Climate change is one of the hottest topics in discussion right now. Scientists predict a rise of average global temperature by just 1.5° Celsius or 2° Celsius. But how can such a small temperature shift make a significant impact on life on Earth?
The following answers we picked out from the internet are the ones that explain this phenomenon the best.
It’s not just about the temperature getting a few degrees warmer. An effect of rising CO2 levels is that the global average temperature will get a few degrees warmer. That average temperature increase is a benchmark only, not the problem in and of itself. It’s the other effects of the same root cause of increasing CO2 levels that are a problem.
The earth is a giant thermodynamic engine that takes in energy in higher amounts near the equator where solar gain is greater than heat radiated back into space, and funnels it to the poles, where solar gain is less than heat radiated to space. CO2 acts like a blanket over the system, keeping more heat in, but the equatorial zones don’t heat much, they just shuttle that extra heat to the poles through ocean and wind currents. The same air currents also shuttle CO2 up to the poles, as can be seen in this NASA model, which further reduces heat radiated back into space at the poles. This means that the poles are heating up a lot more than 2 degrees C. More like 10.
The bulk of earth’s frozen water is at the poles, so this rise of several degrees Celsius in the Polar Regions will melt a significant amount of land based ice, raising sea levels. This is going to cost trillions of dollars to either preemptively try to deal with or as flood damage.
In addition, CO2 in the atmosphere is also absorbed into the oceans. As the CO2 levels in the ocean rise, the oceans acidify, due to the creation of carbonic acid, the same acid in your carbonated soda. You may have seen or heard of people dissolving baby teeth in a can of coke, and the same thing happens to carbonaceous minerals in acidified ocean water. So organisms with calcium carbonate shells like shellfish and coral grow slower and will likely soon reach the point where their structures are dissolving faster than they grow. This kicks the legs out of the base of the ocean’s food web, and will largely collapse ocean life in near shore areas with the exception of algae and jellyfish.
Finally, since the earth is currently being shifted out of equilibrium, the weather patterns are behaving like a top that is starting to topple, with extreme systems swinging across the globe. We are getting high pressure systems that park themselves over an area for weeks at a time, blasting the area with heat. In the ocean, this can kill corals, and much of the earth’s coral reefs are already dying off as a result of these extended heat waves. Over land they reduce crop yields and can kill people. We have a circumpolar band of wind called the polar vortex that will start to meander, bringing snow to Florida and dropping temperatures across the Eastern US by 10-15 degrees C below normal in the middle of winter for weeks at a time, killing native plants and animals that aren’t adapted to being able to survive that kind of cold for that long.
These shifting weather patterns also change climate in areas, such that some areas will see extended drought such that there will no longer be enough water for the people that currently live there. In other areas, heavier rainfall increase flooding and landslide events, which cause millions to billions of dollars of damage to communities and kill people.
Any time the world goes through a climactic shift, it becomes less habitable to the species that were adapted to the old patterns. Because of the interconnectedness of ecosystems, these effects ripple in a positive feedback loop that drives up extinction rates in a runaway process that can radically alter the biome. This is not good for humans in the short run or the long run.
While this is indeed a great explanation of the initial issue, I thought I would underline the apocalyptic aspect of this.
Two big points raised – Melting of ice, death of ocean life. Both of these start off a cycle we may never escape, and may eventually leave earth inhospitable for human life.
Not all life, but certainly human life.
Ice is the most reflective thing in nature, and a large part of our planet is covered in it. This reflects heat back into space. As it melts, it exposes dirt and water, the least reflective things, and they absorb heat, making the problem worse, and so more ice melts, and it gets worse.
As acidic water kills sea life, sea life dies. This creates more carbon, more methane, and makes the water more toxic, which kills more life and makes the problem worse.
This, by my understanding is ‘THE BIG DEAL’, where the little damage we do creates a tipping point where we no longer have any control because it will get worse no matter what we do.
I would compare it more to driving a car toward a distant wall. There will be a point where even if we slam on the brakes, it will be beyond our ability to stop, either due to speed or distance.
Scientists have discovered that wall is closer AND our brakes don’t work as well as we had originally thought.
This diagram explains it well: https://goo.gl/images/gZWzAs
The temperate is a bell curve with lots of average temperature, and not much extreme cold or heat. The area under the curve at the hot end is small.
If you increase the average temperature only a little bit (move the curve to the right) the area above a normal hot day gets exponentially bigger.
Just for some context, between the coldest parts of an ice age, and the warm parts between them, there’s a 6 degrees Celsius difference. We’re supposed to have just come out of a warm period like 8000 years ago and start cooling. So we’re still near the warmest bits. But instead of cooling, we’ve already warmed 1 degree Celsius.
So if 6 degrees means a massive portion of the planet covered in ice and glaciers, it’s clear that warming a couple degrees Celsius can be extreme on a global scale too.