Much has been said about climate changes and global warming. While some groups strictly advocate that global warming is a fact and is caused by human activities, others claim that this theory is nothing but a hoax and that, although there are obvious signs of climate change, these are just consequences of natural factors and not caused by mankind, as for example, a higher solar activity.
Despite being in favour of the theory that global warming is a fact and that despite natural and cyclical factors, the pollution caused by us has accelerated the process, I will try to be as unbiased as possible presenting and commenting on some facts.
Average temperature increase:
Although there are some oscillations, it is unquestionable that the planet’s average temperature has been rising in recent decades, especially in the oceans. But who does not forget the 2003 heat wave? According to some experts, it is quite possible that we will have more identical heat waves, or worse, with closer intervals in the coming decades. Studies indicate that the average temperature has risen 0.8°C since the early 20th century, but about two-thirds of the increase occurred after 1980. However, in the last decade it seems is slowing down, as shown in the following graph:
Increasing of the emission of greenhouse gases:
Another variable to take into account is the increase in the so-called “greenhouse effect” that helps to retain the heat on the surface of our planet. On one hand, the greenhouse is required to keep the sun’s heat, otherwise, temperatures on Earth would be much lower. One of greenhouse gases is carbon dioxide (CO2). CO2 is present in the atmosphere and plays an important rule in the process of photosynthesis in plants. During the day, plants absorb CO2 releasing the oxygen we breathe. In turn, humans and land animals breathe oxygen and release CO2 on exhalation. The plants themselves, overnight, reverse the photo-synthetic process absorbing oxygen and releasing carbon dioxide. Other natural processes produce CO2 such as volcanoes, hot springs and geysers.
Millions of years ago, plants and organisms that died gave place to fossil fuels such as coal, oil and natural gas, both rich in carbon dioxide. Nowadays, these fossil fuels are being used by human activities in a large-scale. Since the industrial explosion, these materials have come to be increasingly used to generate energy through their combustion, which causes a large emission of CO2 to the atmosphere. The increase of vehicles powered by fossil fuel combustion (cars, ships, planes, …) has also contributed to a large increase of CO2 emissions and to an increase of the thickness of the layer of greenhouse gases and hence to an increase in global temperature. Other factors that contribute to the increase in CO2 are the use of fertilizers and deforestation, both from human activities. This reality has been advocated by the IPCC (International Panel on Climate Change). The following graph shows the evolution of the concentration of CO2 in the atmosphere in recent decades:
The graph shows that currently, the concentration of CO2 in the atmosphere has reached the value of 380 ppm (parts per million), which for many scientists is a worrying value, especially for those who argue that human activities are having an active role in global warming.
Climate change cycles:
On the other hand, we know from studies that these changes are cyclical and occur in periods of thousands of years, with increases in the levels of CO2 and subsequently decreases. The same happens with the average surface air temperature. Some studies even indicate that by the time of the dinosaurs the global temperature on Earth was warmer than in our present days.
But have we ever found records of carbon dioxide levels such as those we are registering nowadays? In order to get data of the concentration levels of CO2 in thousands of years ago, scientists analyze multiple layers of ice or even rocks. The following graph shows the changes in CO2 over the last 650,000 years:
According to this chart from NASA in the last 650,000 years the CO2 levels have never been above 300 ppm until the present day! Since 1950 this value was exceeded and is now close to 400 ppm.
If we cross this data with the increased pollution, generated by us, we can easily conclude that the identical increase of these variables is enough to not consider them as a mere coincidence. I think it is obvious that there is a link between increased pollution and CO2 emissions, caused by human activities, and the new records of CO2 concentration in the atmosphere.
The more skeptical about global warming, claim that the records of high temperatures in recent years are related to an increase in solar activity. Many also add that the high concentration of CO2 in the atmosphere is a result of the increase of temperature and not the contrary.
In fact, the solar activities have also shown cyclical. One of the variables that impact in the ionosphere, one of the layers of our atmosphere, is the presence of sunspots on the Sun. These are regions of the Sun where temperature and pressure of the gaseous mass reductions occur, but causing large magnetic activities, influencing our ionosphere.
However, it seems to me that there is some consensus that these magnetic activities, which affect radio and satellite communications, contribute little or nothing to global warming.
Besides, the recorded data on the solar activity in recent years, contradicts the idea that this activity is responsible for global warming. The following chart can shows us that:
Notice that, until 1950 there seems to be some relationship between temperature and sunspots. However, after a peak observed around 1960, the number of sunspots has been decreasing, especially since the mid-80s. However, two other lines continue to rise: The temperature and the concentration of CO2!
Other solar variables such as solar radiation, have been observed. However, the IPCC considers that, although we still know very little about solar variations and their impact on our climate, the records of the amplitudes of the variations of solar radiation are not significant compared to the increase in CO2 levels.
But, in my opinion, it is also true that we do not have sufficient data to get strong conclusions. Although there are signs that the temperature is increasing together with CO2 levels, we do not know if the slowdown in the temperature rise, observed in the last decade, is a possible sign of some stabilization. As we shall see later, in another topic, several climate models point to an increase in air temperature in the coming decades, but with different variations.
Many try to oppose these questions by stating that there are a hoax and by stating that there is no scientific evidence of the link between CO2 emissions by human activities and the increase of the greenhouse effect, thus leading to global warming.
But if we came to the conclusion that in fact there is a link between CO2 emissions, caused by human activities, and that is contributing to this increase in temperature, which could condemn the planet to disastrous consequences, it is also true that there will always be lobbies willing to stifle such truth.Truth or a hoax? I think in a few years we will have a more concrete answer. But if confirmed to be truth, it might be too late to correct our actions…
Keep reading more about this subject in: “Global Warming II: The polar ice caps and the seas“.