32 years have passed since the declaration on the United Nations Framework Convention on Climate Change, that each 26th of March, Global Climate Day would be held. A day to raise awareness about the importance and influence of climate in our lives and on ecosystems. On the other hand, the 24th of October was designed to be the International Day against Climate Change. Three decades have passed since the Convention, commonly known as “Rio 92” [1].

Are we more conscious than then? At which point are we now?

For starters, it is important to remember what climate is. The climate is usually defined as the set of meteorological and atmospheric conditions in a geographically limited zone during a prolonged amount of time. The time detail is important because punctual meteorological and atmospheric conditions are called weather. These conditions are usually referent to wind, precipitation, humidity, atmospheric pressure, and temperature. Temporal trends of these parameters are what make climate up in the different regions of the planet, and many factors may influence them. Among them, are greenhouse gasses (GHGs).

Over the last 30 years, we have seen how emissions affect climate. The most common reference used is the pre-industrial level of GHGs, which refers to the Earth’s situation before the Industrial Revolution (XIX century). In 1990, the International Panel for Climate Change (IPCC) published for the first time an evaluation report affirming that the increment of atmospheric temperature was about +0.3-0.6ºC compared to pre-industrial levels [2]. According to the World Meteorological Organization, last year 2023, the increment spread to +1.45ºC, and a greater increment is expected for this year [3].

It is worth reminding ourselves that, the Paris Agreement of 2015 aimed to limit the increase of global temperatures to +1.5ºC over the pre-industrial era, and an increment of +2ºC was established as the further red line, which must not be trespassed under any circumstances. However according to the last data, the red color seems to be shifting towards orange, and the no-trespassing limit is becoming less clear in some debates [3].

Another indicator of climate change is the ocean water temperature. As atmospheric temperature graphs rise, so do the ones for surface water temperature in the oceans. Water masses are incredibly important when talking about regulating atmospheric temperature and climate regulation. We are all familiar with the feeling of relief we get in summer when we get close to the river, lake or seashore. When compared to the pre-industrial era, we can observe that, although, in less capacity, there has been an increment as well in ocean surface temperature, about +0.65ºC [4]. The increase in oceanic temperature goes hand in hand with a key problem: acidification.

An important balance regulates the amount of CO2 dissolved in water: it is between CO2, which is an acidifier, and HCO3- and salts that basify the water [5]. The key relationship with temperature happens because, as the temperature increases on the water surface, the CO2 absorption is easier.

In the case of oceanic water, the pre-industrial era pH value was 8.2 on average. The current average is now 8.1 [6]. It may not seem that much, but pH is a logarithmic scale – implying that the increase of one unit on the scale translates to a decrease of ten times the amount of protons in the water – and there are many organisms extremely sensitive to pH changes. Among those organisms, coral reefs, which, due to their biodiversity and importance to the marine ecosystem are often said to be comparable to the Amazon Forest in terrestrial ecosystems.

Temperature increases and salinity alterations also affect the oceanic currents. The Atlantic Meridional Overturning Current (AMOC) is a system that regulates climate [7]. The base of the AMOC current system is the movement of water masses due to their temperature and density.  Water close to the Equator is warmer and this weighs less and moves towards higher latitudes on the sea surface. As the water gets close to the poles, it gets colder and denser, which makes it sink to the bottom, where it returns to the tropics. Besides temperature, water currents circulate both nutrients and waste.

What happens with a temperature increase? Poles are melting. More cold water would not mean a huge change in currents per se, but ice is not saline water. Freshwater has less density than saline water, and that means less sinking capability. According to recent studies, the equilibrium that keeps the Atlantic climate – and thus, the surrounding continents – would be losing its balance.

What about the consequences? The “conveyor belts” of nutrients inside this global oceanic system would be disrupted, causing sudden and unexpected changes in precipitation patterns, temperature changes and other climate events [8]. For example, in the North of Europe, by losing the Gulf’s warm current, we could be talking about entering a glacial period.

Climate changes at these levels could arrive in 50 or 100 years if measures are not taken. That is why today we have to claim the importance of climate and its equilibrium, as well as the need to protect it, or better, not to destroy it.

We are already experimenting with what heat waves are, extreme precipitations and floodings, droughts and uncontrolled fires. We need to implement mitigation and adaptation measures for climate change, measures for reducing emissions, research and innovation for green technologies, circular economy, and above all, measures promoting degrowth in both production and consumerism. Climate change is one of this century’s most urgent problems, and we will have to deal with it without the usual half-measures.  As a society, we must reckon the importance of acting now to protect our planet’s climate and ensure a livable future for us and the rest of the inhabitants of the Earth community. 

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Cover and preview image:  “There is no planet B” banner on a demonstration in San Francisco (2019, 17 March). Photo by Li-An Lim on Unsplash.