Is There Evidence That Humans are Causing Climate Change?

A decades-old debate has requested proof of climate change along with any evidence that humans have caused climate change in the first place.

In some circles, this is a very touchy topic that spurs hours of heated discussions.

Scientists have reported that the current global warming trends we see originally began during the mid-20th century and were caused by a human expansion and propagation of the “greenhouse effect.”

As we all know, this is the warming that occurs whenever the Earth’s atmosphere traps the heat coming from the Earth as it travels toward space. And there is lots of proof that global warming is indeed taking place.


Global warming mechanics

Within the atmosphere, certain gases block the heat trying to escape from Earth. Scientists considered such gases long-living as they remain within the atmosphere semi-permanently and never respond chemically or physically to temperature changes and wind up forcing climate change on the planet.

There has been ample research over the years that have appeared in many peer-reviewed scientific journals. As of this writing, some 97% of climate scientists that have published them agree that human activities have likely caused global warming. This implies evidence that climate change is manmade.

evidence of climate change


Rapid and extensive changes in warming

Historical data has long indicated that the climate on Earth has changed dramatically throughout its long history. In fact, within the past 650,000 years, data has revealed that there have been seven cycles of glacial movement, with the last ice age taking place some 11,700 years ago.

The end of this last ice age marks the start of the modern climate era, which includes the birth of human civilization. These climate changes have been mainly attributed to tiny variations within the orbit of Earth. Even small orbital changes can significantly alter the amount of heat and energy received from the sun.

However, the warming that has been witnessed across the past few decades has become way too rapid to be categorized as regular changes of the Earth’s orbit and way too large to be caused by the sun itself.


Scientific proof of climate change

Scientists can now observe the big picture thanks to technology and today’s satellites that roam Earth’s atmosphere. Furthermore, they’ve collected an assortment of data and information about our Earth and its climate on a very expansive global scale.

Through this body of data that has been collected for many years, signs of a changing climate are taking place. Science has long known about the heat-trapping properties of carbon dioxide and other gases – this was demonstrated initially during the mid-19th century.

These gases’ ability to affect the movement of infrared energy within Earth’s atmosphere is so inherent that NASA’s own space flying instruments account for their effect. Therefore, there are no doubts about whether greenhouse gases cause the Earth to get warmer in their presence.

This was proven from various ice cores drawn from Antarctica, Greenland, and other tropical mountain glaciers. These samples revealed that the climate on Earth responds to changes in levels of greenhouse gases.

In addition to this, evidence of climate change is also apparent within coral reefs, tree rings, ocean sediments, and even layers of sedimentary rocks. It has also been discovered that today’s global warming is around ten fasters than the historical rate of ice age recovery warming.

The only explanation is attributed to human causes of climate change because of the rapid increase of carbon dioxide.

human causes of climate change


Specific evidence of rapid climate change sources

During the last century, there has been a rapid increase in fossil fuel burning. This is primarily due to the consumption of oil and coal, which have significantly increased carbon dioxide (CO2) concentrations in the atmosphere.

During these burning processes, carbon combines with carbon in the air to create CO2 molecules. This is pretty strong evidence that humans cause climate change because these fuels were consumed by activities that humans created.

To a smaller extent, whenever land is cleared for industry, agriculture, or other human activity, this also contributes to higher concentrations of greenhouse gases.

As the world continues to heat up, scientists have identified the following sources as the primary culprits to today’s climate change activity.

Global temperature rise

On average, the Earth’s surface temperature has increased about 2 degrees Fahrenheit since the late 19th century. Increasing carbon dioxide emissions have brought on this change into the atmosphere and other human activities. Most of this global warming has taken place within the past 40 years. The most recent years have been the warmest on record.

Warming ocean

Ocean waters have absorbed quite a bit of this increased heat. This has been evident in the top 100 meters of the ocean as it shows an increase of almost one degree. It is important to note that the Earth stores around 90% of its extra energy within its oceans.

Shrinking ice sheets

The Antarctic and Greenland ice sheets have been reduced in mass. Data from NASA’s Gravity Recovery and Climate Experiment indicate that Greenland has lost an average of 279 billion tons of ice annually between 1993 and 2019. Antarctica lost about 148 billion tons annually within the same time frame.

