When did global warming start?

The natural carbon cycle and the water cycle have produced a greenhouse effect that has kept the planet comfortably warm since life began.

Since the start of the Industrial Revolution about 200 years ago man has been burning fossil fuels for industry, transport and the generation of electricity. This burning has released carbon dioxide that had been stored deep underground for millions of years. This extra carbon has disrupted the natural carbon cycle and seriously added to the greenhouse gases in the atmosphere. It is this enhanced, or accelerated greenhouse effect that is causing what we now refer to as global warming, or climate change.

A: The earth has always been warm. This is the result of the greenhouse effect, supported by the natural carbon cycle of the earth, which moves carbon dioxide in and out of the atmosphere. This has kept the earth comfortably warm for as long as life has existed.

Today when we talk about global warming we are referring to the recent warming which has slowly been happening since man began burning fossil fuels and cutting down forests, about 200 years ago. Burning fossil fuels releases extra carbon dioxide making an accelerated greenhouse effect, and deforestation removes trees that have acted as carbon sinks, storing carbon for hundreds of years. A: The Answers.com category defines global warming, or global climate change, as a scientific proposal that the Earth's average atmospheric temperature is currently warming up due to increasing levels of greenhouse gases and/or other factors. This distinguishes it from the natural warming effect of greenhouse gases at their long-term normal level.

Climate scientists say that carbon dioxide and methane levels have been rising since the beginning of the Industrial age, in the middle of the eighteenth century. The present rise in average global temperatures would date from the same time, but instrumental measurements did not commence until 1850, so scientists can only use proxies to estimate temperature changes before that time. Scientists at first doubted that global warming was really occurring or, if it was, that it was occurring at a sufficient rate to be a concern for centuries to come. It was not until the late 1970s that they realised that global warming was real and that it presented a danger in the very short term.