Every October 24, the International Day Against Climate Change is commemorated around the world, a celebration established by the United Nations to raise awareness about its devastating consequences, some of which are already clearly perceptible throughout the planet.

What is climate change?

The answer is very simple. It consists of a change in the pattern of the Earth’s climate due to a gradual, generalized and persistent rise in the temperature of the layer of the atmosphere that is in direct contact with the Earth’s crust and that generates melting of the ice and rising sea levels, between other phenomena.

What causes climate change?

There are lots of things that affect climate change.

The climate on Earth has been changing since it formed 4.5 billion years ago. Until recently, natural factors have been the cause of these changes. Natural influences on the climate include volcanic eruptions, changes in the orbit of the Earth and shifts in the Earth’s crust (known as plate tectonics).

However, the changes that we are currently seeing are happening at a scale and speed that natural cycles cannot explain. Human activity, such as burning fossil fuels, is currently the main driver of climate change.

Are humans responsible for climate change?

When looking at all the evidence, there is a large scientific consensus that humans are the leading cause of climate change. In their latest report, the Intergovernmental Panel on Climate Change (IPPC) stated with over 95% certainty that human activity is the main cause of climate change.

What are greenhouse gases?

Greenhouse gases are gases that trap heat in the atmosphere, acting as a blanket around the Earth which stops the heat escaping into space.

Some greenhouse gases such as carbon dioxide, methane and nitrous oxide come from both human and natural sources. Others, such as fluorinated gases, are only produced by human activity.

Which human activities release greenhouse gases?

The following greenhouse gases are emitted during common human activities:

• Carbon dioxide (CO2). Carbon dioxide enters the atmosphere through burning fossil fuels (coal, natural gas and oil), solid waste, trees and other biological materials. Carbon dioxide is removed from the atmosphere when it is absorbed by plants.
• Methane (CH4). Methane is emitted during the production and transport of fossil fuels. Methane emissions also result from livestock and other agricultural practices.
• Nitrous oxide (N2O). Nitrous oxide is emitted during agricultural and industrial activities, combustion of fossil fuels and solid waste, as well as during treatment of wastewater.
• Fluorinated gases. Fluorinated gases are emitted from a variety of industrial processes, including the production of primary aluminium.

What is the greenhouse effect?

The greenhouse effect is the process by which the greenhouse gases present in the Earth’s atmosphere trap the Sun’s heat. This process makes the Earth much warmer than it would be without the greenhouse effect.

The greenhouse effect is critical to our survival. In fact, without greenhouse gases and the correspondent greenhouse effect, the Earth would be about 30 degrees colder than it is today. Without greenhouse gases and their warming effect, we wouldn’t be able to survive.

However, since the Industrial Revolution and the massive burning of fossil fuels, we’ve been adding more and more greenhouse gases into the air, trapping even more heat. Instead of keeping the Earth at a warm, stable temperature, the greenhouse effect is heating the planet at a much faster rate. This is the main cause of climate change.

How much has the Earth’s temperature increased?

If the global average temperature of the times before large-scale industrial development is compared with the current one, it is found that, after just over 250 years, it has increased by more than 1ºC, a figure that might seem ridiculous, but the fact is that, without anthropogenic action, this degree would take millennia to increase naturally.

How much can the temperature rise before it is too late?

The Intergovernmental Panel on Climate Change (IPCC) recommended that the global temperature should not rise more than 1.5ºC. In the Paris Agreement it was agreed to keep the increase of temperature below 2ºC.

What is the future of our planet?

The sum of the various zonal climate changes, which have become extreme and forceful, have already made up a great comprehensive climate change that affects the entire planet and its impact is known as the “climate crisis”. This not only harms humans, but also wreaks havoc on plants and animals, causing irreversible damage to biodiversity and local and global ecosystems.

What worries most is the future of our planet and that of the generations to come. If the thresholds set in the Paris Agreement are exceeded, scientists warn that there could be a disproportionate increase in extreme weather events. This limit is known as the “tipping point” and once it is reached, the natural terrestrial feedback systems would increase the intra-atmospheric heat more rapidly, turning the planet into the “Greenhouse Earth”.

The year 2020 is a landmark for climate change and its mitigation, especially with the unexpected impact of the novel coronavirus disease (COVID-19) pandemic and the subsequent lockdowns and economic downturn across the world. This is happening when the world is witnessing some of its worst storms, heat waves, ice melting and wildfires, making the twin challenges of climate change and COVID-19 one of the worst periods in human history of the last hundred years.

Even so, many countries are stepping up their commitments to minimise their greenhouse gas emissions in accordance with the Paris Agreement and some are even going beyond to achieve the goal of limiting global warming to well under 1.5 degree Celsius by 2050 through green new deals.

Many countries are also trying to integrate climate change mitigation into their post-pandemic economic recovery strategies.

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