Global Warming vs. Greenhouse Effect

Global warming and greenhouse effect are concepts you’ve certainly heard time and time again on the news, on newspapers or even during a coffee klatch.

Nevertheless, it is quite common to get these terms mixed up.

What is Greenhouse Effect?

Greenhouse effect is an absolutely necessary phenomenon for life on Earth as we know it. Hard to believe?

The concept is similar to what happens inside a greenhouse: the glass walls allows for sunlight to come in and warm up the ground; the ground in turn will emits heat that warms up the air and the surroundings inside the greenhouse. However, the very same glass that allows sunlight in, acts like a barrier blocking the heat from escaping.

Atmospheric Greenhouse Effect

In planets, like Earth, occurs the phenomenon called atmospheric greenhouse effect. The radiation coming from the Sun, be it visible, ultraviolet or infrared, penetrates the layers of gases that surround the Earth – that is, the atmosphere. The surface of the Earth then absorbs this radiation and emits thermal radiation (or heat) in return. It’s this heat that keeps the planet at a nice and warm temperature for its inhabitants.

Did you know?

Without the greenhouse effect, a process that occurs naturally, the average temperature of the Earth would be around -18ºC.

Greenhouse gases

How is it that this heat doesn’t escape back to space? This is the role of the so-called greenhouse gases: retaining atmospheric heat.

The greenhouse gases that prevent the heat from leaving the Earth’s atmosphere are carbon dioxide, methane, water vapour and nitrous oxide. They are naturally a part of our planet’s atmosphere.

When does greenhouse effect become harmful?

In reality, atmospheric the greenhouse effect in itself isn’t bad for the Earth – it is rather essential to the existence of life. The real problem starts when this greenhouse effect is much larger than it should be, and there is increasingly more heat being retained in the atmosphere by those gases.

This happens because there are larger emissions of greenhouse gases into the atmosphere caused by man-made activities such as burning of fossil fuels, use of fertilisers with nitrous oxide, and changes in land use like deforestation with the purpose of farming.

Deforestation is one of the causes of the greenhouse effect.

Deforestation is one of the greenhouse effect causes.

Global warming kicks in

By emitting more greenhouse gases, more heat is retained in the atmosphere and so the average temperature of the Earth increases.
As such, the increase in the average temperature of the oceans and atmosphere that has been happening since the mid-1800s, around the start of the Second Industrial Revolution, is what we call Global Warming.

And it only gets worse

But what are the effects of global warming? At first glance, it is straightforward to think about the retreat of glaciers and the rise of the sea level. However, and very unfortunately, these are not the only consequences. Global warming may negatively affect climate and the seasons of the year directly, dictate the disappearing of some species, affect food production and harm human health – to name a few.

Heavy rainfalls are one of the consequences of global warming.

Global warming can cause heavy rainfalls.

Always hot?

It is important to stress that it does not mean that one of the consequences of global warming is necessarily the weather being always hot. This is one of the most popular myths around this topic but in reality, global warming might lead to climate changes that aren’t always related to heat waves. It can cause heavy rainfalls, storms, floods, droughts, hurricanes and even cyclones, among others.

It all started almost two centuries ago…

Man-made greenhouse gases have caused the average global temperature to increase steeply over the last 100 to 150 years.

To help flatten this growth curve, scientists stress the importance of limiting the increase of temperature to 1,5ºC in relation to the pre-indutrial values. This means it is imperative to rethink the way societies are structured and organised, to transform activity sectors such as energy, agriculture or infrastructures, and to approach specific objectives with solemnity like the net-zero emission goal, defined at the Paris Agreement.

Emissions in times of pandemic

The new coronavirus pandemic alone was enough to dramatically reduce the air contamination levels quite everywhere, as a result of closed factories, less cars on the roads and more people in quarantine. In cities like Lisbon or Madrid, the concentration of pollutants in the air dropped 80% in some areas, in the short period between the 10th and the 28th of March 2020, according to the Earth Observation Laboratoty in the Atlantic International Research Centre (AIR Centre).

We know that the fear and survival instinct is stopping the economies, which also means less CO2 emissions around the world. But will everything go back to the way it was when the factories start up again, cars start moving again, and people can go back to work, go out and hug each other?