The evidence for man-made climate change

Post date: Jun 2, 2017 6:30:22 PM

Source: Boden, T.A., Marland, G., and Andres, R.J. (2017). Global, Regional, and National Fossil-Fuel CO2Emissions. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tenn., U.S.A. doi 10.3334/CDIAC/00001_V2017.

2 - Recorded Observation: Unprecedented rate of sea level rise. From the site above: "Global sea level rose about 8 inches in the last century. The rate in the last two decades, however, is nearly double that of the last century

Sea Level change as measured by coastal tide gauge markers (left) and Satellite Data from NASA (right) both show a rising trend Source: https://climate.nasa.gov/vital-signs/sea-level/

And this National Geographic article goes on to explain "As seawater reaches farther inland, it can cause destructive erosion, wetland flooding, aquifer and agricultural soil contamination, and lost habitat for fish, birds, and plants."

"Most Americans live within 100 miles of a coast, which means many people are vulnearble to sea level rise and damaging coastal storms." The National Oceanic and Atmospheric Administration (part of US Dept of Commerce) put together a Sea Level Rise Viewer to help communities prepare for different scenarios of Sea Level Rise (the quote was the opening line of the video). If sea level rises, communities near the coast will be prone to flooding. We know that we currently live in an unprecedented rate of sea level rise that not only affects Americans, but all coastal communities around the world.

Use the Sea Level Rise Simulator by visiting https://coast.noaa.gov/digitalcoast/tools/slr and clicking "Launch"

A recent LA times article 1-20-17 writes, "Since 1901, levels have already climbed 8 inches, according to the Environmental Protection Agency, and are predicted to rise by 1 to 3 feet by the end of the century. Some 25 million people in the United States alone now live in areas threatened by coastal flooding."

This is a problem that affects not only our planet, but the PEOPLE who live here.

3 - Recorded Observation: Global temperature is on the rise Since the 19th century, the global temperature has increased about 2.0 degrees F (1.1 degrees Celsius). We have been measuring Earth's temperature since 1880. What we keep finding is that ever since we started recording, the CURRENT year (in 2015, 2016, etc.) is hotter than the one that preceded it. No one can dispute that we are on the upward trend - will it flatten out or continue to rise? If it continues to rise, what impact will that have on life on our planet? (likely bad - but how bad?)

History of Earth's surface temperature 1880-2016

Overview: (text taken from site linked below) The animation below shows annual temperatures each year since 1880 compared to the 20th century average, ending with record-warm 2016 video courtesy of this site: https://www.climate.gov/news-features/videos/history-earths-surface-temperature-1880-2016

Yet another way to present the same data (Courtesy of this site: https://www.climate.gov/news-features/videos/earths-temperature-history-roller-coaster)

5 - Recorded Observation: Warming Oceans "The oceans have absorbed much of this increased heat, with the top 700 meters (about 2,300 feet) of ocean showing warming of 0.302 degrees Fahrenheit since 1969" The ocean covers 3/4 of the earth's surface. Slight increases in water temperature can cause huge changes in the way life is distributed in the ocean.

Excerpt from video from the Economist below: "If the ocean surface temperature rises between two to three degrees Celsius then by early next century equatorial waters could become completely uninhabitable for most shallow water fish currently living there. Those that cannot leave will face local extinction. Whether evolution can keep up with climate change in the long run is unknown, but a mass undersea migration has already been happening for decades. (Species have been moving up to five times faster in the ocean than on land)..." If plankton moves away from the equator to the polar region, this will cause their normal predators to move there as well. As a result, entire food webs will be moving. Big changes have been happening beneath the waters and the changes will continue happening as water temperature continues to rise.

"What effects mass migrations will have upon complex ecosystems in the long term is unknown, but as the tropics experience large scale losses of species that are not replaced many [people] will lose the fish they depend on to survive."

This is a problem that affects not only our planet, but the PEOPLE who live here.

2/3 of the world's largest coral reef (called The Great Barrier Reef) has died in a period of 1.5 years and this is attributed to the warming ocean temperature (source: 3-minute radio article/summary from National Public Radio).

LA Times Article on Warming Oceans from 1-20-17: http://www.latimes.com/science/sciencenow/la-sci-sn-sea-surface-temperatures-20170119-story.html

6 - Recorded Observation: Shrinking ice sheets of land ice Data from NASA's GRACE satellites show that the land ice sheets in both Antarctica (upper chart) and Greenland (lower) have been losing mass since 2002. Both ice sheets have seen an acceleration of ice mass loss since 2009". (Source: GRACE satellite data and NASA)

Who cares about land ice? Well, when floating ice melts the net-water level does not rise, but when land ice melts the net-water level rises!

More melting land ice translates into sea level rise; and sea level rise translates into coastal people's losing their homes/becoming displaced, (see Point #2), which brings us back to the main message:

This is a problem that affects not only our planet, but the PEOPLE who live here.

7 - Recorded Observation: Arctic ice sheets are shrinking too Although Artic ice is floating (so it's melting does not cause sea level to rise), but the fact that it is melting at an increased rate is more evidence of global warming.

