How Do We Know That Global Warming Today is Man Made?

Like any detective story, the search for the culprit in the climate change saga takes diligence and the hard and fast rules of scientific investigation. After long and painstaking studies, research has repeatedly found the fingerprints of human activity on current global warming.

How is that possible?

Multiple models and studies have shown that there is a causal correlation between an increase in greenhouse gases and an increase in global temperatures, both of which have been on the rise since the industrial revolution. That is indisputable at this point. Now the reason we can tell that the increases are our fault (rather than due to natural cycles etc..) is because we can actually trace the origins of the greenhouse gases to particular sources, exactly like a fingerprint

fingerprint.jpg

Greenhouse gases from industry have a lighter weight, their 'combined signal' is different than a carbon molecule from natural sources. That is one way we know that human industry and activity is a cause of global warming.

It is clear from extensive scientific evidence that the dominant cause of the rapid change in climate of the past half century is human-induced increases in the amount of atmospheric greenhouse gases
— American Meteorological Society- 2012

All the models used to predict climate change that include human influence come up correct while natural influences either do not correlate or would predict a much different current and future climate than the one we are experiencing. 

In one study researchers managed to "apply diverse analyses to more than 1,700 species, and show that recent biological trends match climate change predictions" Read Article 

As for the notorious 3% of studies that supposedly contradict the scientific consensus on climate? Well a new review of those reports shows that they are all flawed.

Source Climate Central

We cannot continue to ignore or deny our part in climate change nor can we shirk our duty to act to mitigate and reverse global warming. 

The scientific evidence is clear: global climate change caused by human activities is occurring now, and it is a growing threat to society.
— American Association for the Advancement of Science (2006)
Human influence on the climate system is clear, and recent anthropogenic emissions of greenhouse gases are the highest in history. Recent climate changes have had widespread impacts on human and natural systems
— IPCC Fifth Assessment Report, Summary for Policymakers (2014)