Theory of Global Warming
The theory of global warming is nothing new. The Nobel Prize-winning chemist Svante Arrhenius first proposed the idea of global warming in 1896. Carbon dioxide, he knew, traps heat in the Earth's atmosphere. He also knew that burning coal and oil releases carbon dioxide (CO2).
Arrhenius speculated that continued burning of coal and oil would increase concentrations of CO2 in the Earth's atmosphere, making the planet warmer. It's called thegreenhouse effect.
What warms the Earth?
To determine what is causing today's rapid global warming, scientists have examined all the factors that can affect the Earth's temperature. There are essentially three factors that could be responsible for recent rapid global warming: 1. The sun 2. Earth's reflectivity 3. Greenhouse gases
Which of these is causing our current global warming?
It's not the sun: cause of little warming since 1750, none since 1980s
Ultimately, the climate system is powered by the sun: all else being equal, if you turn up the sun, you'll warm up the Earth. According to IPCC estimates, the sun has accounted for just a small portion of warming since 1750. A study of more recent solar activity has demonstrated that since about 1985 the sun has changed in ways that, if anything, should have cooled the planet—even as global temperatures have been rising. So the sun is not causing global warming.
It's not reflectivity: changes point to cooling, not warming
Around 30% of the sun's energy that reaches the Earth is reflected back into space. Changes in how much sunlight is absorbed, and how much is reflected, can affect global temperatures. Using satellite and land-based observations and computer models, scientists have calculated how Earth's reflectivity has changed over time.
These calculations suggest that human-produced particulate pollution, especially reflective sulfur-containing particles, have had a cooling effect on the climate, masking some of the warming effect of greenhouse gases. In
Arrhenius speculated that continued burning of coal and oil would increase concentrations of CO2 in the Earth's atmosphere, making the planet warmer. It's called thegreenhouse effect.
What warms the Earth?
To determine what is causing today's rapid global warming, scientists have examined all the factors that can affect the Earth's temperature. There are essentially three factors that could be responsible for recent rapid global warming: 1. The sun 2. Earth's reflectivity 3. Greenhouse gases
Which of these is causing our current global warming?
It's not the sun: cause of little warming since 1750, none since 1980s
Ultimately, the climate system is powered by the sun: all else being equal, if you turn up the sun, you'll warm up the Earth. According to IPCC estimates, the sun has accounted for just a small portion of warming since 1750. A study of more recent solar activity has demonstrated that since about 1985 the sun has changed in ways that, if anything, should have cooled the planet—even as global temperatures have been rising. So the sun is not causing global warming.
It's not reflectivity: changes point to cooling, not warming
Around 30% of the sun's energy that reaches the Earth is reflected back into space. Changes in how much sunlight is absorbed, and how much is reflected, can affect global temperatures. Using satellite and land-based observations and computer models, scientists have calculated how Earth's reflectivity has changed over time.
These calculations suggest that human-produced particulate pollution, especially reflective sulfur-containing particles, have had a cooling effect on the climate, masking some of the warming effect of greenhouse gases. In