Why is climate change such a concern? What has caused it and what are the risks? The causes of the greenhouse effect that is the result of human activity and the commitments made to invert the trend.
Life on Earth exists thanks to a combination of three factors: our distance from the Sun, the existence of an atmosphere and the presence of the water cycle. Around 4 billion years ago, the energy from the Sun began the phenomenon that we call the greenhouse effect: loaded with energy, the Sun’s rays cross the atmosphere (an external layer of mixed gases spanning around 300 kilometers); they are partly absorbed by the land and the sea, and partly bounce back to be captured by gases (including carbon dioxide, methane and water vapor) that retain the heat from the Sun. Without the natural greenhouse effect, the average temperature on the planet would be around -15°C rather than its actual level of approximately 18°C.
The causes of climate change
If the greenhouse effect is such an advantageous phenomenon, why are we so concerned about it today? What is the significance of global warming? And what is meant by climate change?
Climate change has always existed over the course of our planet’s history. But the global warming that we have been seeing for around the last 150 years is anomalous because it is the result of human activity. It’s called the anthropogenic greenhouse effect and occurs in addition to the natural greenhouse effect. With the industrial revolution, man suddenly began pumping millions of metric tons of carbon dioxide and other greenhouse gases into the atmosphere, doubling the quantity of CO2 present in the atmosphere compared with the minimum levels of the last 700 thousand years (410-415 parts per million compared with 200-180 parts per million). This can be observed on a daily basis thanks to surveys by observatories such as the one active in Mauna Loa, in the Hawaii archipelago. For around 15 years, the data produced by thousands of scientists all over the world, analyzed and organized by the Intergovernmental Panel on Climate Change (IPCC), has confirmed that 97% of global warming derives from the anthropogenic greenhouse effect, i.e., it is caused by human activity. In reality, the scientific basis for the connection between the levels of carbon dioxide and rises in temperature was established back in the last century, thanks to the work of Nobel Prize winner Svante Arrhenius, later confirmed by American scientist David Keeling in the 1960s.
The consequences of climate change
With respect to pre-industrial levels, the average temperature of the Planet has risen by 0.98°C, and the trend that has been observed since 2000 would suggest that, unless action is taken, it could reach +1.5°C between 2030 and 2050.. The impact of global warming is already evident: arctic sea ice has been shrinking by 12.85% each decade, while coastal tide logs show that sea levels have been rising each year by 3.3mm since 1870. The last decade was the hottest ever recorded and 2019 was the second hottest year ever, only just behind the record year of 2016. The “fire seasons” have become longer and more intense, like the one in Australia in 2019; since 1990 the frequency of extreme weather events, such as cyclones and floods, has also increased, occurring even at atypical moments of the year compared with the past and at devastating levels of intensity. Phenomena such as El Niño have become more irregular and have caused dangerous droughts in areas already threatened by chronic aridity, like East Africa, while the Gulf Stream is slowing down and could well change route. Plant and animal species are migrating in unpredictable ways from one ecosystem to another, creating incalculable damage to biodiversity around the world.
Defining all this with the term climate change is accurate but does not give the full picture of what is happening. We must begin by talking about the climate crisis because the climate has always been changing, but never so quickly and never in the presence of such rigid and complex infrastructure as can be found in the cities and production systems of industrialized countries.
The solutions to climate change
Human activities, such as burning fossil fuels and destroying rainforests, have an increasing influence on the climate and the Earth’s temperature. This adds huge quantities of greenhouse gases to those naturally present in the atmosphere, increasing the greenhouse effect and global warming. Causing the most damage is, above all, the consumption of coal, oil and gas, which represent the majority of greenhouse gas emissions. According to McKinsey’s Global Energy Perspective 2019, fossil fuels are responsible for 83% of total CO2 emissions and the production of electricity from coal-fired power stations alone contributes 36%. It is estimated that the current trend of CO2 emissions due to burning coal is responsible for around a third of the increase of 1°C in average annual temperatures above pre-industrial levels, making it the largest source of emissions in all of human history. Outside of the production of electricity, oil is the second largest source of emissions, producing 11,446 million metric tons of CO2 in 2018 (78% of the quantity produced from coal, which was 14,664 million metric tons).
The destruction of forests also causes substantial damage: trees help regulate the climate by absorbing carbon dioxide from the atmosphere, so if they are destroyed, this beneficial effect is diminished and the carbon stored in those trees is emitted into the atmosphere, adding to the greenhouse effect.
Finally, the increase in intensive animal farming and the use of fertilizers containing ozone contribute to increasing emissions of greenhouse gases.
How to remedy the situation? At the United Nations Framework Convention on Climate Change (UNFCC) conference (COP 21) in December 2015, international representatives adopted the Paris Agreement, which provides a credible framework for achieving decarbonization, with long-term goals to tackle climate change and a flexible structure based on contributions from individual governments. The signatory nations committed to limiting the increase in temperature to below 2° centigrade compared with preindustrial levels, with efforts to contain this to within 1.5°, with the ultimate goal of passing peak emissions as soon as possible and achieving carbon neutrality in the second half of the century. In spite of the success of COP 21, many questions concerning the Agreement have remained unresolved. Although the implementation guidelines of the Paris Agreement (the so-called Paris Rulebook) were approved at COP 24 in Katowice, Poland, in 2018, COP 25, held in Spain in 2019, was described by UN Secretary General António Guterres as a missed opportunity.
The road ahead towards decarbonization is clear and is known as the energy transition: the shift from an energy mix based on fossil fuels to one with zero carbon emissions and based on renewable energy sources. The technologies for decarbonization already exist, are efficient and should be implemented at all levels. Science offers clear data, projections and carefully studied future scenarios. Climate change waits for no one and will not stop on its own. What is required is a substantial cultural change, a true paradigm-shift. There is already widespread agreement on what needs to be done: it now needs to be turned into reality.