Human activities are not the only ones that can impact climate, however, and throughout Earth's history natural activities have also caused climate fluctuations see references 3. Solar Output The sun's output shows small variations over the course of an year cycle, so the average amount of solar radiation that reaches Earth's outer atmosphere, the TSI, varies by about 1.
These cyclic changes correlate with the number and frequency of "sunspots," the so-called solar cycle see references 3.
Current evidence suggests the TSI has increased by about. TSI is presently about watts per square meter by way of comparison see references 5.
While these are very important for long-term fluctuations in climate, they have very little impact on shorter timescales because they take place so slowly see references 3. Consequently, water vapor can act as part of feedback loops, where an increase in temperature triggers an increase in water evaporation, which triggers an increase in temperature and so forth see references 2.
As the water vapor concentration increases, however, the water vapor also condenses into clouds, which reflect solar radiation and have an opposite effect see references 2.
Consequently, the role of these feedback loops and their importance is still poorly understood see references 2. Humans have increased atmospheric methane concentrations by growing rice, raising cattle and using natural gas see references 2.
Carbon dioxide is released by animals and other organisms as part of respiration; plants take up carbon dioxide from the atmosphere and fix it into organic compounds see references 2 see references 6. Several hundred million years ago during the Carboniferous period, vast swamp forests of seedless vascular plants fixed huge amounts of carbon, causing atmospheric CO2 concentrations to drop fivefold see references 6.
The resulting global cooling led to an ice age see references 6. Much of this fixed carbon was buried in the swamps and gradually compressed to form coal see references 6. The large quantities of dust and ash scattered by huge eruptions may circulate for some time and reflect solar radiation, keeping Earth slightly cooler than it would be otherwise see references 2.
The last such major event was the eruption of Mount Pinatubo in the Philippines in see references 2.Factors that cause climate change can be divided into two categories - those related to natural processes and those related to human activity.
In addition to natural causes of climate change, changes internal to the climate system, such as variations.
Climate change is a change in global or regional climate patterns, and has attributed greatly to the increased levels of carbon dioxide within the earth’s atmosphere, .
Geological records stretching back millions of years indicate a number of large variations in Earth’s past climate.
These have been caused by many natural factors, including changes in the sun, volcanoes, Earth’s orbit and CO2 levels. Nonhuman factors that are contributing to climate change include that Earth’s climate has always warmed, changes in solar irradiance, In order to reduce the human impact on climate change, we can find other sources of energy, preserving rainforests, and cultivating low-carbon farming%(1).
This is the most important long-lived "forcing" of climate change.
Geological records stretching back millions of years indicate a number of large variations in Earth’s past climate. These have been caused by many natural factors, including changes in the sun, volcanoes, Earth’s orbit and CO2 levels. Human activities contribute to climate change by causing changes in Earth’s atmosphere in the amounts of greenhouse gases, aerosols (small particles), and cloudiness. The largest known contribution comes from the burning of fossil fuels, which releases carbon dioxide gas to the atmosphere. Climate change is a change in global or regional climate patterns, and has attributed greatly to the increased levels of carbon dioxide within the earth’s atmosphere, .
Methane. A hydrocarbon gas produced both through natural sources and human activities, including the decomposition of wastes in landfills, agriculture, and especially rice cultivation, as well as ruminant digestion and manure management associated with domestic livestock.
Human activities are not the only ones that can impact climate, however, and throughout Earth's history natural activities have also caused climate fluctuations (see references 3).