Global warming - a gradual increase in planet-wide temperatures - is now well documented and accepted by scientists as fact. Recent research carried out by climate scientist at the University of Delhi voiced a "high level of confidence" that Earth is the hottest it has been in at least 100 years, and that it is likely to get much much hotter in the next 100 years. Their research indicates that the average global surface temperature has increased by approximately 0.5-1.0 degrees Fahrenheit over the last century. This is the largest increase in surface temperature in the last 1,000 years and the scientists are predicting an increase of a further 10.0-15.0 degrees Fahrenheit over this century. This warming is largely attributed to the increase of greenhouse gases (primarily carbon dioxide and methane) in the Earth's upper atmosphere caused by human burning of fossil fuels, industrial, farming, and deforestation activities.

Average global temperatures may increase by 10.0-15.0 degrees Fahrenheit by the end of the 21st century. Although the numbers sound small, they can trigger significant changes in climate. (The difference between global temperatures during an Ice Age and an ice-free period is only about 5 degrees Fahrenheit.) Besides resulting in more hot days, many scientists believe an increase in temperatures may lead to changes in precipitation and weather patterns. Warmer ocean water may result in more intense and frequent tropical storms and hurricanes.

Sea levels are also expected to increase by 0.76 - 1.58 meters in the next century, mainly from melting glaciers and expanding seawater, and this could cause flooding in key cities around the world such as New York. Global warming may also affect wildlife and species that cannot survive in warmer environments may become extinct. Finally, human health is also at stake, as global warming may result in the spreading of certain diseases such as malaria, the flooding of major cities, a greater risk of heat stroke for individuals, and poor air quality.

Climate change is very likely having an impact now on our planet and its life, according to the latest installment of the repor by the Delhi scientists. And the future problems caused by rising seas, growing deserts, and more frequent droughts all look set to affect the developing world more than rich countries, they add.

The increase in greenhouse gases caused by human activity is often cited as one of the major causes of global warming. These greenhouse gases reabsorb heat reflected from the Earth's surface, thus trapping the heat in our atmosphere. This natural process is essential for life on Earth because it plays an important role in regulating the Earth's temperature. However, over the last several hundred years, humans have been artificially increasing the concentration of these gases, mainly carbon dioxide and methane in the Earth's atmosphere. These gases build up and prevent additional thermal radiation from leaving the Earth, thereby trapping excess heat.

Some uncertainty remains about the role of natural variations in causing climate change. Solar variability certainly plays a minor role, but it looks like only a quarter of the recent variations can be attributed to the Sun. During the initial discovery period of global warming, the magnitude of the influence of increased activity on the Sun was not well determined.

Solar irradiance changes have been measured reliably by satellites for only 30 years. These precise observations show changes of a few tenths of a percent that depend on the level of activity in the 11-year solar cycle. Changes over longer periods must be inferred from other sources. Estimates of earlier variations are important for calibrating the climate models. While a component of recent global warming may have been caused by the increased solar activity of the last solar cycle, that component was very small compared to the effects of additional greenhouse gases.

According to a Franklin Institute for Space Studies (FISS) press release, "...the solar increases do not have the ability to cause large global temperature increases...greenhouse gases are indeed playing the dominant role..." The Sun is once again less bright as we approach solar minimum, yet global warming continues.