Scientists disagree on the cause of climate change, the impact humans have on it, and its possible consequences. For example, the The Petition Project features over 31,000 scientists signing the petition stating “There is no convincing scientific evidence that human release of carbon dioxide will, in the forseeable future, cause catastrophic heating of the Earth’s atmosphere …”.

Thousands of scientists who study the climate of the Earth system, its evolution and human activities, agree that there is a cause and effect relationship between the increase in anthropogenic greenhouse gases and the increase in the Earth’s global temperature. This is confirmed by the reports of the Intergovernmental Panel on Climate Change (IPCC), which summarize the results published by the global scientific community. The consensus that humans are causing recent global warming is shared by 90%–100% of publishing climate scientists according to six independent studies. Those results are consistent with the 97% consensus reported by Cooks research paper in 2013. According to the official positions of every major climate research organisation in the world and the Academy of Sciences in 80 countries, humans are causing global warming. The consensus is overwhelming. Of course, there are individual scientists who are skeptical about this. However, they are very few.

Climate change is part of a natural cycle. Climate’s changed before – it is always changing. We have had ice ages and warmer periods when alligators were found in Spitzbergen. Ice ages have occurred in a hundred thousand year cycle for the last 700 thousand years, and there have been previous periods that appear to have been warmer than the present despite CO2 levels being lower than they are now. More recently, we have had the medieval warm period and the little ice age. The view that humans can influence climate on a global scale, intentionally or not, is a display of hubris.

The existence of climatic variability of natural origin cannot be used as an argument to deny or diminish the existence of global warming due to greenhouse gas emissions; natural variability overlaps with that of anthropogenic origin, and the scientific community has the tools to analyze both components and study their interactions. Many factors affect climate, both natural – changes in solar activity, changes in the Earth’s orbit, volcanic eruptions, etc., and anthropogenic – emissions of greenhouse gases, sulphur dioxide and aerosols, atmospheric pollution, changes in land use, etc. Interestingly enough, the impact of natural factors alone would have caused cooling in recent decades. Therefore, we can conclude that the observed global warming is the result of anthropogenic activity. While the Medieval Warm Period saw unusually warm temperatures in some regions, globally the planet was cooler than current conditions. Scientific analysis shows that greenhouse gases, mainly CO2, have controlled most climate change in the past. They show how sensitive the climate is to fluctuations in the amount of carbon dioxide in the atmosphere. Evidence for this is widespread throughout the geological record. It shows clearly that humans are the cause this time, mainly through the CO2 we emit.

Global warming is a consequence of increased solar activity. Over the past few 100 years, there has been a steady increase in the numbers of sunspots, a trend that has accelerated in the past century, just at the time when the Earth has been getting warmer.

The Sun can influence Earth’s climate, but it isn’t responsible for the warming trend we’ve seen over recent decades. The warming we’ve seen in recent decades is too rapid to be linked to changes in Earth’s orbit and too large to be caused by solar activity. Over the past 35 years, the sun has shown a cooling trend. However, global temperatures continue to rise. If the sun’s energy is decreasing as the Earth warms, the sun cannot be the main element controlling temperature.

CO2 is naturally occuring in the atmosphere, and is not a pollutant.

CO2 is a pollutant (acidification of the ocean), its primary impact is its greenhouse warming effect. While the greenhouse effect is a natural occurrence, too much warming has severe negative impacts on agriculture, health and environment.

Human CO2 is only a tiny % of CO2 emissions. The oceans, land and atpmosphere exchange CO2 continuously so the additional load by humans is incredibly small. A small shift in the balance between oceans and air would cause a CO2 much more severe rise than anything we could produce.

The natural cycle adds and removes CO2 to keep a balance while humans add extra CO2 without removing any.

Volcanoes emit more CO2 than humans. Over the past 250 years, humans have added just one part of CO2 in 10,000 to the atmosphere. One volcanic cough can do this in a day.

Humans emit 100 times more carbon dioxide into the atmosphere than volcanoes. Volcanoes emit around 0.3 billion tonnes of CO2 per year. This is about 1% of human CO2 emissions which is around 29 billion tonnes per year.