Earth Day: 9 Trends That Show the Harsh Reality of Climate Change
By Pam Wright and Jan Wesner Childs
https://weather.com/science/environment/news/2021-04-16-earth-day-climate-trends-data-global-warming
Decades of scientific data including satellite images show that human-caused climate change is real and affecting our planet at an alarming rate, according to multiple agencies and organizations including the United Nations, the National Academy of Sciences, NASA, NOAA and the American Meteorological Society.
While scientists say Earth has experienced cycles of warming and cooling over the ages, the significant warming trend we are now experiencing is nothing like those of the past. The difference, the experts say, is human activity.
From rising sea levels to retreating glaciers to coral bleaching, human-induced global warming is affecting every corner of our planet.
Ancient paleoclimate evidence collected from tree rings, ocean sediment, coral reefs and layers of sedimentary rocks indicates carbon dioxide from human activity is increasing more than 250 times faster than it did from natural sources after the last Ice Age, and current warming is occurring about 10 times faster, according to NASA.
Here are 9 climate trends that show that the planet is in trouble:
1. Seas Are Rising Faster
Global sea levels rose about 8 inches over the last 100 years, according to NASA.
That might not seem like much, but the rate of sea level rise over the past two decades is nearly double that of the entire previous century.
And that's just the beginning.
Scientists at NOAA predict that global sea level is very likely to rise at least 12 inches above 2000 levels by 2100, even on a low-emissions pathway.
Sea level rise is driven by the melting of glaciers and ice sheets, as well as water that expands as it warms.
And with higher sea levels comes more frequent flooding. NOAA estimates that high tide flooding not associated with a major weather event - also known as nuisance flooding - is from 300% to 900% more frequent in many U.S. coastal communities than it was just 50 years ago.
2. Temperatures are Rising
Thanks to an increase in carbon dioxide, along with other human-made emissions spewed into the atmosphere, Earth's average surface temperature has risen about 2 degrees Fahrenheit since the late 19th century, according to the National Oceanic and Atmospheric Administration (NOAA).
"Most of the warming occurred in the past 40 years, with the seven most recent years being the warmest," notes NASA. "The years 2016 and 2020 are tied for the warmest year on record."
The Intergovernmental Panel on Climate Change, which includes more than 1,300 scientists from the United States and around the world, predicts a temperature rise of 2.5 to 10 degrees Fahrenheit over the next 100 years.
3. Oceans Are Warming
Earth's oceans are a key indicator of global warming because they absorb more than 90% of the increased atmospheric heat associated with greenhouse gas emissions caused by human activity.
According to NASA, the top 328 feet of the oceans' surface has warmed 0.6 degrees Fahrenheit since 1969.
The impact of warming oceans is wide-ranging. From melting ice sheets to extreme weather, scientists say the impacts of warming oceans will be felt across the globe as the years roll on.
4. Ice Sheets Are Shrinking
Data from NASA's Gravity Recovery and Climate Experiment shows Greenland lost an average of about 280 billion tons of ice per year between 1993 and 2019, while Antarctica lost about 150 billion tons per year.
Between 25% and 30% of sea level riseis due to glacier ice melt, according to the World Glacier Monitoring Service.
5. More Frequent Extreme Weather Events
Last year was one of weather extremes, including record-breaking wildfires, hurricanes and heat waves. Experts say it wasn't an anomaly - extreme weather events are becoming more frequent and we're likely to see more deadly, destructive and intense years like 2020.
From 1900 to 1980, for example, a new temperature record was typically set every 13.5 years. Since 1981, a new record's been set every three years.
One outcome of global warming and rising sea surface temperatures is changing patterns of precipitation and storm events.
Much of the U.S. west is in extreme drought made worse by changing weather patterns that also help fuel wildfires.
Warmer water is a key ingredient for hurricanes, and recent research has linked climate change to storms that are more intense.
6. Humidity Is Increasing
According to NOAA, measurements taken from weather stations are showing increased humidity due to the amount of water vapor in the air. It's just one more trend that indicates Earth's atmosphere is changing.
7. Snow Cover Has Been Reduced
Satellite data shows that the amount of spring snow cover in the Northern Hemisphere has decreased over the past five decades and the snow is melting earlier, according to NASA.
In late January, the snow cover in the lower 48 states was less than it had been at that time of year in nearly two decades.
"It’s not that Mother Nature hasn’t tried to bring snow to these areas," winter weather expert Tom Niziol wrote in an article for weather.com. "The problem for snow lovers familiar with that beautiful white blanket is that even when it does snow, it won’t stick around for long because it’s been too warm."
While snowfall later in the year can change the overall averages, the long-term trend is clear.
Between 1955 and 2016, the depth of snow on the ground, or snowpack, in early spring in the western United States decreased by more than 90%, while the "average portion of North America covered by snow between 1972 and 2015 decreased at a rate of about 3,300 square miles per year," according to the IPCC.
By 2100, snow cover in the Northern Hemisphere is expected to decrease by about 15%, producing shorter snow seasons and a decreased snowpack in many regions. In northern latitudes, the permafrost is expected to continue to thaw.
8. Glaciers Are Retreating
Because glaciers are so sensitive to temperature fluctuations, scientists say glaciers provide irrefutable clues about the effects of global warming, according to the National Snow and Ice Data Center.
According to the EPA's climate change indicators, glaciers in the United States and around the world have generally shrunk since the 1960s. The rate at which glaciers are melting has accelerated over the last decade.
9. Oceans Are Becoming More Acidic
According to NOAA, the acidity of surface ocean waters has increased by about 30% since the beginning of the Industrial Revolution. Acidification occurs as human-produced carbon dioxide is absorbed by the oceans.
"Estimates of future carbon dioxide levels, based on business as usual emission scenarios, indicate that by the end of this century the surface waters of the ocean could be nearly 150% more acidic, resulting in a pH that the oceans haven’t experienced for more than 20 million years," NOAA notes.
Acidification of oceans imperils marine wildlife, particularly shellfish, which impacts the entire marine food chain, including humans. The reality of a world without seafood, particularly in areas that rely on the consumption of fish, is difficult to contemplate.
