I am still surprised by how much climate change denial we come across.
Recently Connect4Climate  ran the iChange competition , challenging students to present the climate challenge in a 30-second video. We received great responses from around the world and compiled a video with some of the best for MTV. Posting this on our YouTube channel  quickly resulted in more than 7000 views, a hearty discussion, and this comment: “lol i havent even watched this video. but ive read some of the comments. global warming is a MYTH!“
What? Such outright denial! How can this be when the science is so overwhelming clear, when world leaders have shown their support for climate action, when reports left right and centre highlight the dire impacts of climate change, not least the World Bank’s own 4°C report ?
I couldn’t let such comments go without responding.
97% of Scientists agree
First off I responded quoting the recent survey that found that 97% of climate science papers agree global warming is man-made.
Surprisingly sceptics still rebut the overwhelming consensus. The next comment was “WHAT SCIENCE?? you show me the science that PROVES there is such a thing?!!”
What science? Well all the peer-reviewed scientific literature published in amongst others the most renowned scientific papers, as well as the summary reports of the Intergovernmental Panel on Climate Change  (IPCC).
Their most recent report, the 5th Assessment Report , shows that scientists are now 95%, up from 90% in 2007, certain that global warming is caused by humans and that the impacts are speeding up. Being a biologist by training, I understand and fully support the peer-review process scientists employ –findings can only be published in a scientific journal once the report has been thoroughly reviewed by other scientists knowledgeable in the field under discussion.
Tom Tanner has an interesting blog on this subject, Getting Serious on Climate Action  and on when good science is necessary but not sufficient to induce more action on mitigation and adaptation.
It’s the sun. No, it is us!
The next comment was: “And where does heat come from??? THE SUN! Something we humans have no control over!”
I agree. The sun does bring energy to our Earth through short-wave radiation (light) and, yes, we have no control over the sun. But no, the global warming we are experiencing now is due to an enhanced greenhouse effect in the atmosphere brought about by our emissions of greenhouse gases, in particular carbon dioxide and methane. These gases trap more of the long-wave radiation leaving the Earth’s surface and thereby warm the atmosphere.
Our emissions are “thickening” the greenhouse gas layer , which under normal circumstances capture about 5% or the long-wave (inferred) radiation the Earth gives off. As we raise the concentration of the greenhouse gases, we thicken the greenhouse gas “blanket” and increase the amount of energy being trapped, which results in the global warming we are already witnessing as well as the warming we have already committed to by setting the equilibrium out of balance. In short we are giving our Earth a sort of fever, or as the Masai say in my film, “The world has malaria ”.
Yes, the Earth goes through ice ages, driven by our proximity to the sun, roughly every 41,000 years. Other natural climate factors include the sun’s brightness or the frequency and intensity of sunspots and volcanic eruptions. But the current warming cannot be attributed to any natural processes. We should be heading for an ice age. There have been no sun events, nor volcanic activity that correlate with the warming. The overwhelming scientific consensus agrees that global warming is due to our emissions. The warming effect of greenhouse gases has been proven since the 1860s, e.g. Tyndall 1861, Herzberg 1953, Burch 1962, Burch 1970, etc.
It has been warmer before
One of the latest comments was that it has been warmer in the past, implying that we should not care about the warming now.
Normally this relates to the Medieval Warm Period (800-1400 AD). The most recent analysis by Pages 2K  shows that temperatures then were similar to those in Europe today in Europe. The important conclusion is that it was a localised event. In other words only Europe experienced the warming, while other parts of the world were sill cool or cooling. By contrast today we have a warming phenomenon all around the world.
The research supports the hockey-stick graph made famous by Al Gore and presented in the last IPCC, and has contributed to the development of the new “wheelchair ” temperature curve being spread around the media. See below in a variation from Paul Price. 
The global temperature has been stable for the last 10 years
The other favourite denial comment is that there is has been no warming in the last decade. While this may be true, it does not mean the global warming has stopped and we certainly have already started seeing the impacts of a changing climate.
One of the most common misunderstandings amongst climate change sceptics is the difference between short-term noise and long-term signal. The animation below by skepticalscience.com  shows that the same temperature data (green), which is used to determine the long-term global surface air warming trend of 0.16°C per decade (red), can be used inappropriately to cherry-pick short time periods that show a cooling trend simply because the endpoints are carefully chosen and the trend is dominated by short-term noise in the data (blue steps). In short the overall trend is a warming trend, but short periods can show little change.
So although there has been not much change in the last decade, worldwide, 2012 was still among the 10 warmest years on record according to the 2012 State of the Climate report  recently released by the American Meteorological Society, and the World Meteorological Society  has reported that more national temperature records were broken in 2001-2012 that in any previous decade since measurements began in 1850. The latest science indicates  that over the past 10 to fifteen years the Earth surface temperature was kept steady by the cooling waters in the tropical Pacific Ocean.
It is also important to look at other indicators of global warming . Besides the surface temperature record, the oceans have been warming, becoming more acidic and have been rising at an average rate of 3.2 ± 0.4 mm per year over the past two decades. Ice melt is occurring all over the world. In 2012 Arctic sea ice minimum extent (1.32 million square miles, September 16) was the lowest of the satellite era, which was 18% lower than the previous record low extent of 1.61 million square miles that occurred in 2007.
It was interesting to listen to the pannel discussion this week on climate change , where the heads of the World Bank Group and the International Monetary Fund made an economic case for climate action and said their institutions will offer the financial support and knowledge to put emerging economies on a green growth path. A good way forward.
In conclusion I say let us succeed in this fight of our generation. Let’s refute one climate change denial at a time and spread climate change awareness as far as possible. We can still act to stabilise the climate, we must be the climate movement.