Climate change is one of the most significant global challenges of our time. It is now more certain than ever, based on many lines of evidence, that humans are changing Earth’s climate.
These changes are apparent over much of the world and they are projected to grow.
Climate change has already had observable effects on the environment. Globally, the average surface temperature has increased by about 1.5 degrees Fahrenheit (0.85 degrees Celsius) since 1880. Two-thirds of this increase has occurred since 1975, at a rate of roughly 0.15-0.20 degrees Fahrenheit (0.08-0.11 degrees Celsius) per decade.
Besides rising temperatures, climate change seems to cause more extreme weather events. For instance, heatwaves in Europe this past summer, floods in Asia, particularly Pakistan and China, and most recently, hurricane Ian that has caused untold destruction in Florida and other areas.
But, is climate change really causing these extreme weather events?
Climate change and human activity
The primary cause of the warming since the 1950s is human activity, predominantly the burning of fossil fuels such as coal, oil, and natural gas. Burning these materials releases what are known as greenhouse gases into Earth’s atmosphere. There, these gases trap heat from the sun’s rays inside the atmosphere causing Earth’s average temperature to rise.
Climate change not only refers to changes in average temperature, but also encompasses changes in precipitation (amount, distribution, and timing), sea level, and the occurrence of extreme weather events. Together, these different types of climate-related changes are producing widespread impacts on human health, the economy, natural systems, and society as a whole.
Over the last several decades, the concentrations of carbon dioxide (CO2), water vapor, and ozone in the atmosphere have increased markedly, largely due to human activity. These increases have enhanced the greenhouse effect, resulting in more heat being trapped within the lower atmosphere.
The evidence for this is overwhelming. For example, measurements of CO2 in the atmosphere taken at Mauna Loa in Hawaii show a steady increase since 1958, with an acceleration in the rate of increase starting around 1976.
In addition to measurements of atmospheric gases, other lines of evidence also support the conclusion that human activity is the primary driver of current climate change. In turn climate causes or exacerbates extreme weather events. These include:
- Widespread changes in temperature observations from around the world
- Changes in sea level
- Widespread retreat of glaciers and Arctic sea ice
- Changes in the timing of seasonal events (e.g., earlier flowering of plants)
- Changes in the distribution of plant and animal species
All of these observed changes are consistent with what we would expect to see as a result of human-induced climate change.
Climate change and extreme weather
Climate change is causing an increase in the frequency and severity of extreme weather events around the world according to scientists.
One of the most direct effects of climate change is an increase in average global temperatures. As temperatures rise, so does the amount of energy in the atmosphere. This extra energy can lead to more frequent and more intense storms, as well as longer and more damaging floods.
In addition, rising temperatures are also leading to more frequent and intense heat waves. The heatwaves consequently cause droughts, wildfires, and even deaths from heatstroke.
As greenhouse gas concentrations continue to increase, so too will the amount of heat trapped within Earth’s atmosphere. This will cause Earth’s average surface temperature to rise.
The amount of warming projected for the coming decades depends primarily on two factors: (1) how much more greenhouse gas we emit and (2) how sensitive the climate is to changes in greenhouse gas concentrations.
In short, climate change is having a drastic impact on the world’s weather patterns, leading to more extreme and destructive weather events.