In anticipation of Sidmouth Climate Day on October 16 and Cop 26, the Sid Valley Biodiversity Group is publishing some articles on global warming. The first is from Ed Dolphin.
Climate change explained
The Earth’s climate is varied and has always changed, archeology shows that the Sahara was not desert but grassy barely 6,000 years ago. Around the same time, Devon was too cold for oaks. Some people wonder why this is such a hot topic (pun intended) today.
As far as we know, our planet is the only one in the solar system that is home to life. This is because our atmosphere moderates solar radiation and keeps much of the surface at a temperature where life can exist. The planet Mercury has no atmosphere to do the same; daytime temperatures rise to 800o, but they dip to -330o at night. If the atmosphere is too dense, it’s like a winter quilt in summer, the planet retains too much heat. Venus is further from the Sun than Mercury, but its very dense atmosphere keeps most of the planet at around 400o.
Rather than a blanket, this phenomenon is sometimes referred to as the greenhouse effect. Inside a greenhouse, it is hot during the day as much of the sun’s energy enters as light but turns into thermal energy which is trapped by the glass. The atmospheric greenhouse effect is not a new idea. 160 years ago, physicists Eunice Foote and John Tyndall, working separately, showed that carbon dioxide and water vapor play an important role in energy trapping. Analysis of air bubbles trapped in ice caps shows that the amount of carbon dioxide in the atmosphere has increased since the industrial revolution. It is now at its highest level since the last ice age.
In 1896, Svante Arrhenius calculated the change in temperature that would be related to changes in atmospheric carbon dioxide. The atmosphere is a complex system, and Arrhenius’ calculations have been updated and refined over the years. Another problem is that a warmer atmosphere will hold more water vapor, which increases the effect. It is now known that other gases like methane also play a role, but the basic principle is well established, if you increase carbon dioxide, the atmosphere will heat up.
As has always happened, some people say it doesn’t matter, 2o it’s not much, why fuss? This figure is a global average, some places will heat up a lot more, others could cool down. Devon has mild winters due to the warm ocean currents. The warming of the Arctic and the melting of the ice cap could change ocean currents and Devon could experience winters like the North Sea coast in the future.
Two current issues are the speed of change and the growth of the human population. Oaks came to Britain through natural migration because our wooded landscape has adapted to a slow process. The climate is changing at a faster rate today than at any time since the meteor struck 66 million years ago, which precipitated a huge global temperature drop that wiped out most species on Earth .
As the earth’s ice caps warm, their meltwater enters the ocean and global sea level rises. The sea level has varied over the course of geological time. The difference now is that many cities around the world have been built on the coast. People complain that governments are forcing them to change their way of life, the reality is that nature will force much bigger changes if things continue as they are.
Climate change has always been with us, but humans are accelerating change. Global action is needed, but we can play a role. No act will affect climate change but, if enough people do something individually, many small actions will have a big impact, which is the principle behind the environmental work of the Sid Valley Biodiversity Group. We will be collecting pledges on climate change at our stand in the parish church on October 16th. Please join us.
This article only skates the surface of this very important question, learn more about climate change, but you have to be careful. There is a lot of misleading information available, check everything you read including this article.