What is climate change and what causes it? An introduction to the global crisis.
Introduction to Climate Change
One of the most talked about topics in this day and age is **climate change**. It truly is the crisis of our times. The **strange weather patterns, rising sea levels, ocean acidification, species extinction, and the melting of glaciers are all linked to global warming and climate change**.
Although we are not at the point of no return yet, **we’ve reached a point where the implications of climate change can no longer be ignored and serious actions are required**. Though humans are the main cause for climate change, we can also be part of the solution. This is why countries around the globe are holding hands to find solutions and remediation strategies to combat climate change. The world has recently shifted gears to look at alternative low carbon energy solutions to provide a ‘clean’ sustainable future. But will this be enough to save our planet? And will we be able to right the wrongs of fossil fuels that we, as humans, have been depending on for the past few hundred years? Let’s find out!
The Difference between Climate and the Weather
**Weather** and **climate** are sometimes wrongly used as interchangeable terms. So, let’s cut out the confusion and distinguish between them. Both weather and climate describe events taking place in our atmosphere. More specifically, these are events affecting the lowest layer of the atmosphere, called the troposphere.
The main differences between weather and climate basically come down to the measure of time. **Weather is a term that is used for a specific location on a small time scale**, being hours, days or even weeks, and it has a degree of variability. Think of weather forecasts, where the weather is sometimes predicted days or even weeks ahead of time and, as the time progresses, the forecast changes and gets more accurate. There are even forecasts for certain hours during the day and these can include the temperature prediction as well as whether it will rain, be windy, sunny, or cloudy.
**Climate, on the other hand, is the long-term average of these short-term weather patterns**. For example, the climate involves looking at the average rainfall or temperature per year or per decade.
Global Warming vs. Climate Change
If you believe that ‘global warming’ and ‘climate change’ are the same thing, think again. These terms are often used interchangeably, but they are really separate things. **Global warming is a term used to describe the increase in average global temperature over time. Climate change, on the other hand, describes how weather patterns will be affected around the globe, mostly due to this global average temperature increase.** These changes could be manifested as changes in climate averages as well as changes in extremes of temperatures, meaning hot days will get hotter and cold days will get even colder. The degree of these changes will vary from region to region.
Examples of climate changes include changes to the water cycle, ice cover on land and in the polar oceans, and extreme weather conditions. Climate change can also occur naturally as a result of changes in sunlight, the growth of mountains, and the movement of the continents across the earth over a long time interval.
The Natural Greenhouse Gas Effect
**The Earth’s climate depends on the functioning of a natural ‘greenhouse effect,’** which functions similar to a greenhouse, hence the name. Heat-trapping gasses like water vapor, carbon dioxide, ozone, methane, and nitrous oxide form a blanket-like layer over the earth and serve the same purpose as glass in a greenhouse; to trap heat.
As **incoming radiation from the sun is absorbed and re-emitted back from the Earth’s surface as infrared energy**, greenhouse gasses in the atmosphere prevent some of this heat from escaping into space, instead reflecting the energy back to further warm the Earth’s surface. Increasing or decreasing amounts of greenhouse gasses within the atmosphere act to either hold in or release more of the heat from the sun. Without this natural greenhouse effect, the average surface temperature of the Earth would be about 15-16°C colder. This means that the natural greenhouse gas effect is not only good, but necessary to sustain life on Earth.
However, **human activities have been releasing additional greenhouse gasses**, intensifying the natural greenhouse effect, thereby changing the Earth’s climate. This is where the problem comes in. Changing the climate can have some serious repercussions; not only for humans, but for every living thing on our planet.
Climate Forcings and Climate Change
The Earth’s temperature is determined by **a balance of energy entering and exiting the Earth’s atmosphere system**. When the Earth absorbs energy from the sun, an equal amount of energy must eventually be emitted back into space, according to the basic laws of thermodynamics.
Now, in the same way that a pushing force will cause an object to move, climate forcing factors, which are sometimes also called **climate drivers, will cause a change in the climate system**. If the forcings result in incoming energy being greater than the outcoming energy, the planet will warm. Conversely, if the outgoing energy is more than the incoming energy, the planet will cool.
Natural climate drivers include **changes in the sun’s energy output, changes in Earth’s orbit, and large volcanic eruptions** that put light-reflecting particles into the upper atmosphere. Human-caused climate drivers include **emissions of heat-trapping greenhouse gasses, and changes in land use** that cause land to reflect more or less sunlight energy. Since 1750, human-caused climate drivers have been increasing, and their effect has come to dominate all natural climate drivers.
Natural Contributors to Climate Change
Geological records indicate that **there have been slow changes in the Earth’s climate due to natural factors with astronomical, oceanic, and tectonic factors all contributing**. The **astronomical impacts** are caused by variations in the sun’s strength, meteorite impacts, and changes in the Earth’s orbit. The **oceanic impacts** are caused by ocean currents and oceanic carbon dioxide levels. Other factors like **plate tectonics, volcanic eruptions, changes in land cover, and the amount of greenhouse gasses in the atmosphere** also influence the Earth’s climate. The effects of each of these factors are complex, because a change in any one of these can lead to enhanced or reduced changes in the others.
