Dedicated to the balanced discussion of global warming
HowStuffWorks.com is a wonderful site that has very well written articles. This article is a basic description of global warming. I know that many of my regular readers may find this article very basic however, my goal is to make sure that the average person can understand much of the science of climate change. To that end, I offer this article.
Global warming was once an uncommon term used by a few scientists who were growing concerned over the effects of decades of pollution on long-term weather patterns. Today, the idea of global warming is well known, if not well understood. It is not unusual to hear someone complaining about a hot day or a freak storm and remark, “It’s global warming.”
Weather is local and short-term. If it snows in the town where you live next Tuesday, that’s weather. Climate is long-term and doesn’t relate to one small location. The climate of an area is the average weather conditions in a region over a long period of time. If the part of the world you live in has cold winters with lots of snow, that would be part of the climate for the region you live in. The winters there have been cold and snowy for as long as weather has been recorded, so we know generally what to expect.
It’s important to understand that when we talk about climate being long-term, we mean really long-term. Even a few hundred years is pretty short-term when it comes to climate.
In fact, during the last ice age (ice ages recur roughly every 50,000 to 100,000 years), the earth’s average temperature was only 5 Celsius degrees cooler than modern temperature averages.
Other observations from the IPCC include:
- Of the last 12 years, 11 have ranked among the warmest years since 1850.
- The warming trend of the last 50 years is nearly double that of the last 100 years, meaning that the rate of warming is increasing.
- The oceanís temperature has increased at least to depths of 3,000 meters (over 9,800 feet); the ocean absorbs more than 80 percent of all heat added to the climate system.
- Glaciers and snow cover have decreased in regions both in the Northern and Southern hemispheres, which has contributed to the rise of sea levels.
- Average Arctic temperatures increased by nearly twice the global average rate over the last 100 years (the IPCC also noted that Arctic temperatures have are highly variable from decade to decade).
- The area covered by frozen ground in the Arctic has decreased by approximately 7 percent since 1900, with seasonal decreases of up to 15 percent.
- Precipitation has increased in eastern regions of the Americas, northern Europe and parts of Asia; other regions such as the Mediterranean and southern Africa have experienced drying trends.
- Westerly winds have been growing stronger.
- Droughts are more intense, have lasted longer and covered larger areas than in the past.
- There have been significant changes in extreme temperatures Ė hot days and heat waves have become more frequent while cold days and nights have become less frequent.
- While scientists have not observed an increase in the number of tropical storms, they have observed an increase in the intensity of such storms in the Atlantic correlated with a rise in ocean surface temperatures.
Global warming is caused by an increase in the greenhouse effect. The greenhouse effect is not a bad thing by itself — it’s what allows Earth to stay warm enough for life to survive.
…because carbon dioxide absorbs infrared radiation. Most of the energy that escapes Earth’s atmosphere comes in this form, so extra CO2 means more energy absorption and an overall increase in the planet’s temperature.
Although the amounts being released by human activities are not as great as the amounts of CO2, nitrous oxide absorbs much more energy than CO2 (about 270 times as much). For this reason, efforts to curb greenhouse gas emissions have focused on NO2 as well. The use of large amounts of nitrogen fertilizer on crops releases nitrous oxide in great quantities, and it is also a by-product of combustion.
Methane acts much like carbon dioxide in the atmosphere, absorbing infrared energy and keeping heat energy on Earth. The IPCC says that methane’s concentration in the atmosphere in 2005 was 1,774 parts per billion (ppb). While there isn’t as much methane as carbon dioxide in the atmosphere, methane can absorb and emit twenty times more heat than CO2. Some scientists even speculate that a large-scale venting of methane into the atmosphere (such as from the release of huge chunks of methane ice locked under the oceans) could have created brief periods of intense global warming that led to some of the mass extinctions in the planet’s distant past.
Water vapor is more difficult to measure than the other greenhouse gases and scientists are uncertain as to the exact part that it plays in global warming. Scientists believe there is a correlation between the increase of carbon dioxide in our atmosphere and the increase of water vapor.
Less abrupt changes would occur around the world as average temperatures increased. In temperate areas with four seasons, the growing season would be longer with more precipitation. This could be beneficial in many ways for these areas. However, less temperate parts of the world would likely see an increase in temperature and a sharp decrease in precipitation, causing long droughts and potentially creating deserts.
Because the Earth’s climate is so complex, no one is really sure how much a change to one regionís climate will affect other regions. For example, scientists at the University of Colorado theorize that the decrease in sea ice in the Arctic could reduce snowfall in Colorado because Arctic cold fronts would be less intense. This could impact everything from farmlands to the ski industry.
Despite a scientific consensus on the subject, some people don’t think global warming is happening at all. There are several reasons for this:
- They don’t think the data show a measurable upward trend in global temperatures, either because we don’t have enough long-term historical climate data or because the data we do have isn’t clear enough.
- A few scientists think that data is being interpreted incorrectly by people who are already worried about global warming. That is, these people are looking for evidence of global warming in the statistics, instead of looking at the evidence objectively and trying to figure out what it means.
- Some argue any increase in global temperatures we are seeing could be a natural climate shift, or it could be due to other factors than greenhouse gases.
Dr. Peter Tsigaris, an economist at Thompson Rivers University, says that taking steps to curb global warming makes sense from both an environmental and an economic standpoint. He estimates that addressing global warming by changing our dependency on fossil fuels and other behavior would cost an estimated one percent of global Gross Domestic Product (GDP) per year, while taking no action could cost 5 percent of global GDP each year. Extreme climate change could result in a cost of 20 percent GDP or greater.
There is much more to this article than I have relayed above. HowStuffWorks tends to break up their articles in multiple smaller chunks. I prefer to read one long page and that is the URL that I reference here.
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