According to the US National Academy of Sciences, humans are drastically changing the Earth’s climate. This theory is based on several factors, such as the sun’s lack of variations in recent decades. The sun, which is the primary source of energy driving the Earth’s climate system, has shown no increase in output while the Earth’s global surface temperature is believed to have increased. Various reports claim that this proves the sun’s lack of involvement in recent climate change.
Climate changes, including natural ones, are disruptive. In the past they’ve led to the extinction of many species, population migrations, and pronounced changes in the land surface and ocean circulation. A well-known example of this is the ice age. Current climate change may be accelerating faster than most of the past events, making adaption more difficult for human societies and the natural world. The scientists point to the American Pika, which are native to cold alpine conditions but are believed to be dying from rising temperatures.
The report states that human activities have significantly disturbed the natural carbon cycle in many ways. The US National Academy of Sciences notes, since the beginning of the Industrial Revolution, the burning of fossil fuels (coal, oil and gas) has released carbon dioxide (CO2) into the atmosphere. A substantial portion of this CO2 accumulates in the atmosphere, where some of it will remain for thousands of years. CO2 is important gas for controlling Earth’s temperature and it needs to maintain balance. Without greenhouse gases – carbon dioxide, methane and halocarbons – Earth would be frozen at zero degrees Fahrenheit. But with too many greenhouse gases, Earth could ultimately become like the planet Venus, where the greenhouse atmosphere keeps temperatures around seven hundred fifty degrees Fahrenheit.
The Academy of Sciences also indicates that human-induced deforestation is possibly a very significant contributor to climate change. Fewer trees reduce the amount of photosynthesis, a process in which plants remove CO2 from the atmosphere and store it internally. Experts suggest the “slash and burn” technique is commonly used to clear forests. This in turn releases CO2 that had been stored in the plants into the atmosphere. Increasing the amount of CO2 in the atmosphere is just one effect of deforestation on climate change. Permanent destruction of forests can also change the amount of energy from the sun that is reflected by the Earth’s surface. It could change the amount of water vapor released into the atmosphere. This accumulation of atmospheric water vapor can trap additional heat and further increase temperatures. Upon further analysis, scientists believe these factors have a regional effect on temperature.
Due to natural causes, the warming rate of the Earth has varied from time to time and place to place. Researchers believe short-term variations like these are expected and are not responsible for the long-term warming trend. The report indicates the long-term trend is primarily due to human-induced changes in the atmospheric levels of CO2 and other greenhouse gases. Human factors can affect warming from decade to decade with variations in emissions as different practices come and go. The study states that the human factors begin with the Industrial Revolution’s coal-fueled power plants and varied over the years to include other greenhouse gases, aerosols (which can have both warming and cooling effects), vapor trails from planes, soot from fires and components of smog created indirectly by local pollution. While all these factors tend to increase warming, the Academy of Sciences admits that aerosol particles produced by some vehicles and industrial processes tend to bounce sunlight away from the Earth, temporarily counteracting some of the warming caused by greenhouse gases. Studies show human activities have emitted greenhouse gases in the Earth’s lower atmosphere which have also created the potential for more storms and certain severe weather events as it becomes warmer and damper.
The study suggests global warming is a long-term trend, but that does not mean that every year will be warmer than the previous one. Day to day, and year to year, changes in weather patterns will continue to produce some unusually cold days and nights, and winters and summers, even as the climate warms.
Scientists are confident that Earth will warm further over the coming century. The impact of this warming could threaten food production, freshwater supplies, coastal infrastructure, and especially the population currently living in low-lying areas as water levels rise. Scholars conclude, even if emissions of greenhouse gases were to suddenly stop, Earth’s surface temperature would not cool and return to the pre-industrial era level for thousands of years.
The report concludes that climate change is inevitable, but if greenhouse gas emissions continue as they are, future changes will substantially exceed those that have occurred so far. This will be perilous to all life on Earth, making the need for change now extremely dire. There are conflicting theories regarding the cause of the Earth’s rapid climate change. Continue reading for another point of view.
The following information has been collected from Scientist American’s article “The Role of Sunspots and Solar Winds in Climate Change.” Some scientists believe the surface of the sun is going blank, a phenomenon which scientists describe as a natural event in the sun’s current solar cycle. These solar cycles last for 11 years, and see both increases and decreases in sunspots. Appearing as solar flares and dark blemishes, sunspots are darker, cooler areas with magnetic storms on the surface of the sun. The article states that the greatest number of sunspots in any given solar cycle is designated as “solar maximum.” The lowest number is called “solar minimum,” which describes the current state of the sun. This means that normally the surface of the sun looks blotchy and freckled compared to its current appearance which scientists have likened to a cue ball.
But what does this mean for Earth’s climate? Southwestern Law School professor Joerg Knipprath is still trying to determine the answer. Knipprath states, “Solar flares, which are linked to sunspots, consist of strong x-ray flashes and light energy. These flares shoot off into space at the speed of light from the surface of the sun.” Solar wind, according to NASA, consists of solar flares which influence galactic rays. It is believed that these rays may affect atmospheric phenomena on Earth such as cloud cover. In addition, a previous solar minimum which took place in the 1600s and 1700s was marked by cold temperatures and severe winters in Europe and North America. Scientists have deliberated that a decrease in the sun’s ultraviolet emissions may have triggered the change in climate. However, this is just speculation, as it hasn’t been firmly proven that the two phenomena were actually related.
In contrast to the current lack of sunspots, some studies indicate that overall sunspot activity has doubled in the last century. The visible result of this being the sun glowing brighter (by about 0.1 percent) than it did 100 years ago. Those who are skeptics of human-induced climate change claim that these natural variations in the sun’s output are to blame for global warming. Experts explain that it is not a coincidence that sunspot activity increases along with global temperatures. These skeptics further warn that regulation of carbon emissions would negatively affect our economy and what they describe as a “tried-and-true” energy infrastructure.
How can scientists formally conclude which theory is the highest contributing factor to climate change? Only the absence, or extreme reduction, of carbon emissions would allow researchers to conclusively tell how much impact natural influences have on the Earth’s climate. However, obtaining and enforcing the regulations needed to test these theories would be a difficult task in itself. For now, this leaves the conclusion to this debate unresolved.
On May 11, 2001, the White House made a request to the National Academies to identify areas where there are the greatest certainties and uncertainties in the science of climate change. Because of the critical nature of this issue, the Administration asked for a response “as soon as possible” but no later than early June, 2001. A committee with broad expertise and diverse perspectives on the scientific issues of climate change was appointed by the National Research Council and they issued their report June 6, 2001.
To find out more about the National Academies, visit our National Academy of Sciences – National Research Council page.