PMU199 Course Blog

Did you know that…

• The 20th century’s last two decades were the hottest in 400 years.

• Climate-sensitive diseases killed more than 3.3 million people globally in 2002

• Because of extreme weather,  600,000 people died by natural disasters in 1990s, and 95% of those deaths occurred in poor countries.

• One-third of all living species could be extinct by 2050

As a result of the change in climate, more people are becoming aware of global warming, and there are a lot of hypotheses about the outcomes of global warming. One of the hypothesis’s that interests me is “a new ice age”. The movie “Day After Tomorrow (2004)” is a film based on the hypothesis that melting glaciers will shut down the Gulf Stream, which is the part of global conveyor belt. This could cool down the North Atlantic region and cause a new ice age.

The global conveyor belt (also called, thermohaline circulation) is the movement of water in oceans all over the world. (The red and blue belt in the picture represents the global conveyor belt)

(Click the picture if you want to see the website where I got the information about the thermohaline circulation and new ice age)

The amount of salt in water and ocean temperatures move this conveyor belt of water. As you can see in the picture, the conveyor allows the warm surface water to move towards the North Atlantic pole. This brings warmer temperatures to Europe. (It allows Britain to have mild winters) When the warm water reaches the North Atlantic, the water becomes saltier and cooler. Because cold water molecules are packed more tightly together, it has more density than warm water. Therefore, it sinks deep down and pulls the current back around.

(Click the picture if you want to see the website where I got information about the thermohaline circulation)

The difference in temperature in the water enables the thermohaline to move the water around the world. The deep cold current travel around Africa and Asia. Some of the current rises slowly because it gets warmed. The rest of the cold current continues to run toward the Pacific Ocean. In the Pacific, the water will rise to the surface of the ocean due to warm temperatures. The warm water will travel back to the North Atlantic pole, and that completes the cycle of thermohaline. (The completion of the cycle takes around 1000 years.)

But how is the global conveyor belt related to global warming and the ice age?

Recently, scientists discovered that there has been 20% decrease in cold water flow around Gulf. The global conveyor belt heavily depends on the temperature and salinity of water. Nonetheless, if the glacier continues melting due to the increasing in temperature, there will be more fresh water around the Gulf Stream, which will slow down the global conveyor belt. This will no longer bring warm water around the North Atlantic as it will stay in the tropical regions, so North West Europe will face harsher winters. In an extreme case, it could cause the same ice age scenario from the Day After Tomorrow. However, many scientists say that the Day After Tomorrow happened impossibly quickly. If this really occurs, it will take many decades.  However, in the movie, the new ice age happens impossibly quickly. If it happens in real world, it will take few decades to happen. (Link)  Steve Easterbrook who is a professor in University of Toronto said the global warming can cause much colder temperature in Western Europe, and it can trigger a new ice age through more glacier reflecting the sun light and etc. But, that’s a very very extreme case to happen.

(Click the picture if you want to see the website where I got information about the Gulf stream)

Or maybe global warming is not even true, and all the evidence that we are seeing such as rising sea level is just coincidence.  However, what if it’s not coincidence? What if global warming has been caused by the result of human’s civilization? Why do the next generation and other species have to suffer because of our greed?  A lot of evidences show that Global warming is happening, and global warming has been caused by the result of humn’s civilization. (Specifically, it has been triggered by burning carbon dioxide) The evidence also indicates that many bad outcomes such as “a new ice age”  can happen in the future. And we don’t know how soon they will appear because nature is very unpredictable. (I believe we have already started to see some outcomes)

A survey indicates that 53% of Americans believe that global warming is due to human activity such as burning fossil fuels, and 70% responded that it is possible to reduce greenhouse gases, and 59% think individuals can do something about global warming.

We have caused global warming, so it’s time for us to take action against it, and I hope it’s not too late.