By Mark Maslin, Professor of Earth System Science, UCL
The science of climate change is more than 150 years old and it is probably the most tested area of modern science. However the energy industry, political lobbyists and others have spent the last 30 years sowing doubt about the science where none really exists. The latest estimate is that the world’s five largest publicly-owned oil and gas companies spend about US$200m each year on lobbying to control, delay or block binding climate-motivated policy.
This organised and orchestrated climate change science denial has contributed to the lack of progress in reducing global green house gas (GHG) emissions – to the point that we are facing a global climate emergency. And when climate change deniers use certain myths – at best fake news and at worse straight lies – to undermine the science of climate change, ordinary people can find it hard to see through the fog. Here are five commonly used myths and the real science that debunks them.
1. Climate change is just part of the natural cycle
The climate of the Earth has always changed, but the study of palaeoclimatology or “past climates” shows us that the changes in the last 150 years – since the start of the industrial revolution – have been exceptional and cannot be natural. Modelling results suggest that future predicted warming could be unprecedented compared to the previous 5m years.
The “natural changes” argument is supplemented with the story that the Earth’s climate is just recovering from the cooler temperatures of the Little Ice Age (1300-1850AD) and that temperatures today are really the same as the Medieval Warm Period (900–1300AD). The problem is that both the Little Ice Age and the Medieval Warming period were not global but regional changes in climate affecting north-west Europe, eastern America, Greenland and Iceland.
A study using 700 climate records showed that, over the last 2,000 years, the only time the climate all around the World has changed at the same time and in the same direction has been in the last 150 years, when over 98% of the surface of the planet has warmed.
2. Changes are due to sunspots/galactic cosmic rays
Sunspots are storms on the sun’s surface that come with intense magnetic activity and can be accompanied by solar flares. These sunspots do have the power to modify the climate on Earth. But scientists using sensors on satellites have been recording the amount of the sun’s energy hitting Earth since 1978 and there has been no upward trend. So they cannot be the cause of the recent global warming.
Galactic cosmic rays (GCRs) are high-energy radiation that originates outside our solar system and may even be from distant galaxies. It has been suggested that they may help to seed or “make” clouds. So reduced GCRs hitting the Earth would mean fewer clouds, which would reflect less sunlight back into space and so cause Earth to warm.
But there are two problems with this idea. First, the scientific evidence shows that GCRs are not very effective at seeding clouds. And second, over the last 50 years, the amount of GCRs have actually increased, hitting record levels in recent years. If this idea were correct, GCRs should be cooling the Earth, which they aren’t.
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