Sunday, 23rd September 2018

Climate change

If climate is changing, why was it so cold this winter?

Too often we mistake climate for weather and weather for climate. Following a basic definition of weather, weather is a state of the atmosphere at one particular place and one particular time as regards heat, cloudiness, dryness, sunshine, wind, rain, etc. This is different from climate, which is defined as the weather conditions prevailing in an area in general or over a long period.

How does the atmosphere protect and warm us up?

The reason why we humans exist on Earth is thanks to the gas (called Greenhouse gas) of the Atmosphere that warms up our days and nights. For example, on the Moon there is no atmosphere and the temperature can be freezing cold, far below 0 degrees Celsius. On the other hand, this layer should not be too thick. On Venus, the Atmosphere is so thick that life is impossible because of extreme temperatures well over 200 degrees Celsius.
Life on Earth is possible thanks to this balanced mix of gas in the atmosphere. However, since the recent Industrial Revolution, we have modified the composition of the Atmosphere by increasing the concentration of carbon dioxide (CO2) by at least 35%.

Do you have proves of this change?

Precise meteorological science is a relatively recent human activity. Despite of this, we nowadays have accurate figures and information since 1850. According to these data, in 2007, the Intergovernmental Panel on Climate Change (IPCC) took three parameters into consideration: global average surface temperature, sea level and snow cover in the Northern Hemisphere, in order to clearly expose the global modifications related to climate change.

The basic trends found were: The average global temperature and sea level have risen while snow cover has decreased. These simple elements shown in the following graph give us real evidence of the change happening on Earth since 1850.

Is it not just a natural process?

It is not the first time in the history of the Earth that climate changes. Consequently, we can wonder whether this change is natural or not. Then we need to look at the increase in our (human) emissions during the last century.

In 1970 we emitted 29 Gt (1 Gigatonne equals 1 000 billion kilos) of greenhouse gases; in 2004, 34 years later, we increased our emissions by 140% and 49Gt were released in the atmosphere.

In consequence, the concentration of CO2 in the atmosphere has also followed the same trend. Following the measure made in Mauna Loa (Hawaii), in 1960 the concentration of carbon dioxide was about 320ppm (parts per million – it means that in one million molecules in the atmosphere, 320 of them are molecules of CO2); in 2010, the concentration was about 390ppm. The concentration of carbon dioxide in the atmosphere has risen by up to 20% from 1960 to present.

What should we expect for the next years?

Once we know the situation, we have to understand what is going to happen in the next years and the next century. The IPCC has made simulations on different scenarios. These scenarios show that even if we totally stop emitting greenhouse gases today, the global temperature is going to increase by at least 1 degree Celsius.

However, in 2009, the International Energy Agency released its annual review, which focused on climate change. In this review, they acknowledge that if we keep on emitting greenhouse gas on our current trend, the global temperature would rise by up to 6 degrees Celsius. Further on, they explain that this would lead almost certainly to massive climatic change and irreparable damage for the planet.

What will the consequences be? Was 2010 a “normal” year?

If the climate gets warmer, climate change could be really nice and comfortable, and especially in cold countries like Norway. But the change has (one more time) to be considered globally. In 2007, the German reinsurer Munich Re released a report on the cost and number of natural catastrophes they have had to insure since 1950.
The following graph explicitly shows the evidence. The number of geophysical events remained steady during the period, but the number of climate related events (meteorological, water and climatological) has increased by at least 270%!

The year 2010 is probably the worst year considering climate related events so far. With the exceptional heat waves in Russia and the massive floods in Pakistan, we have certainly experienced a bitter foretaste of this 21st century.