How can we see that reducing pollution changes the temperature?
This is a great question! Interestingly, during the peak of the COVID pandemic when a lot of people were in lock-down or choosing to stay home, we did see a small dip in pollution and also a very, very slight change in the rate of warming. This was partly because there was a lot less travel by road and air, and so lower emissions of the greenhouse gases, particularly carbon dioxide. The COVID pandemic was a good example of how our actions locally can make some difference to climate change
On longer timescales than the COVID pandemic, there are two main ways that we can link pollution to global temperature change. The first is by using evidence from the past. For instance, ice cores from Antarctica and Greenland contain information about past temperature, and about many other aspects of the environment. This is because the ice encloses small bubbles of air that contain a sample of the atmosphere – from these it is possible to directly measure the past concentration of atmospheric gases, including the major greenhouse gases: carbon dioxide, methane and nitrous oxide. Records from ice cores and other sources show a close connection between carbon dioxide levels and global temperature. Importantly, there are no examples in the ice core record of a major increase in carbon dioxide that was not accompanied by an increase in temperature.
Global climate models are one of the main tools that scientists use to help understand how reducing pollution into the future might help reverse the increases in global temperature that we have seen over recent decades. Using these models, scientists can explore different scenarios (or future pathways) for reducing greenhouse gas emissions and understand how this will affect global temperature over the next 30 to 100 years. These models indicate that by reducing atmospheric pollution we can slow the rate of temperature increase and eventually reverse it.
