In this chapter we will look at how to know the effects of climate change. How do we know that the climate is changing. We shall just browse through some of the scientific evidence.
Direct observations made on and above Earth’s surface show the planet’s climate is significantly changing. Human activities are the primary driver of those changes.
Earth's climate has changed throughout history. Just in the last 650,000 years there have been seven cycles of glacial advance and retreat, with the abrupt end of the last ice age about 11,700 years ago marking the beginning of the modern climate era — and of human civilization.
1. GLOBAL TEMPERATURE RISE
The planet's average surface temperature has risen about 2.12 degrees Fahrenheit (1.18 degrees Celsius) since the late 19th century, a change driven largely by increased carbon dioxide emissions into the atmosphere and other human activities. Most of the warming occurred in the past 40 years, with the seven most recent years being the warmest. The years 2016 and 2020 are tied for the warmest year on record.
2. WARMING OCEAN
The ocean has absorbed much of this increased heat, with the top 100 meters (about 328 feet) of ocean showing warming of more than 0.6 degrees Fahrenheit (0.33 degrees Celsius) since 1969. Earth stores 90% of the extra energy in the ocean.
3. SHRINKING ICE SHEETS
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.
4. GLACIAL RETREAT
Glaciers are retreating almost everywhere around the world — including in the Alps, Himalayas, Andes, Rockies, Alaska, and Africa.
5. DECREASED SNOW COVER
Satellite observations reveal that the amount of spring snow cover in the Northern Hemisphere has decreased over the past five decades and the snow is melting earlier.
6. SEA LEVEL RISE
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 every year.
7. DECLINING ARCTIC SEA ICE
Both the extent and thickness of Arctic sea ice has declined rapidly over the last several decades.
8. EXTREME NATURAL EVENTS
Increase in natural disasters each year.
9. OCEAN ACIDIFICATION
Since the beginning of the Industrial Revolution, the acidity of surface ocean waters has increased by about 30%. This increase is the result of humans emitting more carbon dioxide into the atmosphere and hence more being absorbed into the ocean. The ocean has absorbed between 20% and 30% of total anthropogenic carbon dioxide emissions in recent decades (7.2 to 10.8 billion metric tons per year).
The evidence of climate change is overwhelming, urging us to climate action. Here are some of the opinions from our Instagram & Facebook family:
Sprut Krankle -
"The Sahara going green."
Prachi Jain -
" 16% above expected levels, forest wildfires, rains."
"Global temperatures rise, warming ocean, decreased snow cover, glacial retreat & ocean acidification."
" So many!!! Wildfires, drought, typhoons, ice on Kilimajaro is almost over. Heat waves, intense drought, rise of sea levels, melting glaciers, extreme weather conditions. "
"Floods and droughts."
"Increased erratic weather."
"Rise in sea levels, abrupt change in weather patterns."
"No rain. Prolonged drought. "
"Temperature fluctuation and melting of ice peaks."
- Vostok ice core data; NOAA Mauna Loa CO2 record
- Gaffney, O.; Steffen, W. (2017). "The Anthropocene equation," The Anthropocene Review (Volume 4, Issue 1, April 2017), 53-61.
- National Snow and Ice Data Center
- World Glacier Monitoring Service
- National Snow and Ice Data Center
- R. S. Nerem, B. D. Beckley, J. T. Fasullo, B. D. Hamlington, D. Masters and G. T. Mitchum. "Climate-change–driven accelerated sea-level rise detected in the altimeter era." PNAS, 2018 DOI: 10.1073/pnas.1717312115