What is Climate Change?

Climate refers to the long-term regional or global average of temperature, humidity, and rainfall patterns over seasons, years, or decades.

While the weather can change in just a few hours, climate changes over a longer period. Climate change is the significant variation of average weather conditions becoming, for example, warmer, wetter, or drier over several decades or longer. It is a longer-term phenomenon on the planet Earth.

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The evidence for climate change is compelling:

1. Global Temperature Is Rising rapidly

The planet’s average surface temperature has risen about 2 degrees Fahrenheit (1 degree Celsius) since the late 19th century, a change driven largely by increased carbon dioxide emissions into the atmosphere and other anthropogenic activities. Global temperature is rising as a direct consequence of climate change, primarily driven by human activities such as the burning of fossil fuels, deforestation, and industrial activities. These actions release large quantities of greenhouse gases, like carbon dioxide and methane, into the atmosphere, trapping heat and causing the Earth’s surface temperature to increase at a rapid pace. The years 2016 and 2020 are tied for the warmest year on record.

 IPCC Sixth Assessment Report, WGI, Technical Summary.

2. The Ocean Is Getting Warmer with rising temperature

The rising temperature of the earth has massively affected the whole earth’s surface. The ocean has absorbed much of this increased heat, with the top 100 meters (about 328 feet) of the ocean showing warming of 0.67 degrees Fahrenheit (0.33 degrees Celsius) since 1969. Warmer oceans have significant consequences for marine ecosystems, including coral bleaching, shifts in species distribution, and the disruption of food chains. Moreover, warmer water expands, contributing to sea level rise, and fuels more intense and frequent storms, such as hurricanes and typhoons.

3. The Ice Sheets Are Shrinking

The ice sheets are shrinking as a result of rising global temperatures, driven by climate change. The Greenland and Antarctic ice sheets have decreased in mass. Data from NASA’s Gravity Recovery and Climate Experiment show Greenland lost an average of 279 billion tons of ice per year between 1993 and 2019, while Antarctica lost about 148 billion tons of ice per year. As the ice melts, it also disrupts global climate systems by altering ocean currents and weather patterns. Furthermore, diminishing ice reduces the Earth’s ability to reflect sunlight (a process known as the albedo effect), which exacerbates global warming.

Glaciers Are Retreating

Glaciers are retreating worldwide due to rising global temperatures caused by climate change. As temperature increases, glaciers lose more ice through melting than they can regain from snowfall, leading to a decline in their size. Glaciers are retreating almost everywhere around the world — including in the Alps, Himalayas, Andes, Rockies, Alaska, and Africa. The loss of glaciers also contributes to rising sea levels, further threatening coastal communities.

4.Sea Levels are rising at a pace

Global sea level rose about 8 inches (20 centimeters) in the last century. The rate in the last two decades, however, is nearly double that of the last century and accelerating slightly with the progression of time. Sea levels is rising primarily due to climate change, driven by two main factors: the melting of ice sheets (glaciers and ice sheets) and the thermal expansion of seawater. This rise poses a significant threat to coastal communities, increasing the risk of flooding, massive storms, and erosion. Low-lying areas, particularly small island nations, and coastal cities, are particularly more susceptible. The continued rise of sea levels is one of the most pressing impacts of climate change, with long-term effects for millions of people around the globe.

5. Extreme Events Are Increasing in Frequency

The number of record high temperature events in the United States has been increasing, while the number of record low temperature events has been decreasing, since 1950. Extreme events are increasing in frequency and intensity as a result of climate change. Rising global temperatures are fueling more severe weather patterns, including stronger heatwaves, intense storms, prolonged droughts, and heavier rainfall. For example, warmer oceans result in more powerful hurricanes and typhoons, while increased evaporation intensifies droughts and wildfires. At the same time, heavier rainfall events can cause flash floods and landslides. The increasing number of extreme events poses significant risks to human health, agriculture, infrastructure, and ecosystems throughout the world.

6. Ocean Acidification Is Increasing

Since the beginning of the Industrial Revolution, the acidity of surface ocean waters has increased with manifold. This increase is due to humans emitting more carbon dioxide into the atmosphere and hence more being absorbed into the ocean. Ocean acidification is increasing as a result of rising carbon dioxide (CO2) levels in the atmosphere. The ocean absorbs about 30% of the CO2 emitted by human activities, such as burning fossil fuels. When CO2 dissolves in seawater, it reacts to form carbonic acid, lowering the ocean’s pH level and making the water more acidic. As ocean acidification increases, marine species struggle to survive, which can disrupt food chains and affect biodiversity. Coral reefs, which support a vast array of marine life, are particularly more vulnerable. The loss of these ecosystems not only affects marine species but also impacts human communities that depend on them for food, coastal protection, and tourism.

References:

In 1824, Joseph Fourier calculated that an Earth-sized planet, at our distance from the Sun, ought to be much colder. He suggested something in the atmosphere must be acting like an insulating blanket. In 1856, Eunice Foote discovered that blanket, showing that carbon dioxide and water vapor in Earth’s atmosphere trap escaping infrared (heat) radiation.

In 1938, Guy Callendar connected carbon dioxide increases in Earth’s atmosphere to global warming. In 1941, Milutin Milankovic linked ice ages to Earth’s orbital characteristics. Gilbert Plass formulated the Carbon Dioxide Theory of Climate Change in 1956.

Special Report on the Ocean and Cryosphere in a Changing Climate, Technical Summary, Chapter TS.5, Changing Ocean, Marine Ecosystems, and Dependent Communities, Section 5.2.2.3.
https://www.ipcc.ch/srocc/chapter/technical-summary/

National Snow and Ice Data Center
World Glacier Monitoring Service

 http://www.pmel.noaa.gov/co2/story/What+is+Ocean+Acidification%3F

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