Why does the graph go up and down every year?
The majority of the landmass and vegetation is north of the equator. So, when the northern hemisphere is tilted towards the sun in the spring and summer, vegetation returns and takes in carbon dioxide from the atmosphere.
In the winter the leaves fall and return carbon dioxide to the atmosphere. This is in effect the earth breathing in and out over the course of the year. Carbon dioxide has been measured scientifically since 1958, and we have seen this pattern rising to this day.
What is the impact?
We can see the visible evidence of the retreating McCarty Glacier, Alaska. This happening in other parts of the world too, such as Patagonia on the southern tip of South America. It’s a much bigger problem in the Himalayas, 40% of people get their drinking water from rivers and spring systems that are fed from the meltwater from the glaciers. Over 1.4 billion people are vulnerable to these changes.
What are core drills?
When the snow falls, it traps bubbles of atmosphere. This allows scientists to measure how much carbon dioxide was in the atmosphere when that snow fell. They can also measure the different types of isotopes in the ice and give a precise temperature the earth was when the bubbles were trapped in the ice. Just like you can read trees rings we can read the glaciers and create a temperature over thousands of years. If you can compare over a thousand years of temperature and carbon dioxide data, we can see the relationship between the sets of data.
In Antarctica, we can trace the data even further back to over 650,000 years. The data shows several ice ages, over this time the carbon dioxide levels have never risen above 300ppm (parts per million). We can see that when there is more carbon dioxide in the atmosphere the temperature rises in tandem with it as it traps more heat coming in from the sun on our planet. Carbon dioxide is currently well above historic data- this is significantly above the natural cycle. In the next fifty years, it will continue to rise significantly.