What is global warming?

Global warming is the rise in average temperatures across the globe, which has been ongoing at least since record keeping began in 1880.
The global annual temperature increased at a rate of 0.13 degrees Fahrenheit (0.07 degrees Celsius) per decade between 1880 and 1980. The rate of increase has gone up since 1981. The global average temperature has increased by 3.6 F (2 C) compared to the preindustrial era. The hottest year on record so far in 2016 is close to falling. The years of 2020 and 2019 were close enough to knock 2016 off its perch. The average global temperature in 2020 was 1.76 F warmer than the 20th century average.
Humans are to blame for modern global warming. The burning of fossil fuels has released greenhouse gases into the atmosphere, which trap warmth from the sun and drive up surface and air temperatures. Climate change has become the preferred term among scientists, though global warming is a synonym.
What causes global warming?

Fossil fuels are the main driver of today's warming. The greenhouse effect is caused by the interaction between Earth's atmosphere and incoming radiation from the sun.
The basic physics of the greenhouse effect was figured out a century ago by a smart guy using only pencil and paper, according to a professor at the University of Pittsburgh.

The "smart guy" was a Swedish scientist named Svante Arrhenius. Solar radiation hits Earth's surface and then bounces back to the atmosphere as heat. Good news for life on the planet, because gases in the atmosphere prevent heat from escaping into space. In 1895, Arrhenius presented a paper showing that greenhouse gases such as carbon dioxide can trap heat close to the Earth's surface, and that small changes in the amount of those gases could make a big difference in how much heat is trapped.

Greenhouse gases cause global warming.

Humans have been changing the balance of gases in the atmosphere since the beginning of the Industrial Revolution. Coal and oil release water vapor, carbon dioxide, methane, ozone and nitrous oxide, which are considered the primary greenhouse gases. Carbon dioxide is a greenhouse gas. Between about 800,000 years ago and the beginning of the Industrial Revolution, CO2's presence in the atmosphere amounted to about 280 parts per million. According to the National Centers for Environmental Information, the average CO2 in the atmosphere was 412.5 parts per million in 2020.
The levels of CO2 haven't been that high since the Pliocene, according to the Scripps Institution of Oceanography. According to research published in the journal Science, the ice-free year of that time was at least part of the year.
According to the EPA, CO2 accounted for 81.6% of the U.S. greenhouse gas emissions.

There is an increase in the amount of CO2 in the atmosphere. We know that CO2 absorbs heat and the global mean temperature is increasing, according to a professor of chemistry at York College of Pennsylvania and his research partner.

CO2 can be found through a variety of routes. Burning fossil fuels releases CO2 and is the biggest U.S. contribution to emissions that warm the globe. According to the EPA report, the U.S. released over 5.8 billion tons of CO2 into the atmosphere in 2016 from fossil fuel burning. The total annual CO2 release in the U.S. is boosted by processes such as non-energy use of fuels, iron and steel production, cement production and waste incineration.

The second most abundant greenhouse gas is methane. Cattle are the largest source of methane production. Mauro_Scarone is credited with the image.

Excess CO2 is a large contributor to the atmosphere. According to the Food and Agriculture Organization of the United Nations, deforestation is the second largest source of carbon dioxide. After a tree dies, it releases the carbon it has stored. Less trees take up carbon from the atmosphere when forest land is transformed into ranching, residential or agricultural land. The good news is that since 2015, the rate of forest loss has slowed.

Methane is the most efficient greenhouse gas at trapping heat. Methane is 25 times more efficient at trapping heat than carbon dioxide, according to the EPA. The gas accounted for 10% of the US's greenhouse gas emissions in 2016 according to the EPA.
Humans cause a large portion of methane emissions through mining, the use of natural gas, the mass raising of livestock and the use of landfills. According to the EPA, cattle are the largest source of methane in the U.S.
What are the effects of global warming?

"climate change" is the preferred term among researchers and policymakers because global warming doesn't just mean warming. While the globe is becoming hotter on average, this temperature increase can have consequences, such as more frequent and severe snowstorms. Climate change can affect the globe in many ways, including melting ice, drying out already-arid areas, causing weather extremes, and disrupting the delicate balance of the oceans.

The ice is melting.

The melting of glaciers and sea ice is the most visible effect of climate change so far. The last century's warming has accelerated the demise of the ice sheets, which have been retreating since the end of the last ice age. According to a study done in 2016 there is a 99% chance that global warming has caused the recent retreat of glaciers. There were 150 glaciers in the late 1800s in Glacier National Park. When the last full survey was taken in 2015, there were 26. The loss of glaciers can cause the loss of human life, when the glaciers are lost, or when the glaciers are lost and the lakes burst.

