Carbon dioxide levels in the atmosphere are on the rise. That’s one thing even the climate change sceptics can’t challenge.
And most climate experts agree that CO2 emissions from humans is increasing Earth’s overall temperatures at a faster rate than at any other time in recorded history.
However, there are some people out there — even scientists — who question whether Earth will, in fact, warm up over the next 100 years and how it will effect Earth’s overall climate and ecosystems.
Here are some of the scientists who have gone on record with their controversial views:
Craig Idso is founder and former president of the Center for the Study of Carbon Dioxide and Global Change, which is a non-profit organisation that publishes the newsletter CO2Science, which sharply disputes scientific opinion on climate change.
Last year, a recurring face at the annual International Conference on Climate Change, Craig Idso said 'There is no dangerous human influence on Earth's climate from a rise in CO2.'
Idso asserts that rising CO2 and resulting warmer temperatures will not only greatly benefit plant growth but will also reduce the risk of cardiovascular deaths in humans, as well as other spectacular claims.
His presentation, which you can watch here, is overwhelmingly positive, choosing to focus on the plants and animals that will thrive from raising CO2 and completely neglecting those that could go extinct, or the islands that will disappear, or the damage done by flooding coast lines.
Patrick Moore is the former president of Greenpeace Canada, a non-governmental environmental organisation that focuses its campaigns on climate change, deforestation, overfishing, and other worldwide issues.
Earlier this year Patrick Moore told Energy Live News 'I am firmly of the belief that the future will show that this whole hysteria over climate change was a complete fabrication.'
According to Greenpeace, Moore 'exploits long-lost ties' with the organisation to sell his anti-environmental opinions on carbon dioxide. Moore thinks that this greenhouse gas is in no way related to global warming and that it's a 'good thing' that we're putting more into the atmosphere. He's forgetting the overwhelming evidence to the contrary.
Anastasios Tsonis is a distinguished professor of atmospheric science at the University of Wisconsin-Milwaukee who's research is widely touted by climate-change-denial outlets like Climate Depot.
Anastasios Tsonis has said he's not a climate change denier, but he also is of the belief that Earth is not necessarily getting any warmer. Tsonis is part of a group of scientists who think that Earth's climate flips between a 'warm mode' and 'cool mode' every 20 to 30 years, driven by oceanic temperatures, particularly the Atlantic Multidecadal Oscillation (AMO) current.
Right now we're in a 'cool mode,' he told British journalist David Rose in 2010. 'We have such a change now and can therefore expect 20 or 30 years of cooler temperatures.' While the AMO is a confirmed natural phenomenon, there is controversy as to its periodic changes and influence on climate.
Denis Rancourt is a former professor of physics at University of Ottawa who was banned from the university in 2008 for his unconventional approach to teaching and grading.
Despite his training and research in physics, Denis Rancourt calls himself the 'Climate Guy' in one of his climate-change-disputing blogs. In 2007, Rancourt published a detailed essay of his opinions that has since served as platform for certain politicians, like American Senator James Inhofe, to discredit scientific results supporting climate change.
'This idea that a global warming could actually negatively impact the environment on its own is very very tenuous,' Rancourt told ClimateDepot.com in 2010. 'I see no evidence of that.'
Rancourt is obviously ignoring -- or simply choosing to be ignorant of -- the thousands of walruses that were stranded last year due to melting ice they would otherwise rest on and the the Great Barrier Reef's continued degradation.
Freeman Dyson is a professor emeritus of the School of Natural Sciences, Institute for Advanced Study. He also holds the prestigious title as a Fellow of the Royal Society.
Famed physicist Freeman Dyson has gone on record as a sceptic of the Intergovernmental Panel on Climate Change's (IPCC's) -- the internationally accepted authority on climate change -- approach on climate change. He's not the only one.
Over a dozen other distinguished scientists, including MIT meteorologist Richard Lindzen, have raised concerns about the predictive power of computer-based climate change models that drive the IPCC's policy guidelines to addressing climate change. Specifically, Lindzen -- who has isolated himself from the scientific community -- has gone so far as to say that Earth is not sensitive enough to increases in atmospheric CO2 to generate disastrous climate change.
Though no one can predict the future, these computer models play a significant role in driving policy to mitigating greenhouse gas emissions, which many climate experts say is a good thing.
Harrison Schmitt is a geologist, Apollo 17 astronaut, and former Republican US Senator. He's one of many featured on the climate-change sceptics blog, the DeSmogBlog.
Harrison Schmitt was one of 16 scientists to sign in support of a 2012 statement regarding how political candidates should attack the issue of climate change. Among the descriptions in the statement, the most vexing read as follows:
'Speaking for many scientists and engineers who have looked carefully and independently at the science of climate, we have a message to any candidate for public office: There is no compelling scientific argument for drastic action to 'decarbonize' the world's economy. Even if one accepts the inflated climate forecasts of the IPCC, aggressive greenhouse-gas control policies are not justified economically.'
Some argue that life survived past peaks in CO2 atmospheric levels in Earth's ancient past, however the rate at which these levels rose was far slower and therefore enabled time for adaptation. There's no telling what these faster rates will do to the ecosystem, but most agree it won't be anything good.
Steven E. Koonin is a theoretical physicist and director of the Center for Urban Science and Progress at New York University.
Steven E. Koonin is what you might call a moderate sceptic. He does not deny the basic facts: Earth's climate is changing and humans play a key role.
However, in a Wall Street Journal editorial in 2014, Koonin voiced concerns that climate change projection models are not sophisticated enough to accurately predict how climate will change over the next 100 years and how humanity will influence that change.
'Society's choices in the years ahead will necessarily be based on uncertain knowledge of future climates,' he wrote. Koonin also urged immediate action for an 'international commitment' of dedicated, detailed climate observations that would help build better predictive models.
While Koonin has a point, we shouldn't necessarily attack current policies to mitigate emissions that scientists have fought so hard for -- we should continue to adjust our policies as climate models improve.
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