If you are like me you probably have encountered a few people that do not believe global warming exists, or if they do, they are not always convinced that humans are contributing to the problem. There are usually a range of issues these skeptics raise in an attempt to cast doubt on climate change evidence. Below are a few responses to some of the more frequent statements these deniers toss our way.
The Skeptics: There is simply no evidence that humans are contributing to climate change, if the earth is even warming.
Answer: As carbon dioxide (CO2) is pumped into the air through human activities, heat becomes trapped in the atmosphere. This phenomenon is commonly referred to as the "greenhouse effect." If the earth's global temperatures rise a mere 3 degrees, there will be catastrophic results all over the world.The Skeptics: CO2 can't possibly be to blame for any so-called climate change as emissions only stay in our atmosphere for up to 10 years. Our oceans and terrestrial carbon sinks absorb this CO2 anyway. In fact, the oceans are so big that they could absorb over 50 times more CO2 than humans contribute now. As such, we can't possibly be to blame for any change in global temperatures today.
Answer: Actually the ocean's ability to store CO2 is not very long. Only 50% of CO2 is absorbed by areas of the ocean that are not very deep. In these areas, CO2 is released back into the atmosphere. Recent studies have shown that only 30% of CO2 is stored in the deep ocean. The rest, some 20%, stays in the atmosphere for thousands of years.
The Skeptics: The evidence that CO2 emissions are linked to any rise in global temperatures is casual at best. Global CO2 emissions do not match Arctic temperatures, which are often used as the best gauge for how to measure the earth's climate.
Answer: While the Arctic may serve as a great resource for measuring climate change, looking at one small area of the planet is not the best way to assess the situation. During the 1930s, for example, warming occurred in the Arctic, but the cause is not exactly known and did not take place all over the planet.
The Skeptics: It's actually been much hotter than it is today during recorded human history. During medieval times, for example, warm temperatures plagued much of Europe. This happened long before humans started burning fossil fuels, which is hard proof that we aren't causing global warming today.
Answer: The warming that happened during 800-1300 AD is considered to be a local warming event, which is quite different than the changes in the global climate we are experiencing today. Ice samples have shown that temperatures around the world varied during that time.
The Skeptics: But ice core sampling is simply not a reliable way to measure changes to our climate because it is an imperfect science. Records come from measuring gas that is trapped in tiny air bubbles. But this air isn't saved in stone, it can seep out over time.
Answer: Specific ice samples may not be completely reliable, this is true. However, in order to reduce error many samples are taken all over the world, which gives us a much better record of the earth's historic climate trends. When used in conjunction with other resources, like tree rings, these records are undeniably accurate and reliable.
The Skeptics: Scientists fix the data all the time. One ice sampling in the Arctic at Siple has shown us that CO2 levels were around 328 parts per million all the way back in 1890. However, global warming believers insist that this level wasn't met until the early 1970s. In order to make their point, graphs have been altered to fix this data in order to have us believe that CO2 emissions, from humans, were to blame for the rise in global temperatures.
Answer: When new evidence is found scientist alter their theories and data. No additional samplings taken anywhere in the world confirm that CO2 levels were above 290 parts per million in the last half of a million years. The Siple ice core samples in the Arctic cannot be used to counter this overwhelming consensus. Perhaps temperatures in the Siple area were elevated for a month or a year, but not consistently and not anywhere else on the planet at the same time. Since new data has come to light to address these findings, scientists have adjusted their graphs.
The Skeptics: Our environment has a great ability to adjust for inflation in CO2 emissions. When an increase occurs, our carbon sinks pick up the slack over a period of decades. So all the hype about global warming is nothing more than hot air.
Answer: Past warming cycles are not the result of greenhouse gas emissions. These warming trends were the result of the earth's rotation around the sun. When the earth heated up in the past, more CO2 was released from our carbon sinks, which created a greenhouse effect. So when humans release CO2 today we are not allowing the earth to go through its natural cycle. Our oceans haven't even started heating up yet. But if they do, and we do not cut CO2 in the atmosphere over the next twenty years, catastrophic effects will ensue.