increase in global average surface temperature from 1951 to 2010 was caused by the increase in greenhouse gas concentrations and other anthropogenic forcings together.”

The most reliable method scientists use to measure previous temperature and atmospheric gas composition is by obtaining ice cores. Ice cores are tubes of ice drilled out of ice sheets to show valuable information dating back to as long ago as 800,000 years. Ice forms and builds up in layers that correlate to specific time periods, similarly to tectonic plates that form mountains. Within the ice core, information about the climate is held in bubbles of air, dust, ash, and radioactive substances can be matched to a specific time. The image below shows an example of an ice core sample. Layers are separated distinctly by the marked lines, which correlate to different seasons.

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The gas trapped in the air bubbles in ice core samples can be analyzed, and the gas composition of the atmosphere can be determined for that time period. Using ice cores, scientists have determined that the concentration of carbon dioxide in the atmosphere is almost twice as much as ever recorded. The figure below shows carbon dioxide levels in the atmosphere back to 400,000 years ago.

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Temperatures hundreds of thousands of years ago can be determined using isotopes. Chemical elements are characterized by the number of protons and electrons they contain, however, the number of neutrons can vary. Isotopes are chemical elements with different numbers of neutrons, which changes how much mass they have.

The number of neutrons and protons an atom has determines its atomic mass number. For example, oxygen can have an atomic mass of 16 or 18, depending on how many neutrons it has. Oxygen isotopes are shown below, where the protons and neutrons are shown by the yellow circle, and the electrons are blue. The oxygen on the left has 8 neutrons to make ¹⁶O and the oxygen on the right has 10 neutrons to make ¹⁸O.

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The amounts of oxygen isotopes present in the atmosphere are indicative of the global temperature. Because oxygen 16 (¹⁶O) is lighter than oxygen 18 (¹⁸O), water molecules (H­₂O) containing ¹⁶O evaporates at a lower temperature. The ratio of ¹⁸O/¹⁶O in ice cores and in present day oceans and glaciers provides us with a full temperature record.

Other evidence of climate change used to study previous habitats include: dendroclimatology (the study of tree rings), pollen analysis, and glacial analysis. These are some of the methods scientists use to correlate temperature and greenhouse gas concentration in the atmosphere.

Although it is true that the climate has been warmer, and it is always going through cycles, the global surface temperature is increasing at a faster rate than ever seen before. This rate of increase is shown in the graph below. The temperature has increased the same amount in the last 50 years as it did over a timespan of 2,000 years previously.

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Warming is not the only consequence of global warming

While scientists are still trying to figure out the exact impact global warming will have in our lifetime, we have already experienced some of the impacts. The oceans are warming, which is causing the glaciers to melt. Glacial melt is causing sea-level rise, which is displacing many native island people and will continue into more populated areas like New York and London.

As the temperature of water rises, it dissolves more gas. The oceans are getting warmer and dissolving more carbon dioxide from the atmosphere, which causes what is known as ocean acidification. Ocean acidification has many consequences for the ecosystem of the ocean. Coral reefs and fish are dying because of the high acidity of the ocean, which will affect recreational industries and food supplies in an already too-crowded planet. Polar Bear extinction is an early indicator of this effect.

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Weather patterns are becoming more severe because of pressure changes resulting from the warming of the tropics and arctic poles. This can cause hurricanes, large drops in temperature (like the polar vortex that has been occurring this year), stronger tornadoes, and drought.

The good news is that scientists think that we can still slow climate change enough if we act now. Our lives literally depend on it. I hope that the political aspect of climate change is cast aside and the public and policymakers alike will start to get more serious about addressing the most important issue our generation will face. If any generation can fix it, I think we can. I’ll toast to that! And then get back to saving the planet…

Thanks for reading, and cheers to your brain!

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