Human caused global climate change

How do we know current global warming is human caused, or man made? Is global warming real, or a hoax? Consider the facts: the climate system is indicated to have left the natural cycle path; multiple lines of evidence and studies from different fields all point to the human fingerprint on current climate change; the convergence of these evidence lines include ice mass loss, pattern changes, ocean acidification, plant and species migration, isotopic signature of CO2, changes in atmospheric composition, and many others. The only identifiable cause explaining these changes with confidence is human influence and increased greenhouse gas emissions. Science has simply not found any other cause factor that can account for the scale of the recent increase in radiative forcing and associated warming.

The Changing Climate Path

How do we know humans cause global warming?

Many are still asking is current global warming natural or human caused? The idea that global warming is natural is not an absurd question. In the natural cycle, global warming is natural. The better question is, 'is current global warming natural'? There are multiple lines of evidence that point us to the origin of our current warming:

1. Greenhouse gases trap infrared heat energy.
2. The isotopic signature clearly shows that the extra CO2 in the atmosphere is from fossil fuels.
3. We are no longer in the natural cycle. We have largely departed from the natural course of climate and there is no natural mechanism that explains it.
4. The models and the observations match.
5. There is simply no other mechanism that can explain the significantly altered climate path and the changes in the radiative forcing other than human causes.

To understand why 'this current' global warming is human caused and not natural cycle, one needs to get an idea of what the natural cycle is and what are the basic mechanisms that cause climate change in the natural cycle. The absolute essentials that you need to understand are the drivers:

To get a more detailed understanding of the mechanisms, you need to learn a little about:

Certain facts about Earth's climate are not in dispute:

• The heat-trapping nature of carbon dioxide and other gases was demonstrated in the mid-19th century. Their ability to affect the transfer of infrared energy through the atmosphere is virtually certain based on the basic physics, measurements and observations and is also indicated in model confirmations. Increased levels of greenhouse gases must cause the Earth to warm in response.

• Evidence against global climate change
• Evidence of global climate change
• What is causing global climate change?
• Causes of global climate change
• Pictures about climate change