Climate Change in the 21st Century •

Climate Change in the 21st Century

Climate change is going to be the largest story of the 21st century. There, I said it! A lot is uncertain about how much the climate will change. We can’t predict how governments will make policies, or how the general public will change their lifestyles in response to a growing climate crisis. We don’t know how much deforestation or reforestation the rest of the century will see. Since we can’t predict these huge unknown factors, we can’t know how much more the planet will warm. Below we will explore some (but definitely not all) of the many faces of climate change.

CO2 Emissions

Carbon dioxide (CO2) is a byproduct of burning fossil fuels, like coal and gas. Most industrial processes, including animal agriculture, travel, and manufacturing, create CO2 emissions. CO2 and other greenhouse gases absorb heat coming out of Earth towards space. Therefore, heat that the planet would’ve formerly lost to space is instead kept within our atmosphere, warming our planet. This is basic science and has been known for at least sixty years (perhaps up to 140 years). The scientific community finds nothing controversial about the concept of greenhouse gases, nor that humans are the cause of global warming.

Where are we Now?

RCP, climate scenario

Climate scenarios used to modeling predictions. Higher on the graph means more carbon emitted, which leads to a larger increase in temperature. Graph by Global Carbon Project

CO2 is measured as a concentration in the air. Currently, there are about 415 parts of CO2 per million (ppm) of everything else in the air. Humans have never lived on an earth with 415 ppm CO2. When our species was roving around the African savannah in small groups, the concentration of CO2 was around 300 ppm. Earth hasn’t experienced CO2 levels this high for 10-15 million years. This should be alarming.

Instead of decreasing emissions, humans increased global carbon emissions by 2% in 2018. Energy demand around the world increased by 3.7%. July of 2019 was the hottest month ever on record, and the last five years were the hottest 5 years since recording began 140 years ago. Earlier this year, the IPCC announced that we have one decade to curb emissions to stay below the widely-agreed upon 2°C warming threshold. Above 2°C, we will see natural systems break down, and perhaps set off irreversible feedback loops by thawing the arctic permafrost. The amount of carbon currently in the air has locked us into 1.5°C in global warming because there is a lag from when carbon comes out of an exhaust pipe and when it warms the world. In fact, 71 counties in the U.S. have already warmed 2°C. This means extreme climate change has already arrived to L.A., parts of the Rocky Mountains, and the Northeastern U.S.


Current climate change in the U.S. Red indicates 2°C warming as of 2019. Yellow is 1°C. Graph by NOAA

If we break down total human carbon emissions through time into quarters, it took us 217 years to emit the first quarter. The second quarter took 23 years. The third, 16 years. The final quarter took only 11 years. Instead of slowing emissions, our current situation appears more as an accelerating freight train.

Predictions for Our Future Climate

The Intergovernmental Panel on Climate Change (IPCC) released four ‘use scenarios’ at the beginning of the 21st century to help climate modeling (see graph above). These range from the least drastic (where carbon emissions peak between 2010 and 2020) to the most drastic (where no policy is put in place to slow carbon emissions, and where we continue with ‘business as usual’). As of 2019, we are on track for the worst climate change scenario the IPCC put out. If we continue on this scenario, global average temperatures will be 9°F higher by the end of the century. And remember, this is average temperatures. Heat waves that formerly peaked in the low 90’s would instead be in the low 100’s. Snowy winter days in the 20’s could become slushy and rainy. A world 9°F hotter is hard to imagine.

Sea Level Rise

sea level rise

Global sea level rise as of 2017. Like the land on Earth, the sea isn’t perfectly flat. That’s why some places have experienced more of a sea level rise than others. Graph by NOAA

Sea level has risen about eight inches from the beginning of the industrial revolution. Additionally, the sea level is rising at an increasing rate. Currently, the rise is about 1/8th of an inch a year. While this may not seem like a lot, any increase in sea level becomes magnified during a strong storm. Scientists believe that sea level rise caused an additional 9 billion dollars in property damage during Hurricane Sandy in New York in 2012. It also put 75,000 more people at risk. Flooding from high tides has increased 300-900% in the U.S. compared to 50 years ago.

Predictions for Sea Level Rise

Scientists predict that sea level could rise another 8 inches to 6.5 feet by the end of the century, depending on how much carbon we put into the atmosphere. An increase of 6.5 feet would permanently flood an area of land equivalent to California, Texas and Alaska combined. It would flood houses for at least 127 million people, who would need to find somewhere else to live. Many of the worlds largest cities are built right on the water. These cities, along with their billions of dollars of infrastructure, would be at risk of catastrophic flooding. Keep in mind 6.5 feet is the worst case scenario for this century, but any increase in sea level rise will displace more and more people. Additionally, the sea level will continue to rise past 2100, and some scholars think that we are already locked in to 10 feet of sea level rise by 2300. This is why low-lying Pacific island nations are some of the strongest advocates for global climate policy.


