Tens of thousands of scientists from more than 100 countries have gathered overwhelming evidence that Humans are responsible. We are the ones who use fossil fuels to produce livestock, clear trees and increase the amount of heat-trapping gas in the atmosphere.
Scientists are sure of human influence on climate change. The primary ones being the increased use of fossil fuels, deforestation, increasingly intensive agriculture and large-scale livestock farming, all of which are required to support a spiralling global population.
So what's the evidence?
There are nine lines of evidence that have been independently examined, but they are physically related to the research:
Simple chemistry – When we burn carbon-based materials, carbon dioxide (CO2) is emitted (research beginning in the 1900s).
Basic accounting of what we burn, and therefore how much CO2 we emit (data collection beginning in the 1970s).
Measuring CO2 and other greenhouse gases in the atmosphere and trapped in ice to find they are increasing, with levels higher than anything we've seen in nearly a million years (measurements beginning in the 1950s).
Chemical analysis of the atmospheric CO2 that reveals the increase is coming from burning fossil fuels (research beginning in the 1950s).
Basic physics that shows us that CO2 absorbs heat (research beginning in the 1820s).
Consensus among scientists who consider all previous lines of evidence and make their own conclusions (polling beginning in the 1990s).
These are some of the evidence that shows humans triggered the climate change process.