Dr Ed Berry explains: "My message to you at the end of 2018 is human CO2 adds only about 18 ppm to the atmosphere while natural CO2 adds about 392 ppm, for a total of about 410 ppm that exists today. There is no valid argument that the human contribution is any larger than 18 ppm. Therefore, all the political actions people are doing to 'address climate change' and to 'save the planet' will have zero effect on climate. These people may call me a 'denier' but it is they who deny science."