Natural Disasters

Weather and climate are different. Weather is the condition of the atmosphere during a specific time an place like Miami, Florida on Augst 12th. Climate is the pattern of weather throughout time, such as cold winters in the Rocky Mountains, followed by strong summer monsoons. Natural disasters, such as hurricanes and droughts, are usually in the realm of ‘weather’ instead of ‘climate.’ However, mounting evidence shows that naturals disasters are strengthened by climate change.

Heavy Rainfall

Heavy downpours that cause flooding have increased almost everywhere in the U.S. over the last 50 years. The Midwest has experienced a 42% increase in massive, rainfall caused flooding over this time period. If we continue with ‘business as usual’ the Midwest and many other regions of the country could see an additional 40% increase in flooding events.


Climate change is making it easier for hurricanes to approach land on the East Coast of the U.S. Historically, the East Coast produced winds that counteracted a hurricane’s force as the storm approached land. However, climate change has decreased this ‘speed bump’, allowing the storms to charge towards cities on the East Coast. Warmer oceans also increase the intensity of hurricanes, and our oceans are certainly warming. Hurricanes are phenomenally expensive events, and it would be wise to curb carbon emissions to help avoid stronger hurricanes in the future.


The western U.S. is already seeing an increase in dry years. The snowpack in this region has dwindled, most famously during the seven-year drought in California between 2011 and 2019. Just a few months ago was the first time the state was drought-free in 376 consecutive weeks. One of the most consistent predictions on climate is that wet places will become wetter, and dry places will become drier. This is concerning in places like Arizona, California, and New Mexico, where water resources are already over-allocated.

refugee camp

Human Migration

Natural disasters strengthened by climate change will cause millions of climate refugees. The World Bank estimates that the planet will see nearly 150 million climate refugees from Latin America, Asia, and Africa by 2050. The U.S. has a current cap of accepting 30,000 refugees per year. Figuring out how to resettle 150 million people whose homes have been lost to desertification, sea level rise, and excessive heat will be a huge issue in the not-so-distant future. It also demonstrates the inequality of the climate crisis. Developing countries contribute the least to climate change, but will likely see the worst impacts from it.

Mass Extinction

We are already in a mass extinction. Species are going extinct at a rate 100 times higher than normal. A third of amphibians are currently threatened with extinction. Perhaps more alarming than the extinction of species is the loss of habitat for all species. A recent study found that, of 177 species of mammals studied, all lost over 30% of their habitat and over 40% lost 80% of their habitat. Climate change is radically changing habitat by changing rain patterns and temperatures. These changes make it more difficult for plants native to these areas to survive. They are trying to live in a place that is unlike the climate they evolved with over millions of years. Without the proper plants, the animals have a more difficult time living as well. While species have evolved with changing climates in the past, these changes have been hundreds of times slower than the ones we are creating. Species simply can’t keep up.

mountain goat

Photo by the author

Let’s think of a charismatic animal, like a mountain goat. These goats live on mountains above the trees, in an alpine ecosystem. Climate change makes the tops of these mountains warmer, so trees can colonize areas that were previously too cold for them. As the trees march up the mountains, the alpine ecosystems shrink. With less land, the mountain tops can’t support as many goats. Perhaps most alarming, when the trees march up high enough, the goats won’t be able to wander between mountains that used to have alpine areas connecting them. The goat populations become smaller and more isolated. These populations are then more at risk to natural disasters, such as parasites and diseases. A small population can disappear much easier than a larger one. Once a population of goats disappears on an isolated mountain top, goats from other mountains won’t be able to reach it to recolonize the area. That population of goats is then extinct.

Climate Change Is Scary, but There Are Things You Can Do.

There is no way to sugar-coat climate change. It is an enormous problem–perhaps the biggest humanity has ever faced. Many people in power have turned a blind eye towards the issue for decades. While the climate crisis must be addressed by new policies, there are a few personal changes all of us can make to reduce our impact.

1) Eat a low carbon diet. Animal agriculture accounts for more emissions than all travel combined. Eating less meat and dairy (in particular, red meat) will reduce your diet’s carbon footprint.

2) Travel and commute smarter. People driving alone in their cars amounts to a significant portion of air pollution and carbon pollution. Consider carpooling, public transport, or biking.

3) Buy less new stuff. Almost every manufactured thing has a carbon footprint. Each new item you buy adds carbon to the atmosphere. Buying more second-hand items is one solution. Another is lending things that you need sometimes, but that you don’t need to use all the time, like lawnmowers or trucks for moving large things.

4) Call your local representatives and urge them to adopt climate policies. Whenever you call a representative, someone is obligated to listen to and record your message. If a representative gets enough calls, they might be persuaded to choose a climate-friendly policy.

There are plenty of other actions you can take to combat the climate crisis. Groups such as, Citizens Climate Lobby, and the Sunrise Movement are all trying their darndest to avert the worst-case scenarios.

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