This is Why it Gets Warmer (Climate Changes)

This is why it gets warmer

The main reason for the warming of the Earth’s climate is the change in the chemical composition of the air that man causes through the emission of greenhouse gases, mainly carbon dioxide. Greenhouse gases enhance the atmosphere’s ability to heat the earth’s surface; the so-called greenhouse effect becomes stronger.

Carbon dioxide emissions through the combustion of fossil fuels worldwide are the main cause of the current climate change. Land use, mainly forest logging, also contributes. Global carbon dioxide emissions have increased gradually, and today amount to approximately 35 billion tonnes per year. The carbon dioxide content of the air has increased by about 50 percent since pre-industrial times, and it continues to rise by about 0.4 percent per year. Other greenhouse gases such as nitrous oxide (nitrous oxide) have increased by about 20 percent, and methane content by about 150 percent.

Natural factors

The climate on earth is affected by natural phenomena such as volcanic eruptions, it is affected by the sun’s activity and by changes in the earth’s movements around the sun and around its own axis. That the temperature began to rise during the first decades of the 20th century may have been partly due to increasing solar activity and decreasing volcanism. In recent decades, however, solar activity has been relatively low, while volcanism has increased. Both of these changes have a cooling effect. Nevertheless, warming has continued, a warming that can only be explained by human impact through greenhouse gas emissions and changed land use.

Greenhouse gas emissions

In addition to carbon dioxide, we release several other greenhouse gases. These include primarily methane and nitrous oxide, but also a number of fluorinated gases, including chlorofluorocarbons (also called CFCs or freons). All of these substances are emitted in far smaller quantities than carbon dioxide, but since they are considerably more efficient as greenhouse gases calculated per tonne, they still make significant contributions to the greenhouse effect. Read more on the page “Other greenhouse gases”.

Particles hide heating

The amplification of the greenhouse effect that we humans have achieved explains the ongoing warming. In fact, greenhouse gas emissions could have raised the temperature even more than what has happened so far. But humans also release pollutants that form particles in the atmosphere, and most such particles have a cooling effect on the climate. In this way, they hide some of the warming effect of greenhouse gases.

Continued temperature rise to wait

In the industrialized countries, particle emissions were particularly high during the decades leading up to the Second World War. This should be an important explanation for why the warming of the Northern Hemisphere temporarily slowed down during the period 1945–1975.

In the southern hemisphere, particle emissions have been smaller, and the temperature has risen at an even rate. In recent years, particle emissions from industrialized countries have decreased, and the warming effect of greenhouse gases has therefore been able to break through with increased force even in the Northern Hemisphere.