Global Warming: Is our climate really warming?

Even today there are still many people who say they don’t believe in Global Warming. This amounts to saying “I don’t believe it’s raining” on a rainy day, simply because one refuses to look out the window. All the facts say that yes, global temperatures are rising.

The 10 warmest years in the modern meteorological record occurred since 2000.

Global temperature rise since the industrial revolution.

NASA uses temperature analysis data from more than 1,000 meteorological stations around the world. They also check satellite observations of sea surface temperatures and Antarctic research station measurements.

All of these show that the average temperature around the globe in 2015 was 1 °C warmer than a mid-20^th century baseline measurement, despite the cooling effects of a strong La Nina influence and low solar activity for the past several years.
2015 was the warmest year ever since they started measuring in 1880.

Meteorological records have shown a steady increase in global temperatures since the industrial revolution as the graphic to the right clearly shows.

Therefore global warming is not a question of ‘believe it or not’, it is a fact recognized by scientists all over the world.

So why is there so much controversy over Global Warming?

Temperature variations since the existance of planet Earth

What is not absolutely certain is the reason for global warming.
Planet Earth has been heating and cooling and heating and cooling again, ever since it came into existence four and a half billion years ago.

As you can see in the graphic to the left the planet has been generally cooling for the last sixty five million years.
It can even be argued that we are actually living in a cold period compared to the planet’s history.

Even in more recent history, over the past 400 thousand years, several ice ages took place and each time a warming period occurred before a new ice age started. Therefore some scientists argue that today’s warming is simply part of a natural cycle in between ice ages. A large part of the scientific community however, ascribes global warming to human activity. This is the bit which is still being discussed, and which you may believe, or not.

Of course scientists usually have a solid foundation for their theories. One of the things which led them to believe global warming is due to human activity is the analysis of ice cores.

Scientists discovered that over time layers formed in the ice, similar to annual rings in a tree, because of the difference in temperature between winter and summer. These layers allowed scientists to date the ice quite precisely up to eight hundred thousand years back.
Each layer of ice encloses air bubbles from the atmosphere at the time it was formed. Therefore ice cores contain copious amounts of climate information.
All scientists need to do is check the composition of the ice layer and measure trapped air bubbles in that specific layer of ice, to know which gases were present in the atmosphere at that time. In this way they can tell what the weather was like up to eight hundred thousand years back and which gases were present in the atmosphere at that time.

This research clearly shows a relationship between atmospheric carbon di0xide levels and global temperatures. The higher the concentration of this gas, the warmer the planet. The graphic below shows this relationship over the past 400,000 years. Temperature variations are in blue and carbon dioxide concentration in the atmosphere in red.

Temperature and atmospheric carbon dioxide correlation

Not only did they discover this relationship between carbon dioxide levels and temperature, they also discovered that up until now, even during the warmest periods between ice ages, carbon dioxide levels never exceeded three hundred parts per million.

Today carbon dioxide levels are more than four hundred parts per million, far above carbon dioxide levels ever registered since human beings evolved.This enormous rise has taken place in a very short time. Shorter ice cores from Antarctica and Greenland have shown that between 1000 AD and the mid-1800s carbon dioxide levels remained fairly constant at about two hundred ninety parts per million.

Rise of carbon dioxide since the Industrial Revolution

Since then carbon dioxide levels have been steadily rising in pace with the industrial revolution and accompanied by a steady rise in global temperatures.

Ice cores show that carbon dioxide levels now are greater than over the past six hundred fifty thousand years and that they have risen thirty percent over the last hundred and fifty years alone.
Therefore present day scientists agree that Global Warming is, with virtual certainty, due to human actions.

This doesn’t mean we know everything. There are still many questions to which the answer remains uncertain. For example Is Global Warming really bad?

Sources:

http://www.earthobservatory.nasa.gov/Features/GlobalWarming/
http://www.upi.com/Science_News/2012/01/19/NASA-Global-warming-trending-up/UPI-52121327015115/