Isn't there still a lot of debate among scientists?

The scientific method is built on debate among scientists, who test a question, or hypothesis, and then submit their results to the scrutiny of other experts in their field. That scrutiny, known as "peer review," includes examining the scientists' data, experiment and/or analysis methods, and findings (read more about peer review here).

The spirited debate around remaining uncertainties in climate science is a healthy indicator that the scientific method is alive and well. But the fundamental elements of climate change are not in dispute. To take just a few examples, we understand


The questions on this page represent many of those raised by debaters who are not actively engaged in climate research. These questions have been answered here and elsewhere with evidence from research that has been tested by the scientific method.

Science is a human activity, and no human is infallible. Science is also a community activity, and scientists rely on each other to question, challenge, and improve one another's work. When corrections are made, this is not a sign that the system is broken but rather that it's working as designed.

The science reported by researchers at NCAR and our collaborating institutions around the world is built on decades of investigation and represents the current state of our knowledge on climate change.

Our understanding of the particulars of climate change continues to evolve, and predictions of specific impacts may be revised upward or downward. However, the majority of climate scientists who specialize in understanding the complex interactions of our atmosphere, Earth, and Sun have concluded that:

Global warming is unequivocal and primarily human-induced (U.S. Global Change Research Program, citing its 2009 report on Global Climate Change Impacts in the United States).

Changes in the atmosphere, the oceans, and glaciers and ice caps now show unequivocally that the world is warming due to human activities (United Nations, citing the IPCC 2007 report)

Here's what several major scientific organizations say about global warming and climate change, including the uncertainties climate scientists continue to examine (each link opens a new window):