8 - Recorded Observation: Glaciers are retreating very similar point to #6 and #7

For dramatic Before-After pictures that show you the retreat of the glaciers, Greenland ice, Antartic ice, and Artic ice, visit: https://climate.nasa.gov/interactives/global-ice-viewer/#/

Here's an example of what you'll see (Mt. Kilimanjaro): Left side is 1993 and right side is 2000

1993 2000

9 - Recorded Observation: Increase in extreme weather events 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. The U.S. has also witnessed increasing numbers of intense rainfall events

10 - Recorded Observation: Oceans are becoming acidified at an unprecedented rate If Carbon dioxide concentration were increasing in the atmosphere, you would expect to see the oceans get more acidic. Carbon dioxide reacts with water to produce carbonic acid in an equilibrium reaction. More carbon dioxide in the atmosphere means greater carbonic acid concentrations, meaning the oceans get more acidic.

source: NOAA: https://www.pmel.noaa.gov/co2/story/Ocean+Acidification

Human beings are sensitive to pH. Blood is maintained at around pH 7.36 (known as "physiological pH). Falling below 7.35 leads to blood acidosis, while rising above 7.37 leads to blood alkalosis. We are sensitive to a 0.01 change in pH. This example is provided just to give you an idea of how important it is to maintain a certain level of pH.

A study from the NOAA found that man-induced carbon dioxide "(anthropogenic carbon dioxide) has caused a pH decrease of approximately 0.1, which is about a 26% increase in the hydrogen ion concentration over the past 100 years." 0.1 might seem like a small number, but it is 10 times larger than that 0.01 pH range we saw earlier, so it's nothing to ignore!

Graph of pH vs time in Mauna Loa, Hawaii from late 1989 to present

(source: NOAA https://www.pmel.noaa.gov/co2/file/Hawaii+Carbon+Dioxide+Time-Series)

Notice that as the concentration of CO2 (green) in Hawaii sea water goes UP, that the pH of the Hawaii seawater (blue line) goes DOWN (becomes more acidic). Also, the concentration of the CO2 in the air above Hawaii correlates nicely with the concentration of the CO2 in the seawater as well.

Other living organisms are sensitive to pH as well. It's known that increasing acidity slows down calcification (prevents marine organisms from growing their shells).

See a 2010 TED talk on the dangers of "Ocean Acidification" by Standard professor Rob Dunbar (start at 14:48 to get to "Ocean Acidification" part).

Excerpt of this talk: "You have to go back about 15 million years to find a time when CO2 levels were about where they are today. You have to get back 30 million years to find a time when CO2 levels are about double where they are today. And what that means is that all the organisms in the sea have evolved in this chemostatted (chemically unchanging) ocean with CO2 levels lower than they are today. That's the reason that they're not able to respond or adapt to this rapid acidification that's going on right now. That's why J.E.N. Vernon came out with this statement in September 2008: 'The prospect of ocean acidification is potentially the most serious of all predicted outcomes of an anthropogenic CO2 increase.' "

another video on the dangers from ocean acidification from Natural Geographic 2014: http://video.nationalgeographic.com/video/short-film-showcase/140623-oceans-warming-evt.

11 - Recorded Observation: Decreased snow cover

The NASA site writes, "Satellite observations reveal that the amount of spring snow cover in the Northern Hemisphere has decreased over the past five decades and that the snow is melting earlier.

NASA Earth Observatory has a nice video showing you the dataset: https://earthobservatory.nasa.gov/GlobalMaps/view.php?d1=MOD10C1_M_SNOW

More reading: http://nsidc.org/cryosphere/sotc/snow_extent.html

Conclusion

In considering these 11 observations, the best explanation is that because we have been putting an unprecedented amount of carbon dioxide into our atmosphere (we are a species that cannot live without fossil fuels for running our lives!) we have been changing our atmosphere in an unprecedented way. The increasing amount of carbon dioxide in the atmosphere is causing our planet to get warmer (because carbon dioxide acts as a insulating "greenhouse" gas), which in turn is causing global temperature to rise, which in turn speeds up the melting of land-based ice, which in turn will cause the sea level to rise, which in turn will have significant impacts on human society (probably bad). In addition, by increasing the amount of carbon dioxide in the atmosphere, we are causing our oceans to become more acidic, which in turn is changing the ecosystem in unprecedented (and likely harmful) ways. If fish and other sea creatures migrate away from certain regions, this will create regions of the ocean (likely near the equator that are "uninhabitable" for ocean life). Thus, a major source of food for people who live by the sea in these equatorial regions will be lost, contributing to famine, another human problem. Every scientific projection shows that things will get worse unless we significantly scale back on the amount of carbon dioxide we are pumping into our atmosphere. The Paris Climate Accords were a step in the right direction because at the end of the day, more than Americans, or Russians, or Chinese, or any other nationality, we are all global citizens who live together here on Earth. Combating global warming is a concrete way to care for our fellow man.