Warming at the North Pole is twice as fast as it is at the middle latitudes, and the sea ice is showing strain. The ice expanse in the northern part of the planet hit record lows in the fall and winter of 2015, and again in the spring. The National Snow and Ice Data Center says that the summer sea ice extent in 2020 was the second-lowest on record. 13 of the smallest values for maximum winter extent of sea ice were measured by NASA over the last 13 years. The ice forms later in the season and can be melted in the spring. Over the past 40 years, the sea ice extent has declined. The scientists think the ice-free summers will happen within the next 20 or 30 years.

The effects of global warming have been more variable in the Antarctic. According to the coalition, the Western Antarctic Peninsula is warming faster than any other part of the world. The peninsula is where the ice shelf broke in July of last year. The Thwaites and Pine Island glaciers are flowing five times faster than they did in 1992, and a quarter of West Antarctica's ice is in danger of collapsing. The Thwaites glacier is vulnerable due to the fact that it sits over a region where Earth's crust is relatively thin.

The effects of global warming have been more severe in East Antarctica. Recent data shows that even this last cold bastion of the southern continent may be feeling the effects of rising temperatures. The glaciers in East Antarctica are moving faster. Sea level rise is caused by more land-based ice headed toward the ocean.
It's heating up.

Things will change between the poles because of global warming. As the world warms, many already-dry areas are expected to get even drier. The southwest and central plains of the United States are expected to experience decades-long "megadroughts" harsher than anything else in human memory.

Benjamin Cook, a climate scientist at NASA's Goddard Institute for Space Studies in New York City, told Live Science that the future of western North America is likely to be worse than the past. These are so far away from our experience that they are almost impossible to think about.

The study predicted that there would be at least 35 years of dry weather in the region. The researchers found that the main driver was the increase in the amount of water that leaves the soil. The arid regions will lose a lot of precipitation.

As the climate warms, many areas will likely see less precipitation. The Mediterranean, the Amazon, Central America, and Indonesia will likely be the hardest hit, according to a study.

The stage for devastating wildfires can be set by the lack of rain. According to the National Interagency Fire Center data, there has been a steady increase in the extent of wildfires since the 1980s. Since 2005, the top 10 years of burned land have all happened.

Extreme weather.

Extreme weather is an impact of global warming. As the planet warms, hurricanes and typhoons are expected to intensify. The hotter oceans evaporate more water. Even if the world diversifies its energy sources and transitions to a less fossil-fuel intensive economy, tropical cyclones are likely to be up to 11% more intense on average according to the U.N Intergovernmental Panel on Climate Change. It means more wind and water damage on vulnerable coastlines.

Climate change may cause more extreme snowstorms. Extreme snowstorms in the eastern United States are twice as common as they were in the early 1900s according to the National Centers for Environmental Information. Warming ocean temperatures lead to an increase in the amount of water in the atmosphere. The continental United States was hit by storms.

The ocean is disrupting.

Beneath the waves are some of the most immediate impacts of global warming. The oceans absorb dissolved carbon dioxide. It isn't bad for the atmosphere, but it isn't great for the marine environment. Ocean acidification occurs when carbon dioxide reacts with seawater and the water becomes more acidic. Many ocean organisms depend on the calcium carbonate shells and skeletons for survival. According to the National Oceanographic and Atmospheric Administration, these creatures include shellfish, pteropods and corals.

Corals are the canary in the coal mine for climate change. Marine scientists have observed alarming levels of coral bleaching, events in which coral expels the symbiotic algae that provide the coral with nutrients and give them their vivid colors. When corals are stressed, they can be bleached. Australia's Great Barrier Reef experienced two back-to-back bleaching events. Coral can survive bleaching, but it's not as likely as it used to be.

Coral bleaching is one of the effects of global warming. The image is courtesy of Brett Monroe Garner.

Global warming facts are fast.

According to NASA.

The levels of carbon dioxide in the atmosphere are at their highest in 650,000 years.
Since 1880, the average global temperature has increased by 1.9 F.
Since 1979 the minimum expanse of summer sea ice has declined.
Land ice at the poles has declined over the last decade.
In the past century, the global sea level has risen 7 inches.

There are more resources on global warming.

Climate.gov contains up-to-date news and data on global warming. The "state of the climate" report is provided by the National Centers for Environmental Information. NASA's Global Climate Change page has answers to frequently asked questions about global warming.

The Intergovernmental Panel on Climate Change Sixth Assessment report provides a deep dive into the science, modeling and predictions surrounding global warming. The general public can find fact sheets and outreach materials on the website.

There is a bibliography.

Hayhoe. Saving Us is a climate scientist's case for hope and healing. Simon & Schuster. September 2021.

Mann, Michael. The fight to take back our planet is called The New Climate War. Public forums. January 2021.
The U.S. Environmental Protection Agency. "Climate change." January 14, 2022.