On Friday, September 20, an estimated 4 million people took to the streets around the world to demand action on climate change. While this isn’t the first, nor is the largest, global protest, there remains something unique and striking about this action. While there isn’t any solid data to support the claim, it has been reported to contain the largest percentage of children and youth. Perhaps this shouldn’t be surprising given that the catastrophic effects of climate change will hit them the hardest.
It is a particularly perverse and insidious facet of climate change that the damage done now, and in the past, will not manifest itself for another 40 years. This effect is known as climate lag. So why is it that today’s greenhouse gas emissions take so long to impact the climate? The two factors responsible are chalked up to the thermal inertia of our oceans and suspended particulate matter in our atmosphere.
By far the thermal inertia of the oceans is the larger contributor of the two factors so we’ll look at that first. To begin let’s define thermal inertia. Most of us will be familiar with Newton’s first law of motion defining inertia- an object at rest stays at rest and an object in motion stays in motion with the same speed and direction unless acted upon by an unbalanced force. Objects with greater inertia are both harder to get moving and harder to slow down or change direction. However, here we are not dealing with motion but rather temperature (that’s the “thermal” part). Basically, thermal inertia is the tendency for matter to remain at its current temperature. Just as it is with motion, different objects or matter have different thermal inertias and water is notorious for having a very large value.
Consider a large pot of boiling water, the pot itself, and the air around it. Nearly instantaneously the air above the flame becomes hot, which is because our atmosphere has very low thermal inertia. Not quite as fast, but still pretty quickly, the metal of the pot will heat to nearly the same temperature as the flame. It never gets as hot as the flame since that heat energy is being absorbed by the water within. Only after a while, depending on how much water is in the pot, will the water heat to the point of boiling. There is substantial lag between the heating of the air around the flame and the water.
I’m guessing you see where I’m going with this. As greenhouse gasses trap energy from the sun the planet starts to warm. But just as it was in the above example, the air warms first. Not too big of a deal initially because the air also cools rapidly once the sun goes away. However, given enough time the oceans also begin to warm.
Who out there knew how important the oceans are to stabilize our climate? If you need proof for yourself just visit Southern California during the summer. Anywhere more than about 50km from the coast will be sweltering. On the very same day along the coast it’s typical for the temperature to rise only to a pleasant warm. The same is true all around the planet. Shoot, why do you think so many people like to live near the coast?
Not only will today’s adults escape most of the worst consequences but from a political standpoint, politicians have little to no motivation to act. What motivates politicians are issue that bolster their chances at re-election. Most of the world’s democracies elect legislators approximately every 2-6 years, which is why new policy nearly always focuses on immediate results. Certainly there are politicians that have put forward legislation and budgets that are designed to address issues in the long term but following elections have not been kind to them.
The effects of climate change we bare witness to today are the result of greenhouse gas emissions from 40 years ago. Take a look at the many charts available showing greenhouse gas emissions and you’ll see that the quantity released into the atmosphere 40 years ago is completely dwarfed by today’s emissions.
However, leading scientists tell us that there is still time to act in order to avoid the most catastrophic effects of climate change. The youth know this and that is why they are on the streets. The voices of the young cannot be ignored since it is their future they are fighting for. If a teenager can understand climate lag, why can’t we?