Retreating glaciers

Pick any place in the world that has glaciers, and you’ll find that almost all of them are retreating. This includes the Himalayas, Alps, Andes, Alaska, Rockies, and Africa. Rising temperatures can no longer sustain them.

Decreased snow cover

Satellites have shown us the evidence of decreasing snow patterns for the past five decades. This is especially prevalent in the Northern Hemisphere.

Sea level rise

Over the past century, we have seen sea levels across the world rise around 8 inches. During the past two decades, this rate of increase has almost doubled and has been accelerating each year.

Declining Arctic sea ice

The mass of Arctic sea ice has rapidly diminished over the past several decades. Not only in surface area and coverage, but its thickness has also declined as well.

Extreme weather events

In recent years, the quantity of record high temperatures in the United States has been rising. At the same time, the number of record low-temperature events has dropped. This trend has been taking place since 1950. The US is also experiencing a sharp increase in extreme rainfall events.

Ocean acidification

When the Industrial Revolution began, productivity and commerce weren’t the only things it caused. The acidity levels in surface ocean waters began to increase. And it has increased some 30% since the Industrial Revolution started.

This trend directly results from humans putting more carbon dioxide into Earth’s atmosphere, which gets absorbed into its oceans. Our ocean waters have absorbed around 20 – 30% anthropogenic carbon dioxide emissions over the past few decades – this amounts to approximately 7 to 11 billion metric tons annually.


The role of human activity

The Intergovernmental Panel on Climate Change (IPCC) represents a group of 1,300 independent scientists worldwide operating under the auspices of the United Nations. The IPCC recently released its Fifth Assessment Report, which concludes there’s a more than 95% statistical probability that human activity has caused global warming over the past 50 years.

It is primarily through the industrial processes of modern civilization that have dramatically raised carbon dioxide levels in the atmosphere. More specifically, it has grown from 280 parts per million (ppm) to 414 ppm over the last 150 years.

The IPCC also states there is better than a 95% probability that the greenhouse gases created by human activities are responsible for the sharp increase in Earth’s temperatures across the last 50 years.


Expected results in the future

While the outcome of increased greenhouse gases can be difficult to forecast, specific effects seem very like to occur. Let’s examine some of them:

Earth will get warmer at faster rates. A few regions may like reaching warmer temperatures, but then others won’t. The real key is how quickly that biological systems and processes will adapt.

Under warmer conditions, we can expect an increase in overall precipitation and evaporation. Individual regions will vary as some will become dryer, and some will be wetter.

A more significant greenhouse effect will undoubtedly warm up the oceans and continue melting glaciers and ice sheets while increasing the levels of the oceans. Let us not forget that water expands when it is heated, which means even greater sea levels.

More significant carbon dioxide (CO2) levels can negatively and positively affect crops and their yields. There are some studies out there that claim elevated levels of CO2 boost plant growth.

But other factors like temperature changes, ozone degradation, and water and nutrient restrictions will prove to be more costly and potentially increase crop yields. Whenever temperatures exceed optimal ranges for certain crops, any earlier gains in yield will be eliminated and possibly even reversed altogether.

We can expect climate extremes like floods, droughts, and extreme temperature events. All of these could lead to losses of crops and threaten the livelihoods of farmers and other agricultural producers – not to mention the world’s food supply. Let us not forget that many pests, weeds, and fungi that damage crops will likely thrive in these warmer and wetter climates.


Final thoughts

As you can see, there are many bleak outcomes associated with an increase in greenhouse gases and global warming. We can also assume that some negative impacts will be subtle and have yet to be identified.

As established by some of the most brilliant environmental scientists in the world, we can further assume that there is sufficient evidence that humans are causing global warming. There are too many correlations supporting this conclusion – especially links to the burning of fossil fuels. It is just too hard to deny all the human causes of climate change.


Sources

https://scienceexchange.caltech.edu/topics/sustainability/evidence-climate-change

https://climate.nasa.gov/