The Instigator
Pigzooka
Pro (for)
Tied
0 Points
The Contender
mayahcw
Con (against)
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Is Climate Change Caused by Humans?

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Voting Style: Open Point System: 7 Point
Started: 10/21/2015 Category: Science
Updated: 1 year ago Status: Post Voting Period
Viewed: 420 times Debate No: 81310
Debate Rounds (3)
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Pigzooka

Pro

Humans do cause climate change. Though natural amounts of carbon in the atmosphere vary from 180 to 300ppm, today the level is at 400ppm - higher than in the past 800,000 years (1). Would the opposition suggest that this is a fluke? In addition, the sea level has risen around 220 mm in just 135 years, neatly coinciding with the Industrial Revolution and the corresponding increase in greenhouse gases (2). These two pieces of evidence, I believe, are enough to demonstrate that climate change does happen and is caused by human activity.

1: https://www.edf.org...
2: http://climate.nasa.gov...
mayahcw

Con

Definitions:
1. Cause: to make (something) happen or exist : to be the cause of (something)
2. Climate: the average course or condition of the weather at a place usually over a period of years as exhibited by temperature, wind velocity, and precipitation

Humans do indeed play a role in climate change, but they do not explicitly 'cause' climate change. Between the years of 900 and 1250, parts of the earth experienced a wide spread warming (Medieval Warm Period). This was before the existence of the Industrial Revolution, the invention of cars, and the widespread use of fossil fuels. Following this warm period, there was a cooling period. Millions of years ago, before humans roamed around, earth's climate had a drastic change. Carbon levels rose, and the earth heated up. A good number of organisms died. It's interesting to note that in both of these cases, humans were either completely absent or in a much lesser number than now. And yet, somehow, the earth was still warming up. Yes, carbon levels are rising. Yes, the earth has warmed up a bit within the past 50 years. Yes, the sea levels have risen. But can we really blame humans and human activity? Climate change does happen, but to say that it is 'caused' by human activity is quite a stretch.

Even though the steady rise in carbon levels and sea levels can be loosely matched with the Industrial Revolution and the rise of humans, this is in no way definitive proof that humans cause climate change. Science has shown us many examples of climate change that did not directly involve humans.

It's also important to understand that volcanoes have much to do with carbon levels and climate change. It's also interesting to note that many scientists believe that volcanic activity has had a slight increase over the past 50-60 years.

http://www.merriam-webster.com...
http://www.merriam-webster.com...
https://www.ncdc.noaa.gov...
Debate Round No. 1
Pigzooka

Pro

Look at figure 5 in source 1. It clearly shows a massive spike in temperature right after the Little Ice Age. It would be easy to dismiss - except that, if you look closely, you see the temperature trending slightly DOWNWARDS before the Industrial Revolution started. Would we live in a much colder present without the Industrial Revolution's negative climatic effects? It's hard to deny the data, and it's even more of a stretch to say that there's no correlation with the IR.

As you said, carbon levels are rising. You attribute this to volcanoes. Yet volcanoes only produce about 1% of the carbon produced by fossil fuel burning (2). Even if the rate of volcanic eruptions quintupled, this would still not explain the dramatic rise in atmospheric carbon. You also state that climate change is part of some "natural cycle." Yet contrary to your beliefs (and, I'll admit, some of my idle thoughts, until I read this article), climate change is definitely not part of the same cycle as the Ice Ages (3). For one thing, it's not happening during the correct alignment of Earth's axis; while we're definitely in a warm period, the temperature should be FALLING, not rising, since the peak of the warm period was a few thousand years ago. Even if climate change WAS caused by the Sun, the troposphere is getting warmer while the stratosphere and -spheres above cool, a fingerprint of greenhouse gas warming. The Sun would be heating all layers equally. That leaves volcanic and oceanic greenhouse gas releases as the only possible candidates - yet they are both tiny climate change contributors, as I explained earlier, and - get this - they actually release a different carbon isotope mix with a different molecular makeup. The oceanic and volcanic carbon has a lower ratio of carbon-12 to carbon-13 - so how do you explain that the ratio has been rising steadily?

