We recently celebrated Earth Day 2015. 97% of climate scientists agree, the danger is real, the consequences large, and the time is now for us to pull together and make changes. Except that some are skeptical of or deny either climate change, human causes of it, or both. Is this a reasonable position to hold? If not, why do many do so?

You can join the free online course, Making Sense of of Climate Science Denial, offered by the University of Queensland on the edX platform. The course starts April 28. John Cook the lead instructor, is the Climate Communication Fellow for the Global Change Institute at the university. He created the site Skeptical Science, which is devoted to refuting climate misinformation with peer-reviewed science, and author of Climate Change Denial: Heads in the Sand. Cook answered some questions for Class Central regarding climate change, its impact, its denial, and the course.

What is your background and how did you become interested in climate change education?

John Cook: My background is in astrophysics, completing a Bachelor of Science at the University of Queensland. I became interested in climate change when I got into some vigorous discussions with my father-in-law, who believed global warming was a hoax. This piqued my curiosity and eventually led to me starting the website Skeptical Science, that debunks climate myths.

After several years of engaging in climate communication, I started looking into the psychological research into debunking. Ever since then, I’ve been researching the psychology of misinformation, leading to where I am now in the final stages of completing a PhD in cognitive psychology.

How much evidence is there that climate changes are caused by humans and how much of it are we causing?

How much of the climate change is caused by us? The short answer is all of it 

John Cook: There are many human fingerprints being observed in our climate system–distinctive patterns that scientists expect from warming caused by increased greenhouse gases. These independent lines of evidence not only confirm that humans are causing global warming, they also rule out other possible explanations such as natural cycles, solar activity or volcanoes. How much of the climate change is caused by us? The short answer is all of it. Scientists’ best estimate is that roughly 100% of the warming since the mid-20th Century is caused by human activity. Current research finds that if humans weren’t around, the climate would actually be cooling slightly

What are the main ways humans are affecting climate change? Factories, energy production, auto emissions, agriculture, livestock, etc.

John Cook: Fossil fuel burning is the major driver of climate change. This adds carbon dioxide, a heat-trapping gas, to the atmosphere. The main producers of greenhouse gases are electricity generation and transport.

How confident are scientists about the impacts of continuing climate change?

John Cook: Our course devotes a whole week to the science of climate impacts. Different parts of our climate are understood at different levels. For example, scientists have a high degree of confidence that human activity has increased the frequency and severity of heat waves, and that this will significantly increase in future decades. They have less confidence in other areas such as the influence of climate change on hurricanes.

Scientists have a high degree of confidence that human activity has increased the frequency and severity of heat waves 

There’s growing evidence that warming is leading to stronger hurricanes–ocean heat is like fuel for hurricanes, but what role climate change plays in the formation of hurricanes is unclear. We know there will be many impacts: the oceans will become more acidic, sea levels will rise, rainfall patterns will change. We don’t know the exact amount of change but even best case scenarios will certainly equate to serious impacts on society and the environment.

How many people are skeptics of human-caused climate change? What are their main critiques?

John Cook: Surveys of the general public (in Australia and in the U.S.) find that people who are dismissive of climate change are a small proportion of the population. Our course looks at the most common critiques of climate change. They cover a spectrum of positions from “global warming is not happening” to “global warming is not caused by humans” to “global warming impacts won’t be bad”.

What we find is all of these critiques share some of the five characteristics of science denial – techniques and fallacies that distort the science. An important part of our MOOC is explaining the fallacy in each climate myth. There are legitimate questions about the exact degree of future climate change. However, arguments that future impacts will be inconsequential are not scientifically founded.

Why do you think skeptics or deniers take the position that they do?

John Cook: There is a great deal of research, which we examine in our course, that finds that the primary driver of climate science denial is political ideology. Specifically, people who dislike solutions that involve regulation of polluting industries are more likely to reject the scientific consensus on climate change. This is a key trait of science denial that distinguishes it from genuine skepticism. Skeptics consider all the evidence before coming to a conclusion. Denialists come to a conclusion (based on their ideology) then reject any evidence that threatens their ideology.

Skeptics consider all the evidence before coming to a conclusion. Denialists come to a conclusion (based on their ideology) then reject any evidence that threatens their ideology. 

How should we respond to climate change?

John Cook: The message from the science is clear. Greenhouse gas emissions are causing climate change. To avoid the worst impacts, we need to stop burning fossil fuels and transition to renewable energy. There are a wide range of possible policy responses that might achieve this, which we don’t cover in our course–our focus is on science of climate change.

How welcoming will your course be to people who may be skeptics or deniers but want to learn more?

John Cook: People who want to learn more about climate change are exactly the type of students we welcome. We will also encourage interaction between the students in our discussion forum.

The course, Making Sense of of Climate Science Denial, open to the public on the edX platform and starts April 28.