For example, **oceans can remove carbon dioxide from the atmosphere**. However, when the carbon dioxide levels in the atmosphere increase, the temperature rises – less energy is able to escape back into space. This results in **warmer ocean temperatures, which leads to less carbon dioxide absorption** by the oceans because warm ocean waters are not as effective in carbon dioxide removal. This is due to decreasing solubility of gasses with increasing temperature. This means that cold ocean waters will take up more carbon dioxide and less will be escaping into the air.
Less carbon dioxide absorption by oceans means that there’s more atmospheric carbon dioxide, which, in turn, causes the temperature to rise again. And so the cycle continues.
**This is an example of a process called ‘feedback’ which is the Earth’s response to climate forcings**. Positive feedback accelerates temperature rise, whereas negative feedback slows it down. In short, if the temperature starts increasing or decreasing, it will increase or decrease by an even faster rate.
Human Influence on Climate: Carbon Dioxide and Fossil Fuels
The Earth’s climate is influenced by human activities, along with natural forcings. Individually, **neither natural forcings nor anthropogenic forcings can fully explain the warming experienced since 1850**. Scientists have found that the rate of climate change that we are experiencing today can only be explained by taking both these sources into account.
While natural forcings do have an impact on climate change, **experts have come to the conclusion that human activities have had the largest impact on the rate of climate change since the 1950s**, according to the Intergovernmental Panel on Climate Change’s (IPCC’s) report. Ever since the industrial revolution, the concentration of carbon dioxide in the atmosphere has been increasing due to clearing forests, burning fossil fuels, and the increase of various other greenhouse gas emissions. In fact, for the past 50 years, the concentration of carbon dioxide in the atmosphere has been the biggest source of global warming.
All this can be directly attributed to human industry, and, while we’ve progressed a lot as a species since the industrial revolution, that progress has clearly come at a cost to our environment.
Carbon-eating and Carbon-releasing Systems Explained
Within the Earth’s many climate systems and subsystems, **there are factors that directly and indirectly affect the overall stability of the global climate and our temperature**. Some climate systems and subsystems have **‘carbon-eating’ or ‘carbon-releasing’** qualities which have an influence on the global climate. Collectively, these systems are also sometimes referred to as heat-controlling systems.
**When a system has a carbon-eating quality, it means that it takes carbon out of the atmosphere**, which ultimately helps to reduce global warming to some extent. If something has a carbon-releasing quality, it means that carbon is released into the atmosphere, which causes an increase in global warming. All of these systems are interrelated and affect one another.
The Earth’s Heat-controlling Systems and Subsystems: Plants and Oceans
The Earth has many heat-controlling systems that are used to either reduce or increase the amount of carbon in the atmosphere. Some of these systems include plants or forests, ocean plankton and currents, ground soil, and volcanic eruptions.
**Plants help to balance the greenhouse effect because they consume carbon dioxide and give off oxygen**. All plants, from trees to plankton found in the sea, use the energy of sunlight, and through the process of **photosynthesis** they consume carbon dioxide found in the air. When it gets too warm, trees will take less carbon out of the air and, when trees die, their stored carbon is released back into the atmosphere.
**The ocean also absorbs about 27% of excess carbon dioxide in the air**. Unfortunately, the increased carbon dioxide in the ocean changes the water, making it more acidic – specifically carbonic acid. This is called ocean acidification. Also, when too much carbon is absorbed, the oceans begin the process of emitting carbon back into the atmosphere. This will cause temperatures to rise.
The Earth’s Heat-controlling Systems and Subsystems: Oceans and Volcanoes
**More acidic ocean water can be harmful to ocean creatures**, such as certain shellfish and coral. A study shows that more acidic waters make it difficult for plankton to absorb nutrients, rendering them vulnerable to disease and toxins. This means that the **acidity will eventually kill some, or all, of the carbon-eating and oxygen-producing plankton**. Warming oceans can also be harmful to these organisms and are the main reason behind coral bleaching, a phenomenon where stress causes coral to expel the algae which they need for food and survival. Stress from heating oceans can cause this to occur, and can eventually lead to the death of a coral reef.
Another factor that can cause a cooling effect, believe it or not, is volcanoes. More specifically, **the eruptions of supervolcanoes can cool the earth**. Although volcanoes are known to release greenhouse gasses like methane and carbon dioxide into the air during eruptions, one of their less-talked about effects on climate is actually a cooling effect caused by particles, or ash, released into the air. The volcanic ash and droplets of sulfuric acid raises the Earth’s albedo, which can be defined as the proportion of light reflected from the Earth’s surface. This increases the reflection of solar radiation, after a large, particularly explosive volcanic eruption. Such an eruption could actually cool the planet and can lead to what’s known as a volcanic winter. This can lead to air temperature declines of up to 10°C in the first year after the eruption, and 3-5°C for up to 10 years after the eruption.
