From municipal and agricultural water supplies to flood management and aquatic ecosystem protection, climate change affects all aspects of water resource management in Texas and across the world. But what is climate change? To understand the why behind what’s happening around us, we need to be familiar with how Earth’s climate functions.
It all comes down to how energy from the sun interacts with the atmosphere, land, and oceans. Sunlight reaching the planet is either reflected back into space or is temporarily absorbed, heating up the surface. The same amount of energy absorbed by Earth is always released back into space. Greenhouse gases like water vapor, carbon dioxide, and methane in our atmosphere cause a delay between when energy is absorbed and when it is released. This delay is what allows life to exist on the plant. Think of the greenhouse effect like wearing clothes: without an insulating layer of fabric keeping the heat in, you’d be a lot colder. And space is a frigid place; nobody enjoys being naked while outside in a Blue Norther!
Certain types of clothes keep heat in better than others. Gases that make up most of the atmosphere, like oxygen and nitrogen, are equivalent to wearing light and breathable fabrics. At the same time, water vapor, carbon dioxide, and methane are thick warm blankets. That’s why they’re called greenhouse gases; they blanket Earth and help keep us warm. Our cover of greenhouse gases is made of the perfect material. It keeps us warm while still being breathable enough not to make us too sweaty.
The quality of this blanket is controlled by many different biological, chemical, and geological processes—climate results from the long-term patterns of these processes. Earth’s axis is tilted at an angle, causing a different amount of sunlight to be distributed across the planet at varying points during its journey around the sun. This creates our recurring seasonal changes in temperature, in turn affecting precipitation patterns. Mountains, valleys, and other geologic features change how energy is transported and interacts with the atmosphere and the surface. Oceans cover 70% of the planet and substantially impact global and regional climate; they absorb a large amount of solar radiation and transport it across vast distances in ocean currents and atmospheric water vapor. This redistribution of energy in water warms some areas of the world and cools others. Over time, it also stores large amounts of carbon as ocean life dies and sinks deep to the floor, eventually forming new rocks in the geological cycle.
Water vapor is the most important greenhouse gas as it is excellent at storing large amounts of energy. It can evaporate from oceans, rivers, lakes, soils, and plants during photosynthesis. Again, this influences regional cooling/warming patterns. Plants also exert control over the amount of carbon dioxide in the atmosphere. The gas is used in photosynthesis, so as plants grow, they can store carbon as living or dead biological material. Over time, it accumulates in soils. As living things die, they decompose, which releases both carbon dioxide and methane. These gases can either re-enter the atmosphere or are stored under the surface or in frozen permafrost soils. All these different processes are complex and interconnected, so even a small change in just one part can greatly impact how all other Earth system components behave.
As the climate is considered the average daily weather conditions over long periods, scientists can reconstruct what previous climates looked like using geological records. Changes are easy to identify as they show significant and persistent variation. Natural records stored in tree rings, glacial ice, ocean floors, and lake sediment beds establish that the global climate has shifted significantly in the past. Current observations over the last 100 years show us that our environment is rapidly changing. Computational models based on our collective knowledge of all the biogeochemical processes controlling climate agree that it will continue to change in the future. Today, Earth’s average temperature is warmer than in the last 1,300 years and has changed dramatically over the previous 50 years. While Earth’s rotation and orbit around the sun naturally change—affecting periods of warming or cooling like ice ages and the warmer interglacial period we’re currently in—these changes are slow and happen over 100,000 years. The unequivocal scientific consensus agrees that human activity is responsible for these recent rapid changes.
Human activity in recent decades has drastically altered the planet’s landscape (for example, building concrete cities, widespread deforestation, and large-scale agricultural and industrial operations). When combined with the burning of fossil fuels since the Industrial Revolution, scientists can unequivocally confirm that the observed increase in global average temperatures is a direct consequence of these behaviors. Widespread deforestation and the burning of fossil fuels emits large stores of CO2 into the atmosphere faster than natural processes can remove it. Over time, this has increased the amount of carbon dioxide in the atmosphere, which will stay there for over a century. Other greenhouse gasses that humans have created will be there for thousands to millions of years. This adds additional layers to our metaphorical planetary blanket, so we retain more of the solar energy we receive. In turn, the planet must heat up, so we still release the same amount of energy to stay in balance, making things sweaty. By looking at over 88,000 peer-reviewed scientific studies since the 1800s, over 99% agree that modern climate changes are caused by humans.
All organisms on Earth have specific ranges of temperature, precipitation, sunlight, and humidity in which they can survive. Suppose any of these environments change outside of their tolerance zones. In that case, organisms will either adapt to new conditions, migrate somewhere else with more hospitable conditions, or die. Excluding the last few decades, geologic records show that modern life on Earth has evolved in the previous 10,000 years in the most stable period in our planet’s climate history. This includes human society. Our agricultural, economic, and transportation systems operate within their own climate niche. They are as vulnerable as any other form of life to any major changes in climate. As ecosystems are forced to confront these rapid changes, many species can no longer be supported by their environments, substantially reducing their ecological resiliency and lowering biodiversity.
What does all this mean for humans? Sea-level rise from melting glaciers and ice sheets—and the thermal expansion of water from warmer ocean temperatures—endangers millions of people living along low-lying coasts. This causes displacement, reduces infrastructure stability, and elevates the risk of damage and death from storm surges during hurricanes. The reliable availability of freshwater is at stake as warming temperatures and shifting precipitation patterns lower runoff to rivers and reservoirs and decrease recharge to aquifers. Climate models project longer and more intense droughts. This threatens agricultural production and food security, especially as the frequency and intensity of extreme weather events continue to increase damage and reduce crop yields.
Warmer conditions on land extend the range of bacteria and viruses like malaria, allowing them to migrate and infect larger and previously unexposed populations. Overall health and mortality rates are vulnerable to drought-caused food insecurity, lower air and water quality, and greater hazards in coastal and low-lying areas. These effects have and will continue to vary across regions, but vulnerable communities are particularly at risk. Due to climate change, depending on where you live on the planet, a child born in 2020 will experience 2 to 36 times as many extreme weather events than someone born in 1960. An attribution study with machine learning suggests that around 85% of the world’s population has already been impacted by climate change, with those impacts becoming more severe as warming and subsequent feedbacks continue to rise.
We will continue to examine these impacts in more detail in follow-up posts, especially related to life here in Texas. We will also explore what is, and can be, done to adapt and mitigate these consequences.
While our climate has and will continue to naturally change over time, the rise in atmospheric greenhouse gases since the Industrial Revolution is directly attributed to human activity. This has undeniable consequences on all aspects of life through changes in global and regional climates. Our action—or inaction—over the next two decades will determine how severe our consequences are.
Is it just me, or is it getting hotter than a jalapeño in here?