What are GHG emissions and why companies need to act now

"It’s now or never if we want to limit global warming to 1.5°C." This was the clearest and strongest message so far by Jim Skea, co-chair of Working Group III of the Intergovernmental Panel on Climate Change and one of the most renowned UN scientists, in an appeal urging government and business leaders around the world to take climate action immediately. The most recent UN climate report, known as the Sixth Assessment Report of the IPCC, comes with a crystal-clear warning: “without immediate and deep emission reductions across all sectors, it will be impossible” to combat climate change.

But there is some good news: the IPCC from 2022 shows that keeping global temperature rise under 1.5°C by the end of the century is still possible, but it will require rapid, immediate, and economy-wide greenhouse gas (GHG) emission reductions, as well as the removal of carbon from the atmosphere. But why is it crucial to reduce GHG emissions?

It is not too late to act: limiting global warming under 1.5°C is just possible. But it requires immediately concrete climate action.

You may have heard that increasing global warming is causing climate change which is responsible for extreme weather events such as longer and more frequent droughts, heat waves, heavy downpours, tornadoes, tropical cyclones, and floods. This climate change poses challenges for governments, businesses, and people around the world.

For better understanding, we first need to define different terms that are used in this article: "weather" and "climate." According to NASA, the weather describes "atmospheric conditions that occur locally over short periods from minutes to days" such as rain, snow, clouds, winds, floods, or thunderstorms. While the term climate refers to "the long-term regional or even the global average of temperature, humidity and rainfall patterns over seasons, years or decades." So, to combat climate change the answer is clear: we need to limit anthropogenic, human-caused, global warming to 1.5 °C.

To understand why it is unequivocal to drastically reduce and cut down those emissions, we need to shed light on the characteristics of the major GHG emissions caused by human activities and their impact on climate change.

There are two distinct elements between the different types of GHGs: Firstly, their ability to absorb energy, which is called radiative efficiency. Secondly, their lifetime, which means how long they stay in the atmosphere. A scientific metric, called the Global Warming Potential (GWP), was developed to determine these key factors.

GWPs are values that allow direct comparison of the impact of different GHGs on Earth’s warming by comparing their ability to absorb the energy and how long they remain in the atmosphere compared to CO₂. Carbon dioxide is taken as the gas of reference and given a 100-year GWP of 1 because it has a very long residence time in the atmosphere that can last thousands of years.

A report from the World Meteorological Organization predicted that the world could reach 1.5°C above pre-industrial levels by 2025, in only the next four years. Going beyond that red line means significantly increasing the impact of climate change, like extreme weather conditions and rising sea levels, just to name a few examples. "Every fraction of additional warming beyond 1.5°C will result in increasingly severe and expensive impacts," as the UN Environment Program stated.

The answer is clear: To limit global warming to 1.5 degrees Celsius compared to pre-industrial levels, it is abundantly obvious that we need to drastically reduce greenhouse gas emissions by at least 43% by 2030 below 1990 levels and reach net zero emissions by 2050, as enshrined by the Paris Agreement.