Lastly, you cited the Medieval Warm Period as evidence that the Earth goes through natural cycles of warming and cooling. Look at the map of the MWP warming pattern in source 4, and compare it to the map of today's manmade climate change. They look - ahem - a little bit different. The only part of the Earth that really saw significant warming during the MWP was Viking territory, and a larger part of the Earth actually got cooler. The lower map, of today's carbon, is like a goldfish that's been beaten to death - red with purple spots - and shows a much more uniform warming pattern.

Please explain.

1: http://www.skepticalscience.com...
2. http://ete.cet.edu...
3. http://www.skepticalscience.com...
4: http://www.skepticalscience.com...
mayahcw

Con

While your arguments are certainly convincing, they still in no way prove that humans are the direct cause of climate change. If humans were "the cause" of climate change, as you stated, all the past spikes in temperature would be marked by human activity, which, in fact, is not the case.

As I said before, there could possibly be a correlation with the IR and the steady rise in temperatures. But is that enough to claim that humans are the cause? The issue under debate is not that humans play a significant part in climate change, it's that humans are the cause of climate change. Volcanoes and oceanic emissions make up a very small percentage when it comes to carbon emission, but the numbers are still there.

How did the volcanic CO2 emissions measure up 300 years ago? 200 years ago? 100 years ago? Climate change has been a very long and drawn out event. It is not an overnight change. Volcano eruptions in the past did outweigh the emissions made by humans. Humans began producing and thriving at a much greater level, and now, human emissions outweigh volcanic eruptions. So how can we attest climate change to humans when hundreds of years ago (when the climate was still rising) volcanic activity outweighed human emissions? If humans cause climate change, please explain why the climate spiked in the past, even when humans were hardly making a significant impact on CO2 levels in the atmosphere.
Debate Round No. 2
Pigzooka

Pro

You seem to be misunderstanding the question. Neither the question nor I ever said humans were "THE cause" of climate change, but they are far and away the most destructive and sudden cause. Look at Graph 1. If, as you said, humans had no effect on climate change, how do you explain that extreme anomaly? While it certainly began at the peak of an Ice Age temperature/carbon cycle, the real production did not start until much later, and, as the graph shows, half the rise has been produced SINCE 1950. You ask me to explain how the climate spiked in the past - the answer is that it was a natural cycle, as you said. I NEVER claimed that all historical climate change was caused by humans. But this is an anomaly. Look at Source 2: Climate change now is 50 to 100 times faster than at any point in the past 65 million years. The biggest mistake climate skeptics make is to say that man-made climate change goes at anything like the pace of natural climate change: It does not. It's faster, so muchly-much faster that it's unattributable to volcanoes and oceans. Skeptics tend to say that atmospheric temperature can't rise as fast as scientists say it can, since the atmosphere is big, but it can. My point is that this is a different kind of cycle, far beyond anything since the dinosaurs went extinct.

I already explained how this cycle is different, actually. Look at my Source 4. Warming is more balanced in natural cycles. During the Ice Ages, Africa was heating up while Europe was being covered in ice. The planet can regulate its own temperature, but not in extreme circumstances, which we've now created. So the entire Earth is warming. Nothing has gotten colder, except once every twelve months when all the deniers come out of their houses and say their opinion is valid because there's snow on the ground. This change is fundamentally different from all before it. For the sake of our children and grandchildren, we need to act now.

1. http://climate.nasa.gov...
2. http://www.scientificamerican.com...
mayahcw

Con

The spikes in temperature are not that much of an anomly when compared to climates in the past. And the entire earth is not warming. According to NASA, the ice in Antarctica is really building up, and there's actually more ice there than before[1]. Now why would that happen if the "entire earth" was warming up? It seems to me that the Earth is regulating itself. At one end of the globe, things are heating up, but in the Antarctic, things are getting even cooler.

I see where you are coming from, however I have to respectfully disagree. It's also interesting to note that whenever the earth gets warmer, scientists immediately jump to climate change and global warming. When the earth gets cooler, somehow, it's still considered to be global warming.

[1] http://www.theguardian.com...
Debate Round No. 3
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